96-26838. Approval, Exhaust Gas Monitoring, and Safety Requirements for the Use of Diesel-Powered Equipment in Underground Coal Mines

[Federal Register Volume 61, Number 208 (Friday, October 25, 1996)]
[Rules and Regulations]
[Pages 55412-55534]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-26838]



[[Page 55411]]


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Part III





Department of Labor





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Mine Safety and Health Administration



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30 CFR Parts 7, et al.



Approval, Exhaust Gas Monitoring, and Safety Requirements for the Use 
of Diesel-Powered Equipment in Underground Coal Mines; Final Rule

Federal Register / Vol. 61, No. 208 / Friday, October 25, 1996 / 
Rules and Regulations

[[Page 55412]]



DEPARTMENT OF LABOR

Mine Safety and Health Administration

30 CFR Parts 7, 31, 32, 36, 70, and 75

RIN 1219-AA27


Approval, Exhaust Gas Monitoring, and Safety Requirements for the 
Use of Diesel-Powered Equipment in Underground Coal Mines

AGENCY: Mine Safety and Health Administration, Labor.

ACTION: Final rule.

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SUMMARY: This final rule establishes new requirements for the approval 
of diesel engines and other components used in underground coal mines; 
requirements for monitoring of gaseous diesel exhaust emissions by coal 
mine operators; and safety standards for the use of diesel-powered 
equipment in underground coal mines. The final rule is derived in part 
from existing MSHA regulations, and provides protection against 
explosion, fire, and other safety and health hazards related to the use 
of diesel-powered equipment in underground coal mines. The final rule 
also amends certain equipment safety standards in part 75 previously 
applicable only to electric-powered equipment to apply to diesel-
powered equipment. The new standards are consistent with advances in 
mining technology, address hazards not covered by existing standards, 
and impose minimal additional paperwork requirements.

EFFECTIVE DATES: This regulation is effective April 25, 1997, except 
for subparts E and F of part 7, the removal of part 31, the amendments 
to part 36, and Sec. 75.1907 which are effective November 25, 1996. 
Incorporations by reference were approved by the Director of the 
Federal Register as of April 25, 1997.

FOR FURTHER INFORMATION CONTACT: Patricia W. Silvey, Director, Office 
of Standards, Regulations, and Variances, Mine Safety and Health 
Administration, 4015 Wilson Boulevard, Arlington, VA 22203-1984. Ms. 
Silvey can be reached at [e-mail] (Internet E-mail), 703-235-
1910 (voice), or 703-235-5551 (facsimile).

SUPPLEMENTARY INFORMATION:

I. Background

    Coal mine operators began to introduce diesel-powered equipment 
into underground mines in the early 1970's. The number of diesel units 
operating in underground coal mines has increased from approximately 
150 in 1974 to over 2,900 units operating in 173 mines in 1995. MSHA 
projects that the number of diesel units operating in underground coal 
mines could increase to approximately 4,000 in 250 underground coal 
mines by the year 2000.
    Although diesel-powered equipment does not have the inherent 
electrocution hazard of electric-powered equipment, it nonetheless 
presents a number of safety and health risks. By introducing an 
internal combustion engine into an environment where explosive levels 
of methane can be present, diesel-powered equipment brings with it 
risks of fire or explosion. Diesel engines also have high temperature 
exhaust components which, in the presence of coal and other 
combustibles in the underground mine environment, present a fire 
hazard. The handling and storage of diesel fuel underground also 
present potentially serious fire hazards. Finally, diesel engines 
produce exhaust gases containing carbon monoxide, oxides of nitrogen, 
and particulate matter, presenting potentially serious health risks to 
miners.
    Before publication of this final rule, MSHA's regulations contained 
limited safety and health and machine approval requirements that 
specifically addressed the use of diesel-powered equipment in 
underground coal mines. In the 1980's, the increase of the numbers of 
this equipment in underground coal mines, coupled with the health and 
safety risks associated with its use, highlighted the need for a 
regulatory approach specifically tailored to diesel-powered equipment 
operated in underground coal mines.
    In response to this need, the Secretary of Labor convened a Federal 
advisory committee in 1987 to evaluate and make recommendations for the 
safe and healthful use of diesel-powered equipment in underground coal 
mines. The Diesel Advisory Committee addressed approval issues--
covering equipment design and performance; use issues--addressing the 
safe use of diesel equipment in the mine environment; and health 
issues--concerning the evaluation and control of health hazards 
associated with diesel equipment. In July 1988, the Committee issued a 
report of its recommendations entitled ``Report of the Mine Safety and 
Health Advisory Committee on Standards and Regulations for Diesel-
Powered Equipment in Underground Coal Mines''. In its report the 
Committee concluded that MSHA should develop regulations to govern the 
approval and use of diesel-powered equipment in underground coal mines, 
and identified a number of specific areas to be addressed.
    On October 4, 1989, the Mine Safety and Health Administration 
published a Notice of Proposed Rulemaking in the Federal Register [54 
FR 40950] that included criteria for the approval of diesel engines and 
other related equipment; addressed exposure limits, monitoring, and 
recordkeeping requirements for certain diesel emissions; and provided 
corresponding safety standards for the use of diesel-powered equipment 
in underground coal mines, including the safe storage and transport of 
diesel fuel, and the training of persons performing work on diesel 
equipment. On the same day, MSHA also published an Advance Notice of 
Proposed Rulemaking [54 FR 40996] soliciting comment on the approach 
and scope of an MSHA approval program for diesel machines. MSHA held 
four public hearings on the proposed rule: in Salt Lake City, Utah; 
Pittsburgh, Pennsylvania; Chicago, Illinois; and Birmingham, Alabama.
    This final rule, which includes specifications for the approval of 
diesel engines as well as provisions for the safe and healthful use of 
such equipment in underground coal mines, is derived from the data, 
information, and public comments compiled during the rulemaking 
process. The final rule, like the proposal, takes an integrated 
approach to the control of diesel safety and health hazards, requiring 
clean-burning engines on diesel-powered machines, maintained by persons 
who have been adequately trained for the task. Sufficient ventilating 
air is required where diesel-powered equipment is operated to control 
the potential health hazards of diesel exhaust. Sampling every shift 
confirms the effectiveness of the mine ventilation system in addressing 
these hazards.

Part 7 Equipment Approval

    MSHA regulations require the Agency's approval of the design of 
electrical equipment to be used in the production areas of underground 
coal mines. This equipment must be designed to eliminate fire and 
explosion hazards. MSHA's approval program has been very successful in 
reducing the number of fires, explosions and other hazards associated 
with electric-powered equipment. The final rule establishes a similar 
approach for diesel-powered equipment used in areas of underground coal 
mines where permissible (explosion-proof) electric equipment is 
required, ensuring the same level of safety in mines where diesel-
powered equipment is used.

[[Page 55413]]

    The permissibility requirements for diesel-powered equipment used 
in gassy non-coal mines in MSHA's part 36 regulations have been in 
place for a number of years. Although specific regulations did not 
exist for diesel-powered equipment operated in underground coal mines, 
MSHA has used the ventilation plan approval process to require the use 
of permissible diesel-powered equipment, approved under part 36, in 
those areas of underground coal mines where permissible electric 
equipment is required. However, mine ventilation plans have generally 
only addressed fire and explosion protection for equipment operating 
near the point of coal extraction (inby), and other locations where 
methane may be present, and have not addressed other possible safety 
hazards associated with the use of diesel-powered equipment in other 
(outby) areas. Additionally, mine ventilation plans have not dealt with 
such important concerns as the storage and handling of diesel fuel and 
regular maintenance of diesel equipment.
    The final rule requires that only approved engines be used in 
diesel-powered equipment in underground coal mines, and establishes 
approval requirements for diesel engines to be used in both permissible 
areas (inby) and nonpermissible areas (outby) under part 7, subpart E. 
The subpart E approval requirements are modeled after existing approval 
requirements in part 36 for engines used in gassy non-coal mines. 
Certain other safety features, such as flame arresters, spark 
arresters, and water scrubbers, must be added to the engines used in 
permissible areas to ensure that they can be operated safely in the 
coal mine environment. An engine in combination with these safety 
features is termed a diesel power package. A separate approval was 
established in the final rule for the power package because the power 
package manufacturer is normally a company other than the engine 
manufacturer and controls the assembly of the power package. In 
addition, approval requirements for power packages under part 7, 
subpart F, are incorporated into machines approved under existing part 
36. This is similar to the approach taken for electrical equipment 
where explosion-proof components are incorporated into machines 
approved under part 18.
    In order to protect miners from harmful contaminants emitted from 
diesel engines, the approval requirements in the final rule contain 
test procedures and limits on the concentrations of carbon monoxide and 
oxides of nitrogen. Based on commenters' recommendations, the final 
rule requires that the same test cycle be used for testing both the 
gaseous and particulate emissions. In response to commenters' 
recommendations, the final rule is based on ISO 8178, an international 
consensus standard, which establishes a common test cycle for the 
measurement of gaseous and particulate emissions. All equipment testing 
under part 7 is intended to be conducted at test sites other than MSHA 
facilities, such as manufacturers' laboratories, independent testing 
laboratories, or other government or university laboratories.

Part 70 Exhaust Gas Monitoring.

    The final rule addresses the monitoring and control of gaseous 
diesel exhaust emissions. The final rule requires area sampling as part 
of the onshift examination during every work shift. These monitoring 
provisions will ensure, in a reliable and systematic manner, that 
miners will be protected from exposure to harmful levels of gaseous 
contaminants.
    The final rule requires that mine operators take representative 
samples of carbon monoxide and nitrogen dioxide in strategic locations 
to determine concentrations of these contaminants in miners' 
workplaces. The sampling locations are based on knowledge of the 
specific operation of diesel equipment underground and the behavior of 
gaseous emissions generated by these machines. Samples exceeding an 
action level of 50 percent of the threshold limit values 
(TLV) for carbon monoxide and nitrogen dioxide trigger 
corrective action by the mine operator.

Part 75 Safety Requirements

    The final rule specifies minimum ventilating air quantities in 
areas where diesel equipment is operated, and requires that the 
quantities be incorporated into the mine operator's approved mine 
ventilation plan. As part of the equipment approval process in part 7 
of the final rule, diesel engines used underground are tested for 
gaseous and particulate emissions. The required minimum ventilating air 
quantity is determined based on the results of these emission tests and 
is included on the approval plate for each unit of diesel-powered 
equipment. The approval plate quantity of ventilating air is the air 
quantity needed to dilute the exhaust gases to their permissible 
exposure limits. This air quantity should be used in ventilation system 
design by the mine operator and in the evaluation and approval of 
minimum air quantities in ventilation plans by MSHA.
    Under the final rule individual units of diesel equipment must be 
ventilated, as a general rule, with the air quantity specified on the 
equipment's approval name plate. The quantity of air required in areas 
where multiple units of equipment are operated is based on a simple 
addition of approval plate air quantities. The final rule also allows 
for adjustments in air quantities for multiple units of equipment, if 
sampling of contaminants indicates that lesser air quantities will 
result in dilution to the necessary levels. In addition, the final rule 
establishes specific locations where air quantities must be measured.
    Under the final rule, low sulfur fuel must be used to operate 
diesel-powered equipment underground. Low sulfur fuel, which is readily 
available and widely used throughout the United States, will lower 
gaseous and particulate emissions, helping to protect miners from 
exposure to harmful diesel exhaust contaminants. In addition, the final 
rule prohibits the use of flammable liquids as additives in diesel fuel 
used underground and requires that only additives registered with the 
Environmental Protection Agency in accordance with 40 CFR Part 79 be 
used in diesel-powered equipment.
    The use of diesel fuel underground can present risks to miners' 
safety, because the spilling of fuel on hot surfaces or electric 
components, or the inadvertent ignition of stored diesel fuel, can 
result in fire. Additionally, a fire started with a combustible 
material other than diesel fuel that then spreads to diesel fuel stored 
underground could be catastrophic. Diesel fuel handling and storage are 
addressed in the final rule by specific requirements for diesel fuel 
storage and the transportation of fuel from one location to another.
    New design, installation, and maintenance requirements are 
established under the final rule for fire suppression systems installed 
on diesel-powered equipment and fuel transportation units. The 
requirements in the final rule address the risk of fire on diesel-
powered equipment caused by, for example, hot exhaust components, 
dragging brakes, and shorted electrical components igniting diesel 
fuel, hydraulic fluid, brake fluid, lube oil, and other combustible 
materials. The final rule also requires that automatic fire-suppression 
systems be listed or approved by a nationally recognized independent 
testing laboratory.
    The final rule recognizes that regular maintenance of diesel-
powered equipment is essential. Inadequate equipment maintenance can 
result in the creation of a fire or explosion

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hazard, and the levels of harmful gaseous and particulate components in 
diesel exhaust can rise when equipment is not adequately maintained. In 
response, the final rule requires diesel-powered equipment to be 
examined on the same weekly basis as electric equipment. The rule 
specifically requires that air filters be changed and scrubbers be 
flushed regularly, and that weekly gaseous emission tests be conducted 
on certain diesel equipment while the engine is operating. The final 
rule also requires that persons performing certain work on diesel-
powered equipment be qualified. Commenters agreed that requiring 
diesel-powered equipment to be maintained in approved condition is 
necessary to ensure that features installed to reduce the risk of fire, 
explosion, and harmful emissions are operating properly. The final rule 
does not adopt the proposal that MSHA approve the training plans used 
for qualification. Under the final rule, training to establish 
qualification for persons performing maintenance may be obtained 
through the equipment manufacturer, community colleges, training 
schools, or other training providers.
Amendments to Existing Part 75 Requirements
    The final rule amends certain existing MSHA regulations in part 75 
by extending their applicability to diesel-powered equipment. The final 
rule requires that certain types of diesel-powered equipment be 
equipped with methane monitors to detect dangerous levels of methane, 
and also with cabs or canopies to protect miners from roof falls. 
Additionally, the final rule clarifies that accumulation of coal dust 
and other combustible materials is prohibited on diesel-powered 
equipment. These safety features have been proven to save miners' 
lives.

II. Discussion of the Final Rule

A. General Discussion

Recordkeeping Requirements in the Final Rule
    Recordkeeping requirements in the final rule are found in 
Secs. 7.83 and 7.97, Application requirements; Secs. 7.90 and 7.105, 
Approval marking; Secs. 7.108, Power package checklist; Sec. 75.363, 
Hazardous condition; posting, correcting and recording; Sec. 75.371 
(r), (kk), (ll), (mm), (nn), (oo), and (pp), Mine ventilation plan, 
contents; Sec. 75.1901(a), Diesel fuel requirements; 
Sec. 75.1904(b)(4)(i), Underground diesel fuel tanks and safety cans; 
Sec. 75.1911(i) and (j), Fire suppression systems for diesel-powered 
equipment and fuel transportation units; Sec. 75.1912(h) and (i), Fire 
suppression systems for permanent underground diesel fuel storage 
facilities; Sec. 75.1914 (f)(1), (f)(2), (g)(5), (h)(1) and (h)(2), 
Maintenance of diesel-powered equipment; Sec. 75.1915(a), (b)(5), 
(c)(1), and (c)(2), Training and qualification of persons working on 
diesel-powered equipment.
    The paperwork burden imposed on manufacturers by the final rule 
totals 558, which is an increase of 790 burden hours for the transfer 
of hours from part 36 approval requirements, and a decrease of 232 
hours for the removal of parts 31 and 32. In the first year the final 
rule is in effect, the burden hours on mine operators will be 56,258, 
of which large and small mine operators will incur 54,774 and 1,484 
hours, respectively. After the first year, the burden hours to mine 
operators will be 52,228, of which large and small mine operators will 
incur 50,949 and 1,279 hours, respectively.
    In the first year that the final rule is in effect, the total new 
paperwork burden hours to mine operators and manufacturers will be 
56,816 [56,258 + (790-232)]. After the first year, the total new 
paperwork burden hours to mine operators and manufacturers will be 
52,786 [52,228 + (790-232)].
    MSHA solicited comments regarding the burden estimates or any other 
aspect of the collection of information in the proposed rule. Proposed 
paperwork requirements were submitted to the Office of Management and 
Budget (OMB) for review in accordance with section 3504(h) of the 
Paperwork Reduction Act of 1980 (PRA 80). Comments by OMB were filed 
under comment numbers 1219-0111, 1219-0112, and 1219-0114. Control 
number 1219-0100 was approved for proposed paperwork burden hours 
required by part 7.
    When proposed in 1989, the information collection requirements in 
the diesel equipment regulations were calculated under PRA 80. The 
final rule calculations are done in compliance with the Paperwork 
Reduction Act of 1995 (PRA 95). Generally, changes in the final rule 
burden hour and cost estimates from the proposed requirements result 
from the revision necessitated by PRA 95. When the change represents a 
regulatory change, it is so noted in the discussion of the appropriate 
section within the preamble. For details on the calculation of 
paperwork hours and costs see ``VII, Paperwork Reduction Act of 1995'' 
in the Regulatory Impact Analysis, which may be accessed electronically 
or may be requested from MSHA's Office of Standards, Regulations, and 
Variances.
    Information is to be recorded, maintained for the period specified, 
and made accessible, upon request, to authorized representatives of the 
Secretary and to miners' representatives. Records are to be stored in a 
manner that is secure and not susceptible to alteration, to preserve 
the integrity of records for review by interested parties. This may be 
done traditionally, by recording in a book, or electronically by 
computer.
    Examples of books that MSHA considers to be secure and not 
susceptible to alteration include, but are not limited to, record books 
that are currently approved by state mine safety agencies, and 
permanently bound books. Examples of books that would not be considered 
secure include loose-leaf binders and spiral notebooks.
    Recognizing the trend of electronic storage and retrieval of 
information through computers to be an increasingly common business 
practice, MSHA permits the use of electronically stored records, 
provided that they are secure and not susceptible to alteration, that 
they are able to capture the information and signatures required, and 
that information is accessible to authorized representatives of the 
Secretary and miners' representatives. ``Secure'' is intended to mean 
unalterable or unable to be modified. An example of acceptable storage 
would be a ``write once, read many'' drive. Electronic records meeting 
these criteria are practical and as reliable as traditional records. 
Although the final rule does not require backing up the data, some 
means is necessary to ensure that the condition and existence of 
electronically stored information is not compromised or lost.
    The 1995 Paperwork Reduction Act mandates agencies to encourage the 
use of electronic submission of responses to minimize the burden of the 
collection of information on respondents. Likewise, one of the major 
objectives of Executive Order No. 12866 is to make the regulatory 
process more accessible and open to the public as a means to reduce the 
duplication of information between agencies. Elsewhere in this 
preamble, MSHA announces the electronic availability of its rulemaking 
documents with access instructions. The mining community and other 
interested parties are encouraged to access on-line material as needed.

B. Section-by-Section Discussion

    The following section-by-section portion of the preamble discusses 
each provision affected. The text of the final

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rule is included at the end of the document.
General Discussion of Diesel Equipment Approvals and Safety 
Requirements
    One of the three major areas addressed by the Diesel Advisory 
Committee was the approval of diesel-powered equipment. Historically, 
MSHA and its predecessor agencies have approved equipment intended for 
use in areas of mines where methane and other substances pose the 
danger of a fire or explosion. Through the approval process, equipment 
is evaluated against technical requirements which, when met, will 
render the equipment safe for its intended use in the mine environment. 
In part as a result of this process, the approved equipment used in 
mines in the United States is recognized as among the safest in the 
world.
    The Advisory Committee recommended that diesel-powered equipment 
for use in underground mines be subject to MSHA approval in much the 
same way that electrical equipment has been regulated. Under existing 
standards, electrical equipment operated in the area of extraction and 
in return airways of underground coal mines and gassy metal and 
nonmetal mines, where methane may accumulate, must be approved as 
permissible (explosion-proof). Electrical equipment operated elsewhere 
in these mines is not required to be permissible, but is subject to 
certain safety requirements to protect against fire, shock, and other 
hazards of operation. The Advisory Committee further recommended:
     Only diesel-powered equipment currently considered 
permissible should be permitted to continue to operate in areas of coal 
mines where permissible electrical equipment is required.
     Separate specifications should be developed for diesel-
powered equipment used in areas where permissible equipment is required 
and elsewhere.
     An approval program for diesel-powered equipment and 
portable, attended equipment should be established. This program should 
identify those equipment design features most readily addressed by the 
equipment manufacturers.
     A time schedule should be developed to allow for 
conversion of outby equipment presently in use through retrofits, 
replacement, or additional interim safety features to meet the 
applicable new requirements.
     Equipment newly introduced underground after a fixed date 
should meet the new standards.
     Current safety requirements including those that are 
applicable to electric equipment should apply to diesel equipment as 
appropriate.
     Only approved diesel engines should be used in underground 
equipment and the approval requirements should include measurements of 
exhaust gas pollutants and determination of a nameplate airflow 
quantity. Measurement of particulate generation should also be included 
in the engine approval process.
    In the proposed rule, MSHA outlined three new subparts for existing 
part 7, which set approval requirements for diesel engines and power 
packages to be used in underground coal mines. The Agency also gave 
notice of its intention to develop approval requirements for fully 
assembled diesel-powered machines under a proposed subpart H for 
permissible equipment and subpart I for large outby equipment. 
Requirements for a limited class of light-duty equipment and stationary 
unattended equipment were proposed in part 75. A special class of 
equipment consisting of ambulances and fire fighting equipment was 
proposed that could be used in emergency situations as part of the 
mine's evacuation plan. The proposal also included provisions to permit 
fire prevention features in lieu of surface temperature controls for 
diesel locomotives.
    Currently, MSHA approves diesel equipment under 30 CFR Part 36 for 
use in ``gassy noncoal mines''. In underground coal mines, ventilation 
plans specify the use of diesel-powered equipment approved as 
permissible under part 36 in areas where permissible electric equipment 
is required. In addition to the equipment approval under part 36, MSHA 
regulations address the approval of diesel mine locomotives in 30 CFR 
Part 31, and of mobile diesel-powered equipment for noncoal mines in 30 
CFR Part 32. The proposal suggested that parts 31, 32, and 36 could be 
revised or revoked, and solicited comment. Some commenters favored 
retaining all of the existing diesel approval regulations since they 
still could have some application for equipment used in metal and 
nonmetal mines. Commenters generally agreed that the proposed rules for 
part 7 should supersede any applicability these existing approval 
regulations have for diesel engines used in underground coal mines.
    The final rule for part 7 governs the approval of diesel engines 
intended for use in underground coal mines. As recommended by the 
Advisory Committee and as set forth in the proposed rule, the final 
rule requires that all diesel engines used in underground coal mines be 
approved.
    Part 7 was originally promulgated in 1988 to establish application 
procedures and requirements for MSHA approval of certain products for 
use in underground mines, with testing conducted by the applicant or a 
third party. Traditionally, MSHA's role in approving products for 
safety emphasized testing by the Agency. Under part 7, testing is 
performed by the applicant or by a third party selected by the 
applicant, with MSHA maintaining the right to observe product testing. 
This approach has permitted MSHA to focus on its product audit function 
and keep pace with technological improvements in mining products.
    As originally promulgated, part 7 applied to only two types of 
products: brattice cloth and ventilation tubing under subpart B, and 
battery assemblies under subpart C. Subsequently, three additional 
subparts were developed covering multiple-shot blasting units; electric 
motor assemblies; and electric cables, signaling cables, and cable 
splice kits. As designed, part 7 expedites the approval process, while 
providing greater assurance that the products are manufactured in 
accordance with safety specifications.
    The final rule for part 7 is organized into two subparts--E and F. 
Subpart E sets diesel engine performance and exhaust emission 
requirements. As more fully discussed elsewhere in the preamble, 
subpart E creates two classes of engine approvals--one for Category A 
engines and one for Category B engines. Engines intended for use where 
permissible electric equipment is required in underground coal mines 
must have a Category A approval; engines for use elsewhere in 
underground coal mines must meet the requirements for Category B 
engines.
    Subpart F of the final rule sets standards for safe design of 
diesel engines with respect to both fire and explosion hazards. The 
final rule establishes requirements for approval of diesel ``power 
packages'' on engines intended to be used where electric equipment is 
required to be permissible under existing standards. The term ``power 
packages'' refers to an approved engine and those components added to 
the engine, such as flame arresters, which prevent the ignition of 
methane, and surface temperature controls, which prevent the ignition 
of accumulations of combustible materials and combustible liquids. 
Permissible equipment is designed to be explosion-proof.
    Subpart G of the proposed rule would have established requirements 
for diesel

[[Page 55416]]

power packages intended for use in areas of underground coal mines 
where permissible electrical equipment is not required. As this 
equipment is not designed to be operated in a potentially explosive 
methane environment, the proposed rule would not have required these 
power packages to have explosion-proof features. However, these diesel 
engines do present fire hazards which must be controlled. Under the 
proposal, subpart G would have set standards for surface temperatures, 
exhaust cooling, and safety system controls. As discussed more fully 
below, the final rule does not retain subpart G, but addresses these 
hazards through new requirements in part 75.
    The proposed rule, responding to a recommendation of the Advisory 
Committee, also established a category of ``limited class of light-duty 
diesel-powered equipment.'' This category included machines with light-
duty cycles, such as pickup trucks and personnel carriers. This 
equipment, while light-duty as compared to production equipment, can, 
nevertheless, present a fire hazard. For this ``limited class'' of 
diesel-powered equipment, instead of requiring surface temperature 
controls, the proposal set standards for fire prevention features that 
would prevent fuel, hydraulic fluid, and lubricants from coming into 
contact with hot engine surfaces. Features such as special fuel system 
protection, fire suppression systems, safe electrical systems, and 
engine compartment sensors that shut down the engine in the event of 
overheating were specified in the proposal for additional fire 
protection. Other necessary safety features, such as braking systems, 
were also addressed by the proposal. As recommended by the Advisory 
Committee, these requirements were not made part of the approval 
process described above, but were set forth in the proposal as safety 
standards for underground coal mines, appearing in 30 CFR Part 75.
    The final rule retains many of the provisions of the ``limited 
class'' concept in the proposal, but broadens the scope of the 
equipment subject to these requirements to include all equipment not 
required to be permissible (outby equipment). This change eliminates 
the need for formal approval of outby equipment, and simplifies the 
final rule. This aspect of the final rule, and the diesel-powered 
equipment approval requirements, are discussed in detail under the 
section-by-section analysis which follows.
    In the proposed rule MSHA notified the public of its intentions to 
develop two new approval regulations. Subpart H would have established 
requirements for the approval of fully assembled permissible diesel-
powered equipment, and subpart I would have established approval 
requirements for fully assembled nonpermissible diesel-powered 
equipment. These sections would have included machine features 
currently required by part 36 for permissible equipment and similar 
features, described above, for ``limited class'' equipment. These 
subparts would have required the incorporation of appropriate power 
packages as described in proposed subparts F and G.
    In the advance notice of proposed rulemaking, which accompanied the 
proposed rule, MSHA requested comments on this regulatory approach. 
Commenters objected to a formal approval program for nonpermissible 
equipment, but supported the incorporation of machine safety features 
in the use requirements specified in part 75. Commenters also supported 
the need for continuing the approval program for permissible equipment.
    In response to these comments, the final rule retains part 36 as 
the basis for the approval program for permissible diesel-powered 
equipment and adopts the machine safety features specified for the 
limited class of light-duty equipment in the proposal for all 
nonpermissible equipment. Subparts H and I are not further developed. 
Instead, the final rule adopts the fire prevention features specified 
for limited class equipment for all nonpermissible equipment. 
Additionally, the final rule enhances the fire prevention features that 
now apply to all nonpermissible equipment. This approach eliminates the 
need for subpart G of the proposal dealing with power packages for 
outby equipment.
    The final rule makes certain revisions to part 36 to update and 
make these existing requirements more flexible. The final rule revises 
part 36 to remove references to ``gassy noncoal mines and tunnels'', 
thus making these existing regulations applicable to equipment intended 
for use in coal as well as in metal and nonmetal mines. In addition, 
part 36 is amended to afford equipment manufacturers the option of 
incorporating in equipment submitted for approval either a part 7, 
subpart F power package, or engine and safety component systems that 
meet the existing requirements of part 36. Under the final rule, part 
36-approved equipment with a part 7, subpart F power package will be 
suitable for use in underground coal mines where permissible electrical 
equipment is required. Part 36 equipment with engine and safety 
component systems certified under part 36 will continue to be 
recognized for use in metal and nonmetal mines where permissible 
equipment is required.
    These changes are responsive to commenters who recommended that 
part 36 continue to be utilized for approving diesel-powered equipment. 
The final rule revisions to part 36 also retain, as recommended by 
commenters, a distinction between approval requirements for equipment 
used in coal mines and approval requirements for metal and nonmetal 
mining equipment.
    The final rule revokes parts 31 and 32. MSHA previously identified 
these regulations for elimination in its response to the President's 
March 4, 1995, Regulatory Reform Initiative. Parts 31 and 32 are 
outdated and, with the final rule changes to parts 7 and 36, are 
obsolete. Only nine approvals have been issued under part 31 since its 
inception, and none have been issued since 1977. No other MSHA 
standards require part 31-approved equipment, and diesel mine 
locomotive manufacturers have submitted approval applications under 
part 36 for locomotives intended to be used where permissible equipment 
is required. With the revocation of part 31, diesel mine locomotive 
manufacturers may continue to acquire equipment approvals under part 
36.
    The part 32 approval requirements for mobile diesel-powered 
equipment used in noncoal mines are likewise unnecessary. No MSHA 
regulation requires the use of part 32 equipment, and no part 32 
machine approval has been issued since 1981. Part 32 engine 
certifications have continued to be issued by MSHA, however, and some 
state and federal agencies' regulations make reference to part 32. 
State and federal agencies that reference part 32 are directed to look 
to part 7, subpart E, which contains engine requirements, and to 
Secs. 75.1909 and 75.1910, which contain the requirements for other 
machine features. Together, these final standards cover the 
requirements previously found under part 32. These new sections of the 
final rule will continue to accommodate those government agencies that 
reference MSHA approval or certification regulations.
    Likewise, manufacturers seeking part 32 engine approvals will be 
able to acquire the requisite engine approval through the new part 7, 
subpart E. Existing part 32 engine approvals continue to be valid.
    A significant issue for the Advisory Committee and in the proposal 
was the schedule set for compliance with the new standards for diesel-
powered equipment. The Advisory Committee

[[Page 55417]]

recommended that MSHA require diesel equipment newly introduced 
underground to meet the new standards after a certain date. The 
Committee further recommended that MSHA set a schedule for existing 
diesel equipment to meet any new requirements.
    The proposal called for the part 7 approval requirements to be 
effective 60 days after publication of the final rule. The schedule for 
requiring in-mine use of diesel equipment meeting the new requirements 
was set by proposed Sec. 75.1907. Under these provisions, the new 
requirements would have been met over a schedule ranging from six 
months to five years after the effective date of the final rule.
    The final rule follows the approach of the proposal, setting 
effective dates for the new approval requirements, as well as the 
schedule for requiring in-mine use of diesel-powered equipment which 
meets the new requirements. In response to the comments and as a result 
of not adopting proposed subparts G, H, and I, the final rule sets a 
compliance schedule ranging from 60 days to three years after 
publication of the final rule. In order to facilitate implementation of 
the final rule, MSHA will begin accepting approval applications under 
revised parts 7 and 36 immediately. In addition, MSHA will continue 
power package testing until the Agency determines that a competitive 
capacity exists in the private sector. At that time, MSHA will 
discontinue power package testing and rely solely on the part 7 testing 
provisions.
Subpart E Overview
    Subpart E of the final rule is new and amends existing part 7. As 
an amendment to these existing regulations, the general administrative 
provisions of subpart A of part 7 apply to the new subpart E 
application requirements.
    Subpart E establishes engine performance and exhaust emission 
requirements for MSHA approval of diesel engines for use in underground 
coal mines. As discussed elsewhere in this preamble, diesel engines for 
use in metal and nonmetal mines are approved under part 36.
    The final rule, like the proposal, creates two classes of engine 
approvals--Category A and B--for diesel engines to be used in 
underground coal mines. Several commenters objected to the proposed 
approval of diesel engines for use in outby areas, noting that outby 
electrical equipment is not subject to approval under existing 
standards. However, other commenters stated, and the Diesel Advisory 
Committee acknowledged, that all diesel engines in underground coal 
mines should meet certain safety and performance specifications. In its 
report the Advisory Committee suggested that, depending on equipment 
location and use, different requirements would be appropriate for 
diesel engines. One commenter to the proposal recommended that all 
diesel engines be approved as permissible.
    For underground coal mines, MSHA believes that clean-burning 
engines are critically important. Unlike electrical equipment, diesel 
engines emit exhaust which contains toxic gases that can be harmful to 
miners. Inappropriately designed engines can pollute the mine 
atmosphere excessively, elevating toxic gases to levels that cannot be 
controlled with normal ventilation practices.
    To achieve the objective of clean-burning, appropriately designed 
engines in mines, the final rule sets performance standards for all 
diesel engines, whether they are operated in the face area or outby.
    The emission test requirements for Category A and B engines are the 
same, except that Category A engines are tested with methane injected 
into the intake system. Equipment operating at or near the point of 
coal extraction and in return air courses may encounter concentrations 
of methane gas, which is liberated during mining. Testing an engine 
with methane injected in its intake simulates operation of the engine 
in these areas of coal mines. Operation in methane atmospheres causes 
an increase in exhaust emissions, which requires higher ventilation 
rates.
    Under the final rule, diesel equipment used in areas where 
permissible electrical equipment is required by existing standards 
incorporate fire and explosion prevention features provided by a power 
package. Such a power package must include a Category A engine and 
components added to the engine to prevent the ignition of methane and 
accumulations of combustibles. Power packages intended for use with 
Category A diesel engines must be approved under part 7, subpart F of 
the final rule.
    Current safety standards require that intake air courses in areas 
away from or outby the mining face be maintained free of explosive 
concentrations of methane. Engines used on equipment operated in these 
outby areas must have a Category B approval under the final rule. 
Engines approved under Category B are emission tested without the 
injection of methane into the engine's intake system.
    The proposed technical requirements for diesel engines addressed 
the control of gaseous exhaust emissions and quantification of the 
engines' particulate matter generation. The proposed rule also set 
specifications for the equipment used and the standard laboratory test 
conditions for determining gaseous and particulate output for diesel 
engines. The proposed requirements for measuring gaseous emissions were 
derived from now-removed part 32 and existing part 36, and the proposed 
requirements for measuring diesel particulate were based on the 
Environmental Protection Agency's requirements published in 40 CFR Part 
86. In addition, the proposal specified the engine operating parameters 
as well as a method to calculate the ventilation rate and particulate 
index for the engine.
    Engine manufacturers do not manufacture engines specifically for 
mining. Typically, ``off-road'', heavy-duty diesel engines are utilized 
in mining equipment. Over-the-road utility vehicles and smaller general 
industry equipment are also used in mines. At the time of the proposed 
rule, the only certification test specifications designed for engines 
used in mining were the MSHA engine certification standards in now-
removed part 32 and in existing part 36.
    In the proposal, MSHA used its rules in now-removed part 32 and 
existing part 36 for the steady-state test for gaseous diesel exhaust 
emission. The test equipment specified in the proposal for diesel 
exhaust particulate measurement was modeled after the transient test 
equipment required in 40 CFR Part 86, subpart N.
    Commenters to the proposal stated that a correlation should not be 
made between MSHA's proposed rule and then-current EPA testing, because 
the proposal used a test with specific points in a ``steady state'', 
while EPA used a ``transient test.'' Commenters also recommended using 
the same test cycle for both gaseous and particulate matter. In 
addition, commenters generally recommended comparability of testing for 
similar types of tests and indicated a desire to use international 
standards whenever possible.
    The International Organization for Standardization (ISO) has 
prepared ``ISO 8178 Reciprocating Internal Combustion Engines--Exhaust 
Emission Measurement'', which includes test specifications for off-road 
diesel engines. The ISO is a recognized international standard-setting 
body. Equipment manufacturers, as well as other standard-setting 
bodies, make reference to and adopt the standards developed by the ISO.

[[Page 55418]]

    ISO 8178 is an international test standard for measuring off-road 
diesel engine emissions. It contains a detailed description of the test 
equipment requirements and standard procedures for conducting a steady-
state test to determine both gaseous and particulate emissions. The ISO 
8178 procedures also specify an 8-point test cycle for measuring both 
gaseous and particulate emissions. ISO 8178 does not set emission 
limits.
    The final rule is based on the ISO 8178 ``Reciprocating Combustion 
Engines--Exhaust Emission Measurement'', part 1 test procedures that 
apply to gaseous and particulate emission testing for diesel engines. 
This change from the proposal is responsive to commenters' concerns 
about correlating the proposed rule and EPA diesel engine tests, and 
simplifies the test procedures. For example, under the final rule the 
gaseous emission tests are reduced to 8 test points from 39 test points 
under the proposal. The particulate emission tests are also reduced 
from 10 to 8 test points. In addition, the final rule permits the tests 
for exhaust gaseous and particulate emission tests to be performed 
concurrently following the same test cycle, rather than independently 
following different cycles. A number of minor changes are made in 
Secs. 7.86, 7.87, 7.88, and 7.89 of the final rule, so that the tests 
performed under these sections conform to the ISO 8178 requirements. 
Substantive changes to these sections are discussed in this overview 
and in the section-by-section discussion that follows.
    The final rule adds one requirement to the ISO 8178 test 
procedures. Section 7.89(a)(5)(iii) requires that 1.0 percent of 
methane be added to the intake air for testing Category A engines. This 
addition to the ISO 8178 procedure should present no technical 
difficulties for manufacturers or third-party laboratories. MSHA, 
however, will provide technical assistance for setting up this aspect 
of the test procedure upon request. The final rule also requires a test 
to determine the maximum fuel-to-air ratio, and specifies requirements 
for determining the gaseous ventilation rate and particulate index for 
diesel engines.
    Basing the final rule on an international consensus standard 
enables diesel engine manufacturers to test with a single set of 
procedures common to both the United States and foreign markets. Also, 
existing test facilities established to perform tests to these 
international standards can be used to perform the tests prescribed by 
this final rule. In addition, use of the ISO 8178 test procedures leads 
to better comparability with international testing practices, and 
provides a more competitive posture for American products in foreign 
markets. Many off-road engine manufacturers are already complying with 
EPA and California Air Resources Board (CARB) requirements, which 
include testing in accordance with ISO 8178 procedures.
    One commenter to the proposal objected to permitting engine 
manufacturers or third-party laboratories to test diesel engines for 
conformance to approval standards, questioning the objectivity of such 
an approach. MSHA experience over eight years with manufacturers and 
third- party laboratory testing under existing part 7 and the Agency's 
program for off-site testing (POST) of diesel engines confirms that 
non-MSHA testing is performed competently and produces reliable 
results. In addition, MSHA will initially witness all tests conducted 
by manufacturers and third parties to ensure continued reliability of 
test results. In all cases, MSHA will accept only results of tests 
performed by manufacturers or third-party laboratories which have the 
capability to competently perform the required tests with properly 
calibrated instrumentation.
    Section 7.81  Purpose and effective date. The part 7, subpart E 
approval requirements are effective November 25, 1996. MSHA will begin 
accepting applications under subpart E immediately, but will complete 
any in-house part 32 applications, or evaluate such applications under 
the new part 7, subpart E, at the applicant's choice. As discussed 
elsewhere in this preamble, the requirements for the use of approved 
diesel engines in underground coal mines are effective in 3 years.
    Commenters to the proposal generally supported the approval 
requirements of subpart E for diesel-powered equipment to be used in 
underground coal mines. Several commenters suggested, however, that a 
phase-in period, up to three years, be established. According to these 
commenters, manufacturers would use the phase-in period to gain 
experience with the new test procedures, become familiar with new 
engine approval application procedures, and re-evaluate their existing 
approvals.
    The final rule does not incorporate a phase-in period for diesel 
engine approvals. Diesel engine manufacturers and third-party testing 
facilities are familiar with the ISO 8178 test procedures on which the 
final rule is based, and have the capability to perform these tests in 
their laboratories with minor changes. In fact, two engine 
manufacturers and a testing laboratory have tested diesel engines for 
MSHA approval using the ISO 8178 procedure.
    With this diesel engine testing experience and capability already 
present in the marketplace, MSHA finds no reason to provide an extended 
phase-in period for the approval standards for diesel-powered 
equipment, and anticipates that manufacturers and third-party testing 
laboratories can immediately begin testing engines under subpart E.
    Section 7.82  Definitions. In addition to the existing definitions 
in Sec. 7.2, Sec. 7.82 of the final rule sets out and clarifies the key 
terms which apply in subpart E. Commenters generally agreed with the 
proposed definitions, which were derived from definitions developed for 
ISO 8178 and the Society of Automotive Engineers (SAE) Recommended 
Practice J177.
    No comments were received on the proposed definitions for 
``Category A engines'', ``Category B engines'', ``corrosion-resistant 
material'', ``diesel engine'', ``exhaust emission'', ``percent load'', 
and ``steady-state condition''. These terms and their proposed 
definitions are adopted in the final rule.
    The definitions of the terms ``rated speed'' and ``intermediate 
speed'' in the proposed rule have been modified in the final rule in 
response to a commenter who recommended that MSHA's definitions of 
these terms conform to definitions contained in internationally 
accepted standards. The definitions of these terms in the final rule 
are conformed to the definitions in ISO 8178.
    The term ``peak torque speed'' in the proposed rule has been 
changed to ``maximum torque speed'' in the final rule to conform with 
ISO 8178. Both terms convey the same meaning.
    One commenter objected to the definition of ``diesel particulate 
matter'' as ``any material, with the exception of water, which is 
collected on a filter passed by an air diluted exhaust stream.'' 
According to this commenter the proposed definition was vague and too 
dependent on the filter used and method of sampling. The final rule 
does not include the proposed definition, adopting instead the 
definition for diesel particulates contained in ISO 8178. The ISO 
definition is more specific, providing that diesel particulates are 
``any material collected on a specified filter media after diluting 
diesel exhaust gases with clean filtered air at a temperature less than 
or equal to 325 K (52 deg. C) as measured at a point immediately 
upstream of the primary filter. This is primarily carbon, condensed 
hydrocarbons, and sulphates

[[Page 55419]]

and associated water.'' In addition, the filter and sampling methods, 
which are well detailed in ISO 8178, are included in the final rule. 
The objective of this definition is to facilitate accurate, repeatable 
tests for the diesel particulate matter in an engine's exhaust. Other 
definitions may be more appropriate for addressing health effects.
    The same commenter also objected to the proposed definition of 
``total oxides of nitrogen'' as focusing only on nitric oxide and 
nitrogen dioxide. The commenter suggested revisions to these 
definitions and offered definitions for several other terms used in the 
proposed rule, including ``gaseous ventilation'', ``particulate 
index'', ``threshold limit value'', ``permissible exposure limit'' and 
``recommended exposure limit.'' According to the commenter, these terms 
were not used consistently in the proposal. The final rule does not 
adopt these suggested changes. Many of these terms have accepted 
meanings that are well known. However, changes throughout the final 
rule have been made to be sure the terms are used consistently and 
appropriately.
    The proposed definition of rated horsepower is revised in the final 
rule to conform with current procedures for evaluating engines under 
existing part 36. This change will help define an engine's power output 
as it is related to performance testing. A definition for the term 
``operational range'' is added to also conform with current procedures 
for evaluating engines under existing part 36.
    Section 7.83  Application requirements. The proposed application 
requirements were derived from now-removed part 32 and existing part 36 
and are largely unchanged in the final rule. The application procedures 
are designed to provide sufficient information to demonstrate 
compliance with the technical requirements of subpart E, and form the 
basis for approval of diesel engines.
    The final rule adopts the proposal to permit applicants to submit 
composite drawings in lieu of individual drawings. This approach 
reduces paperwork and affords applicants flexibility in the preparation 
of their drawings.
    The final rule also provides for certain information to be 
submitted after approval testing. This information includes the 
ventilation rate and particulate index for the engine, and the fuel 
deration chart, which provides guidance for how to adjust approved 
engines to compensate for altitude.
    Like existing part 7 and other MSHA approval standards, the 
documentation formulated in the application process forms the basis for 
MSHA's approval. Approved diesel engines must be manufactured in 
accordance with the specifications contained in the approval and, once 
put into service, approved engines must be maintained and operated 
within the parameters set in the MSHA approval.
    In general, commenters concurred with the proposed application 
requirements. One commenter suggested that a description of the design 
features which promote efficiency and control over production of toxic 
emissions specifically include fuel injection timing. MSHA agrees that 
specifications for the fuel injection system of diesel engines and the 
fuel injection timing are key in controlling exhaust emissions. The 
proposal included a requirement that the fuel injection system be 
detailed in approval applications. However, a requirement specifying 
the fuel injection timing was not included in the proposed rule.
    The final rule adopts the proposed requirement for a description of 
the fuel injection system, and adopts in paragraph (b)(6) the 
suggestion that fuel injection timing also be specified. This 
information had been required in now-removed part 32 and is required 
for part 36 engine approvals and to help ensure accurate measurement of 
the engine's emissions during the tests and proper maintenance of the 
engine's fuel injection timing.
    Although the Agency allows electronic record storage in other areas 
of this regulation, electronic computer submission of part 7 approval 
applications is not yet available. MSHA's Approval and Certification 
Center is developing a means for computer submission, and at present 
has pilot programs to facilitate the use of electronic reporting. 
However, the system is in the formative stage and is not yet available 
for public use.
    The paperwork hours in the approval application, including test 
requirements, are assigned OMB control number 1219-0100.
    Section 7.84 Technical requirements. This section of the final rule 
sets the specific technical requirements for Category A and Category B 
diesel engines. The objective of this aspect of the final rule is to 
set standards which, when met, will produce clean-burning diesel 
engines that are safe and appropriate for use in the confined 
environment of underground coal mines.
    Like the proposal, the final rule's requirements for the gaseous 
emissions of diesel engines are based on appropriate sections of 
existing part 36 approval regulations for diesel engines. Experience 
confirms that compliance with these regulations, which address fuel 
injection adjustments and fuel-to-air ratios, produces engines that 
operate without excessive gaseous emissions that can be harmful to 
miners.
    One commenter to the proposal suggested that the fuel injection 
system on approved diesel engines be required to be fixed and sealed so 
that it could not be changed. According to the commenter, sealing the 
system would prevent unauthorized changes.
    The final rule does not adopt this suggested change, as adjustments 
to diesel engine fuel injection systems are necessary for maintenance 
and to compensate for altitude. Adjustments such as these permit the 
fuel-to-air ratio for diesel engines to be maintained at a level which 
minimizes exhaust emissions.
    The final rule does, however, adopt the proposed security 
requirements to prevent unauthorized fuel injection system adjustments. 
Fuel injection system adjustments are required to be changeable only 
after breaking a seal, or by altering the injection system's design. 
For example, a shim may be added or removed to change the fuel pump's 
performance. These parts are supplied by engine manufacturers and must 
be used in accordance with the engine's approval. For engines with 
electronic fuel injectors, specialized computer interface equipment is 
used to adjust the computer programming sequence. The programming 
sequence must be installed by the engine manufacturer and is listed 
with the engine approval documentation. After adjustments are made in a 
fuel injection system, any seal removed must be replaced. Failure to 
follow these procedures for adjusting a fuel injection system would 
result in the engine no longer being in approved condition. Under 
Sec. 75.1914(a) of the final rule, diesel engines used in underground 
coal mines are required to be maintained in approved condition.
    Consistent with a recommendation of the Diesel Advisory Committee, 
the technical requirements for diesel engines also include undiluted 
exhaust limits for carbon monoxide and oxides of nitrogen, both of 
which have toxic properties which can be harmful to miners. The limits 
set for these gases, which are determined when the engine is operated 
at its maximum fuel-to-air ratio, are derived from existing 
Sec. 36.26(b) and now-removed Sec. 32.4(f). As noted in the proposal, 
applying these exhaust gas limits to diesel engines for use in outby 
areas is new.
    One commenter questioned why the proposal set the same undiluted 
exhaust gas limits for Category A and B engines, except that the carbon 
monoxide limit

[[Page 55420]]

was 0.30 percent for Category A engines, while the carbon monoxide 
limit for Category B engines was set at 0.25 percent. This aspect of 
the proposal, which is adopted without change in the final rule, 
recognizes a difference in the test procedure between Category A and B 
engines. As noted above, Category A engines must be designed to operate 
safely in face areas and return air courses where methane may be 
present. Thus, Category A engine testing is performed with 1.0 percent 
methane injected into the intake air. The methane acts as additional 
fuel in the engine, which affects the fuel-to-air ratio. This change in 
fuel-to-air ratio increases emission levels, especially carbon monoxide 
and oxides of nitrogen. Thus, the final rule technical requirements 
permit a slightly elevated carbon monoxide level for Category A engines 
during testing so as to avoid imposing an unnecessarily strict test 
requirement for this class of diesel engines. The ventilating air 
requirement, however, is based on the actual emissions measured during 
testing.
    The final rule also defines procedures to establish the ventilating 
air quantities necessary to maintain the gaseous emissions of diesel 
engines within existing required ambient limits. Emissions from both 
Category A and Category B engines are diluted to the same ambient 
levels when their ventilating air requirements are calculated. Like the 
proposal and consistent with the recommendations of the Diesel Advisory 
Committee, the final rule addresses this issue by requiring that a 
ventilation rate be set for each engine model. Under the final rule, 
this ventilation rate must appear on the engine's approval plate. The 
ventilation rate, calculated under Sec. 7.88 of the final rule, 
indicates the amount of air necessary to dilute carbon dioxide, carbon 
monoxide, nitric oxide, and nitrogen dioxide to within allowable 
levels. For consistency, the levels specified in the final rule are 
those set by existing Sec. 75.322. These exposure standards are based 
on the 1972 threshold limit values set by the American Conference of 
Governmental Industrial Hygienists (ACGIH) and have applied to 
underground coal mines for nearly 25 years. This aspect of the final 
rule comports with the recommendation of the Diesel Advisory Committee 
that gaseous diesel exhaust components not be treated differently from 
contaminants generated by other mining sources. The final rule does not 
adopt updated exposure standards at this time because this issue 
remains in the rulemaking process for Air Quality standards.
    The exposure levels adopted by the final rule for purposes of 
calculating the ventilation rate for an engine will lead to lower 
required air quantities for ventilating subpart E-approved engines, as 
compared to engines approved under now-superseded part 36. This is 
because engines previously approved under part 36 were required to 
dilute oxides of nitrogen and carbon dioxide to levels lower than 
currently specified by the threshold limit values (TLV's) in 
Sec. 75.322. The ventilation rates set for engines under the final rule 
will be more precisely related to current exposure standards. In 
addition, Sec. 75.325(g) of the final rule revises the percentage of 
the approval plate air quantity that is required when multiple units of 
diesel equipment operate in the same air current. Finally, as discussed 
elsewhere, the final rule is designed to produce an integrated system 
of controls to protect miners from overexposure to harmful diesel 
emissions.
    Commenters generally accepted the value and purpose of setting a 
ventilation rate for each diesel engine model. Knowledge of the 
ventilation rate needed to control gaseous emissions to safe levels 
will allow comparison of the efficiency and ventilation demands of 
different engine models, and facilitate evaluation of their general 
ventilation needs during use. One commenter, however, urged that the 
gaseous ventilation rate for control of diesel engine exhaust gases not 
be part of the approval process. According to this commenter, existing 
ventilation and air quality standards are adequate.
    The final rule adopts the requirements for determining the 
ventilation rate necessary to dilute diesel engine exhaust 
contaminants. Ventilation systems provide different quantities of air 
at different locations in the mine. Knowing the ventilating air 
quantities needed for diesel-powered equipment will allow the mine 
operator to make informed decisions about equipment selection and 
utilization and mine ventilation.
    Other commenters, who acknowledged the purpose of establishing 
ventilation rates for approved diesel engines, recommended for the sake 
of clarity that the levels set for the gases be specified in the final 
rule. In the proposal, MSHA had set these levels by reference to the 
time weighted average (TWA) concentrations for the gases. The final 
rule adopts this suggestion and the levels for carbon dioxide, carbon 
monoxide, nitric oxide and nitrogen dioxide are specified in the final 
rule. The levels in the final rule are identical to the levels in 
existing Sec. 75.322, and MSHA intends that the levels in the final 
rule conform with any levels that may ultimately be updated. 
Specifically, if any of the levels for any of these contaminants are 
revised as part of MSHA's Air Quality rulemaking, MSHA intends to 
conform the levels in this section to any revised levels.
    The proposed requirement for fuel deration received no comments. 
The purpose of this requirement, which is adopted without change from 
the proposal, is to ensure that the fuel-to-air ratio does not increase 
due to the lower density of air at higher altitudes. Not correcting the 
maximum fuel delivery on the engine for higher altitude operation 
results in increased emission levels. The fuel injection rate 
established during the approval may be required to be reduced when the 
engine is used at a higher altitude.
    Implementing a recommendation of the Diesel Advisory Committee, the 
proposed rule also called for a particulate index to be set for 
approved diesel engines. The particulate index specifies the quantity 
of air needed to dilute the particulate generated by the engine to 1 
milligram of diesel particulate matter per cubic meter of air. The 
control of particulate matter in diesel engine exhaust was a 
significant issue for the Advisory Committee. The Committee concluded 
that whole diesel exhaust represents a probable risk for causing human 
lung cancer, and recommended that MSHA develop a regulatory scheme to 
monitor and control diesel particulate underground. The Committee did 
not recommend an exposure level, but did urge that consideration be 
given to what level of exposure to diesel particulate presents a health 
risk to miners. MSHA is currently developing regulations, separate from 
this rule, to address this issue.
    The Diesel Advisory Committee also recommended that a particulate 
index be set for engines so that the mining industry and MSHA could 
compare the particulate levels generated by different engines in terms 
of a ventilating air quantity. For example, if the particulate indices 
for diesel engines of the same horsepower were established as 7,500 
cubic feet of air per minute (cfm) and 12,000 cfm respectively, an 
equipment manufacturer, mine operator, and MSHA personnel could use 
this information, along with consideration of the type of machine the 
engines would power and the area of the mine in which it would be used, 
to make certain decisions. For example, a mine operator could use this 
information when choosing an engine to roughly estimate an engine's 
contribution of diesel particulate to the mine's total respirable

[[Page 55421]]

dust. MSHA would use this information when evaluating mine dust control 
plans. Equipment manufacturers can use the particulate index to design 
and install exhaust after-treatments.
    The final rule retains the proposed requirement for a particulate 
index to be set for approved diesel engines. Unlike the ventilation 
rate set for each engine, the particulate index value will not appear 
on the engine's approval plate. The particulate index, calculated under 
Sec. 7.89 of the final rule, indicates what air quantity is necessary 
to dilute the diesel particulate in the engine exhaust to 1 milligram 
of diesel particulate matter per cubic meter of air. This information 
will be available to the mining industry from the engine manufacturer 
and MSHA.
    Some commenters to the proposal objected to the use of a 
particulate index to establish required ventilation air quantities for 
diesel engines. These commenters noted that a diesel particulate 
permissible exposure level has not yet been set and maintained that 
suitable monitoring technology is not available for widespread field 
use. These commenters also urged that control of diesel particulate in 
underground mines be accomplished through a combination of measures, 
including fuel requirements, equipment design, and controls such as 
ventilation and equipment maintenance. The commenters recommended that 
the particulate index not be part of the engine ventilation rate, and 
concluded that such an index should be viewed as a guideline providing 
useful information about diesel engines. The commenters further 
suggested that additional evaluation be undertaken to determine 
appropriate procedures for setting a particulate index.
    The overall approach of the final rule is to control diesel 
emissions in the underground mine environment through various 
established methods, including those suggested by commenters. The 
information provided by the particulate index is part of the multi-
level approach recommended by the Diesel Advisory Committee.
    As explained above, the particulate index value determined for a 
diesel engine is intended to provide useful information about diesel 
engines, as the commenters suggested. In addition, the particulate 
index value does not appear on the equipment's approval plate and 
therefore is not considered in setting the engine's required 
ventilation rate.
    Section 7.85  Critical characteristics. Critical characteristics, 
which are specified for all part 7-approved products, are those 
features or specifications which, because of their importance to proper 
operation of the equipment, must be inspected or tested on each unit 
manufactured. The proposal called for inspecting or testing each diesel 
engine to verify that the fuel rate is set to altitude, and the fuel 
injection pump adjustment is sealed, if applicable. No comments were 
received on this aspect of the proposal, and the final rule adopts the 
proposal without substantive change. Instead of requiring the fuel rate 
to be set to altitude, the final rule specifies that the fuel rate be 
properly set.
    As discussed elsewhere in this preamble, the rate of fuel delivery 
to a diesel engine significantly affects its gaseous and particulate 
emission. As noted earlier, correct adjustment of the fuel injection 
pump is essential to the efficient operation of diesel engines.
    Inspecting or testing the proposed critical characteristics for 
diesel engines approved under part 7, subpart E reasonably ensures that 
the performance and emission characteristics of production engines will 
be equivalent to those of the engine tested for approval. As a result, 
miners are protected against harmful exposure to diesel emissions.
    No comments were received on this aspect of the proposal, which is 
adopted by the final rule, with the change noted above.
    Section 7.86  Test equipment and specifications. This section 
adopts the measurement and evaluation methods for emissions from diesel 
engines as described in ISO 8178-1. The final rule describes the 
apparatus, or test cell, required for testing diesel engine 
performance, and sets the specifications for operating this testing 
equipment to perform steady-state tests for both gaseous and 
particulate emissions.
    The major components of a test cell are a dynamometer with engine 
operating controls, and gaseous and particulate emission measurement 
systems. This test cell is used to perform the test required by 
Secs. 7.87, 7.88, and 7.89 of the final rule. Most engine testing 
laboratories today have the equipment and meet the specifications 
called for by ISO 8178-1 and the final rule.
    The final rule's test cell requirements are substantially the same 
as the proposed requirements, except that the specifications for the 
testing apparatus and test conditions are revised to conform with ISO 
8178-1. Commenters to the proposal did not direct attention to these 
requirements, but did express concern about correlating the proposed 
rule test requirements and Environmental Protection Agency diesel 
engine tests, and recommended that the MSHA procedures conform to 
internationally accepted test procedures. The adoption of the ISO 8178-
1 provisions eliminates this issue and is responsive to commenters' 
concerns.
    Like the proposal, the final rule also sets specifications for the 
fuel to be used during testing of diesel engines. The proposed rule 
would have required No. 2D diesel fuel with certain properties. A 
uniform test fuel is important to obtaining repeatable test results and 
test data that can be compared. Commenters did not direct their 
attention to this aspect of the proposal, except that they generally 
encouraged adoption of international standards to the extent possible.
    The final rule revises the proposed requirements for diesel engine 
test fuel to conform with the fuel requirements in Sec. 75.1901. 
Section 75.1901 of the final rule specifies the use of diesel fuel 
containing no more than 0.05 percent sulfur. Under this section, diesel 
fuel used for engine testing must also be low in sulfur content. In 
addition, the properties specified for test fuel conform with the test 
fuel EPA requires for testing diesel engines that use low sulfur fuel. 
Thus, the final rule will not require testing laboratories to acquire 
special fuel to comply with the final rule.
    The final rule also adopts the proposal that Category A engines, 
which are intended for operation in areas of mines where concentrations 
of methane gas could be encountered, be tested with 1.0 percent of 
methane added to the engine's intake air. As noted above, this addition 
to the ISO 8178 test procedure adopted by the final rule should present 
no technical difficulties for manufacturers or third-party 
laboratories. MSHA, however, will provide technical assistance for 
setting up this aspect of the test procedure upon request.
    Metering in 1.0 percent of methane to the intake air of Category A 
engines replicates a foreseeable operating condition in underground 
mines. In addition, methane gas acts as a fuel when it is aspirated 
into a diesel engine, increasing its output of carbon monoxide and 
oxides of nitrogen. These emission effects need to be accounted for in 
determining the gaseous ventilation rate for Category A engines.
    Section 7.87  Test to determine the maximum fuel-to-air ratio. As 
noted earlier, the tests prescribed by this section are performed using 
the test cell meeting the requirements of Sec. 7.86. Determining the 
maximum fuel-to-air ratio for diesel engines is essential to 
controlling harmful diesel engine emissions. Too rich a fuel and air

[[Page 55422]]

mixture produces engine exhaust with elevated levels of carbon monoxide 
and oxides of nitrogen.
    Under this section, engines are required to be operated at several 
speed/torque conditions to determine the concentrations of carbon 
monoxide and the oxides of nitrogen. Acceptable performance is achieved 
when the levels of these exhaust gases do not exceed the limits set by 
Sec. 7.84(b) of the final rule throughout the operational range of the 
engine.
    Commenters did not address the proposed test to determine the 
maximum fuel-to-air ratio for diesel engines. The final rule adopts the 
proposal without change.
    Section 7.88  Test to determine the gaseous ventilation rate. The 
test to determine the gaseous ventilation rate for a diesel engine is 
required by the final rule to be performed using the test cell required 
by Sec. 7.86. This test may be performed together with the test to 
determine the particulate index required by Sec. 7.89.
    The test required by this section measures the undiluted exhaust 
gas concentrations of carbon monoxide, carbon dioxide, nitric oxide, 
and nitrogen dioxide in the exhaust. These constituent gases of diesel 
engine exhaust are potentially harmful to miners in the confined 
environment of underground mines.
    In accordance with Sec. 7.86, exhaust gas measurements must be made 
at 8 specified points while the engine is operated at each rated speed 
and horsepower requested by the approval applicant. For Category A 
engines, 1.0 percent methane is added to the engine's intake, as 
discussed above.
    Like the proposal, the final rule specifies the calculations to be 
performed using the results obtained from the test procedure. These 
calculations produce a gaseous ventilation rate for the diesel engine. 
As discussed above, the ventilation rate indicates the amount of 
ventilating air necessary to dilute carbon monoxide, carbon dioxide, 
nitric oxide and nitrogen dioxide to within permitted levels. The 
ventilation rate for each approved Category A or B diesel engine will 
appear on the engine's approval plate. Knowledge of the ventilation 
rate needed to control gaseous emissions to safe levels will allow 
comparison of the efficiency and ventilation demands of different 
engine models, and their general ventilation needs during use can be 
evaluated.
    As discussed above, commenters generally accepted the value and 
purpose of setting a ventilation rate for each diesel engine model. One 
commenter urged that the ventilation rate not be part of the approval 
process, while others supported the approach taken in the proposed and 
final rules. These commenters, however, suggested that the levels for 
the exhaust gases be stated in the final rule. The final rule adopts 
this suggestion in Sec. 7.84(c).
    Section 7.89  Test to determine the particulate index. Like the 
other engine tests prescribed by the final rule, the test to determine 
the particulate index for an engine is required by the final rule to be 
performed using the test cell required by Sec. 7.86. As noted above, 
this test may be performed concurrently with the test to determine an 
engine's gaseous ventilation rate required by Sec. 7.88.
    The test required by this section measures the amount of 
particulate in the engine's exhaust when it is operated at eight 
specified operating conditions. For Category A engines, 1.0 percent 
methane is added to the engine's intake, as discussed above.
    The proposed rule would have required that the particulate index be 
determined using a different set of test points than those used to 
determine the gaseous ventilation rate. The particulate index tests 
were based on a cycle of 10 test points. In response to commenters' 
suggestions that the particulate and gaseous emissions tests be 
conducted using the same test cycle and internationally accepted test 
procedures, the final rule adopts the same ISO 8178-4, 8-point test 
cycle for both the particulate and gaseous emissions tests.
    The Diesel Advisory Committee observed that whole diesel exhaust 
represents a probable risk for causing human lung cancer. While 
proposing no specific exposure level, the Diesel Advisory Committee 
recommended control of diesel particulate in engines used underground 
through a combination of measures, including equipment design.
    Like the proposal, the final rule does not set a particulate limit 
for engines. Instead, the final rule specifies the calculations to be 
performed using the results obtained from the test procedures in this 
section. From the calculations, a particulate index is derived. As 
discussed above, the particulate index for an engine does not appear on 
its MSHA approval plate. This information will be available, however, 
from MSHA and the engine manufacturer.
    Section 7.90  Approval markings. This section requires that each 
approved diesel engine be identified with a permanent approval plate 
containing certain information. Approval markings to identify equipment 
appropriate for use in mining have been used for more than 85 years, 
and are routinely relied upon by users of mining equipment as well as 
state and federal inspection authorities.
    The information required to be displayed on diesel engine approval 
plates includes the MSHA-assigned approval number, together with the 
engine's model number, ventilation rate, rated power, high idle 
setting, and the altitude above which the engine must be derated. 
Including these specifications on diesel engine approval plates gives 
engine users convenient, immediate access to information important to 
proper maintenance and operation of diesel engines.
    Commenters directed little attention to this aspect of the 
proposal, which is adopted without change in the final rule. Commenters 
who objected to setting a ventilation rate for diesel engines as part 
of the approval process repeated this concern with respect to the 
requirement for the ventilation rate to appear on engine approval 
plates. As discussed above, setting a gaseous ventilation rate for 
diesel engines comports with the recommendations of the Diesel Advisory 
Committee and provides diesel equipment users with information 
important to protecting miners. Knowledge of the rate of ventilation 
needed to control the gaseous exhaust emissions of a diesel engine 
facilitates comparison of the efficiency and ventilation demands of 
different engine models.
    The other information required by the final rule to appear on an 
engine's approval plate likewise provides engine users needed data. The 
high idle setting informs maintenance personnel of the engine speed 
appropriate for conducting several of the tests to be performed as part 
of the engine's permissibility checklist. Together, an engine's 
approval number, model number, and its rated power and speed facilitate 
use of the manufacturer's maintenance procedures. The maintenance 
procedures, along with the altitude above which the engine must be 
derated, specify the adjustments which must be made to ensure that an 
engine continues to operate in approved condition.
    Burden hours required to make and mount MSHA approval plates are 
assigned OMB control number 1219-0100.
    Section 7.91  Post-approval product audit. This section 
incorporates the standard audit requirement for part 7-approved 
equipment, specifying that approval holders must make a diesel engine 
available for audit by MSHA, at no cost to the Agency. The obligation 
to

[[Page 55423]]

supply an engine for audit under this section arises only upon request 
by MSHA, and is limited to no more frequently than once a year, except 
for cause. Under existing Sec. 7.8(b), the approval holder may observe 
any tests conducted under the audit.
    Post-approval audits are a critical part of MSHA's quality control 
program for approved equipment. By inspecting and testing an engine for 
continuing compliance with its approval specifications, potential 
problems can be detected and confidence in the approval process is 
maintained. Since the inception of post-approval product audits under 
part 7, MSHA has detected numerous discrepancies, which have been 
effectively corrected.
    Commenters directed no attention to this aspect of the proposal, 
which is adopted without change from the proposal.
    Section 7.92  New technology. This section is designed to 
facilitate the introduction of new technology or new applications of 
existing technology. It allows MSHA to approve a diesel engine that 
incorporates technology for which the requirements of subpart E are not 
applicable, provided that MSHA determines the engine is as safe as one 
which meets the requirements of subpart E. To make this determination, 
MSHA develops appropriate technical requirements and test procedures 
when novel designs are submitted for approval. Experience with this 
provision under existing regulations has shown that new innovations can 
be effectively evaluated and made available for use in a prompt 
fashion, thus serving the best interests of miners' safety and health.
    Commenters supported this aspect of the proposal, stressing that 
research and technological improvements in diesel engines can be 
expected. The final rule adopts the proposal without change.
Subpart F Overview
    Subpart F of the final rule amends existing part 7, which specifies 
testing by the approval applicant or a third party. As an amendment to 
the existing regulations, the general administrative provisions of 
subpart A of part 7 apply to these new subpart F application 
requirements.
    Subpart F establishes design and performance requirements for MSHA 
approval of ``diesel power packages'' for use in areas of underground 
coal mines where permissible electrical equipment is required by 
existing safety standards. A ``diesel power package'' is a diesel 
engine, together with the attached safety components, such as flame 
arresters, spark arresters, surface temperature controls, shut down 
systems, and the exhaust cooling system that make a diesel engine 
explosion-proof and reduce the engine's surface temperature to a safe 
level. Like the proposal, the final rule requirements for diesel power 
packages are largely derived from existing MSHA approval regulations in 
part 36, which apply to diesel engines for use in gassy underground 
mines. The final rule is also consistent with current MSHA practices 
for coal mines using diesel-powered equipment and with the 
recommendations of the Diesel Advisory Committee. The Advisory 
Committee specifically recommended an approval program for diesel power 
packages.
    Commenters generally accepted the proposal for MSHA approval of 
diesel power packages, recognizing the need for diesel-powered 
equipment used in underground coal mines to meet critical 
specifications and to be properly tested for safe operation in a 
potentially explosive atmosphere. Some commenters directed their 
attention to the effective date of subpart F, expressing concern about 
the availability of commercial testing facilities. For the reasons 
discussed below, the final rule does not adopt an extended phase-in 
period. However, accommodations are made in the final rule to simplify 
the implementation of testing in the private sector, and MSHA will 
continue to perform diesel power package testing to subpart F 
specifications for up to 3 years, pending the development of private 
sector resources.
    Other commenters recommended that diesel engine exhaust after-
treatment devices, such as particulate filters or catalytic converters, 
be required as part of diesel power packages. These commenters also 
suggested that the ventilation rate and particulate index set under 
Secs. 7.88 and 7.89 of the final rule credit the use of such devices.
    The final rule responds to these comments in part. Under the MSHA 
approval program in subpart E, MSHA will evaluate exhaust gas and 
particulate controls, provided these devices are integral to the engine 
design and are part of normal production engines. The effectiveness of 
such controls will also be considered in setting the engine's 
ventilation rate and particulate index. This approach will ensure that 
the controls are compatible with the engine and are effective. MSHA has 
already approved, under existing regulations, engines which incorporate 
techniques such as electronic fuel injection systems. Exhaust after-
treatment devices that are not part of an engine's design and 
production have been developed which can reduce the particulate matter 
in diesel engine exhaust. Also, catalytic converters are available 
which can be added to engines to reduce the levels of some harmful 
gaseous emissions. MSHA encourages the use of these devices, and under 
existing regulations has approved, as safe, several power packages that 
utilize catalytic converters and particulate filters. However, under 
the final rule MSHA will not evaluate the effectiveness of these 
exhaust after-treatment devices. Exhaust after-treatment devices 
encompass a wide range of concepts that have demonstrated varying 
degrees of effectiveness and reliability. The evaluation of these types 
of after-treatment devices is beyond the scope of a part 7 approval 
program.
    For the same reasons, the final rule does not adopt a commenter's 
suggestion that the particulate index for an engine be adjusted to 
reflect the use of a diesel particulate filter. Also, the particulate 
index for an engine is intended to be used by manufacturers and mine 
operators as an aid for, among other things, selecting appropriate 
after-treatment devices such as particulate filters. Therefore, under 
the final rule the particulate index for an engine will indicate the 
particulate contained in the raw engine exhaust.
    Other aspects of the final rule will, however, recognize exhaust 
after-treatment controls. The positive effects of catalytic converters 
in lowering levels of harmful exhaust gases may be considered under 
Sec. 75.325(i) for reducing the quantity of ventilating air required 
where multiple pieces of diesel-powered equipment are in use. Also, 
particulate filters can be effective in maintaining compliance with the 
respirable dust standard set by existing Sec. 70.100.
    During the course of this rulemaking, the question has been raised 
as to whether the final rule should require that some or all diesel 
engines be equipped with particulate filters. As noted above, MSHA 
encourages the use of such filters and other emission controls. 
However, the proposed rule did not raise this issue and MSHA received 
only limited comment regarding the appropriate role of diesel 
particulate filters. The final rule, therefore, does not require the 
use of these filters. However, MSHA is currently developing a proposed 
rule to address control of miners' exposure to diesel particulate. This 
rulemaking will afford an opportunity to fully develop this issue.
    Other commenters suggested that diesel engine cooling system

[[Page 55424]]

components, such as radiators, not be included as part of the approval 
of diesel power packages so as to permit changes in cooling system 
components to be made in the field without affecting the engine's 
approval. The final rule does not adopt this suggestion. The inter-
relationship of the components in the cooling system of a diesel engine 
is critically important to controlling power package surface 
temperatures, which, when elevated, can lead to a fire. Consequently, 
the engine cooling system components must be considered an integral 
part of a diesel power package. This aspect of the final rule does not 
prohibit field radiator changes, provided that the inter-relationship 
of the engine's cooling system components is maintained in approved 
condition.
    A number of minor changes are made in Secs. 7.97, 7.98, 7.100, 
7.101, 7.102, and 7.103 of the final rule to clarify the requirements 
of these sections. Substantive changes to these sections are discussed 
in the section-by-section discussion which follows.
    Section 7.95  Purpose and effective date. The final rule's part 7, 
subpart F approval requirements apply to diesel power packages intended 
for equipment used in areas of underground coal mines where this 
equipment is required to be permissible. The design, performance and 
testing requirements of this section are effective November 25, 1996. 
MSHA will begin accepting applications under new subpart F immediately. 
To accommodate all interests, the Agency also will complete any in-
house part 36 safety component certification applications, or evaluate 
such applications under new subpart F, at the applicant's choice. As 
noted elsewhere in this preamble, the requirements for approved diesel 
power packages in equipment used in underground coal mines become 
effective in 3 years.
    As noted above, several commenters urged that an extended phase-in 
period of several years be included in the final rule. According to the 
commenters, a phase-in period is needed to allow for the development of 
competent third- party testing facilities, particularly with respect to 
explosion-proof testing. Other commenters suggested that subpart F be 
made effective immediately, so as to accelerate conformance to the new 
requirements for the benefit of miners' safety.
    A number of the final rule's test requirements can be performed 
effectively with inexpensive, simple test equipment or facilities, or 
with the power package installed in the mining equipment. For example, 
the static pressure test required by Sec. 7.104 to evaluate the 
structural integrity of power package components can be performed using 
currently available hand pump devices. Likewise, explosion-proof 
testing can be performed in inexpensive test chambers of relatively 
simple design.
    Nonetheless, MSHA recognizes that some testing capabilities are not 
immediately available in the private sector, such as surface 
temperature testing and exhaust gas cooling efficiency testing with 
methane gas injection in the intake air. To facilitate the approval of 
power packages and accommodate the needs of applicants, MSHA may be 
consulted for simple alternative procedures which can be used to 
provide the same results. In addition, MSHA will perform the tests 
required by subpart F for diesel power package approval at its Approval 
and Certification Center upon request by applicants. MSHA anticipates 
providing these test services, for the fees set in accordance with 30 
CFR Part 5, for up to 3 years, or until private sector testing 
capability is available. MSHA reserves the right to determine when 
competent private sector testing capability is available and to 
discontinue MSHA testing.
    Section 7.96  Definitions. In addition to the existing definitions 
in Secs. 7.2 and 7.82, this section of the final rule sets out and 
clarifies the key terms used in subpart F.
    Commenters did not direct specific attention to this aspect of the 
proposal. The final rule adopts the proposed definitions, with five 
exceptions, adds two terms and definitions, and deletes three 
definitions from the proposal which now appear in subpart E. These 
changes are intended to add flexibility to the final rule and respond 
to confusion among some commenters with respect to the substantive 
requirements of subpart F.
    The definition for ``exhaust conditioner'' has been revised to 
remove the words ``corrosion-resistant.'' The requirement for the 
exhaust conditioner to be made of corrosion-resistant material is 
adopted from the proposal in Sec. 7.98(s)(4)(i). The definitions for 
``exhaust system'' and ``intake system'' are revised to include the 
phrase ``but is not limited to'', to recognize the use of components 
not otherwise mentioned in the definitions for these terms. The term 
``explosive mixture'' has been changed to ``flammable mixture'' to 
conform with part 36, and the definition for this term has been 
modified with the non-substantive change of removing the word 
``violently.'' The definition for ``fastening'' has been modified for 
the sake of clarity to remove the words ``device such as'' when 
referring to bolts, screws, or studs. The term ``high idle speed/no 
load'' has been revised to ``high idle speed.'' This is another non-
substantive change, since ``no load'' is specified in the definition of 
the term. New definitions for ``dry exhaust conditioner'' and ``wet 
exhaust conditioner'' are added to the final rule to more clearly 
differentiate between the requirements for these systems. Under the 
final rule, a dry exhaust conditioner is defined as a device which 
cools exhaust gases without direct contact with water, such as a heat 
exchanger. A wet exhaust conditioner is defined as a system which cools 
exhaust gases through direct contact with water. Minor changes to the 
definitions for ``step (rabbet) joint'' and ``threaded joint'' have 
been made for the sake of clarity. The terms ``corrosion-resistant 
material,'' ``idle speed/no load,'' and ``rated speed'' and their 
definitions are deleted from subpart F. These terms are common to both 
subparts E and F, and have already been defined in subpart E. Section 
7.96 has been modified to incorporate the definitions of subpart E, 
Sec. 7.82.
    Section 7.97  Application requirements. This section is derived 
from existing part 36 and requires that an application for approval of 
a diesel power package contain sufficient information to document 
compliance with the technical requirements of the final rule. The list 
of information specified for inclusion in the approval application, 
which is revised from the proposal in response to commenters and to 
fully identify the engine and the fan blade material, is intended to 
help applicants supply the data necessary for a prompt evaluation. The 
final rule permits applicants to submit composite drawings. This 
approach reduces paperwork, affords applicants flexibility in the 
preparations of their drawings, and has proven to be effective in other 
MSHA approval programs.
    Like existing part 7 and other MSHA approval standards, the 
documentation formulated in the application process under Sec. 7.97 
forms the basis for MSHA's approval of a diesel power package. Approved 
diesel power packages must be manufactured in accordance with the 
specifications contained in the approval and, once put into service, 
approved power packages must be maintained and operated within the 
parameters set in the MSHA approval.
    The paperwork hours in the approval application, including test 
requirements, are assigned OMB control number 1219-0100.
    Section 7.98  Technical requirements. This section of the final 
rule sets specific technical requirements

[[Page 55425]]

for diesel power packages. Diesel power packages are intended for use 
with Category A engines so that they can be operated safely and not 
create a fire or explosion hazard. Consistent with the Advisory 
Committee's recommendation that permissible diesel equipment be 
required in areas of underground coal mines where permissible electric 
equipment is required, the final rule's technical specifications 
introduce many of the safety features currently required for 
permissible electric-powered equipment.
    Like the proposal, the final rule is derived largely from existing 
technical requirements in part 36 for diesel-powered equipment intended 
for use in gassy non-coal mines. The final rule also addresses the 
hazard of combustible coal dust by specifying a maximum surface 
temperature of 302  deg.F (150  deg.C). This is the same technical 
requirement applied to permissible electric-powered equipment. Other 
aspects of the final rule set specifications necessary to control 
engine surface temperatures, sparking, and the passage of flame from 
the exhaust system or components to the external atmosphere. Any of 
these conditions could ignite an explosion or fire in the underground 
coal mine environment.
    Commenters generally accepted the proposed technical requirements, 
which, as noted above, are based on long-standing regulations which 
have been proven effective and workable. Commenters did, however, raise 
several issues.
    Some commenters sought wider tolerances for explosion-proof 
enclosures in diesel power packages, citing experience in the United 
States and Europe. These commenters directed their attention to the 
proposed specifications for joints in engine exhaust systems, and 
suggested that MSHA review the proposed specification of 0.004 inches 
for maximum clearance for joints all in one plane.
    The final rule retains this specification, which has proven to be 
effective for decades. Commenters offered no basis for the 
recommendation for a wider tolerance.
    Other commenters suggested that electric starting devices for 
diesel engines be prohibited. The proposed rule recognized the 
conventional use of hydraulic, pneumatic or other mechanically actuated 
starting mechanisms, but also retained the flexibility to evaluate 
other means of starting under Sec. 7.107 of the rule concerning new 
technology. This aspect of the proposal differs from the existing part 
36 regulations from which this proposal was derived.
    The final rule is intended to serve as a flexible set of 
regulations that will continue to be workable over a period of years. 
Throughout the final rule MSHA has adopted the more current practices 
and, where appropriate, provides that alternatives may be developed 
which are safe and effective. With this in mind, the final rule does 
not expressly prohibit the use of electric starting devices for diesel 
engines, adopting the proposal to permit MSHA to evaluate other 
starting mechanisms. Such alternatives are subject to evaluation under 
Sec. 7.107 and must be found by MSHA to be as safe as the pneumatic and 
hydraulic starting mechanisms presently in use.
    Some commenters asked for clarification of proposed paragraph (i) 
with respect to the safety shutdown system required for diesel power 
packages. The safety shutdown system is required to automatically shut 
off the fuel supply and stop the engine in response to certain 
dangerous engine conditions. MSHA intended in the proposal, and the 
final rule clarifies, that the shutdown system must respond to both 
high exhaust temperature and low water level in the engine's exhaust 
conditioner. Either of these conditions can rapidly lead to a fire or 
explosion hazard.
    In addition, the final rule has been revised from the proposal to 
cover other safety system shutdowns that may be installed by the 
applicant. Section 75.342 requires methane monitors on some permissible 
equipment, and the final rule requires permissible equipment to be 
provided with a fire suppression system meeting the requirements of 
Sec. 75.1911. Both of these standards specify that the diesel engine 
must shut down when either an elevated level of methane is encountered 
or when the fire suppression system is actuated. This requirement will 
most likely be satisfied by a connection to the safety shutdown system. 
The technical requirements of this rule now cover these additional 
sensors.
    Another commenter suggested that the safety shutdown system include 
automatic brake lock-up to prevent diesel-powered equipment from 
rolling. This aspect of a machine's safety is evaluated under the 
existing requirements of part 36 and is not part of a diesel power-
package approval. Thus, the final rule does not adopt this suggestion.
    The final rule adopts clarifying revisions in addition to changes 
made in response to commenters. In several instances more precise 
language is adopted to differentiate between requirements for wet and 
dry exhaust conditioner systems. Proposed Sec. 7.98(d) has been revised 
in the final rule to refer to ``nonmetallic rotating parts'' instead of 
``fans'', to conform with other MSHA regulations. Paragraph (p)(2)(ix) 
has been revised to require that the minimum thread engagement of 
fastenings must meet the requirements of the explosion tests in 
Sec. 7.104. This is a correction. This change conforms to paragraph 
(p)(2)(viii), which requires both tests for acceptance of a minimum 
thread engagement of fastenings less than \3/8\ inch. In addition, 
paragraph (q)(7) of the final rule does not retain the proposed 
requirement that a ``minimum of four fastenings'' be used for 
explosion-proof joints. MSHA's experience shows that flange designs 
with fewer than four fastenings have proven to be effective. Paragraph 
(r)(5) has been revised to note that the opening for connection of a 
gage to measure the intake vacuum must be closed by a plug or other 
suitable device that is sealed or locked in place except when in use. 
This language conforms to the language of part 36, and closing of this 
opening is necessary to perform certain tests in this subpart. 
Paragraph (s)(1) has been revised to require that the flame arrester 
prevent the discharge of glowing particles, conforming it to the 
requirement in part 36. Finally, paragraph (s)(5) has been revised to 
note that the opening for connection of a gage to measure the 
backpressure must be closed by a plug or other suitable device that is 
sealed or locked in place except when in use. This language also 
conforms to part 36, and is needed to perform some of the tests under 
this subpart.
    Section 7.99  Critical characteristics. Critical characteristics, 
which are specified for all part 7-approved products, are those 
features or specifications which, because of their importance to proper 
operation of the equipment, must be inspected or tested on each unit 
manufactured. The proposal focused on power package features essential 
to preventing fires and explosions in the underground coal mine 
environment, such as flame-arresting path clearances and the explosion-
proof integrity of the power package. Commenters did not direct their 
attention to this aspect of the proposal, which is adopted without 
change in the final rule.
    Section 7.100  Explosion tests. This section describes the tests to 
be performed on diesel power packages to ascertain whether they are 
explosion-proof, as specified by the technical

[[Page 55426]]

requirements in Sec. 7.98. Like the proposal, the final rule is derived 
from existing Sec. 36.46. Using an explosive mixture of natural gas and 
air, or methane and air, the tests prescribed by the final rule 
determine the power package's integrity in the event of an explosion 
inside the intake or exhaust system. This could be caused by an engine 
backfire during starting or ingestion of methane into the engine while 
it is running. The prescribed tests determine whether flame arresters 
and joints are capable of preventing propagation of the internal 
explosion to the surrounding atmosphere. These tests also determine the 
lowest water level in the exhaust conditioner that will act effectively 
as a flame arrester, and the peak explosion pressures generated in each 
segment of the intake and exhaust system. Excessive pressures may be an 
indication of a design flaw.
    Commenters did not raise issues regarding the proposed explosion 
tests. However, the final rule includes one change from the proposal to 
better ensure the ability of a diesel power package to withstand an 
internal explosion, and another change to revise the speeds at which 
dynamic tests are to be conducted. The final rule also includes non-
substantive changes for clarification and to conform the final rule 
with existing MSHA regulations.
    Paragraphs (a)(2) (v) and (vi) of the final rule specify an 
internal peak pressure of 110 psig instead of the proposed 125 psig, 
during power package explosion-proof testing. Excessive internal 
pressures during explosion-proof testing indicate the potential for 
failure of the diesel power package in use, with potentially 
catastrophic results in the underground coal mine environment. Lowering 
the peak pressure expected during explosion-proof testing recognizes 
that diesel power package designs differ and that it is difficult to 
select the optimum location for pressure measurements. When pressures 
greater than 110 psig are measured during testing, the final rule 
specifies redesign of the system to reduce the pressure or more 
rigorous testing to verify the integrity of the system. Due to the 
critical nature of this test, MSHA has adopted the same approach in its 
explosion-proof test requirements for electric motors. The final rule 
conforms these like requirements.
    Paragraph (a)(2)(vii) of the final rule requires that dynamic tests 
be conducted at two speeds--1800200 RPM and 
1000200 RPM--instead of at rated speed and 50 percent of 
rated speed specified in the proposal. The speeds set by the final rule 
correspond to the speeds at which dynamic tests are performed 
successfully at MSHA facilities. Also some test facilities may not be 
capable of performing tests at the rated speed called for by the 
proposal. This change is also reflected in paragraphs (a)(3)(iii) (A) 
and (B).
    For clarification, the final rule also adopts more precise language 
to identify requirements which apply to wet exhaust conditioners, 
distinguishing them from dry systems. The final rule also defines 
natural gas that may be used in explosion-proof testing in a manner 
that better recognizes the variables in the make-up of the hydrocarbons 
found in natural gas. As a result, the final rule affords greater 
flexibility for manufacturers and testing laboratories.
    Section 7.101  Surface temperature tests. This section describes 
the tests necessary to ascertain that diesel power packages will not 
create a fire hazard in underground coal mines due to coal dust or 
other combustible materials contacting hot surfaces. Like the proposal, 
the final rule is derived from Sec. 36.48, and sets a maximum external 
surface temperature of 302  deg.F (150  deg.C). The test protocol 
simulates the operation of a diesel power package under heavy use 
conditions. A note has been added to this section to alert the 
applicant that this test may be done simultaneously with the exhaust 
gas cooling efficiency test described in Sec. 7.102 of the final rule.
    Commenters did not direct their attention to this aspect of the 
proposal. The final rule is unchanged from the proposal, except for a 
non-substantive clarifying change regarding wet exhaust conditioners 
and the elimination of the reference to the use of natural gas. A 
reference to natural gas, which consists primarily of methane, is 
redundant. Instead, the final rule specifies the percentage of methane 
to be added to the intake. Elimination of the reference to natural gas 
also conforms this section to similar tests, which also determine 
engine performance and which only specify methane, in subpart E of part 
7.
    Section 7.102  Exhaust gas cooling efficiency test. This section 
describes the test procedures for measuring the temperature of the 
exhaust gas at the discharge point from the exhaust conditioner. 
Acceptable performance under this test is exhaust gases that do not 
exceed 170  deg.F (76  deg.C) for power packages with a wet exhaust 
conditioner, and 302  deg.F (150  deg.C) for a dry system. The proposed 
and final rules are derived from existing Sec. 36.47 and address the 
hazard of hot exhaust gases creating a fire or explosion hazard.
    Commenters raised only one issue concerning this aspect of the 
proposal, suggesting clarification of the different performance 
requirements for wet and dry exhaust conditioners. The final rule 
adopts this suggestion.
    Section 7.103  Safety system controls test. This section is derived 
from Sec. 36.47 and describes tests to evaluate the performance of the 
safety shutdown systems required for diesel power packages. As 
discussed above, these systems automatically shut down a diesel engine 
in response to potentially dangerous conditions, such as overheating. 
The tests prescribed introduce failure modes, such as loss of engine 
coolant, and initiate the safety system. Acceptable performance is 
achieved when the safety system automatically shuts down the engine 
before the technical requirements for approval are exceeded.
    Commenters recommended that the final rule more clearly delineate 
the different requirements for wet and dry exhaust conditioners. The 
final rule adopts this suggestion in paragraphs (a)(3), (a)(4), (b)(2), 
and (b)(3).
    Commenters also suggested that paragraph (a)(7)(ii) be amended to 
include a caveat about the surface temperature of a turbocharger not 
exceeding 302 deg. F (150 deg. C). This comment is not adopted because 
the final rule addresses surface temperature control under Sec. 7.101 
and requires that all external surfaces of power packages, including 
turbochargers, not exceed 302  deg.F (150 deg. C). Paragraph (b)(7) has 
been revised to accept starting mechanisms constructed of nonsparking 
materials in addition to starting mechanisms that prevent the 
engagement of the starter while the engine is running. This revision 
conforms to Sec. 7.98(j)(1), which permits both options under the final 
rule, as it would have under the proposal.
    Section 7.104  Internal static pressure test. This section 
describes tests to determine if the design of the intake and exhaust 
system components of diesel power packages is structurally sound. The 
prescribed tests specify internally pressurizing each segment of the 
intake and exhaust system. The pressure required to be applied is four 
times the maximum pressure observed in the tests performed under 
Sec. 7.100, or 150 psig (5 psig), whichever is less. 
Acceptable performance is based on an assessment of key points in the 
intake and exhaust system, such as joints and welds, for evidence of 
leakage or damage.
    Commenters raised no issues with respect to the proposal. Paragraph 
(b)(2)(vi) has been added to limit

[[Page 55427]]

permanent distortion of any planar surface of the diesel power package 
to 0.04-inches/linear foot or less. This change conforms this 
requirement to the same requirement applied to the explosion tests in 
Sec. 7.100(b)(7).
    Section 7.105  Approval markings. This section requires that each 
approved diesel power package be identified with a permanent approval 
plate inscribed with the MSHA approval number. If the power package 
includes a wet exhaust conditioner that functions as an exhaust flame 
arrester, the final rule requires that the approval plate also indicate 
the grade limitation for the power package. This information is 
important so that users are aware of the maximum grade on which the 
exhaust conditioner will be effective as a flame arrester.
    As noted elsewhere in this preamble, approval markings have been 
used for more than 85 years, and are routinely relied upon by users of 
mining equipment as well as state and federal authorities to identify 
equipment appropriate for use in mining.
    Another commenter suggested clarification of the proposal with 
respect to the grade limitation for certain diesel power packages. The 
final rule has been revised in response to this commenter to clarify 
that the grade limitation applies to systems which use a wet exhaust 
conditioner as a flame arrester. No grade limitation is appropriate for 
power packages with a dry exhaust conditioner.
    Burden hours required to make and mount MSHA approval plates are 
assigned OMB control number 1219-0100.
    Section 7.106  Post-approval product audit. This section 
incorporates the standard audit requirement for part 7-approved 
equipment, specifying that approval holders must make a diesel power 
package available for audit by MSHA, at no cost to the Agency. The 
obligation to supply a power package under this section arises only 
upon request by MSHA, and is limited to no more frequently than one a 
year, except for cause. Under existing Sec. 7.8(b), the approval holder 
may observe any tests conducted under the audit.
    Post-approval audits are a critical part of MSHA's quality control 
program for approved equipment. By inspecting and testing a diesel 
power package for continuing compliance with the specifications for its 
approval potential problems can be detected and confidence in the 
approval process is maintained. Since the inception of post-approval 
product audits under part 7, MSHA has detected numerous discrepancies 
which have been effectively corrected.
    Commenters directed no attention to this aspect of the proposal, 
which is adopted without change from the proposal.
    Section 7.107  New technology. This section is designed to 
facilitate the introduction of new technology or new applications of 
existing technology. It allows MSHA to approve a diesel power package 
that incorporates technology for which the requirements of subpart F 
are not applicable, provided that MSHA determines the power package is 
as safe as one which meets the requirements of subpart F. To make this 
determination, MSHA develops appropriate technical requirements and 
test procedures when applications for the approval of novel designs are 
submitted. To provide confidence in the adequacy of the design, such 
tests may be required to be performed by MSHA. Experience with this 
provision under existing regulations has shown that technological 
innovations can be effectively evaluated and made available for use in 
a prompt fashion, thus serving the best interests of miners' safety and 
health. Commenters generally supported this aspect of the proposal, and 
the final rule adopts the proposal without change.
    Section 7.108  Power package checklist. This section requires that 
approved diesel power packages be accompanied by a description of the 
features which must be checked and tests that must be performed to 
ascertain that the power package is in approved condition. These 
instructions, which are developed as part of the approval process, are 
intended to aid power package users in keeping this equipment in safe 
operating condition.
    Commenters did not direct specific attention to this aspect of the 
proposal, which is adopted without change in the final rule.
Part 7, Subparts G, H and I
    The final rule does not adopt proposed subpart G to part 7, nor 
further develops the advance notice of rulemaking published 
concurrently with the proposal concerning subparts H and I to part 7. 
Subpart G-approved power packages would have been required for 
nonpermissible, heavy-duty diesel-powered equipment used in underground 
coal mines. Subpart H would have established regulations for the 
approval of fully assembled permissible diesel-powered machines, and 
subpart I would have set requirements for the approval of fully 
assembled nonpermissible, heavy-duty diesel-powered equipment. In lieu 
of this approach, the final rule responds to the commenters who urged 
that safety and fire protection features for nonpermissible diesel-
powered equipment be addressed in the Agency's part 75 safety standards 
for underground coal mines. Existing part 36 is retained by the final 
rule and revised to specifically apply to permissible diesel-powered 
equipment for use in underground coal mines. Subpart H is not further 
developed by the final rule.
    In the proposal, subparts G and I were developed as an approach to 
several of the Advisory Committee's concerns. In its deliberations, the 
Advisory Committee considered the risk of fire on nonpermissible 
diesel-powered equipment caused by hot surfaces igniting combustibles 
such as hydraulic and lubricating oils, diesel fuel, and coal dust. To 
address this hazard, the Committee recommended limiting engine surface 
temperatures. Under the proposal, surface temperature controls and 
other machine safety features for heavy-duty nonpermissible diesel 
equipment would have been addressed in subparts G and I.
    The Committee, however, also recognized the difficulty of applying 
such controls to all nonpermissible diesel-powered equipment, 
especially light-duty, utility equipment. The Advisory Committee, 
therefore, recommended that a ``limited class'' of light-duty equipment 
be identified for which less complex fire prevention measures would be 
required, such as fire suppression systems which shut down the engine, 
guarded drive shafts to prevent damage of fuel and hydraulic lines in 
the event of a shaft failure, protection of the fuel tank and lines, 
and proper design of the electrical system to prevent electrical arcs. 
The proposal included these requirements for a ``limited class'' of 
light-duty equipment in the part 75 safety standards for underground 
coal mines.
    The Advisory Committee also examined what additional features 
should be included in the approval requirements for completely 
assembled units of diesel-powered equipment. The Committee recommended 
that MSHA develop an approval program that would emphasize other 
equipment safety features which could be readily addressed by equipment 
manufacturers. These features included safeguarding of the fuel system, 
an exhaust gas dilution system, a fire suppression system, and 
appropriate electrical and braking systems. As a completely assembled 
machine, the interrelationship of these systems would be evaluated as 
part of the approval process contemplated in the proposal under subpart 
H.
    A number of commenters objected to the approval of nonpermissible 
diesel-

[[Page 55428]]

powered equipment. These commenters maintained that such an expansion 
of MSHA's approval process would result in regulating diesel-powered 
equipment differently than electric-powered equipment without 
justification, and would present severe technical and economic 
difficulties in meeting certain proposed requirements. The commenters 
recommended that the final rule adhere to the long-standing regulatory 
approach for electric-powered equipment, which sets performance-
oriented safety requirements for nonpermissible equipment in the 
Agency's part 75 safety standards for underground coal mines. According 
to the commenters, this approach would be responsive to the hazards 
posed by diesel-powered equipment, and provide sufficient flexibility 
to facilitate the introduction of new and safer technology.
    In contrast, one commenter urged that all diesel-powered equipment 
be approved as permissible, without regard to the equipment's use in 
the mine. This commenter pointed out that diesel-powered equipment 
presents different hazards than electric equipment, inasmuch as it 
contains both a fuel source and an ignition source. The commenter 
further maintained that permissible diesel-powered equipment receives 
better maintenance than nonpermissible equipment, and explosive 
accumulations of methane can be encountered anywhere in an underground 
coal mine. This commenter noted that since 1969, 10 explosions occurred 
in areas where nonpermissible equipment is permitted, and seven of 
these explosions were caused by equipment that was not maintained in 
permissible condition.
    Another commenter agreed that heavy-duty nonpermissible equipment 
should have approved engines and power packages to limit harmful 
emissions from the engine and protect against the fire hazard presented 
by hot engine surfaces. This commenter, however, objected to MSHA 
approval of fully assembled nonpermissible machines as contemplated by 
subpart I.
    MSHA acknowledges that fire prevention and other machine safety 
features can be successfully introduced for nonpermissible equipment, 
without a formal approval program. This regulatory approach has been 
effectively implemented through MSHA's part 75 safety standards for 
underground coal mines as they apply to nonpermissible electric-powered 
equipment. For example Sec. 75.518 provides fire protection by 
requiring electrical system overload protection for nonpermissible 
electric-powered machines. Section 75.523-3 provides a machine safety 
feature by requiring automatic emergency parking brakes. Setting such 
performance-based requirements for nonpermissible equipment maximizes 
the flexibility afforded mine operators and manufacturers to minimize 
the hazards of this equipment, and facilitates the introduction of new 
technology for dealing with these hazards. For example, new heat 
insulating materials have been developed since the publication of the 
proposed rule, which can be used to control surface temperatures on 
diesel-powered equipment.
    To adapt this regulatory approach to nonpermissible diesel-powered 
equipment, the final rule extends the proposal's safety requirements 
for limited class equipment. Under the final rule, nonpermissible 
diesel-powered equipment is not required to be approved by MSHA. 
Instead, this equipment must comply with the final rule's safety 
requirements in Secs. 75.1909 and 75.1910. These standards include 
requirements for fire prevention and machine safety features such as 
protection of hydraulic, fuel and electrical systems and adequate 
brakes and operator controls.
Part 36
    Existing part 36, previously known as schedule 31, has been in 
effect since 1961. It sets approval requirements and specifications for 
diesel-powered equipment used in ``gassy noncoal mines and tunnels''. 
The final rule retains these existing regulations as the basis for 
approval of diesel-powered equipment and, in lieu of further developing 
subpart H, includes amendments which expand part 36 to apply to 
equipment used in underground coal mines. Specifically, part 36 is 
amended to afford manufacturers the option of incorporating into their 
equipment part 7-approved power packages. Diesel-powered equipment with 
approved power packages will be suitable for use in areas of 
underground coal mines where permissible equipment is required. The 
existing part 36 approval requirements for diesel-powered equipment 
used in metal and nonmetal mines are unchanged by the final rule. Part 
36-approved equipment with certified engines and safety component 
systems will continue to be recognized for use in metal and nonmetal 
mines where permissible equipment is required. MSHA will issue approval 
numbers that differentiate between equipment for use in coal mines and 
equipment for use in metal and nonmetal mines. Machines approved under 
revised part 36 specifically for use in underground coal mines will be 
identified with an MSHA approval number in a new sequence ``36c-''. 
This will indicate that the equipment has been approved for use in 
underground coal mines. A part 36 MSHA approval number in the sequence 
``31-'' will indicate that the equipment has been approved for use in 
metal and nonmetal mines.
    These changes are responsive to a number of commenters who urged 
that the existing part 36 regulations for the approval of diesel-
powered equipment be retained and continue to apply to equipment for 
use in metal and nonmetal mines. In addition, the final rule expands 
the scope of part 36, eliminating the need for separate approval 
regulations for diesel-powered equipment for use in underground coal 
mines as contemplated by subpart H in the proposal.
    To retain part 36 and include the approval of diesel-powered 
equipment for use in underground coal mines, the final rule re-titles 
part 36 and eliminates references to ``gassy noncoal mines and 
tunnels'' and related definitions. In addition, the application 
requirements of Sec. 36.6 and design requirements of Sec. 36.20 are 
revised to recognize the use of part 7-approved power packages, which 
substitute for Secs. 36.21 through 36.26 (except Secs. 36.25(f) and 
36.43 through 36.48).
    The final rule also updates part 36 in several respects. Section 
36.20, concerning the quality of material, workmanship and design, is 
revised to eliminate an outdated reference to Sec. 18.24 of part 18, 
schedule 2F. In its place, the final rule requires compliance with 
Sec. 7.98 of the final rule, which provides structural and flame path 
requirements for explosion-proof enclosures. This aspect of the final 
rule reflects long-standing requirements for explosion-proof 
components.
    The definition of ``low-volatile hydrocarbon (diesel) fuel'' in 
Sec. 36.2(i) is deleted by the final rule. This definition is outdated 
and potentially confusing in context with Sec. 75.1901 of the final 
rule, which specifies requirements for diesel fuel.

C. 30 CFR Part 70 Discussion

Section 70.1900 Exhaust Gas Monitoring
    As outlined in the proposal, the Advisory Committee regarded the 
health effects of diesel exhaust as a key area of concern. In its final 
report, the Advisory Committee focused on two areas--exposure limits 
and a sampling strategy to monitor the concentration of diesel exhaust 
in miners' work environment.

[[Page 55429]]

    The Committee recommended further research to develop information 
about diesel particulate exposure levels at which health effects 
accrue. The Committee also addressed gaseous diesel exhaust components, 
concluding that suitable protection for miners would be achieved by 
relying on coal mine air quality standards, either as they currently 
exist or may be revised in the future. The Advisory Committee further 
concluded that exposure limits for gaseous contaminants of diesel 
exhaust should not be unique from the exposure limits set by the same 
contaminants generated by other mining sources, such as blasting. The 
Committee specifically recommended a periodic sampling strategy for 
carbon monoxide, nitric oxide and nitrogen dioxide and sampling for 
sulfur dioxide if diesel fuel containing more than 0.25 percent sulfur 
is used. In addition, the Advisory Committee recommended a sampling 
strategy which utilized return air course samples to trigger personal 
exposure sampling. The Advisory Committee's recommendations served as 
the basis for the proposed rule.
    The proposed rule did not contain a diesel particulate exposure 
standard. At the conclusion of their deliberations the Advisory 
Committee recommended that the Secretary of Labor set in motion a 
mechanism whereby a diesel particulate standard could be set, and that 
the Secretary work in concert with the Bureau of Mines (BOM) and the 
National Institute for Occupational Safety and Health (NIOSH) to 
develop a sampling strategy and a program for its implementation. 
Subsequent to those deliberations, MSHA has been working closely with 
the BOM and NIOSH to develop methods for measuring diesel particulate 
and for the development of criteria for reducing miners' exposure to 
diesel particulate. In 1991, MSHA issued an advance notice of proposed 
rulemaking seeking additional information for the development of a 
rule. MSHA also held three workshops in 1995 that provided a forum for 
mine operators, labor unions, trade organizations, engine 
manufacturers, fuel producers, exhaust after-treatment manufacturers, 
and academia, to present and discuss information about technologies and 
approaches that can be utilized to limit the exposure of miners to 
diesel particulate. MSHA is currently using the information obtained 
from the advance notice of proposed rulemaking and the workshops to 
develop a proposed rule for reducing miners' exposure to diesel 
particulate.
    The proposal generally followed the Advisory Committee 
recommendations for sampling and permissible exposure limits. Under the 
proposal, samples of carbon monoxide, nitric oxide and nitrogen dioxide 
would be taken weekly in the immediate return airways of each split of 
air where diesel equipment is used. When sampling results exceeded 50 
percent of any permissible exposure limit set by the proposal, personal 
exposure monitoring would have been required. If personal exposure 
samples showed concentrations which exceeded 75 percent of the 
permissible exposure standard, sampling would continue each operational 
shift until, with 95 percent confidence, it was established that 
exposure was at or below the permissible level.
    Commenters to the proposed rule generally accepted the need for 
regular sampling to evaluate miners' working conditions for the 
presence of potentially harmful gaseous diesel exhaust components. A 
number of commenters, however, noted that the proposed rule was too 
focused on sampling, and gave inadequate attention to requiring 
corrective action.
    Some commenters recommended an alternative to sampling in return 
air courses. These commenters suggested a personal sampling approach 
keyed to the person in each mechanized mining unit likely to experience 
the highest diesel exhaust exposure. This ``designated occupation'' 
would be identified in the mine's ventilation plan. According to the 
commenters, this approach would recognize differences in mine 
configuration and mining methods.
    Some commenters considered the proposed action level for area 
samples, set by the proposal at 50 percent of the permissible exposure 
limit values for the gaseous emission components being measured, to be 
reasonable. One commenter, in support of the action level concept, 
noted that sampling in the immediate return air course would measure 
the contribution of all diesel equipment on the mining section, thereby 
yielding readings that would give reasonable assurance that miners 
working on the section were protected.
    Other commenters considered the 50 percent action level possibly 
too low for mines with naturally occurring ambient levels of carbon 
monoxide near the action level. Some of these commenters also foresaw 
possible problems at mines operating near the 50 percent action level. 
These commenters were concerned that an unnecessarily burdensome cycle 
of area sampling followed by personal sampling could result. Commenters 
also noted that the 50 percent action level could be raised because the 
permissible exposure limits themselves include a safety factor. No 
commenters offered data or specific support for a particular action 
level.
    Commenters also expressed concern about how effectively the 
proposed sampling procedures would address variations in the 
concentration of diesel exhaust in miners' workplaces. A number of 
commenters suggested different strategies with more frequent samples to 
better monitor the presence of the gaseous components of diesel 
exhaust. Some commenters suggested special sampling to evaluate peak 
exposure when, for example, equipment was operated under load. Other 
commenters opposed such an approach, citing difficulties in determining 
when peak conditions might occur. Another commenter recommended, in 
addition to weekly samples in return air courses, weekly personal 
samples of each diesel equipment operator, and at the same time samples 
for at least two miners working inby all pieces of diesel equipment on 
the same split of air. According to this commenter, the suggested 
sampling strategy would yield better information about what diesel 
exhaust control measure modifications may be needed. Other commenters 
noted the dynamic nature of the underground mining environment, which 
varies the concentrations of diesel exhaust in miners' workplaces. 
These commenters recommended sampling be performed every shift in 
miners' work areas to timely detect the onset of elevated levels of 
diesel exhaust contaminants.
    A number of commenters also noted that, in addition to sampling in 
the immediate return air course, attention should be given to the area 
of the section loading point. According to these commenters, diesel 
exhaust contaminants are often elevated at this location due to high 
engine loads at a single stationary point. Commenters also noted the 
need to address situations when diesels are used in locations outby the 
working faces. According to these commenters, construction projects can 
involve significant diesel usage at some mines.
    The proposed rule did not specify sampling methods for evaluating 
the gaseous components of diesel exhaust. In the preamble discussion to 
the proposal, however, MSHA made reference to electrochemical analyzers 
and detector tubes as technology that could be used to determine 
concentrations of the gases to be measured. Commenters did not suggest 
specific sampling methods or object to those mentioned in the preamble 
discussion. Some commenters, however, emphasized that the methods 
chosen should not be highly technical in

[[Page 55430]]

nature. Several commenters urged that the task of sampling be something 
miners generally could perform with proper training.
    As discussed elsewhere in this preamble, the final rule as a whole 
is designed to lay a foundation for the safe and healthful operation of 
diesel equipment in the confined, potentially explosive underground 
coal mine environment. To accomplish this objective, the final rule 
sets standards for diesel engines, suitable for mining. For the 
operation of this equipment, the final rule sets practicable standards 
for the use of low sulfur fuel and for adequate ventilation and proper 
maintenance of diesel equipment. These standards are intended to work 
together as an operating system to create a more healthful and safe 
working environment for miners.
    Paragraph (a) of the final rule adopts a streamlined sampling 
strategy that is keyed to this operating system approach. The 
requirements of proposed Sec. 70.1900 have been revised in the final 
rule to integrate sampling for gaseous components of diesel exhaust 
with existing on-shift workplace examination requirements and to take 
advantage of modern sampling instrumentation. The final rule also 
incorporates by reference the threshold limit values (TLV's) 
adopted by the American Conference of Governmental Industrial 
Hygienists (ACGIH). These TLV's are also incorporated by 
reference in MSHA's existing standards for exposure limits in 
Sec. 75.322. The final rule retains the proposed action level concept 
with some modifications responsive to commenters. However, the final 
rule does not adopt the proposed requirement that area samples over the 
action level trigger personal sampling. Instead, paragraph (c) of the 
final rule requires corrective action to be taken immediately to reduce 
gaseous diesel exhaust concentrations to or below the action level. The 
final rule's sampling requirements are intended to provide a regular 
and timely check on how the total operating system of diesel exhaust 
control is working, with an emphasis on prompt corrective action.
    Although the final rule does not require personal sampling, 
existing standards regulate miners' exposure to harmful airborne 
contaminants. These standards do not permit miner exposures over the 
established TLV's incorporated in this section of the final 
rule and in Sec. 75.322. MSHA enforces these standards during mine 
inspections through personal and other sampling methods.
    Like the proposal, paragraph (a) of the final rule specifies area 
samples in the ventilation return airways of each working section where 
diesel equipment is used, at a location which represents the 
contribution of all diesel equipment on the section. This approach was 
recommended by the Advisory Committee, and generally was supported by 
the commenters. In response to commenters, the final rule also requires 
samples in the area of the section loading point if diesel haulage 
equipment is operated on the working section, and at the point inby the 
last unit of diesel equipment on the longwall or shortwall face where 
mining equipment is being installed or removed. Depending on the mining 
system used, these are strategic locations in which to take area 
samples to evaluate the overall effectiveness of the control measures 
for diesel exhaust.
    In addition, the final rule authorizes the MSHA district manager to 
specify area samples at other strategic locations on a mine-by-mine 
basis in order to accommodate circumstances which can result in 
significant concentrations of diesel exhaust. This aspect of the final 
rule responds to commenters' concerns about situations which can 
involve significant diesel usage in areas outby the working face, such 
as construction projects. The paperwork aspect of this provision 
results in a minimally increased burden since existing Sec. 75.370 of 
this chapter requires that all underground coal mines have ventilation 
plans. Although this provision of the final rule is new, proposed 
Sec. 75.390(b) would have required that the mine operator include 
certain minimum ventilation quantities in the mine's ventilation plan. 
Under the proposal, these minimum air quantities would have been 
related to the number of diesel-powered units operating and the air 
quantity necessary to control gaseous diesel emissions. Thus, this 
final rule provision is consistent with proposed Sec. 75.390(b).
    Monitoring of gaseous diesel exhaust components during the on-shift 
examination required by existing Sec. 75.362 of this chapter makes 
checks for diesel exhaust concentrations part of the workplace 
examinations which have been historically conducted in the coal mining 
industry. On-shift examinations are designed to detect hazards which 
can develop during a working shift when normal mining operations are 
underway. Such examinations include tests for methane gas accumulations 
and oxygen deficiency, and determinations of air direction and 
velocity. Tests for diesel exhaust gases can be readily made during the 
on-shift examination by the same mine personnel. Currently, multi-gas 
detectors are available and in use in a significant number of mines in 
the industry which can sample simultaneously and directly read out 
results for methane, oxygen, carbon monoxide and nitrogen dioxide. 
Making checks of the mine's diesel exhaust control system part of the 
existing practice of on-shift examinations minimizes the burden of 
compliance with the final rule's sampling requirements. Under the final 
rule, special staff and a separate diesel exhaust sampling schedule 
should be unnecessary.
    Sampling as part of the on-shift examination also increases the 
frequency of diesel exhaust concentration monitoring from the proposed 
weekly schedule, and responds to commenters who questioned the adequacy 
of the proposal in this regard. The final rule's increased frequency of 
sampling affords more timely and meaningful information about the 
performance of the mine's overall diesel exhaust control system. Diesel 
equipment is highly mobile and the mining environment changes rapidly 
as mine development progresses. Monitoring each shift alerts the mine 
operator to emerging problems with the control of diesel exhaust, 
before miners are overexposed to harmful contaminants.
    Consistent with existing Sec. 75.362 of this chapter, the final 
rule also requires sampling to be performed by a certified person 
designated by the operator. This aspect of the final rule is generally 
consistent with the proposal as it requires that competent persons 
perform the sampling, the results of which form the basis for important 
decisions about miners' work environments.
    Under the final rule, sampling would be required for two gaseous 
components of diesel exhaust: carbon monoxide and nitrogen dioxide. The 
final rule does not retain the proposal for sampling sulfur dioxide 
when diesel fuel containing more than 0.25 percent sulfur is used. 
Section 75.1901 of the final rule requires the use of low-sulfur fuel 
at all times, rendering this aspect of the proposed rule unnecessary. 
The final rule also deletes the proposed requirement for sampling 
nitric oxide.
    Both carbon monoxide and nitric oxide are produced in significant 
quantities when diesel engines operate under load. Elevated carbon 
monoxide is also indicative of engine faults such as misadjusted fuel 
systems, failure to derate engines for altitude, or dirty air cleaners. 
Conditions of use such as prolonged diesel engine idling can also 
produce elevated levels of carbon monoxide. Catalytic converters, 
designed to remove carbon monoxide

[[Page 55431]]

from the exhaust, work poorly under these conditions due to lower 
equipment operating temperatures.
    Nitric oxide concentrations generally do not reflect engine faults. 
In addition, nitric oxide is readily converted to nitrogen dioxide in 
the mine atmosphere, making representative measurement difficult under 
the final rule's area sampling strategy. Also, in MSHA's experience the 
TLV for carbon monoxide will be exceeded before the 
TLV for nitric oxide. Sampling for nitric oxide, therefore, 
is not retained in the final rule.
    The final rule also requires sampling for nitrogen dioxide. 
Nitrogen dioxide is readily detectable and potentially harmful to 
miners. The TLV for nitrogen dioxide is 5 parts-per-million 
(ceiling), which cannot be exceeded at any time. Therefore, the final 
rule adopts the proposed requirement to sample for nitrogen dioxide.
    The final rule addresses the collection of carbon monoxide and 
nitrogen dioxide samples with performance-based requirements. In 
response to commenters, the task of sampling is significantly 
simplified. The sampling requirements also emphasize prompt 
availability of sample results, consistent with the final rule's 
emphasis on corrective action to protect miners from the risk of 
overexposure.
    Paragraph (b)(1) provides that monitoring of carbon monoxide and 
nitrogen dioxide is to be performed in a manner which makes the results 
available immediately to the person collecting the samples. This aspect 
of the final rule recognizes that direct-readout sampling instruments 
are now available that can measure carbon monoxide and nitrogen 
dioxide. Use of these hand-held instruments requires no specialized 
technical background so that persons may be easily trained to perform 
this task. Mine-wide monitoring systems, with properly located sensors, 
could also be employed to collect the required carbon monoxide and 
nitrogen dioxide samples.
    Paragraph (b)(2) of the final rule generally adopts the proposal, 
and specifies that samples are to be collected by appropriate 
instrumentation that has been maintained and calibrated in accordance 
with the manufacturer's recommendations. These provisions establish 
sound practices necessary for accurate sample results, while retaining 
the flexibility for new instrumentation that may be developed in the 
future.
    Paragraph (b)(3) requires that samples be collected during periods 
that are representative of conditions during normal operations. This 
aspect of the final rule is consistent with the proposal and serves the 
underlying purpose of the sampling requirements, which is to gauge the 
performance of the diesel exhaust control system under normal operating 
conditions. Like the proposal, the final rule does not prescribe 
special requirements to measure the performance of the diesel exhaust 
control system under peak load conditions. As some commenters noted, 
determining when peak load conditions occur would be difficult to 
predict. In addition, such an approach would increase the complexity of 
the final rule unnecessarily.
    Regular sampling during on-shift examinations will afford a 
realistic picture of the performance of the diesel operating system. To 
meet the requirement that samples be taken during periods that are 
``representative of conditions during normal operations,'' MSHA intends 
that tests for carbon monoxide and nitrogen dioxide be made when 
diesel-powered equipment is being used as it typically is in the mining 
process. Thus, for example, sampling is appropriate when diesel haulage 
equipment is moving coal or diesel-powered roof bolters are installing 
bolts.
    Some commenters noted the need to monitor exhaust concentrations 
during longwall moves with diesel-powered equipment, expressing concern 
that moving the component parts of a longwall to a new block of coal 
for mining can involve heavy usage of diesel equipment over the course 
of multiple shifts. As a result, miners could be exposed to elevated 
levels of diesel exhaust gases. The final rule addresses these comments 
through the increased frequency of samples to monitor diesel exhaust 
gases. On-shift examinations are required under Sec. 75.362 of this 
chapter when longwall moves are being performed and, under the final 
rule, tests of the concentrations of carbon monoxide and nitrogen 
dioxide are required at the point immediately inby the last piece of 
diesel equipment on the longwall or shortwall face. If these samples 
indicate carbon monoxide and/or nitrogen dioxide concentrations greater 
than the action level, immediate corrective action is required. This 
approach protects miners through early detection of elevated 
concentrations of diesel exhaust gases, and prompt adjustments to the 
mine's diesel exhaust controls.
    Paragraph (c) of the final rule is modeled after other MSHA 
standards for potentially hazardous gases, such as methane, and 
requires immediate corrective action when sample results indicate gas 
concentrations exceeding the action level. This change in the proposal 
is responsive to commenters who pointed out that the proposal gave 
inadequate attention to corrective action. The final rule retains the 
proposed action level concept tied to the TLV's for carbon 
monoxide and nitrogen dioxide. The exposure limits incorporated are 
those already incorporated in existing Sec. 75.322 of this chapter. 
These exposure standards are based on the 1972 threshold limit values 
set by the American Conference of Governmental Industrial Hygienists 
(ACGIH) and have applied to underground coal mines for nearly 25 years. 
This aspect of the final rule comports with the recommendation of the 
Advisory Committee that gaseous diesel exhaust components not be 
treated differently from contaminants generated by other mining 
sources. The final rule does not adopt updated permissible exposure 
standards at this time, as referenced in the proposal, because this 
issue remains in the rulemaking process for Air Quality standards.
    Under paragraph (c) of the final rule, the action level is set at 
50 percent of the TLV's for carbon monoxide and/or nitrogen 
dioxide for samples collected in the areas identified in paragraph (a). 
As noted in the proposed rule, an action level is used to minimize the 
risk that workers will be overexposed. An action level is not a 
compliance limit for miners' exposure. Instead, an action level is 
intended to provide a timely trigger for reviewing the mine's diesel 
exhaust control system. Exceeding an action level under the final rule 
is not, by itself, a violation.
    The 50 percent action level concept is well-recognized in 
industrial hygiene practice as an effective, practical screening tool 
for minimizing the risk of workers' overexposure. This approach, based 
largely on statistical considerations, was developed by the National 
Institute for Occupational Safety and Health (NIOSH) for regulations 
promulgated by the Occupational Safety and Health Administration 
(OSHA), ``Leidel et al., NIOSH Publication No. 77-173.''. It is 
designed to afford a single value trigger for simplicity of application 
and to reduce exposure monitoring burdens. ``Patty's Industrial Hygiene 
and Toxicology, 1994, p. 528.'' Based on the work of Nelson A. Leidel 
and others, the 50 percent action level is considered a reliable 
indicator that there is a low probability of worker exposures which 
exceed the TLV linked to the action level.
    The action level of 50 percent of the TLV's for carbon 
monoxide and nitrogen dioxide is well-suited to the

[[Page 55432]]

purposes of this final rule, and will afford miners protection from 
overexposure to potentially harmful diesel exhaust emissions. Samples 
collected in accordance with paragraph (a) of this section will yield 
results showing the concentration of diesel exhaust emissions in key 
places under representative conditions on a regular basis. Applying the 
50 percent action level to these routine sample results will account 
for sources of variability affecting miners' exposure, such as the 
diesel activity level, ventilation rates, and duty cycles. The action 
level also provides a simple means of evaluating the status of the 
mine's overall diesel exhaust control system. As discussed elsewhere, 
this operating system approach to the control of diesel exhaust 
emissions is a key underpinning of the final rule.
    The final rule also permits adjustments to the 50 percent action 
level on a mine-by-mine basis. Under Sec. 75.325(j) of the final rule 
the MSHA district manager may approve an alternative action level in 
the mine's ventilation plan. Ventilation plans are required for all 
underground coal mines by existing standards under Sec. 75.370 of this 
chapter. Under the final rule, any change in the 50 percent action 
level must be based on the results of sampling which demonstrate that 
miners' personal exposure will not exceed the applicable TLV. 
Thus, a mine operator may show that a 60 percent action level, for 
example, is appropriate for the miners working on a section. To do 
this, the operator must demonstrate through sampling that miners 
working on the section are not overexposed to diesel exhaust gases when 
samples in the immediate return air course show that concentrations of 
carbon monoxide and/or nitrogen dioxide are maintained at 60 percent of 
the TLV. Based on this data, the 50 percent action level 
could be revised, with the approval of the district manager. The higher 
action level would be made part of the mine's approved ventilation plan 
and, thereby, become a compliance requirement at the mine. If, with 
experience, the revised action level was shown to be inappropriate, 
changes would be made through the mine ventilation plan approval 
process. Mine ventilation plans are required by existing standards to 
be reviewed at least every six months.
    The sampling necessary to demonstrate that the personal exposure of 
miners would not exceed the TLV is not specified by the final 
rule, recognizing that many approaches can be taken. For approval to 
revise an action level, however, MSHA will require clear evidence that 
a proposed change in an action level is appropriate. As discussed 
above, the purpose of an action level is to trigger a review of the 
mine's diesel exhaust control system before miners are overexposed to 
harmful gases. As the action level is raised closer to the 
TLV, the reliability of the action level as a timely warning 
diminishes. Thus, MSHA does not anticipate approval of action levels 
that provide a nominal margin of protection.
    The final rule does not specify what corrective action is required 
when an action level for carbon monoxide and/or nitrogen dioxide is 
exceeded. Instead, this determination is to be made by the mine 
operator, who is in the best position to implement changes appropriate 
to the situation and sufficient to promptly return carbon monoxide and/
or nitrogen dioxide concentrations to or below the applicable action 
level. Corrective action may involve addressing ventilation 
deficiencies, controlling the number of diesel machines operating in an 
area, or correcting engine faults. Elevated levels of carbon monoxide 
and/or nitrogen dioxide may indicate that appropriate corrective action 
is revision of the mine's ventilation plan. Modifying the mine's 
ventilation plan integrates needed controls into the operating system 
for the mine.
    The final rule does not retain the proposed requirement to conduct 
personal sampling when the action level for gaseous diesel exhaust 
components is exceeded. Proposed Sec. 70.1901 therefore is not included 
in the final rule. While the Advisory Committee recommended a two-
tiered approach of area sampling which could trigger personal sampling, 
MSHA believes that the final rule's sampling strategy will better 
protect miners. As discussed above, the sampling strategy adopted 
focuses on the performance of the mine's control system for diesel 
exhaust, rather than measurements of individuals' exposure levels. This 
approach safeguards miners from overexposure by frequent testing for 
gaseous diesel exhaust components in key areas, and establishing action 
levels for initiating corrective action that responds to emerging 
problems. In addition, MSHA mine inspections will include regular 
checks on miners' exposure to harmful airborne contaminants, including 
carbon monoxide and nitrogen dioxide, as part of determining compliance 
with the TLV's in Sec. 75.322 of this chapter. MSHA's current 
practice is to sample, at least annually, all diesel equipment 
occupations on each mechanized mining unit. It is MSHA policy to also 
sample half of the diesel equipment occupations in areas outby the 
face. As a result, MSHA is confident that miners will be adequately 
protected.
    The final rule changes also respond to commenters who objected to 
the proposed personal monitoring requirements as fostering excessive 
sampling. In its guidance comments, the Office of Management and Budget 
counseled that the criteria for personal monitoring had the potential 
for an unnecessarily burdensome paperwork loop in which a mine would be 
required to conduct area sampling one week and personal sampling the 
next week. Other commenters also foresaw the potential for a cycle of 
area sampling followed by personal sampling, particularly at mines with 
naturally occurring high levels of carbon monoxide. These commenters 
also objected to the proposal that when personal exposure monitoring 
results indicate levels greater than 75 percent of the permissible 
exposure limit, such sampling would be required to continue on each 
operational shift until compliance was established with 95 percent 
confidence. By focusing the final rule's sampling requirements on 
monitoring the performance of the mine's diesel exhaust control system 
and taking timely corrective action, this potential problem is 
eliminated.
    The proposed rule recordkeeping requirements were tied to MSHA's 
proposed Air Quality standards in Secs. 72.200 (d), (e), (f) and (g) of 
this chapter. Commenters objected to the proposal's reference to MSHA's 
proposed Air Quality standards concerning exposure monitoring and 
referenced the comments they had submitted on those proposed rules. 
Under the proposal, the results of miners' personal samples were to be 
maintained for 5 years and include personal identification information 
as well as data about sampling location, duration, and results. The 
proposed requirements also required a record of the corrective action 
taken if miners' exposure readings exceeded the permissible limit. In 
addition, the proposed rule set requirements for access to miners' 
personal exposure records, provided miners or their representatives 
with the opportunity to observe monitoring, and called for notification 
of miners when samples indicate they have had exposures exceeding the 
permissible limit.
    In the Air Quality rulemaking, commenters objected to MSHA's 
proposal that adjustments to calculations of exposure be made for novel 
workshifts when a miner worked longer than eight hours. Commenters also 
objected to mine operators having to take corrective action to reduce

[[Page 55433]]

exposures based on one sample showing overexposure. In addition, 
commenters objected that it was burdensome to include the mine 
operator's corrective action in exposure monitoring records. Other 
commenters supported this requirement. These commenters further stated 
that the period for record retention should be 30 years for 
epidemiological purposes and to be consistent with the Occupational 
Safety and Health Administration's general industry requirements.
    For the reasons discussed above, the final rule re-focuses sampling 
for the gaseous components of diesel exhaust on early detection of 
diminishing performance of the mine's diesel exhaust control system. As 
a result, personal samples are not required. Certain limited 
recordkeeping is, however, necessary to support the final rule's 
objective of tracking the performance of the mine's diesel exhaust 
control system. To accomplish this objective with the least 
recordkeeping burden, paragraph (d) of the final rule revises the 
recordkeeping requirements of the proposal, conforming them to the 
existing requirements for on-shift examinations. Under the final rule, 
a record is required to be made of the results of samples taken under 
this section which exceed the applicable action level for carbon 
monoxide and/or nitrogen dioxide. Like the proposal, the data to be 
recorded under the final rule include the location where the sample was 
taken; the concentration of carbon monoxide and/or nitrogen dioxide 
measured; and the corrective action taken to reduce the concentration 
of carbon monoxide and/or nitrogen dioxide to below the applicable 
action level. A record of the instrumentation used, which would have 
been required under the proposal, has not been adopted in the final 
rule, because this is not essential information under the sampling 
scheme of the final rule.
    This aspect of the final rule is intended to minimize recordkeeping 
by requiring a record only when sample results are over the appropriate 
action level. This information is key to an effective monitoring system 
and provides essential data for assessing how the mine's diesel exhaust 
control system is functioning.
    For ease of administration by mine operators, the final rule 
specifies that recordkeeping under paragraph (d) follow the same 
requirements contained in existing Sec. 75.363 of this chapter. These 
standards prescribe the recordkeeping requirements for hazardous 
conditions found during a shift, including on-shift examinations. 
Section 75.363 of this chapter requires that the record be kept in a 
book maintained for the purpose on the surface of the mine, and that 
the record be completed by the end of the shift. Section 75.363 
requires that the record be made by the certified person who conducted 
the examination, or a person designated by the operator. In the latter 
case, the certified person must verify the record by the end of the 
shift. Records made under Sec. 75.363 also must be countersigned by the 
mine foreman or equivalent mine official by the end of the mine 
foreman's or equivalent mine official's next regularly scheduled 
working shift. These features of Sec. 75.363 emphasize the importance 
of mine management using and responding to data about working 
conditions in the mine.
    Section 75.363 also recognizes the use of electronic recordkeeping 
technology, provided it is made secure and not susceptible to 
alteration. MSHA encourages the use of such systems to ease 
recordkeeping burdens and facilitate analysis of this important 
information.
    The final rule does not retain certain proposed recordkeeping 
requirements which related to personal exposure monitoring. These 
include notification of miners if they are exposed over permissible 
limits, the opportunity for miners to observe personal monitoring being 
conducted, and access to personal exposure records by miners and their 
representatives. Since personal sampling is not required by the final 
rule, these provisions of the proposal are no longer appropriate.
    The final rule does, however, make results from area samples 
required by this section available for inspection by miners' 
representatives and MSHA inspectors through Sec. 75.363 of this 
chapter. This aspect of the final rule is consistent with the statutory 
role of miners' representatives and facilitates meaningful mine 
inspections. The retention period for the records required by paragraph 
(d) is at least one year, through the existing requirements of 
Sec. 75.363 of this chapter.
    Paragraph (e) of this section of the final rule provides that 
exhaust gas monitoring be conducted in accordance with Sec. 70.1900 as 
of 12 months after the publication date of the rule. This compliance 
deadline should provide mine operators with adequate time to implement 
the requirements of this section, and corresponds to the 12-month 
compliance deadline for the new ventilation requirements for diesel-
powered equipment in Sec. 75.325 of the final rule. Persons who are 
qualified to take the required gas measurements should be available at 
the mine, given the fact that air sampling for other gases, such as 
methane, is already required.

D. 30 CFR Part 75 Discussion.

Section 75.325  Air Quantity
    Diesel engines produce exhaust containing carbon monoxide, the 
oxides of nitrogen, and particulate matter, presenting potentially 
serious health risks to miners. Ventilation systems at underground coal 
mines where diesel-powered equipment is operated must be designed to 
dilute and carry away diesel exhaust contaminants, to ensure that 
miners' exposure to contaminants is maintained within acceptable 
limits. This portion of the final rule establishes minimum air quantity 
requirements in areas of underground coal mines where diesel-powered 
equipment is operated. These requirements recognize that effective mine 
ventilation is a key component in the control of miners' exposure to 
diesel exhaust contaminants.
    Air quantity requirements for diesel equipment were proposed in 
Sec. 75.390. Under the final rule these requirements have been 
consolidated with the other air quantity requirements for underground 
coal mines located in existing Sec. 75.325.
    The final rule provides that the minimum air quantity required to 
ventilate an individual unit of diesel-powered equipment is the 
quantity listed on the equipment approval plate. The approval plate 
quantity, which is calculated under Sec. 7.88 of the final rule for 
each engine model, is the amount of air necessary to dilute carbon 
monoxide (CO), carbon dioxide (CO2), nitric oxide (NO), and 
nitrogen dioxide (NO2) to the levels set by existing Sec. 75.322 
for those gaseous contaminants. This ventilation rate must be displayed 
on the engine's approval plate. The approval plate air quantity must be 
maintained: in any working place where an individual unit of diesel 
equipment is being operated; at the section loading point during any 
shift the equipment is being operated on the working section; in any 
entry where equipment is being operated outby the section loading point 
in areas of the mine developed on or after the effective date of the 
final rule; and in any air course with single or multiple entries where 
equipment is being operated outby the section loading point in areas of 
the mine developed prior to the effective date of the final rule. The 
district manager may also designate, in the ventilation plan, 
additional locations where minimum air quantities must be maintained 
for individual units of equipment.

[[Page 55434]]

    In areas of the mine where multiple units of diesel-powered 
equipment are operated, the final rule provides that the minimum air 
quantity will be the sum of the approval plate air quantities of all of 
the equipment. The air quantity must be maintained in the last open 
crosscut of each set of entries or rooms in each working section; in 
the intake, reaching the working face of each longwall; and at the 
intake end of any pillar line. The final rule allows certain types of 
equipment to be excluded from the multiple unit calculation for air 
quantity, based on the fact that the emissions from those types of 
equipment would not significantly affect the exposure of miners to 
contaminants. The final rule also authorizes the district manager to 
allow reduced air quantities in the ventilation plan for multiple units 
of diesel-powered equipment, if the mine operator presents evidence 
that justifies the reduction. Under this section mine operators are 
also permitted to obtain district manager approval for an action level 
other than the 50 percent level specified in Sec. 70.1900, if evidence 
submitted by the mine operator supports such a change.
    The Diesel Advisory Committee recommended that MSHA establish 
minimum ventilating air quantities for areas of the mine where diesel-
powered equipment operates, and that these minimum quantities be 
specified in the mine operator's ventilation plan. The Advisory 
Committee further recommended that required air quantities be based on 
the approval plate air quantities, with appropriate provisions made to 
address multiple units of equipment in the same air course. The 
Committee also concluded that allowances should be made for adjustment 
to minimum air quantities, if operating experience and workplace 
sampling indicate that such an adjustment is appropriate. Finally, the 
Committee recommended that a particulate index be developed for each 
piece of diesel-powered equipment and be reported on the engine 
approval plate.
    Under the proposed rule, the minimum quantity of air in any split 
of air where an individual unit of diesel-powered equipment was 
operated would have been the approval plate air quantity. The minimum 
air quantity on any split of air where multiple diesel units were 
operating would have been calculated using the sum of 100 percent of 
the highest approval plate air quantity, 75 percent of the second 
highest approval plate air quantity, and 50 percent of any additional 
approval plate air quantities. This was referred to as the ``100-75-
50'' approach during the public hearings and throughout the rulemaking 
process. Minimum air quantity requirements would also have applied when 
face equipment was being installed or removed.
    The proposed rule would also have established a minimum ventilation 
quantity based upon the particulate index determined for each type of 
diesel engine. The particulate index would have specified the quantity 
of air needed to dilute the diesel particulate matter generated by the 
specific engine to 1 milligram per cubic meter of air. In some cases 
the minimum air quantity derived from the particulate index would have 
been greater than the air quantity specified on the machine approval 
plate.
    A major concern of many commenters was the use of approval plate 
air quantities in establishing ventilation requirements for both 
individual and multiple units of diesel-powered equipment. A number of 
commenters stated that the air quantities specified on engine approval 
plates are not always necessary to dilute contaminants generated by the 
equipment to permissible levels. Several commenters expressed concern 
that the proposal represented a simplistic approach to complex issues, 
given the great variety of ventilation systems in underground coal 
mines.
    Some commenters stated that determining minimum air quantities on a 
mine-by-mine basis was more appropriate than the across-the-board 
approach taken in the proposal. Most of these commenters stated that if 
a mine's air quality is acceptable, air quantity should not be an 
issue, advocating a performance-based approach. These commenters 
believed that the final rule should give mine operators much more 
flexibility than the proposal would in designing their ventilation 
systems.
    A number of these commenters recommended that approval plate 
quantities be used only as a guideline for determining minimum air 
quantities for diesel equipment, and that a number of other variables 
be taken into account in determining the quantity of air needed to 
dilute exhaust contaminants. Commenters stated that such variables 
should include the minimum volume and velocity of air proposed by the 
mine operator; the number of diesel-powered units operating on the 
section; the equipment approval plate quantities; the duty cycles of 
the equipment; and the duty cycles of equipment that is not typically 
operating, such as equipment used for longwall moves.
    Some commenters recommended the exclusion of certain equipment, 
such as limited class equipment and equipment that is vented directly 
into return air courses, from minimum air quantity calculations. 
Commenters also suggested that administrative and engineering controls 
designed to maintain contaminant levels within acceptable limits, as 
well as respiratory protection practices implemented at the mine, 
should be taken into account in calculating minimum air quantities.
    One commenter pointed out that an engine's approval plate air 
quantity is based on the worst point of the operational range of the 
engine. The commenter further stated that this engine rating fails to 
take into account a number of factors that affect the gaseous emissions 
levels actually discharged into the mine environment, including the 
equipment power package; the engine duty cycle; the mine's elevation; 
the fuel used; and equipment maintenance.
    Other commenters stated that the proposal would give no credit to 
mine operators who used low emission technology, and that consideration 
should be given to calculating approval plate quantities after rather 
than before exhaust gases are treated. Other commenters stated that 
approval plate air quantities were well below average ventilation 
quantities currently provided in any given split of air.
    The final rule does not incorporate the approach advocated by 
several commenters for individual units of diesel-powered equipment. 
Instead, paragraph (f) adopts the proposed requirement and provides 
that the minimum ventilating air quantity where an individual unit of 
diesel- powered equipment is operated is the approval plate air 
quantity.
    Although commenters are correct in stating that the goal of air 
quantity requirements is to ensure that exhaust contaminants produced 
by the diesel engine are diluted to within acceptable limits, thereby 
preventing overexposure of miners, a pure performance-oriented 
approach, based on sampling to determine whether contaminants are 
within acceptable limits, is not the best way to achieve this goal. 
Elimination of minimum air quantities and adoption of the performance-
based scheme advocated by some commenters would by necessity demand an 
extensive and burdensome regimen of personal sampling to ensure that 
miners are not being overexposed. In contrast, the mandatory minimum 
ventilating air quantities in the final rule will give reasonable 
assurance that contaminant levels are being adequately controlled, 
while the sampling that an operator must perform has been minimized. 
The

[[Page 55435]]

amount of air required by the approval plate quantity to ventilate a 
diesel engine is a scientifically-based determination of the minimum 
air needed to maintain gaseous contaminants, particularly NO2, 
within acceptable limits and avoid overexposures of miners. The 
sampling under the final rule confirms that the integrated system of 
protections--diesel engines that are well maintained and effectively 
ventilated--continues to function as intended.
    The approach taken by the final rule is an effective method of 
minimizing miners' exposure to unhealthful diesel emissions. As 
explained above, the approval plate air quantity is derived from a 
mathematical determination of the amount of air that is needed to 
dilute CO, CO2, NO, and NO2 to the TLV's 
established in existing Sec. 75.322, which have applied in underground 
coal mines for the last 25 years. The TLV's for these 
contaminants, with the exception of NO2, are time-weighted 
averages, which means that the average concentration of the contaminant 
over an 8-hour period must be within allowable limits, although the 
levels of these contaminants may spike up significantly in excess of 
the TLV in short excursions over the measurement period. In 
contrast, the NO2 limit of 5 parts per million is a ceiling limit, 
which means that concentrations of NO2 must never exceed the 
TLV, even for a brief period of time. This is because 
elevated concentrations of NO2 can be very toxic, and even short 
exposure to high levels of NO2 can cause inflammation of the 
lungs, possibly resulting in pulmonary edema and lung hemorrhaging. The 
only external sign of NO2 poisoning is shortness of breath. 
Sufficient dilution by adequate quantities of air of all contaminants, 
and in particular of NO2, during the entire period that diesel-
powered equipment operates is therefore essential in protecting miners' 
health.
    It is important to note that the approval plate calculation assumes 
total mixing of the exhaust gases in the ventilating air, and that 
levels of exhaust gases that are higher than the TLV's will 
likely occur close to the machine's exhaust, before the gases are fully 
dispersed and diluted by the ventilating air. Essentially, this means 
that the approval plate air quantity represents the best-case scenario 
for contaminant dilution. The approval plate air quantity is therefore 
the smallest amount of air that will ensure that contaminants are 
within acceptable levels at all points in the engine's duty cycle.
    It should also be noted that the oxides of nitrogen (NO and 
NO2) have been the controlling gases for engine approval plate 
quantities for the vast majority of diesel engines that have been 
approved in the past. This means the approval plate quantity is 
determined by the air needed to dilute those two gases; a lesser 
quantity of air is sufficient to dilute the other gaseous contaminants 
produced by the engine. Although NO does not have the same toxic 
effects as NO2, it does convert to NO2 over time. As 
mentioned above, sufficient dilution of NO2 is essential to 
protect miners from its potentially severe effects.
    The approval plate air quantity calculation takes into account the 
worst operating point of a properly maintained engine tested under 
laboratory conditions. Some commenters asserted that approval plate air 
quantities were unnecessarily high, because the quantities were 
calculated for the worst operating point of the machine, when the 
machine generated the highest levels of gaseous contaminants. Although 
commenters are correct in stating that the approval plate calculation 
represents the air quantity needed to dilute contaminants at the point 
where the engine produces the highest level of emissions, diesel engine 
emission levels are high over a range of operating points. See, Report 
of the Bureau of Mines, U.S. Department of the Interior, ``Relationship 
of Underground Diesel Engine Maintenance to Emissions'' (December 
1983). Contrary to the assertions of some commenters, the engine 
approval plate quantity does not represent an unrealistically high 
quantity of air, but is an accurate determination, based on testing, of 
the ventilating air quantity needed to protect miners working in the 
vicinity of the equipment over their working shift. Finally, as pointed 
out by one commenter, the approval plate air quantity is calculated 
using new engines, whose performance will likely degrade to some extent 
over time, with the potential for increased emission levels, even if 
the engines are well maintained.
    The performance-based approach advocated by several commenters 
could provide another method for determining minimum air quantities, 
but, for the reasons stated earlier, would substitute a rather 
intricate sampling process that would result in a determination that 
essentially the same minimum air quantities are needed to ventilate the 
equipment. Mandating approval plate quantities as the minimum air 
quantities is not the only approach to ventilation of diesel-powered 
equipment, but it is the most workable and practical.
    The final rule does not adopt the suggestion of commenters who 
advocated factoring in exhaust after-treatment in determining minimum 
air quantities. The after-treatment technology currently available is 
ineffective in reducing the oxides of nitrogen. Consequently, the gases 
used to determine the approval plate air quantities for the vast 
majority of diesel engines that have been approved cannot be controlled 
by existing exhaust after-treatment technology. This recommendation has 
therefore not been adopted in the final rule.
    The locations where minimum air quantities must be maintained for 
individual units of diesel equipment have been modified in the final 
rule from what would have been required under the proposal. The 
proposal would have required minimum air quantities for individual 
units of equipment to be maintained in any split of air where the 
equipment was being operated. A number of commenters disagreed with 
this provision, stating that the term ``split'' was vague and 
ambiguous, and did not adequately specify areas of the mine where 
individual units of equipment were likely to operate and generate high 
levels of diesel exhaust contaminants. Commenters also identified outby 
areas and section loading points as locations where diesel exhaust 
levels tended to be a particular problem and where additional 
ventilating air was needed. Several commenters stated that it was 
essential to have adequate ventilation across the mine's dumping points 
to ensure that diesel emissions are swept out of the area. These 
commenters stated that the rule should also address outby operation of 
diesel-powered equipment, because excessive diesel emissions occur in 
idled areas of the mine and during non-production times, when less air 
is typically required for ventilation because dangerous levels of 
methane tend to be less of a problem during those periods. Other 
commenters were of the opinion that the rule should not designate 
locations where minimum air quantities must be maintained, and 
supported determining these locations on a mine-by-mine basis.
    In response to commenters, the final rule does not adopt the 
proposed requirement that the air quantity for individual units of 
equipment be maintained in any ``split'' where the equipment was being 
operated. Instead, paragraphs (f)(1) through (f)(5) list the specific 
locations where the minimum air quantity must be maintained, and 
include those locations identified by commenters where diesel equipment 
is typically inadequately ventilated and

[[Page 55436]]

where levels of exhaust contaminants are likely to be high. These 
locations include any working place where the equipment is being 
operated; at the section loading point during any shift the equipment 
is being operated on the working section; in any entry where equipment 
is being operated outby the section loading point in areas of the mine 
developed on or after the effective date of the final rule; in any air 
course with single or multiple entries where the equipment is being 
operated outby the section loading point in areas of the mine developed 
prior to the effective date of the final rule; and at any other 
location required by the district manager and specified in the approved 
ventilation plan.
    Paragraph (f)(1) provides that the minimum ventilating air quantity 
for an individual unit of diesel-powered equipment must be maintained 
in any working place where the equipment is being operated. This 
responds to commenters' concerns and clarifies the intent of the 
proposal, which would have required that the minimum air quantity be 
maintained in the ``split'' where the equipment operates. As discussed 
above, a number of commenters did not consider the term ``split'' to be 
sufficiently descriptive, and the final rule has been revised in 
response. Under the final rule required air quantities must be 
maintained in the ``working place,'' which is defined in existing 
Sec. 75.2 as ``The area of a coal mine inby the last open crosscut.'' 
This location is designed to address ventilation of an individual unit 
of diesel-powered equipment that is working at an inby location, near 
the face.
    Paragraph (f)(2) adds the specific requirement that the minimum air 
quantity for an individual unit of equipment be maintained at the 
section loading point during any shift that the equipment is being 
operated on the working section. This provision responds to commenters 
who singled out loading points as one of the locations where excessive 
levels of diesel contaminants were a particular problem. Commenters 
pointed out that the ventilating air quantities at these locations were 
frequently insufficient to dilute exhaust contaminants and protect 
miners from unhealthful levels of exhaust gases. Because different 
types of equipment move in and out of a section loading point on a 
regular basis, the minimum required air quantity will be the greatest 
approval plate quantity among all of the diesel-powered equipment that 
is operated at the loading point during the shift. This will ensure 
that miners are protected from overexposure to contaminants at all 
times during the shift, regardless of which unit of diesel equipment is 
at the loading point.
    Paragraphs (f)(3) and (f)(4) have been added to the final rule to 
address the concerns of those commenters who stated that minimum 
ventilation requirements should apply to diesel-powered equipment that 
is being operated in outby areas. These two provisions, one of which 
applies to areas of the mine developed before the effective date of the 
final rule and the other which applies to areas developed on or after 
the effective date, recognizes that the ventilation system design at 
some mines with multiple common haulage entries would make it 
difficult, if not impossible, to maintain minimum air quantities in a 
single entry. Consequently, the final rule allows the minimum air 
quantity to be maintained in the air course rather than in a single 
entry, in areas of the mine developed before the effective date of the 
final rule. In areas of the mine developed on or after the effective 
date, the minimum air quantity must be maintained in a single entry. 
This means that mines with multiple common entries that use diesel 
equipment must alter their approach to future mine development no later 
than the effective date of the final rule.
    This two-pronged approach to ventilation of outby diesel equipment 
recognizes that the location and direction of required air quantities 
have an impact on how effectively the air will dilute diesel engine 
emissions. Air that is coursed directly over diesel equipment will 
dilute contaminants more effectively than air of the same volume and 
velocity that is dispersed over a wider area. Consequently, providing 
the air quantity in a single entry rather than over multiple entries is 
a more desirable method of ventilation. However, this approach also 
takes into account that a number of mines would be unable to comply 
with the location requirements of (f)(3) in areas that have already 
been developed, without significant capital expenditures and 
substantial disruption of mining operations. This aspect of the final 
rule therefore strikes a balance between the concerns of commenters 
regarding adequate ventilation of diesel equipment operated in outby 
areas, and the economic infeasibility of a complete overhaul of areas 
of the mine that have already been developed.
    It should be noted that Sec. 75.1907 of the final rule does not 
require diesel equipment used in outby areas to have an engine approved 
under subpart E of part 7 of the final rule until 3 years after the 
publication date of this rule. During this transitional period, 
equipment with unapproved engines that do not have an approval plate 
will not be subject to the minimum air quantity requirements of the 
final rule. However, mine operators are under a continuing obligation 
to ensure that air contaminants are maintained within the limits 
established in Sec. 75.322, and diesel-powered equipment must be 
ventilated with sufficient quantities of air to prevent overexposure of 
miners.
    Paragraph (f)(5) has been added to the final rule to give the 
district manager the authority to require other locations where minimum 
air quantities for individual units of equipment must be maintained. 
These locations must be specified in the ventilation plan. This 
provision has been added in response to commenters who were concerned 
about inadequate ventilation in areas where diesel-powered equipment 
was operating, other than those locations specified in paragraphs (f) 
(1) through (4). These locations could include, for example, 
underground repair shops, permanent fuel storage facilities or 
temporary fuel storage areas, or construction sites where diesel-
powered equipment is regularly operated and where minimum air 
quantities are needed to keep contaminant levels within acceptable 
limits.
    The final rule adopts the proposal's approach of using the engine 
approval plate air quantity to determine the minimum air quantity in 
areas where multiple units of diesel-powered equipment are being 
operated. Paragraph (g) provides that the minimum ventilating air 
quantity where multiple units of diesel-powered equipment are operated 
on working sections and in areas where mechanized mining equipment is 
being installed or removed, must be the sum of 100 percent of the 
approval plate quantities for all of the equipment. As mentioned 
earlier, this is a change from the 100-75-50 percent approach of the 
proposal.
    The final rule, like the proposal, also specifies certain equipment 
that may be excluded from the calculation of minimum air quantity, and 
also permits a mine operator to obtain a reduction in the required 
minimum air quantity for multiple units if sampling evidence 
establishes that a lesser ventilating air quantity will maintain 
continuous compliance with the TLV\'S in Sec. 75.322.
    Several commenters advocated that approval plate air quantities be 
used only as guidelines for ventilation of multiple units of equipment, 
for the same reasons outlined in the discussion of ventilating air 
quantities for individual units of equipment. These commenters stated 
that there were a

[[Page 55437]]

number of variables that must be considered in establishing ventilation 
for diesel equipment, and advocated determining minimum air quantities 
on a mine-by-mine basis.
    Some commenters were opposed to the 100-75-50 approach, stating 
that it would not adequately protect miners. These commenters took 
issue with the assumption that multiple units of diesel-powered 
equipment could not be operating at their worst point, i.e., generating 
the highest levels of emissions--simultaneously. Commenters also 
pointed out that the 100-75-50 approach assumed that engines perform at 
a consistent level from the day they are purchased until the end of 
their useful life, and advocated that the sum of 100 percent of the 
approval plate air quantities be used instead as the minimum 
ventilation quantity.
    The final rule, like the proposal, specifies that engine approval 
plate quantities are the minimum ventilating air quantity for diesel-
powered equipment. The approval plate quantity is required for multiple 
units for the same reasons that it is required for individual units: it 
is an accurate calculation of the amount of air that is needed to 
dilute gaseous diesel exhaust contaminants to acceptable levels. 
However, the final rule, like the proposal, allows mine operators to 
seek reductions in the required air quantities if they are able to 
demonstrate that contaminant levels will be kept within required limits 
at reduced ventilating air levels. This provision recognizes that, as 
stated by commenters, there may be variables of mine design, equipment 
operation, or ventilation in areas where multiple units operate that 
may result in less air being needed to keep air quality within 
healthful limits. For example, if the diesel machines on a section are 
not operated so that all machines are producing maximum emissions 
simultaneously, reduced minimum air quantities may be appropriate.
    The final rule does not adopt the 100-75-50 approach, in response 
to commenters' concerns that it would not provide adequate protection 
for miners, and for several other reasons. First, the 100-75-50 formula 
was designed to account for differences in duty cycles among the 
equipment, since the approval plate air quantity is based upon the 
worst point of the operating range of the equipment relative to gaseous 
emissions. The 100-75-50 approach assumed, as has been pointed out by 
commenters, that multiple units of equipment would not have been 
operating at their worst points at the same time. As discussed above, 
although the approval plate air quantity is calculated for a worst case 
engine operating point, research has shown that engines generate high 
levels of contaminants over a range of engine operating points. The air 
quantity available on the section should be sufficient to control the 
engine emissions under all conditions.
    The 100-100-100 approach also recognizes that approval plate air 
quantities will be calculated differently under part 7 than they have 
been under part 36, prior to the promulgation of this final rule. As 
discussed in the preamble to subpart E of part 7, an engine's approval 
plate air quantity under the final rule will be determined by the 
amount of air needed to dilute contaminants to the TLV's in 
Sec. 75.322. Up until now, approval plate quantities have been 
determined under part 36 based on the amount of air needed to dilute 
contaminants to 50 percent of the TLV's that were in effect 
when part 36 was first promulgated in 1961. Although the levels to 
which CO and NO2 must be diluted remain the same under the final 
rule, the dilution levels for NO and CO2 are twice as high. 
Consequently, less air will be needed to dilute these two gases to the 
higher levels, and the approval plate quantity will be lower for most 
if not all engines. However, the approval plate quantity will now 
directly correlate to existing TLV's. It follows that 100 
percent of the approval plate quantity, rather than some fraction 
thereof, must be provided to adequately dilute the gaseous diesel 
engine contaminants.
    Approval plate quantities determined under the final rule may also 
be slightly lower than before under old part 36, as a result of the 
revision in part 36 that requires engines to be tested with 1.0 percent 
methane injected into the engine air intake, rather than the current 
1.5 percent. Because injection of methane into the engine increases 
engine emissions, the lower concentration of methane used under the 
final rule will result in lower emissions and will require a lower 
quantity of air to dilute.
    Because of these factors, the 100-100-100 calculation for multiple 
units of equipment will not result in minimum air quantities that are 
significantly greater than air quantities currently required in 
ventilation plans using the 100-75-50 method of calculation. In fact, 
in some cases, the air quantity required for multiple units may be less 
than what was required before, depending on the diesel equipment that 
is being operated.
    Under the proposal, air quantities in excess of the 100-75-50 
calculation for multiple units of equipment would have been required 
when the particulate index established for the equipment indicated that 
a greater air quantity was needed to maintain diesel particulate levels 
within acceptable limits. The particulate index indicates the quantity 
of air required to dilute particulate emissions from that specific 
engine to a concentration of 1 milligram per cubic meter of air. The 1 
milligram value was chosen to make the use of a diesel particulate 
permissible exposure limit with an engine's particulate index a matter 
of simple multiplication, and is not meant to be an indicator of the 
level of any diesel particulate standard that may be set by MSHA in the 
future.
    Under the proposal, MSHA intended to apply the particulate index in 
two phases, before and after the setting of a diesel particulate 
standard. Before the promulgation of a standard, MSHA intended to take 
an engine's particulate index into account in approving minimum air 
quantities in a mine operator's ventilation plan by estimating the 
contribution of diesel particulate to the total respirable coal mine 
dust concentration. After the promulgation of a diesel particulate 
standard, the minimum air quantity would be determined using the 
particulate index to calculate the air quantity needed to dilute the 
particulate concentration to whatever level was required.
    A number of commenters stated that, because MSHA has not yet 
established a permissible exposure limit for diesel particulate, a 
requirement for increased air quantities based upon a diesel 
particulate index was inappropriate. Other commenters supported the use 
of a particulate index as a point of comparison among different diesel-
powered engines, but they were strongly opposed to the use of the index 
to require minimum air quantities. Other commenters stated that 
accurate measurement of diesel particulate is not possible, because 
diesel particulate matter is indistinguishable from other respirable 
coal mine dust. One commenter stated that the particulate index fails 
to take into account that the diesel engine is itself only one factor 
in how cleanly the machine operates as a whole. This commenter 
recommended that other factors be considered, including the 
effectiveness of water scrubbers, dilutors, catalytic convertors, and 
particulate traps or filters, any one of which could significantly 
reduce diesel particulate emissions.
    Although MSHA is currently developing a proposed rule to control 
miners' exposure to diesel particulate, MSHA agrees with commenters who 
believe that the use of the particulate

[[Page 55438]]

index for determining minimum ventilation requirements would be 
premature in the absence of a standard for diesel particulate. The 
final rule therefore does not adopt the proposal's requirement for 
increased air quantities based on a diesel engine's particulate index. 
However, MSHA will still calculate an engine's particulate index as 
part of the approval process. As was true under the proposal, the 
particulate index will be determined under part 7 of the final rule. 
The particulate index for the engine will be reported in the approval 
letter that MSHA sends to the engine manufacturer notifying the 
manufacturer that the engine has been approved. A copy of this letter 
also accompanies the equipment when it is purchased by the mine 
operator. The particulate index for all MSHA-approved diesel engines 
will also be included on MSHA's list of approved products, which is 
issued on a regular basis to the individuals and companies on MSHA's 
mailing list. MSHA anticipates that, until a diesel particulate 
standard has been set, mine operators and machine manufacturers will 
use the engine particulate index in selecting and purchasing engines. 
During this time mine operators may also use an engine's particulate 
index to roughly estimate the engine's contribution to the mine's 
levels of total respirable coal mine dust.
    Under the proposal multiple units of equipment would have been 
required to be ventilated by specified minimum air quantities in the 
last open crosscut of each working section or in the intake splits of 
longwall sections. The proposed rule would also have required minimum 
air quantities to be maintained when face equipment was being installed 
or removed.
    One commenter stated that air on a dieselized section should be 
coursed throughout the section and should not be concentrated in the 
last open crosscut. This commenter recommended that the total intake 
air quantity going into the section intake and the total return air 
quantity leaving the section should be measured. Another commenter 
stated that air measurements are more accurate in the immediate return 
of each split, rather than at the last open crosscut.
    Several commenters pointed out that too much air across the face 
area was detrimental to the effective operation of respirable dust 
scrubbers on continuous miners. Several commenters identified longwall 
moves as periods when miners were exposed to high levels of diesel 
exhaust, due to the increased use of diesel-powered equipment on the 
sections during these periods and the increased diesel engine loads. 
These commenters stated that during longwall moves the exhaust from one 
diesel machine would be ``rebreathed'' by another diesel machine, 
resulting in a doubling of carbon monoxide levels.
    Paragraphs (g)(1) through (g)(3) of the final rule set forth the 
specific locations where minimum air quantities must be maintained 
where multiple units of diesel-powered equipment are operating. Under 
the proposal, as described above, minimum air quantities would have 
been required in the last open crosscut of each working section or in 
the intake splits of longwall sections.
    The final rule essentially adopts the approach of the proposal, 
although the term ``split'' used in the proposal has not been adopted 
in the final rule because, as explained in the discussion under 
paragraph (a) of this section, commenters considered the term ``split'' 
to be vague and ambiguous. The final rule provides more specific 
description of the locations where air quantities must be maintained, 
although the location requirements themselves are essentially the same 
as they would have been under the proposal. Paragraphs (g)(1) through 
(g)(3) of this section require the minimum air quantity in working 
sections to be maintained: in the last open crosscut of each set of 
entries or rooms in each working section; in the intake, reaching the 
working face of each longwall; and at the intake end of any pillar 
line.
    The final rule does not adopt the suggestion of commenters that air 
measurements be taken at locations other than those specified in the 
proposal. The recommendation that the total intake air quantity 
entering a section and the total return air quantity leaving a section 
be measured has not been adopted because this method of measurement 
will not provide an indication of the air quantity that is actually 
reaching the working section. The air could be short-circuited before 
it reaches the diesel machine, but still be measured as part of the 
return air quantity. Further, the recommendation that air measurements 
be taken in the immediate return of each split, rather than at the last 
open crosscut, has not been incorporated into the final rule because 
measurement at that location will give a less accurate indication of 
the air that is actually ventilating the diesel equipment. Finally, the 
measurement of air quantities at the last open crosscut under the final 
rule is also consistent with air measurement requirements currently in 
most underground coal mine ventilation plans.
    The final rule does not respond to commenters who stated that too 
much air across the face area could have a negative impact on the 
effectiveness of respirable dust scrubbers on continuous miners. While 
it is true that increased air quantities could in some cases have an 
adverse effect on dust scrubber effectiveness, this impact must be 
balanced against the need to control harmful diesel exhaust 
contaminants. There are other dust control technologies that are 
available to supplement dust scrubbers if the need arises.
    In response to the many commenters who expressed concern about 
exposure of miners to high levels of diesel exhaust contaminants during 
installation or removal of longwall equipment, the final rule adopts 
the proposed requirement that minimum air quantities be maintained in 
areas where mechanized equipment is being installed or removed.
    Paragraphs (h)(1) through (h)(4) of this section of the final rule, 
like the proposal, allow certain types of equipment to be excluded from 
the minimum air quantity calculation of paragraph (g). The rationale 
behind these exclusions is that the specified equipment is operated or 
ventilated in such a way that it does not significantly affect the 
exposure of miners to diesel exhaust contaminants. Commenters were 
generally in favor of allowing certain equipment to be excluded, such 
as equipment with light-duty cycles or equipment that is only used 
intermittently. One commenter stated, however, that MSHA should verify 
information submitted by the operator to support exclusion of 
equipment, and that the final rule should require mine operators to 
notify miners or their representatives to allow them to comment on the 
operator's request for exclusion of equipment from the air quantity 
calculation.
    In response to this comment the final rule, unlike the proposal, 
requires district manager approval of all exclusions and requires the 
exclusions to be specified in the ventilation plan. This will allow 
MSHA review of all equipment that will be excluded from the air 
quantity calculation, and responds to commenter concerns about MSHA 
verification of excluded equipment. Additionally, requiring excluded 
equipment to be specified in the ventilation plan will ensure that 
miners and their representatives, who are required under existing 
regulations to be provided with proposed revisions to an operator's 
ventilation plan, are notified of an operator's intention to exclude 
certain equipment. This

[[Page 55439]]

responds to commenters who advocated that miners' representatives be 
notified of and be given an opportunity to comment on such matters.
    Paragraph (h)(1) allows the exclusion of self-propelled equipment 
meeting the requirements of Sec. 75.1908(b) of the final rule. The 
proposal would have allowed the exclusion of the limited class of 
equipment meeting the requirements of proposed Sec. 75.1908, except 
diesel-powered air compressors that are regularly used. The 
requirements of proposed Sec. 75.1908 included specific objective 
criteria limiting equipment horsepower and weight. In response to 
commenters and for reasons explained in detail in the preamble to 
Sec. 75.1908, equipment categories are defined in the final rule by the 
equipment function rather than by weight or horsepower. Equipment that 
meets the requirements of Sec. 75.1908(b) is light-duty equipment that 
does not, among other things, cut or move rock or coal or move longwall 
components. Because the equipment is not operated under heavy load, it 
is not expected to produce high levels of exhaust emissions, and may 
therefore be excluded if specified in the mine operator's approved 
ventilation plan. Although the proposal did not explicitly limit the 
exclusion to self-propelled equipment, as does the final rule, the only 
portable equipment included in the proposed limited class was 
compressors and welders, and compressors were not eligible for 
exclusion under the proposal if they were regularly operated. The final 
rule takes a different approach and only includes self-propelled light-
duty equipment in the automatic exclusion under paragraph (h)(1), 
because some types of non-self-propelled light-duty equipment, such as 
compressors and generators, can produce high levels of exhaust 
emissions. However, light-duty equipment that is not self-propelled 
whose emissions would not significantly affect the exposure of miners 
may be excluded from the air quantity calculation if approved by the 
district manager under paragraph (h)(4).
    Also eligible for exclusion, under paragraphs (h)(2) and (h)(3), is 
equipment that discharges its exhaust into an intake air course that is 
vented directly into a return air course, or that discharges its 
exhaust directly into a return air course. Paragraph (h)(3), which 
exempts equipment vented directly into a return air course, has been 
adopted without change from the proposal. Paragraph (h)(2), which 
exempts equipment that discharges its exhaust into intake air that is 
coursed directly to a return air course, has been added to the final 
rule to be consistent with other MSHA regulations, which require 
certain equipment, such as electrical equipment, to be vented either 
directly into a return air course or into an intake air course that is 
coursed directly into a return air course. The rationale for both of 
these exceptions in the final rule is the same: that the diesel exhaust 
of equipment that discharges into a return air course or into an intake 
air course that goes directly into a return air course will not, in 
most cases, come into contact with miners because most of them will be 
working in intake air in the face area where production occurs. 
Commenters did not indicate any opposition to the reasoning behind 
these exceptions.
    Paragraph (h)(4), like the proposal, allows mine operators to 
obtain MSHA approval for the exclusion of other equipment from the air 
quantity calculation in paragraph (g). Equipment may be excluded under 
this paragraph if its duty cycle is such that the emissions would not 
significantly affect the exposure of miners. Mine operators who seek to 
exclude equipment must identify the equipment in the ventilation plan 
that is submitted to MSHA for approval. Equipment that may be eligible 
for exclusion under paragraph (h)(4) includes equipment with a very 
small engine (less than 10 horsepower) or heavy-duty equipment that is 
operated infrequently, for very short periods of time, or when other 
diesel equipment normally operated on the section is shut down or not 
operating. An example of equipment that could be considered for 
exclusion under this paragraph is a supply vehicle that is driven up to 
the section, shut down and unloaded, started up and immediately driven 
off of the section. Equipment that is operated in a location so that 
its exhaust does not pass over miners could also be eligible for this 
exclusion. All other equipment, such as nonpermissible heavy-duty 
equipment and face equipment which discharges its exhaust into an 
intake air course of the working section, must be included in the 
minimum air quantity calculation required by paragraph (g).
    Paragraph (i) of the final rule, like the proposal, allows the 
district manager to approve a lesser air quantity than what would 
otherwise be required under paragraph (g) for multiple units of diesel 
equipment. The final rule allows such a modification if sampling 
results demonstrate that miners exposure to diesel contaminants will 
not exceed applicable TLV's at the modified ventilation 
quantity.
    The proposed rule would have allowed the district manager to 
approve lesser air quantities for multiple units of equipment if the 
results of a comprehensive personal monitoring program indicated that 
contaminant exposure levels were below 75 percent of the applicable 
contaminant standards with 95 percent confidence. The proposed rule 
also specified the information that mine operators would have been 
required to submit to MSHA for consideration in reducing minimum air 
quantities, including the actual sampling plan and an evaluation of the 
sampling results.
    Some commenters were opposed to requiring a 95 percent confidence 
level for the sampling used to support a reduction in air quantity, 
stating that this requirement was too technical and unrealistic for 
practical application. Some commenters strongly opposed allowing 
reduction of air quantities under the procedure set forth in the 
proposal, stating that miners and their representatives would not be 
given sufficient opportunity to participate in the process. One 
commenter advocated use of petition for modification procedures under 
section 101(c) of the Federal Mine Safety and Health Act when mine 
operators seek to revise their ventilation plans, stating that under 
these procedures miners and miners' representatives would have the 
right to review and comment on the proposed plan modifications.
    The final rule takes a more performance-oriented approach to 
reduction in minimum air quantities, and requires that samples of 
contaminants demonstrate that a lesser air quantity will maintain 
contaminant levels within permissible limits. This is consistent with 
the streamlined procedures for contaminant sampling in Sec. 70.1900 of 
the final rule, and also responds to commenters' recommendations that 
this aspect of the rule should be less technical.
    The objective of this aspect of the final rule is the same as that 
of the proposal: that reduction of minimum air quantities required by 
the final rule is permitted if a mine operator can establish that 
miners will not be overexposed to gaseous diesel exhaust contaminants 
at the lesser ventilating air quantities.
    The final rule does not adopt the suggestion of commenters that 
reductions in air quantity be granted only under the modification 
procedures of section 101(c) of the Mine Act. Since the time of the 
submission of these comments, MSHA has issued a final rule governing 
underground coal mine ventilation, which includes revisions to the 
existing ventilation plan submission and approval process [61 FR 9764] 
and addresses several of these commenters' concerns. The revised 
ventilation rules

[[Page 55440]]

provide an increased role for the representative of miners in the 
ventilation plan approval process. Mine operators are now required to 
notify the representative of miners at least 5 days before a 
ventilation plan or plan revision is submitted to MSHA for approval, 
and make a copy of the proposed plan or plan revision available for 
inspection to the miners' representative. The representative of miners 
is given the opportunity to submit written comments to MSHA for 
consideration during the plan review process. Under this process, 
operators seeking reduction in the minimum air quantities required 
under paragraph (g) are required to notify miners' representatives, who 
then have the opportunity to comment on the reduction. No provisions 
have therefore been made to address these comments in the final rule, 
because the comments have already been addressed appropriately in the 
revised ventilation rule.
    Paragraph (j) allows modification of the 50 percent action level 
specified in Sec. 70.1900(c) if sampling results demonstrate that 
miners will not be exposed to contaminants that exceed permissible 
limits at the modified action level. As described in detail in the 
preamble discussion for Sec. 70.1900, any change to the action level 
must be based on the results of sampling that demonstrate that miners' 
personal exposure will not exceed the applicable TLV.
    Paragraph (k) provides that, as of 12 months after the publication 
date of the final rule, the ventilating air quantity required where 
diesel-powered equipment is operated shall meet the requirements of 
paragraphs (f) through (j) of this section. Compliance with the 
ventilation requirements of the final rule will in some cases require 
modifications to the mine's ventilation system. These revisions, along 
with other information required to be specified in the mine ventilation 
plan under paragraphs (f) through (j) of this section, should be 
included in a revised ventilation plan submitted to MSHA for review and 
approval.
Section 75.371  Mine Ventilation Plan; Contents
    The requirements for diesel-powered equipment that are included by 
the final rule in existing Sec. 75.325 identify information that must 
be specified in the mine operator's ventilation plan. Existing 
Sec. 75.371, which lists the information that must be provided by mine 
operators in their mine ventilation plans, is amended by the final rule 
to conform to the new requirements in Sec. 75.325.
    As was true under the proposal, minimum air quantities for 
individual units of diesel-powered equipment are not required to be 
included in the ventilation plan, because individual units are required 
to be ventilated with at least the engine approval plate air quantity 
while they are operating. The final rule does require that the 
ventilation plan specify where air quantity will be maintained at the 
section loading point for individual units of equipment, as well as any 
additional locations required by the district manager where a minimum 
air quantity must be maintained for an individual unit of equipment.
    The final rule, like the proposal, requires the ventilation plan to 
specify ventilation quantities for multiple units of equipment, as well 
as to include a description of equipment that is excluded from the 
multiple unit calculation of Sec. 75.325(g).
    Existing Sec. 75.371(r) is revised by the final rule to include a 
cross-reference to Sec. 75.325 (d), (g), and (i). Paragraph (r) 
requires the ventilation plan to identify the minimum quantity and the 
location of air that will be provided during the installation and 
removal of mechanized mining equipment, as well as the ventilation 
controls that will be used. The addition of a cross-reference to 
Sec. 75.325 clarifies that minimum air quantity requirements for 
diesel-powered equipment must be considered when determining 
ventilation quantities during mechanized equipment installation and 
removal.
    New paragraph (kk) has been added to Sec. 75.371 and provides that 
the ventilation plan shall include any additional areas designated by 
the district manager under Sec. 70.1900(a)(4) of the final rule for CO 
and NO2 sampling. As explained in more detail in the preamble to 
Sec. 70.1900, the district manager is authorized under the final rule 
to require sampling in strategic locations on a mine-by-mine basis, in 
order to address situations involving significant concentrations of 
diesel exhaust. Paragraph (kk) conforms the content requirements for 
ventilation plans to this new provision.
    New paragraph (ll) provides that the ventilation plan must specify 
the location where the air quantity will be maintained at the section 
loading point.
    New paragraph (mm) provides that the ventilation plan include any 
additional locations required by the district manager, under 
Sec. 75.325(f)(5), where a minimum air quantity must be maintained for 
an individual unit of diesel-powered equipment.
    New paragraph (nn) provides that the ventilation plan must specify 
the minimum air quantities that will be provided where multiple units 
of diesel-powered equipment are operated. To comply with this 
requirement, mine operators should indicate the equipment that is being 
used in the normal mining cycle, and the minimum air quantities that 
must be provided to ventilate the specified equipment.
    New paragraph (oo) provides that the ventilation plan must specify 
the diesel-powered equipment excluded from the calculation under 
Sec. 75.325(g). MSHA does not intend that this provision require the 
itemization or the serial numbers of specific equipment. Instead, the 
mine operator should provide a general description that is sufficient 
to identify the types of equipment that are excluded from the 
calculation.
    New paragraph (pp) conforms ventilation plan content requirements 
to Secs. 70.1900(c) and 75.325(j), and provides that the ventilation 
plan shall identify any action levels that are higher than the 50 
percent level specified by Sec. 70.1900(c). As described in greater 
detail in the preamble discussion of Sec. 70.1900, mine operators may 
obtain a higher action level if they are able to demonstrate that 
miners will not be overexposed to contaminants at the higher level. If 
a higher action level is approved by the district manager under 
Sec. 75.325(j), it must be specified in the mine ventilation plan.
Section 75.1900  Definitions
    This section of the final rule contains definitions of terms used 
in subpart T of part 75. These definitions are provided to assist the 
mining community in understanding and complying with the requirements 
of the final rule. As a general matter, terms which are unique to the 
final rule are defined, while those terms that are commonly used and 
understood in the mining industry have not been included for 
definition.
    The proposed rule defined two terms: ``fixed underground diesel 
fuel storage facility'' and ``mobile underground diesel fuel storage 
facility''. The final rule adopts the proposed definition for ``fixed 
underground diesel fuel storage facility'', although the term itself 
has been slightly modified, with the substitution of the word 
``permanent'' for the word ``fixed'' to more accurately reflect the 
nature of the facility. A ``permanent underground diesel fuel storage 
facility'' is defined as a facility designed and constructed to remain 
at one location for the storage and dispensing of diesel fuel, and 
which does not move as mining progresses. Such facilities are designed 
to remain at

[[Page 55441]]

one location for an extended period of time. Additionally, the final 
rule also adopts, with slight modification, the proposed definition for 
``mobile underground diesel fuel storage facility'', although that term 
has been changed in the final rule to ``temporary underground diesel 
fuel storage area'' to be more accurately descriptive. A ``temporary 
underground diesel fuel storage area'' is defined as an area of the 
mine provided for the short-term storage of diesel fuel in a fuel 
transportation unit, which moves as mining progresses.
    The final rule also includes additional definitions for the terms 
``diesel fuel tank'', ``diesel fuel transportation unit'', 
``noncombustible material'', and ``safety can''.
    Several commenters believed that the definitions in the proposal 
were too narrow in scope and did not accurately reflect the different 
fuel storage facilities currently in use in underground coal mines or 
the different applications of mobile diesel-powered equipment. These 
commenters recommended the definition of two additional categories of 
underground diesel fuel storage facilities: ``temporary'' and ``self-
propelled.'' Commenters offered definitions for these two additional 
types of facilities, but they have not been adopted in the final rule, 
although, as mentioned above, the word ``temporary'' has been 
substituted for the word ``mobile'' in describing areas provided for 
short-term fuel storage that move as mining progresses. The suggested 
definition for ``self-propelled diesel fuel storage facility'' has not 
been included because it is similar in function and definition to a 
``diesel fuel transportation unit,'' which has been defined in the 
final rule.
    The definition offered by commenters for ``temporary diesel fuel 
storage facility'' reflected commenters' concerns that the proposed 
construction requirements for mobile fuel storage facilities were too 
extensive, and would make it difficult for the facility to move with 
the section and keep pace as mining progressed. Commenters therefore 
recommended the creation of a category of fuel storage facility with 
more flexibility than the mobile storage facilities under the proposal.
    In response to these comments, requirements for temporary fuel 
storage are addressed separately from those for permanent facilities in 
the final rule, and reflect a more practical approach to temporary fuel 
storage, which is explained in detail in the discussion of 
Sec. 75.1903, below. A definition for ``temporary fuel storage 
facility'' is consequently unnecessary and has therefore not been 
adopted in the final rule.
    One commenter recommended that several other terms be defined in 
the final rule, including ``container,'' ``safety can,'' ``tank,'' and 
``fuel transportation unit.'' This commenter pointed out that these 
terms are used throughout subpart T, and definition of these terms 
would enhance understanding of the requirements of the final rule.
    MSHA agrees that definition of certain terms will facilitate 
compliance with the requirements of subpart T, and has therefore 
included definitions for ``diesel fuel tank,'' ``diesel fuel 
transportation unit,'' ``noncombustible material,'' and ``safety can.'' 
Because the term ``fuel storage container'' is not used in the final 
rule, a definition for this term is not included in the final rule.
    The term ``diesel fuel tank'' is defined in the final rule as a 
closed metal vessel specifically designed for the storage or transport 
of diesel fuel. Metal tanks are required based on metal's demonstrated 
ability to contain diesel fuel in the event of a fire, documented by 
the Bureau of Mines in a 1985 Report of Investigation entitled ``Fire 
Tests of Five-Gallon Containers Used for Storage in Underground Coal 
Mines'' (RI 8946). This type of construction is also consistent with 
the National Fire Protection Association (NFPA) ``Standards for 
Portable Shipping Tanks for Flammable and Combustible Liquids'', (NFPA 
386).
    The term ``diesel fuel transportation unit'' is defined as a self-
propelled or portable, wheeled vehicle used to transport a diesel fuel 
tank. This definition includes diesel-powered vehicles such as lube 
units, maintenance trucks, tractors, and scoops. This definition also 
includes locomotives that pull rail-mounted, portable diesel fuel 
transportation units. Under the final rule fuel transportation units 
must be wheel-mounted, since skid-mounted units are more likely to be 
damaged during loading and unloading in a scoop bucket or while being 
dragged through the mine. Required safety features for these units are 
contained in Sec. 75.1902 and Secs. 75.1904 through 75.1906 of the 
final rule. Additionally, self-propelled fuel transportation units that 
are diesel-powered, and diesel-powered equipment used to tow portable 
fuel transportation units are considered heavy-duty equipment under 
Sec. 75.1908(a). Heavy-duty equipment must be provided with the safety 
features specified in Sec. 75.1909, including an automatic fire 
suppression system and additional specifications for the equipment's 
braking system.
    Under the final rule, permanent underground diesel fuel storage 
facilities must be constructed of ``noncombustible materials,'' and 
stationary tanks in those facilities must be placed on 12-inch supports 
constructed of ``noncombustible material.'' ``Noncombustible material'' 
is defined in the final rule as a material that will continue to serve 
its intended function for 1 hour when subjected to a fire test 
incorporating an ASTM E119-88 time/temperature heat input, or 
equivalent. This test, contained in the publication ``Standard Test 
Methods for Fire Tests of Building Construction and Materials'' of the 
American Society for Testing and Materials, is used to establish fire 
resistance ratings in minutes or hours for a particular building 
assembly such as a roof, wall, or beam. This means that a material 
maintains its integrity under a fire exposure test used by the building 
industry to classify assemblies for their ability to resist fire. This 
definition is consistent with the definition of ``noncombustible 
material'' in existing Sec. 75.301, which applies to the construction 
of ventilation controls in underground coal mines.
    One commenter who recommended that ``noncombustible material'' be 
defined in the final rule suggested that the definition specify a 2-
hour fire rating. The definition in the final rule specifies a 1-hour 
rating, which will provide protection in the event of a fire in 
underground fuel storage areas by confining the fire within the area 
for a sufficient period of time to allow miners to safely evacuate the 
mine. Additionally, the final rule requires automatic fire suppression 
systems and audible and visual alarms for permanent underground fuel 
storage facilities. For these reasons, adequate protection of miners 
against fire is provided, and a 2-hour fire rating has not been adopted 
in the final rule.
    The term ``safety can'' is defined in the final rule as a metal 
container with a nominal capacity of no more than 5 gallons used for 
storage, transport, or dispensing of diesel fuel that is listed or 
approved by a nationally recognized independent testing laboratory. 
Commenters supported the use of approved safety cans to transport small 
amounts of diesel fuel. This definition provides assurance that 
adequate construction and performance specifications for fire 
protection are met. The limitation on the capacity of safety cans to no 
more than 5 gallons will control the amount of diesel fuel being 
transported and minimize potential fuel

[[Page 55442]]

spillage. Such specifications and limitations are necessary in light of 
accident reports of 10 fires in Canadian mines that resulted from 
diesel fuel spillage during refueling.
    A safety can that meets this definition could be listed by 
Underwriters Laboratories or approved by Factory Mutual, Inc. Some 
nationally recognized independent testing laboratories have established 
specific construction specifications for the type and thickness of 
materials; material strength, stability and resistance to leakage; and 
standards for fire exposure that ensure that the can will safely vent 
if exposed to a heat source such as a fire.
    The final rule defines ``safety can'' as a metal container. Thus, a 
plastic safety can listed or approved by a nationally recognized 
independent testing laboratory would not be acceptable under the final 
rule. A metal container is specified because metal is superior to 
plastic in containing diesel fuel in the event of a fire. The safety 
advantage provided by metal cans has been documented in the 1985 Bureau 
of Mines' Report cited earlier. Specific design requirements for safety 
cans are addressed in Sec. 75.1904 of the final rule.
Section 75.1901  Diesel Fuel Requirements
    This section of the final rule establishes specifications for the 
fuel used in diesel-powered equipment in underground coal mines. 
Satisfying the requirements of this section will lower diesel engine 
gaseous and particulate emissions, and will reduce equipment 
maintenance by limiting the amount of sulfur in the fuel. The risk of 
fire in underground coal mines is also reduced by the minimum flash 
point for the fuel required by the final rule. The safety benefits that 
result from this aspect of the final rule are particularly important in 
the confined environment of an underground coal mine.
    Paragraph (a) of this section requires that diesel fuel used in 
underground coal mines contain no greater than 0.05 percent sulfur and 
have a flash point of 100 deg. F (38 deg. C) or greater. The final rule 
also requires the mine operator to provide an authorized representative 
of the Secretary, upon request, with evidence that the diesel fuel 
purchased for use in diesel-powered equipment underground meets these 
requirements.
    The proposed rule would have required ASTM D975 No. 2D diesel fuel, 
with a flash point of 125 deg. F or greater, at standard temperature 
and pressure. Many commenters objected to the requirement for ASTM D975 
No. 2D diesel fuel, stating that the reference to No. 2D fuel was a 
manufacturing classification, did not describe a type of diesel fuel 
that was commercially available, and would unnecessarily limit the use 
of diesel fuel in underground coal mines.
    MSHA agrees with commenters that the proposed fuel specifications 
do not describe a fuel that is commercially available, and the fuel 
specifications contained in the final rule respond to these comments. 
The reference to ASTM D975 No. 2D diesel fuel has been eliminated, and 
a minimum flash point and maximum sulfur content for diesel fuel have 
been specified. The fuel described by the final rule is in widespread 
use throughout the United States, and is easily obtained by mine 
operators. The fuel specifications in the final rule are based on 
Environmental Protection Agency on-highway fuel requirements for 
commercially available diesel fuel.
    A number of commenters were concerned that the required flash point 
of diesel fuel not be set too low, stating that any diesel fuel 
specifications must keep the fuel within the class of combustible 
liquids, ensuring that hazards associated with diesel fuel are no 
greater than those associated with other combustible liquids used 
underground. Some of these commenters recommended that the flash point 
for diesel fuel be set at 140 deg. F, stating that lower flash points 
would increase the risk of vaporization and increased aromatic content, 
especially at warmer mine temperatures. These commenters stated that 
increased aromatic content has an effect on particulate emissions.
    Other commenters stated that the proposed flash point of 125 deg. F 
was too high. Some commenters reported that the flash point of diesel 
fuel is intentionally lowered when fuel suppliers mix it for a winter 
blend, to depress the cloud point of the diesel fuel and reduce the 
temperature at which the fuel begins to jell. These commenters believed 
that a flash point of 125 deg. F would virtually eliminate their 
ability to use diesel-powered equipment in cold temperatures, unless 
the rule specifically allowed the use of winter blends of diesel fuel 
with flash points below 125 deg. F. These commenters pointed out that 
the ASTM 975 specification for diesel fuel is being changed to lower 
the minimum flash point of D1 diesel fuel to 100 deg. F (38 deg. C) 
when the cloud point is lower than 10 deg. F, and that a reduction of 
the flash point in the final rule was appropriate.
    Another commenter believed that the diesel fuel autoignition point 
does not change in the lower range of flash point for diesel-powered 
equipment, concluding that the safety of diesel fuel exposed to hot 
surfaces would not change with changing flash points.
    No demonstrated hazard exists to justify raising the flash point of 
diesel fuel above the proposed flash point of 125 deg. F. However, MSHA 
acknowledges commenters' concerns that the proposed flash point may 
unintentionally limit the use of diesel fuel during the winter. To 
address this issue, the flash point has been lowered in the final rule 
to 100 deg. F (38 deg. C) or greater.
    Several commenters suggested that the terms ``flash point'' and 
``combustible liquid'' be defined, with some commenters offering 
recommended language for the definitions. The final rule does not 
include definitions for these terms. The term ``flash point'' is 
commonly understood in the mining industry to mean the lowest 
temperature at which a liquid will give off sufficient vapor to ignite 
on application of a flame, and does not need to be defined in this 
rule. The suggested definition offered by commenters for the term 
``combustible liquid'' specifies a flash point temperature. Because the 
final rule sets a minimum flash point temperature for diesel fuel, such 
a definition is unnecessary.
    The proposal did not set a limit on sulfur content for diesel fuel, 
but would have required sampling for sulfur dioxide when diesel fuel 
was used that contained more than 0.25 percent sulfur. This approach 
was taken because, although the proposal recognized that use of low 
sulfur fuel was desirable, it was not readily available nationwide at 
the time the proposal was published in October 1989.
    Some commenters stated that the sulfur content of diesel fuel 
should be limited in all cases to 0.25 percent. Others stated that a 
sulfur content requirement should be phased in, ultimately reaching the 
Environmental Protection Agency's maximum sulfur level of 0.05 percent. 
One commenter stated that a requirement for low sulfur fuel would 
provide a health benefit to miners by reducing particulate emissions.
    MSHA agrees that the sulfur content of diesel fuel should be kept 
at a low level. Sulfur in diesel fuel contributes to diesel particulate 
emissions. Additionally, some types of exhaust after-treatment 
technology designed to lower hazardous diesel emissions work better 
when the sulfur content in the fuel is low. More effective strategies 
for after-treatment technology will result in reduced hydrocarbons and 
carbon monoxide levels. Low sulfur fuel also

[[Page 55443]]

greatly reduces the sulfate production from the catalytic converters 
currently in use in underground coal mines, thereby decreasing exhaust 
pollutants. Today, low sulfur fuel is readily available and widely used 
by on-road commercial vehicles. For these reasons, the final rule 
requires that diesel fuel contain no greater than 0.05 percent sulfur, 
which fuel is readily available nationwide.
    Under Sec. 70.1900 of the proposal, mine operators would have been 
required to provide MSHA with a certified statement if the sulfur 
content of the fuel used in their diesel equipment was 0.25 percent or 
less. This provision was included with exposure monitoring requirements 
because use of high sulfur fuel under the proposed rule would have 
triggered weekly area sampling requirements. Specifications for diesel 
fuel are now addressed in paragraph (a) of this section of the final 
rule, and the operator's obligation to verify the fuel's sulfur content 
has also been included in this section.
    The final rule requires the mine operator to provide to an 
authorized representative of the Secretary, upon request, evidence that 
the diesel fuel purchased for use in diesel-powered equipment 
underground meets the requirements of paragraph (a). This will not be a 
burdensome requirement. MSHA anticipates that the mine operator's 
contract with the mine's fuel supplier will document the type of fuel 
that is being purchased. The verification required under this paragraph 
may also be provided by a copy of a fuel analysis, which can be 
performed by a supplier's quality control laboratory or a private 
laboratory at minimal or no cost to the operator. MSHA recognizes that 
purchase orders and invoices may be kept at a mine's administrative 
office rather than at the mine site. Although the final rule does not 
specify a location or manner of recordkeeping for the document 
evidencing diesel fuel content, the mine operator may choose to keep an 
additional copy of the document to be easily accessible to a 
representative of the Secretary. A small recordkeeping burden is 
estimated for this requirement under the Paperwork Reduction Act of 
1995.
    Paragraphs (b) and (c) of this section of the final rule address 
additives for diesel fuel used in diesel-powered equipment in 
underground coal mines. The requirements of these two paragraphs were 
not part of the proposal but have been added to the final rule in 
response to commenters' concerns over the types of substances that 
could be safely added to diesel fuel.
    Paragraph (b) prohibits the addition of flammable liquids to diesel 
fuel. One commenter expressed concern that the proposed rule would not 
prohibit flammable liquids, such as gasoline, from being mixed with 
diesel fuel underground to assist in machine starting and operation 
during cold weather. Because gasoline is highly flammable, adding it to 
diesel fuel could cause the flash point of the fuel to drop below 
100 deg. F (38 deg. C) and transform the fuel into a flammable liquid. 
Further, use of gasoline as a diesel fuel additive could ruin an 
engine's fuel system by reducing the lubricating properties of the 
fuel. In response to these concerns, the final rule prohibits the 
addition of flammable liquids, such as gasoline, to diesel fuel. This 
restriction will promote the safe use of diesel fuel underground.
    Kerosene, on the other hand, is commonly used as a cutter stock for 
lowering the cloud point in diesel fuel. Because kerosene has a flash 
point above 100 deg. F (38 deg. C) it is classified as a combustible 
rather than a flammable liquid and therefore may be added to diesel 
fuel under the final rule.
    Paragraph (c) permits only diesel fuel additives that have been 
registered with the Environmental Protection Agency (EPA) under 40 CFR 
Part 79 [59 FR 33042] to be used in diesel-powered equipment 
underground. Because the proposed rule was silent on whether the use of 
diesel fuel additives would be permitted, a number of commenters raised 
additives as an issue and advocated that the final rule permit them to 
be used. These commenters stated that additives served to depress the 
cloud point of diesel fuel during cold weather to prevent jelling of 
the fuel. A cloud point depressant works by breaking down larger size 
crystals to smaller crystals, thus allowing the fuel to flow more 
freely. Several commenters expressed concern about the effect additives 
may have on diesel exhaust particulate emissions when mixed with diesel 
fuel. Other commenters wanted to be permitted to use additives, such as 
barium additives, with diesel fuel used to power equipment underground. 
One commenter stated that MSHA should encourage further research on the 
use of additives.
    The wide variety of diesel fuel additives currently on the market 
makes control of the use of these additives difficult. The final rule 
addresses this issue by limiting fuel additives used underground to 
those registered under specific EPA regulations.
    EPA regulations at 40 CFR Part 79 forbid manufacturers from placing 
any fuel additive into commerce unless the additive has been registered 
with the EPA Administrator. The EPA registration process requires the 
submission of extensive test data for specific health effect endpoints, 
as well as a general systemic and organ toxicity literature search on 
the health and welfare effects of the fuel additive emissions, 
including the characteristics of the emissions. Registered fuel 
additives are maintained by the EPA on a list that is available to the 
public.
    The requirements of this paragraph do not place an undue burden on 
mine operators, because operators need only verify with their fuel 
supplier or distributer that the additive purchased is included on the 
EPA registration list.
Section 75.1902  Underground Diesel Fuel Storage--General Requirements
    This section of the final rule provides general requirements for 
the safe storage of diesel fuel underground. These requirements are 
intended to minimize risks associated with fire hazards in the areas 
where diesel fuel is stored. This section limits the receptacles that 
may be used for diesel fuel storage underground to diesel fuel tanks 
and safety cans; allows only one diesel fuel transportation unit in a 
temporary fuel storage area; places a 1000-gallon limit on the capacity 
of stationary diesel fuel tanks in permanent fuel storage facilities; 
and limits the location of permanent fuel storage facilities and 
temporary fuel storage areas underground.
    A number of commenters were concerned about the additional hazards 
that would be created by the storage of a combustible--diesel fuel--in 
underground coal mines. Some commenters opposed any type of fuel 
storage underground, while others believed that diesel fuel can be 
safely stored. Those commenters who opposed the storage of diesel fuel 
underground stated that it would present numerous safety hazards, 
including an increase in the probability of the fuel becoming involved 
in a mine fire and cutting off the avenue of escape for miners. These 
commenters recommended that language in existing MSHA regulations at 
Sec. 31.9 (c)(2) and (c)(3) be incorporated in the final rule. These 
regulations address refueling of diesel locomotives underground and 
provide that, whenever possible, locomotive fuel tanks be filled on the 
surface; contain specific requirements when locomotives are refueled 
underground; and prohibit underground fuel storage.
    Commenters opposed to allowing storage of diesel fuel underground 
suggested that mine operators could file a petition for modification 
under Section 101(c) of the Mine Act if they

[[Page 55444]]

had a compelling need to store diesel fuel underground. These 
commenters felt that a case-by-case approach would more effectively 
address hazards associated with diesel fuel storage.
    Commenters were also concerned with maintenance and upkeep of 
diesel fuel areas. These commenters stated that fuel spills and hose 
leakage could possibly contribute to fire hazards. Commenters expressed 
reservations about storage, transport, and dispensing of diesel fuel 
from 5-gallon cans, particularly during refueling, stating that 
temporary storage should not be allowed. These commenters wanted 
assurance that if diesel fuel storage were allowed underground, 
protections such as fireproof enclosures and pumps and other provisions 
that address fuel spillage would be provided.
    Some commenters suggested that diesel fuel storage should be 
allowed only if it is tightly controlled, and that fuel spills must not 
be tolerated in areas of the mine that cannot be cleaned. A number of 
commenters recommended setting limits on the maximum quantity of fuel 
allowed on a production section, ranging from a 24- to a 48-hour 
supply. Other commenters supported permitting diesel fuel storage 
underground, but raised a number of issues related to fuel storage, 
such as appropriate construction requirements for underground 
facilities; fire protection; and the logistics of transporting and 
dispensing fuel in an underground environment. One commenter cited 
years of positive industry experience with safe underground storage and 
transport of diesel fuel. He stated that his own experience in safely 
operating an underground coal mine, including diesel fuel delivery, 
storage, transport and transfer, countered the proposition that 
proliferation of diesel fuel storage facilities would occur in an 
uncontrolled manner, resulting in unlimited quantities of diesel fuel 
being stored in underground mines.
    MSHA has carefully reviewed all of the comments in determining how 
to address the storage of diesel fuel underground. Both MSHA and 
industry experience demonstrate that diesel fuel can be safely stored 
underground in limited quantities under controlled conditions. Allowing 
limited storage on the section will minimize other safety concerns 
cited by commenters, such as fuel leaks and spills. Underground fuel 
storage will also eliminate the need for frequent fuel trips, thus 
reducing hazards that are inherent in the transportation of diesel 
fuel. MSHA does not believe that it is useful or practical to restrict 
diesel fuel quantities based on projected use. The final rule instead 
sets specific gallon limits on the capacity of underground fuel storage 
tanks.
    The final rule establishes safety requirements, including design 
and performance specifications for storage tanks, transportation 
vehicles, and cans for fuel storage; a limitation on the number of fuel 
storage units that may be parked on a section; and a limitation on the 
capacity of underground fuel storage facilities. MSHA believes that 
these requirements will provide a significant measure of additional 
protection from the hazards associated with the storage and handling of 
diesel fuel, and permit efficient and safe transportation and refueling 
of diesel equipment in underground coal mines. Under the final rule, 
miners are afforded protections that are equal to or greater than the 
protections of existing standards.
    Paragraph (a) of this section provides that diesel fuel shall be 
stored in: (1) Diesel fuel tanks in permanent underground diesel fuel 
storage facilities; (2) diesel fuel tanks on diesel fuel transportation 
units in permanent diesel fuel storage facilities or temporary diesel 
fuel storage areas; or (3) safety cans. The proposal did not explicitly 
limit fuel storage underground to tanks and safety cans, and would have 
required that diesel fuel be transported in containers specifically 
designed for the transport of diesel fuel.
    MSHA recognizes that large quantities of diesel fuel must be used 
in some mines. However, to protect against fires, spills, and other 
hazards, large quantities can only be stored in permanent facilities 
under this final rule.
    The final rule permits fuel storage in tanks on fuel transportation 
units, but only under certain conditions and in limited quantities 
spelled out in other requirements in this section. A number of 
commenters recommended that the rule accommodate the need for fuel 
supplies to move as the production section moves. Other commenters 
expressed concerns that multiple mobile storage tanks might be located 
on the section at the same time, exposing miners to hazards, 
particularly from fire. The final rule also allows diesel fuel to be 
stored in safety cans.
    The restrictions contained in paragraph (a) respond to commenters' 
concerns that storage of diesel fuel underground would lead to 
prolific, uncontrolled storage practices, and strictly limit the 
locations and receptacles for diesel fuel storage.
    Paragraph (b) of this section limits the capacity of stationary 
diesel fuel tanks in permanent underground fuel storage facilities to 
1,000 gallons. It is important to note that, while the total capacity 
of the fixed tanks is set, there is no limit on the number of 
stationary tanks that may be located in the facility. This means that 
the 1,000 gallons may be stored, for example, in two 500-gallon tanks 
or four 250-gallon tanks.
    Like the final rule, the proposal prohibited storage of more than 
1,000 gallons of diesel fuel in a permanent facility. Commenters' 
opinions of this provision varied, from those who opposed any kind of 
fuel storage underground, those who recommended limited storage, to 
those who believed that diesel fuel could be safely stored underground. 
The final rule balances the concerns raised by those opposed to storage 
against the need to store fuel underground to minimize other fuel 
handling hazards. The fire protection and construction requirements for 
fixed storage tanks and permanent storage facilities in Secs. 75.1903 
and 75.1904 of the final rule appropriately and adequately address fire 
and other hazards involving diesel fuel, and, when satisfied, will 
afford safe storage of the fuel quantities allowed under this section.
    Under the final rule, the storage of safety cans and parking of 
fuel transportation units in permanent storage areas would also be 
permitted. The 1,000-gallon limit applies to the total capacity of 
stationary tanks in the fuel storage facility, and the quantity of fuel 
in safety cans stored or fuel transportation units parked in the 
facility would not be counted as part of the 1,000-gallon limitation 
under this paragraph.
    The final rule permits storage of diesel fuel on a working section 
or in an area of the mine where equipment is being installed or 
removed, but places specific restrictions on such storage in paragraphs 
(c)(1) through (c)(4) of this section.
    The proposal did not separately address storage of diesel fuel on a 
working section. MSHA received many comments both opposing and 
supporting section fuel storage. Those opposed stated that storage on 
the section would present fuel leakage and spillage hazards, creating 
fire and escape hazards for miners. Those supporting fuel storage on 
the section stated that, because the production section advances 
rapidly, the final rule must permit diesel fuel storage on the section. 
These commenters further stated that properly designed fuel 
transportation units should be allowed on mining sections, as long as 
they are parked within reasonable proximity to

[[Page 55445]]

the work area and comply with specific safety requirements.
    MSHA agrees with commenters who supported allowing mobile fuel 
storage on the section, which can move as mining progresses, but also 
agrees with commenters who believe that such storage must be carefully 
controlled. In response to these concerns, paragraph (c)(1) permits 
only one temporary diesel fuel storage area for each working section or 
in areas of the mine where equipment is being installed or removed. 
Paragraph (c)(2)(i)-(iii) requires that the temporary fuel storage area 
be located within 500 feet of the loading point; within 500 feet of the 
projected location of the future loading point where equipment is being 
installed; or within 500 feet of the location of the last loading point 
where equipment is being removed. This requirement will ensure that the 
fuel storage area will be located close enough to miners to allow any 
hazards that may develop to be quickly addressed. This provision is a 
logical outgrowth of the rulemaking because it addresses commenters' 
concerns that fuel storage be allowed in close proximity to the mining 
section, while at the same time recognizing that safety concerns 
dictate limitations on where fuel may be stored.
    Consistent with the final rule's approach of allowing limited 
storage on the section, paragraph (c)(3) prohibits more than one diesel 
fuel transportation unit at a time to be parked in a temporary diesel 
fuel storage area. This requirement is consistent with sound fire 
protection engineering principles for the storage and handling of 
diesel fuel, and is supported by experiences in the field and 
applicable NFPA standards. It should be noted, however, that a 
``parked'' diesel fuel transportation unit under this paragraph would 
not include a unit that is in the process of refueling equipment or 
that is itself being refueled. This means, for example, that a 
temporary fuel storage area could contain more than one diesel fuel 
transportation unit at one time, so long as only one unit is parked. 
Any other units in the area must be in use and attended.
    The proposal would have allowed fuel to be stored in free-standing 
tanks in mobile diesel fuel storage facilities. The final rule allows 
fuel to be stored in temporary fuel storage areas, but only in tanks on 
diesel fuel transportation units. These units are specially designed to 
provide both mobility and protection for the fuel tanks. Protection is 
provided by requiring the tank to be permanently affixed to the 
transportation unit. The construction and design requirements for fuel 
tanks are contained in Sec. 75.1904 of the final rule.
    Paragraph (d) of this section of the final rule imposes limitations 
on the location of permanent fuel storage facilities and temporary fuel 
storage areas, and has been revised from the proposal for clarity. This 
aspect of the final rule requires diesel fuel to be kept out of areas 
where the potential for fire is greatest. The final rule prohibits 
permanent storage facilities and temporary storage areas from being 
located within 100 feet of shafts, slopes, shops, or explosives 
magazines, or within 25 feet of trolley wires or power cables, or 
electric equipment not necessary for the operation of the storage 
facilities. The fuel storage facilities or areas must also be in a 
location protected from damage by other mobile equipment.
    Some commenters stated that the proposed requirement that diesel 
fuel storage facilities be located at least 100 feet away from shafts, 
slopes, or shops was not adequate in light of the amount of diesel fuel 
involved and the amount of spillage that could occur. Another commenter 
stated that requiring shops to be located at least 100 feet away from 
fuel storage facilities was inconsistent with proposed Sec. 75.1903(c), 
which would have prohibited welding and cutting within 50 feet of 
storage facilities. The commenter also noted that in some cases it may 
be best to locate the fuel storage facility within 100 feet of the shop 
near a return, because this would provide the best direct ventilation 
to the return for both the shop and storage facility, but that the 
proposed 100-foot requirement could prevent this. The final rule, like 
the proposal, adopts separation distances that are consistent with the 
National Fire Protection Association 123 Standard for Fire Prevention 
and Control in Bituminous Coal Mines. NFPA 123 requires fixed 
combustible liquid storage areas to be located a minimum of 100 feet 
from explosive magazines, electrical substations, shaft stations, and 
shops. MSHA disagrees with commenters who considered a 100-foot 
separation distance insufficient in light of the amount of diesel fuel 
that could be stored. The design, construction, and fire suppression 
system requirements in the final rule that apply to permanent fuel 
storage facilities provide adequate protection to miners with a 100-
foot separation distance.
    MSHA also disagrees with the commenter who believed that requiring 
shops to be located at least 100 feet away from fuel storage 
facilities, where cutting and welding are likely to occur, was 
inconsistent with a prohibition against welding and cutting within 50 
feet of storage facilities. The high volume of vehicle traffic in and 
out of the area of the shop warrants a greater separation distance than 
for cutting and welding alone.
    Finally, the final rule does not adopt the recommendation of the 
commenter who advocated allowing a permanent fuel storage facility 
closer to a shop than 100 feet, to allow better ventilation of both the 
shop and the storage facility. The fire protection afforded by the 100-
foot separation distance outweighs any advantage in ventilation that 
would result from allowing a lesser distance.
    Paragraph (d)(3) provides that permanent fuel storage facilities 
and temporary fuel storage areas must be in a location that is 
protected from damage from other mobile equipment. Under the proposal, 
fuel storage facilities would have been required to be at least 25 feet 
away from haulageways, which are entries where miners and materials are 
normally transported. The rationale for this requirement was that areas 
where diesel fuel is stored should be out of the line of mine traffic, 
where tanks would be exposed to damage from collision with other mine 
vehicles. Instead of adopting the proposed requirement, the final rule 
takes a performance-oriented approach by providing that storage 
facilities and areas be located where they are protected from damage. 
This responds to a commenter who indicated the importance of keeping 
fuel storage facilities out of the line of traffic.
    Paragraph (e) prohibits permanent fuel storage facilities from 
being located in the primary escapeway, which provides miners with a 
route of escape from the mine in the event of an emergency. This 
restriction was not included in the proposal, but has been added to 
this section of the final rule in response to commenters' concerns 
relative to diesel fuel storage facilities' impeding miners' ability to 
escape in the event of a mine fire, explosion, or other emergency. This 
prohibition recognizes that the primary escapeway should be kept clear 
of obstructions and potential hazards, to ensure that miners are able 
to safely evacuate the mine in the event of an emergency.
Section 75.1903  Diesel Fuel Storage Facilities And Areas; Construction 
And Safety Precautions
    This section of the final rule establishes construction and design 
requirements for permanent diesel fuel storage facilities and temporary 
diesel fuel storage areas. These requirements are intended to minimize 
fire hazards associated with storage of diesel fuel

[[Page 55446]]

underground, and provide safety protections for miners during the 
storage, transportation, and dispensing of diesel fuel.
    The proposal did not distinguish between construction and design 
requirements for those diesel fuel storage facilities that are fixed 
and remain in one location indefinitely, and those that move as the 
production section advances. A number of commenters stated that the 
proposed requirements were suitable for permanent facilities but were 
unnecessary and impractical for facilities that would be temporary. 
Some commenters were concerned that some mine operators would not be 
able to complete construction of the temporary facility before the 
facility would have to be moved to keep pace with the advancing 
section. In support of this position, commenters stated that compliance 
with the proposed requirements would be impractical and would force 
mine operators to transport fuel to the section to refuel equipment on 
a shift basis, creating increased hazards due to transportation.
    Another commenter voiced similar concerns, noting that the rapid 
advance of mining in modern underground coal mines makes it more 
practical for fuel stations to be advanced with mining activity, and 
that properly designed transportation units should be allowed on mining 
sections as long as they are parked in accordance with specific 
safeguards in reasonable proximity to the working area. The commenter 
stated that a specific parking requirement with proper safeguards would 
be much safer than the requirements in MSHA's proposal. Another 
commenter stated that the Diesel Advisory Committee made general 
recommendations for permanent and temporary storage facilities that 
were not intended to eliminate fuel trailers and their use. On the 
other hand, several commenters believed that the fact that the proposal 
would not have required mobile storage facilities to have a drain 
system and sump would provide no incentive for operators to construct 
fixed facilities, and that the construction of an unlimited number of 
mobile facilities would result.
    In response to the comments, the final rule reflects a clear 
distinction between construction and design requirements for permanent 
underground diesel fuel storage facilities and temporary underground 
diesel fuel storage areas. MSHA recognizes that temporary diesel fuel 
storage areas move frequently as mining advances, and that construction 
specifications must take this fact into account. Requirements for 
permanent storage facilities have therefore been addressed separately 
from those for temporary facilities in the final rule. The final rule 
provides a more practical approach for the construction and design of 
areas designated for temporary fuel storage, and eliminates several 
proposed construction requirements that are unnecessary from a fire 
protection engineering standpoint. Specifically, the final rule does 
not adopt the proposed requirements that temporary fuel storage areas 
be constructed of noncombustible material, be provided with a self-
closing door, and be provided with a fire suppression system. Because 
construction of temporary storage areas with these features would make 
it extremely difficult for these facilities to be built as fast as 
mining progressed, transportation of fuel between permanent storage 
facilities and the section would increase significantly. The risk of an 
accident involving a fuel transportation unit would also increase, and 
with it the risk of fuel spillage and the risk of fire. The final rule 
therefore reduces the construction requirements for temporary fuel 
storage areas, to provide better control of the fire hazards inherent 
in fuel transportation and storage.
    Paragraphs (a)(1) through (a)(7) of this section establish 
construction and design requirements for permanent underground diesel 
fuel storage facilities. Consistent with basic fire protection 
engineering principles, the final rule requires permanent storage 
facilities to be constructed of noncombustible materials; provided with 
self-closing doors or a means for automatic enclosure, and with a means 
for entry and exit after closure; ventilated with intake air; equipped 
with an automatic fire suppression system; and provided with a means to 
contain diesel fuel and with a concrete floor or equivalent to prevent 
spills from saturating the mine floor. These requirements are intended 
to reduce the fire hazards inherently present in areas where diesel 
fuel is stored and increase protection in the event of a fire.
    The proposal contained requirements similar to those in the final 
rule, but the final rule has been modified in response to commenters. 
Some commenters were generally opposed to the proposed requirements, 
stating that diesel fuel systems currently in use do not pose the 
degree of hazard that would warrant such extensive requirements. One 
commenter stated that the requirements of the proposal suggested that 
the hazards of diesel fuel storage exceed the hazards of the storage of 
explosives underground by several-fold. Other commenters stated that 
the proposed requirements for construction of storage facilities with 
noncombustible materials and with a means for automatic enclosure were 
too vague and not stringent enough. These commenters recommended that 
MSHA require at a minimum that diesel fuel be stored in an enclosure 
with at least a 2-hour fire-resistance rating.
    Paragraph (a)(1) provides that permanent underground fuel storage 
facilities shall be constructed of noncombustible materials, including 
floors, roofs, roof supports, doors, and door frames. Exposed coal 
within the fuel storage areas is required to be covered with 
noncombustible material. If they are used, bulkheads are required to be 
built of or covered with noncombustible material.
    The proposal would have required that the storage facility be 
constructed of noncombustible material, a term that was not 
specifically defined. As discussed above, the term ``noncombustible 
materials'' is defined in Sec. 75.1900 of the final rule as materials 
meeting the equivalent of a one-hour fire resistance rating test. 
Paragraph (a)(1) also incorporates NFPA 123 requirements. These 
requirements clarify which components of the facility must be 
noncombustible, including floors, roofs, roof supports and door frames, 
and specify that exposed coal must be covered with noncombustible 
material and bulkheads either built of or covered with noncombustible 
materials.
    MSHA's Approval and Certification Center has established guidelines 
to determine the suitability of trowelable or sprayable coatings for 
protecting coal surfaces against fire, which meet the requirements of 
paragraph (a)(1). In addition, textile-type thermal barriers may also 
be used to provide isolation of the combustible surfaces within the 
storage facility. Materials meeting the ``Performance Criteria for 
Materials used for Welding and Cutting Curtains and/or Thermal Barriers 
in Underground Coal Mines'' (Luzik, MSHA Report No. 01-098-92) may also 
be used. MSHA has also established guidelines for noncombustible doors. 
Additionally, MSHA has tested certain designs of high-temperature 
silica fabric curtains and published the results in Coal Magazine, June 
1993, pp. 102-104, ``MSHA Develops New Fire Resistant Check Curtains''. 
For purposes of the final rule, MSHA will accept as doors the curtain 
constructions described in this article. Facilities constructed to meet 
these requirements will afford protection to miners working in the 
production areas inby in the event of a fire and should provide ample 
time for miners to exit.

[[Page 55447]]

    Paragraph (a)(2) of the final rule requires that permanent fuel 
storage facilities be provided with either self-closing doors or a 
means for automatic enclosure. This paragraph provides mine operators 
with flexibility in the method used to comply with the final rule. The 
proposal would have required that the facility be provided with a means 
for automatic enclosure, which suggests that the door must be closed by 
powered means, such as electrically or pneumatically. The proposal did 
not specifically include non-powered self-closing doors as an 
alternative, although they were not intended to be excluded. Self-
closing doors serve the same function in containing a fire as 
automatic-closing doors, and the final rule clarifies that they are 
permitted.
    Paragraph (a)(3) requires that permanent fuel storage facilities be 
provided with a means for personnel to enter and exit the facility 
after closure. This provision has been added to the final rule to 
ensure that miners who are inside the fuel storage facility when the 
automatic enclosure activates will be able to exit from the facility. 
This requirement is also intended to allow miners to gain access to the 
facility to suppress an incipient fire that may develop. This paragraph 
also requires a means for exit and entrance when self-closing doors are 
used. Self-closing doors that are specifically designed to be manually 
opened would be in compliance with this paragraph. This aspect of the 
final rule is necessary to prevent miners from being trapped in the 
facility, and is a logical outgrowth of the rulemaking.
    Paragraph (a)(4) of this section of the final rule requires that 
permanent fuel storage facilities be ventilated with intake air that is 
coursed into a return air course or to the surface and that is not used 
to ventilate working places, using ventilation controls meeting the 
requirements of existing Sec. 75.333(e). The proposal would have 
required that both fixed and mobile fuel storage facilities be 
ventilated directly into a return air course using noncombustible 
materials for ventilation controls. Some commenters stated they were 
already venting fuel storage areas in their mines directly to the 
return.
    The final rule adopts the proposed requirement only for permanent 
fuel storage facilities, with some modification. The final rule 
requires that the facility be ventilated with intake air coursed to a 
return air course or to the surface that is not used to ventilate 
working places. This language, which is consistent both with existing 
requirements at Sec. 75.340 for the ventilation of underground 
electrical installations and with the current definition of ``return 
air'' in existing Sec. 75.301, is intended to eliminate the confusion 
caused by the phrase ``directly to a return air course''. The final 
rule clarifies that the intake air ventilating the fuel storage 
facility may not be used to also ventilate active working places. Thus, 
the air may be coursed into other entries before being coursed into a 
return, so long as the air is not used to ventilate a working place.
    Temporary underground diesel fuel storage areas are not required to 
be vented directly to the return in the final rule, in response to 
commenters who advocated more flexibility and less restrictive 
requirements for temporary fuel storage that moves as mining 
progresses.
    If the permanent facility is equipped with self-closing doors that 
would normally be closed, an opening will have to be provided in the 
doors to allow intake air to flow through the facility. This opening 
will prevent the build-up of diesel fuel vapors in the facility and 
prevent smoke generated during the incipient stages of a fire from 
entering the intake air courses. The opening is not intended to prevent 
smoke and other products of combustion from backing up into the intake 
airway if the fire is not extinguished in its incipient stages. For 
automatic closing doors, which would normally be open, a vent in the 
doors may not be needed since enclosure is required to seal the 
facility to cut off oxygen to the fire after the doors have closed.
    The requirements of paragraph (a)(4) are also intended to ensure 
that, if an enclosure has self-closing doors that are normally closed, 
precautions are taken to adequately vent diesel exhaust emissions from 
the facility. Such precautions could include the use of a regulator in 
the door to bring air into the facility that would then be vented to 
the return. In the case of a diesel fuel transportation unit that must 
have its engine running to dispense fuel, the unit's exhaust could be 
vented either directly to the return, if it incorporates a power 
package approved under subpart F of part 7, or into intake air which is 
coursed directly to a return air course. A fuel transportation unit 
that is equipped with a subpart F-approved power package will have fire 
and explosion prevention features that would permit the engine to 
exhaust directly into the potentially methane-rich atmosphere of the 
return. When the unit is exhausted into intake air, the fire and 
explosion prevention features of a subpart F power package are not 
required. However, the emissions from the engine must be vented 
directly to return air to prevent unnecessary exposure of miners to 
diesel exhaust.
    Paragraph (a)(5) adopts the requirements of the proposal and 
provides that permanent fuel storage facilities must be equipped with 
an automatic fire suppression system that meets the requirements of 
Sec. 75.1912 of the final rule. This paragraph also includes an 
additional requirement, not included in the proposal, that actuation of 
the automatic fire suppression system shall initiate the means for 
automatic enclosure. One commenter stated that the proposed requirement 
for automatic enclosure was not sufficiently stringent, that these 
storage facilities should be designed with fire containment capability, 
and that automatic enclosure should be triggered by actuation of the 
automatic fire suppression system. MSHA agrees, and the final rule 
enhances the capabilities of the automatic fire suppression system by 
requiring that initiation of the system will activate closure of the 
doors to the facility if self-closing doors are not used. Operation of 
the system in an environment with minimal air movement, which would 
exist when the doors are closed, will improve the effectiveness of fire 
suppressant agents in extinguishing a fire.
    Paragraph (a)(6) requires that permanent fuel storage facilities be 
provided with a means of containment capable of holding 150 percent of 
the maximum capacity of the fuel storage system. This provision is 
intended to address hazards associated with diesel fuel spillage and 
leakage--both slip and fall and fire hazards. The proposal would have 
required that permanent facilities be equipped with a drain system and 
a sump capable of holding 150 percent of the maximum capacity of the 
fuel storage system. Instead of requiring a drain system and sump, the 
final rule requires a ``means of containment''. This change 
acknowledges that a suitable drain system is generally considered 
overly difficult to design and install, and will also allow more 
flexibility in design of fuel containment systems. Additionally, 
spilled diesel fuel is best left confined in the facility where the 
fire suppression system is located. One commenter offered a case that 
illustrates this principle where the fuel escaped into the mine during 
a fuel spill because the drain valve at the bottom of the remote sump 
that serviced the storage area was left partially open.
    It is important to note that, in cases where fuel is piped from the 
surface to an underground fuel storage facility, the containment 
capacity must account for

[[Page 55448]]

the total fuel capacity. This means that the capacity of the 
containment must equal at least 150 percent of the surface tank's 
capacity, plus 150 percent of the underground tank's capacity, plus 150 
percent of the volume of the piping system connecting the surface tank 
to the underground tank. In cases where there is no underground tank, 
the maximum capacity includes the surface storage tank and the piping 
system from the surface. Where a stationary tank is located in a 
permanent facility and is not connected to a surface tank, the means of 
containment must account for 150 percent of the capacity of the largest 
stationary tank. If the underground fuel storage facility is not 
equipped with a stationary tank but is used for the storage of only 
diesel fuel transportation units, the single largest transportation 
unit tank would be counted in the maximum capacity for purposes of this 
paragraph. However, diesel fuel transportation units that may be parked 
in permanent fuel storage facility where a piping system from the 
surface terminates or where a larger stationary tank is housed would 
not be considered part of the ``fuel storage system'', and the capacity 
of the transportation unit tank would not be included. The rationale 
behind this is that only one component in a fuel storage facility would 
be expected to fail at one time, such as a burst piping system or a 
leak in a stationary tank or in a transportation unit tank.
    In support of the requirement of this paragraph, one commenter 
noted that a fuel spill occurred when valves in the piping system from 
the surface storage tank failed, allowing the static head pressure to 
be imparted on the dispensing hose which caused it to rupture and fuel 
to escape.
    Commenters stated that it is important that the storage location be 
designed to contain fuel spills and tank ruptures to stop the spread of 
fuel. The final rule's containment capacity requirement of 150 percent 
of the capacity of the fuel system will provide a prudent safety factor 
in view of the potential fire hazard created by the release of large 
amounts of diesel fuel into an underground mine.
    Paragraph (a)(7) has been added to the final rule and requires that 
permanent fuel storage facilities be provided with a competent concrete 
floor or equivalent to prevent fuel spills from saturating the mine 
floor. This provision is intended to ensure that spilled diesel fuel 
can be easily cleaned up and will not accumulate, creating a fire 
hazard. This requirement is added in the final rule in response to 
commenters who suggested that the floor of the storage facility should 
be noncombustible and impermeable to oil and diesel fuel. These 
commenters argued persuasively that a requirement for a concrete floor 
would preserve the integrity of a noncombustible facility.
    Under the requirements of this paragraph a permanent fuel storage 
facility must be provided with a competent floor made of concrete or an 
equivalent material. The term ``competent'' is used to make clear that 
a cracked concrete floor or a porous mine floor would not satisfy this 
requirement. A brattice-type lining or rubber membrane would not be 
considered equivalent because it could easily be torn during refueling 
of vehicles, and diesel fuel could leak through and accumulate 
underneath. This provision has been added to the final rule in direct 
response to commenters, many of whom testified at the Agency's public 
hearings on the proposal. MSHA believes that this provision constitutes 
a logical outgrowth of the proposal because of commenters' stated 
concerns in ensuring that spilled fuel will not saturate the mine floor 
and create a fire hazard.
    The requirements of paragraph (b) of this section of the final rule 
apply to both permanent underground fuel storage facilities and 
temporary underground fuel storage areas. This paragraph requires that 
these storage facilities or areas be: equipped with a 240 pounds of 
rock dust and at least two fire extinguishers, or, in the alternative, 
with at least three fire extinguishers; be conspicuously marked; and be 
maintained to prevent the accumulation of water. These basic 
requirements address potential fire hazards in these facilities and 
ensure that mine personnel are aware of the presence and location of 
such facilities.
    Paragraph (b)(1) requires that permanent fuel storage facilities 
and temporary fuel storage areas be equipped with at least 240 pounds 
of rock dust and provided with two portable multipurpose dry chemical 
type (ABC) fire extinguishers that are listed or approved by a 
nationally recognized independent testing laboratory and have a 
10A:60B:C or higher rating. Both extinguishers must be easily 
accessible to personnel, and at least one must be located outside of 
the facility or area, upwind of the facility in intake air. Paragraph 
(b)(2) provides, as an alternative to the requirement of paragraph 
(b)(1), that three fire extinguishers may be provided.
    The proposal would have required fixed and mobile fuel storage 
facilities to be equipped with at least two 20-pound multipurpose dry 
chemical type fire extinguishers, and would not have required that rock 
dust be provided. One commenter recommended that foam generating 
machines or fire extinguishers of 150 pounds or more be required. The 
final rule does not adopt the suggestion of this commenter, because 
MSHA considers it too hazardous to fight a diesel fire underground that 
cannot be extinguished in its incipient stages. The fire extinguishers 
and fire suppression equipment required by this section are intended to 
be used to extinguish small fires, such as could occur on equipment in 
the facility.
    The final rule redefines the type of dry chemical extinguishers 
that are required, based on specifications recommended by the National 
Fire Protection Association for the particular hazard involved. The 
rating of the fire extinguishers has been adopted from NFPA 123 and is 
in accordance with NFPA 10-Standard for Portable Fire Extinguishers. 
Also, extinguishers must be listed or approved by a nationally 
recognized independent testing laboratory, which provides assurance 
that the extinguishers will perform effectively in the event of a fire 
emergency. The final rule requires that the fire extinguishers be 
located so that miners will have quick access to them in the event of a 
fire. To allow flexibility in complying with the requirements of this 
paragraph, the final rule addresses the location of only one fire 
extinguisher. The location of the other extinguisher should be 
determined based on mine conditions and the particular usage of the 
facility. The final rule specifies that the fire extinguisher be 
located upwind of the facility, which has been added to ensure that if 
a fire occurs miners will be able to reach the fire extinguisher 
without being exposed to the heat or smoke of the fire.
    The final rule adds a requirement for 240 pounds of rock dust to be 
kept in the storage facility in response to comments concerning the 
effectiveness of rock dust in fighting diesel fuel fires and the 
ability of rock dust to contain spills. The requirement for 240 pounds 
of rock dust is consistent with Sec. 75.1100-2(f), which requires 240 
pounds of rock dust to be provided at permanent underground oil storage 
stations, and is included in the final rule as an added measure of fire 
protection in response to the concerns of commenters. However, 
paragraph (b)(2) allows an additional fire extinguisher to be 
substituted for the rock dust required under paragraph (b)(1), which is 
consistent with provisions in existing petitions for

[[Page 55449]]

modification for fire protection at electrical installations. The 
requirements of the final rule strike a balance between those 
commenters concerned about the need for additional fire protection 
provided by rock dust in locations where diesel fuel is stored, and 
those who were concerned that the storage of rock dust in those 
locations was inadvisable in mines that tended to be wet.
    Paragraph (b)(3) adopts the requirement of the proposal that 
permanent diesel fuel storage facilities and temporary fuel storage 
areas be identified with conspicuous markings designating diesel fuel 
storage. The proposal would have required the facilities to be 
designated as ``combustible liquid storage,'' but MSHA has concluded 
that precise identification as areas of diesel fuel storage is more 
appropriate, and will ensure that mine personnel are aware of the 
locations where diesel fuel is stored underground.
    Paragraph (b)(4) requires that fuel storage facilities or areas be 
maintained to prevent the accumulation of water. The proposal would 
have required that fixed and mobile underground storage facilities be 
located in an area as dry as practicable, a concept which several 
commenters considered to be vague and potentially difficult to comply 
with. This requirement has therefore been revised to require that 
permanent underground diesel fuel storage facilities and temporary fuel 
storage areas be maintained to prevent the accumulation of water. This 
provision recognizes that tanks or other components of the storage 
facility may corrode as a result of exposure to water. Additionally, 
accumulated water can increase the fire hazard present by a fuel spill, 
because diesel fuel will float on top of water and may be spread more 
easily throughout the storage facility. The requirement of this 
paragraph addresses these hazards.
    Paragraph (c) adopts the proposed prohibition on welding or 
cutting, except as provided in paragraph (d) of this section, from 
being performed within 50 feet of a diesel fuel storage facility or 
area. This requirement is intended to minimize fire hazards and is 
consistent with National Fire Protection Association requirements (NFPA 
123). No comments were received on this aspect of the proposal.
    Paragraphs (d)(1) and (d)(2) adopt the requirements of the proposal 
and set forth specific precautions to be followed when welding, 
cutting, or soldering pipelines, tanks, or other containers that might 
have contained diesel fuel. MSHA received only a few comments on this 
aspect of the proposal, which is consistent with NFPA requirements. A 
review of MSHA's accident data reveals that a fatal accident occurred 
when the victim was welding a diesel fuel storage tank. The victim had 
drained the tank, which had been filled with water, and attempted to 
repair a small leak which remained in the tank. Vapors from the 
residual fuel were ignited by the heat of welding, and the tank 
exploded. The requirements of this paragraph are intended to address 
such hazards, and recognize that welding can be performed safely 
underground as long as appropriate safeguards are followed. 
Additionally, the large size of certain vessels used for the storage of 
diesel fuel underground would make it impractical to restrict welding 
of such containers to the surface. The precautions in paragraph (d)(1) 
include thoroughly purging and cleaning or inerting the pipelines, 
containers, or tanks before welding or cutting, with a vent or opening 
provided in the container or tank to release pressure before heat is 
provided. The final rule also prohibits diesel fuel from entering 
pipelines, tanks, or other containers that have been welded, soldered, 
brazed, or cut until the metal has cooled to ambient temperature. A 
slight change has been made in the language of this requirement to 
conform the references to the diesel fuel containers that are the 
subject of these requirements. The phrase ``pipelines, tanks, or other 
containers'' is used throughout. Additionally, the reference in 
proposed paragraph (d)(1) to containers or tanks that ``have contained 
combustible or flammable materials'' has been changed in the final rule 
to pipelines, tanks or other containers ``that have contained diesel 
fuel,'' to eliminate the inconsistency that existed between this 
provision and other language in this paragraph and to clarify the scope 
of these requirements.
    One commenter recommended that a cleanup program be required for 
underground fuel storage facilities and areas. This recommendation has 
not been adopted in the final rule, because existing Sec. 75.400-2 
already requires mine operators to establish and maintain programs for 
regular cleanup of accumulations of coal and other combustibles. MSHA 
will require that underground diesel fuel storage facilities and areas 
be covered by the cleanup program under Sec. 75.400-2, which will 
ensure that these locations are kept clear of any combustible 
materials.
Section 75.1904  Underground Diesel Fuel Tanks And Safety Cans
    This section includes requirements for the design of diesel fuel 
tanks and safety cans and for emergency venting devices for diesel fuel 
tanks for venting vapors to protect against the buildup of pressure in 
the tank, which could lead to its rupture if the tank is exposed to 
fire. The requirements of this section are responsive to comments and 
are consistent with NFPA, Underwriters Laboratories, and American 
Petroleum Institute standards for storage tanks for combustible 
liquids. A number of commenters suggested restructuring and 
reorganizing the proposed design requirements for diesel fuel tanks, 
and the final rule is revised in response to these comments.
    Paragraph (a) of this section of the final rule contains 
construction and location requirements for underground diesel fuel 
tanks in permanent underground fuel storage facilities and temporary 
underground fuel storage areas. These requirements are intended to 
guard against leakage of diesel fuel and to minimize fire hazards.
    Paragraph (a)(1) requires that underground diesel fuel tanks have 
steel walls of a minimum \3/16\-inch thickness or walls made of other 
metal of a thickness that provides equivalent strength. This 
specification has been added to the final rule to ensure that diesel 
fuel storage tanks are properly designed for their intended purpose, 
and in response to commenters who were concerned that diesel fuel tanks 
be durably constructed. MSHA explored alternatives for an objective 
measurement of durable construction. The requirement of this paragraph 
is consistent with prevailing industry standards, and is intended to 
serve as a minimum design standard for substantially constructed tanks. 
This requirement is derived from Department of Transportation (DOT) 
Spec. 51 Section 178-245-2(b), and is consistent with DOT requirements 
for over-the-road vehicles that transport diesel fuel. This 
specification is also recognized by the National Fire Protection 
Association in many of its fire protection standards as a design 
guideline for tanks used for storage of combustible liquids. 
Manufacturers of fuel transportation units currently produce diesel 
fuel storage tanks with \3/16\-inch thick steel walls, and this 
specification will allow mine operators to buy diesel fuel tanks off-
the-shelf.
    Paragraph (a)(2) requires diesel fuel tanks to be protected from 
corrosion. The proposal would have required these tanks to be 
constructed of ``noncorrosive

[[Page 55450]]

material.'' The language of the final rule will allow mine operators 
the option of either using a tank that has been constructed of 
noncorrosive material, such as galvanized or stainless steel, or of 
protecting a tank from corrosion that has been constructed of an 
oxidizing material, such as common steel. Protection from corrosion can 
be achieved by applying a protective coating.
    Paragraph (a)(3) requires diesel fuel tanks to be of seamless 
construction or fabricated with liquid tight welded seams. MSHA has 
added this requirement to the final rule in response to comments 
raising concerns about the durability of fuel tanks in use underground, 
to provide an objective measurement of substantial construction. Bolted 
and crimped joints are not allowed under the final rule because they 
are prone to leakage. The requirement of this paragraph is consistent 
with DOT Spec. 51 Section 178-245-2(b), and is intended to ensure that 
diesel fuel tanks are well constructed and designed not to leak.
    Paragraph (a)(4) requires that diesel fuel tanks not leak, and has 
been added in the final rule in response to commenters' concerns that 
tanks not contribute to a fire. Under the final rule, all attachments 
to the tank, such as vents, caps, hoses, pumps, valves, and nozzles, 
must also be free from leaks. Many commenters were concerned with 
leakage hazards presented by the storage of diesel fuel underground. 
These commenters were particularly concerned about leakage in temporary 
diesel fuel storage areas. MSHA believes that the requirement of this 
paragraph, in conjunction with the other provisions in this final rule, 
will greatly minimize hazards associated with storage of diesel fuel 
underground.
    Paragraph (a)(5) requires stationary tanks in permanent underground 
diesel fuel storage facilities to be placed on noncombustible supports 
so that tanks are at least 12 inches above the floor. Under the 
proposal such tanks would have been required to be supported by 
concrete, masonry, protected steel, or equivalent supports. Steel 
supports, except for steel saddles less than 12 inches from the floor, 
would have been required to be protected by materials having a fire 
resistance rating of not less than two hours. The proposal did not 
specify the minimum distance the tank must be from the floor. 
Commenters stated that positioning tanks at least 12 inches off the 
floor would allow for proper cleaning, rock dusting and quick detection 
of leaks. MSHA agrees with these comments and has revised the final 
rule accordingly. Additionally, the final rule provides that the tank 
supports must be made of noncombustible material, which is defined in 
Sec. 75.1900 of the final rule, making unnecessary the reference in the 
proposal to ``concrete, masonry, protected steel, or equivalent 
supports''. The reference has therefore not been adopted in the final 
rule.
    Paragraph (b)(1) requires diesel fuel tanks to be provided with 
devices for emergency venting that are designed to open at a pressure 
that does not exceed 2.5 pounds per square inch. Under this 
requirement, the venting devices must also meet minimum size 
requirements based on the capacity of the tank. The rule provides 
minimum vent device specifications for two ranges of tank sizes: tanks 
with a capacity of 500 gallons or less and tanks with a capacity of 
more than 500 gallons. The requirements of this section are 
incorporated in NFPA standards for portable tanks for transporting and 
storage of combustible liquids, as well as in American Petroleum 
Institute design standards. These vents are designed to activate at a 
pressure which is below the expected yield point of the tank and to 
provide the necessary volumetric flow rate to maintain safe internal 
pressure if the tank shell were to heat up as a fire develops. Opening 
of the device will allow the vapors to be safely vented and will 
prevent the tank from rupturing under this condition. Some commercially 
available emergency vents have been listed or approved by nationally 
recognized independent testing laboratories and can be expected to 
provide adequate pressure relief in a fire situation. The vent sizes 
required in the final rule were determined by design calculations 
outlined in National Fire Protection Association, Underwriters 
Laboratories, and American Petroleum Institute standards for a range of 
tank sizes typical for underground diesel fuel storage. These 
calculations take into account the probable maximum rate of heat 
transfer per unit area; the size of the tank and the percentage of the 
area likely to be exposed; the time required to bring the tank contents 
to a boil; the time required to heat unwet portions of the tank shell 
or roof to a temperature where the metal will lose strength; and the 
effect of drainage, insulation and the application of water in reducing 
the fire exposure and heat transfer. MSHA believes that specifying the 
minimum size of vent for two ranges of tank sizes is preferable to a 
requirement that would require the operator to design vents for a given 
size. The types of emergency vents required under this paragraph are 
commercially available and relatively inexpensive. The requirement of 
this paragraph respond to concerns of commenters regarding the hazards 
of fuel storage underground.
    Paragraph (b)(2) requires tethered or self-closing caps for 
stationary tanks in permanent underground diesel fuel storage 
facilities, and self-closing caps for diesel fuel tanks on diesel fuel 
transportation units. The proposed rule would have required self-
closing caps for all diesel fuel storage tanks, and did not include the 
alternative of a tethered cap for stationary tanks. One commenter 
suggested that self-closing caps are not needed on fixed tanks since 
they are unlikely to incur fuel spillage. The final rule permits the 
optional use of a tethered cap for stationary tanks, which adds 
flexibility and provides the same degree of protection as a self-
closing cap.
    Paragraphs (b)(3), (b)(4), (b)(5), and (b)(6) are unchanged from 
the proposal, with the exception of paragraph (b)(6) which has been 
revised to reflect commenters' concerns with respect to the location of 
shutoff valves. Paragraph (b)(3) addresses the size of vents, and will 
permit the free flow of fuel out of the tank without creating a vacuum 
in the tank that could damage its shell. Paragraph (b)(4) addresses 
requirements for liquid tight connections, and will minimize the risk 
of leaks and the resulting risk of fire. Paragraph (b)(4)(i) requires 
that liquid tight connections for all tank openings be identified by 
conspicuous markings that specify the function. Because this provision 
is performance-oriented and allows the mine operator to choose the 
manner in which markings identify connections, MSHA anticipates the 
burden time under the Paperwork Reduction Act of 1995 to be minimal.
    Paragraph (b)(5) addresses requirements for vent pipes, and will 
minimize the possibility of fuel leaking from vent lines.
    Paragraph (b)(6) is derived from proposed Sec. 75.1906(c)(5) and 
requires that shutoff valves be located as close as practicable to the 
tank shell. The proposal would have required shutoff valves to be 
located within 1 inch of the tank shell. Because shutoff valves that 
extend for any distance from the fuel tank can be inadvertently damaged 
or broken off, making it impossible to shut off the flow of liquid from 
the fuel tank, the valves must be located close to the tank where they 
are protected from damage. However, one commenter was concerned that 
the proposal was too restrictive because it may not always be possible 
from a practical standpoint to locate the shutoff valve within 1 inch 
of

[[Page 55451]]

the tank shell. The final rule responds to this commenter's suggestion 
by allowing greater flexibility, and provides that the valve be located 
as close as practicable to the tank shell.
    Paragraph (b)(7) adopts the requirement of the proposal for an 
automatic closing, heat-actuated valve on each withdrawal connection 
below the liquid level. The final rule does not adopt the proposed 
exception for connections used for emergency disposal, because this 
exception is not relevant to underground coal mines. The proposed rule 
required the installation of heat-actuated shutoff valves only on tanks 
in fixed storage facilities. The final rule extends this requirements 
to all diesel fuel tanks used underground, which would include tanks on 
diesel fuel transportation units. Automatic closing, heat-actuated 
valves shut the flow of fuel off when exposed to high temperatures. 
These valves prevent additional fuel from being discharged from the 
tank in the event of a fire. This requirement has been extended to 
tanks on transportation units, and is warranted in light of the scaling 
back of construction requirements for temporary fuel storage areas in 
the final rule in response to commenters' concerns that the 
requirements were impractical.
    Paragraph (c) addresses tanks with openings for manual gauging, and 
requires that liquid tight, tethered or self-closing caps or covers be 
provided and be kept closed when not open for gauging. The alternative 
of tethered caps or covers has been added to the final rule for 
flexibility. MSHA believes the use of self-closing or tethered caps 
will provide necessary protection against overflow.
    Paragraph (d) requires that surfaces of the tank and its associated 
components be protected against collision. This provision has been 
added to the final rule in response to commenters who were concerned 
about protecting the tanks from moving equipment. MSHA agrees that it 
is essential that diesel fuel storage tanks be protected from damage by 
collision with other equipment. Stationary tanks in permanent fuel 
storage facilities may need guards or barricades, depending upon their 
location, to prevent moving equipment from colliding with the tank.
    Paragraph (e) sets forth requirements for leakage tests for tanks 
and their associated components, except that tanks and components 
connected directly to piping systems must be properly designed for the 
application. The final rule requires a leakage test at a pressure equal 
to the working pressure. The proposed rule would have required both a 
strength test and a leakage test, at a pressure equal to the static 
head, for diesel fuel storage tanks before the tanks were placed in 
service. Commenters recommended that tanks and their connections be 
tested at a pressure twice the working pressure.
    The final rule does not require testing at twice the working 
pressure, in light of the detailed construction and design requirements 
for diesel fuel storage tanks in the final rule. The term ``static 
head'' in the proposed rule has been replaced with the term ``working 
pressure'' in the final rule. Although the meanings are the same in 
this context, the term ``working pressure'' is more widely used and 
more commonly understood in the mining industry. Compliance with the 
requirement of this paragraph will provide protection from hazards 
associated with leakage of diesel fuel underground. Under the final 
rule, mine operators are expected to verify that no leaks exist after 
installing the tank underground and connecting all of the tank's 
associated components before placing the tank in service. All 
components must be rated for the working pressures in the system. Both 
the static head and the maximum pump pressure, if applicable, must be 
considered when designing and selecting tanks and associated components 
connected to a piping system. For tanks connected to a piping system 
from the surface, the static head pressure could easily exceed several 
hundred pounds per square inch (psi), either during normal operation or 
because of a fault in the system. For these systems, MSHA advises mine 
operators to plan for a worst-case (highest pressure) scenario and 
select a tank and tank components that are designed for use at this 
pressure.
    MSHA has concluded that the strength test for tanks that was 
included as part of the proposal is unnecessary, given the other 
specifications for tanks. This proposed requirement has therefore not 
been included in the final rule.
    The proposal would have imposed additional requirements on tanks in 
underground diesel storage facilities that were not located in ``dry 
areas.'' Such tanks would have been required under the proposal to be 
placed on noncombustible supports so that the tanks were at least 6 
inches above water or wet bottom, and such tanks would also have been 
required to be constructed of noncorrosive material. Commenters stated 
that the concept of ``dry areas'' was ambiguous and should not be 
adopted. MSHA agrees with these comments, and this aspect of the 
proposal has therefore not been included in the final rule. However, 
under the final rule, stationary tanks in permanent underground storage 
facilities must be placed on noncombustible supports at least 12 inches 
above the floor to allow for proper cleaning, rock dusting and quick 
detection of leaks. Tanks will also be protected by this requirement 
from wet floors. Further, the final rule requires all diesel fuel 
storage tanks to be protected from corrosion. These requirements will 
ensure that tanks are sufficiently shielded from water damage.
    Paragraph (f) establishes design and size requirements for safety 
cans. These requirements have been added to the final rule to ensure 
that small amounts of diesel fuel can be transported and stored in a 
safe manner. Although the proposed rule contemplated the use of safety 
cans to transport small amounts of diesel fuel underground, the 
proposal would not have set design requirements for safety cans. 
Commenters were concerned that widespread and uncontrolled use of 
safety cans underground would result in fuel spills and accumulations 
on mine equipment and mine floors. The provisions of this paragraph are 
intended to address commenters' concerns about the hazards presented by 
safety cans used to store and transport diesel fuel in the underground 
mine environment.
    The final rule establishes specific design requirements for safety 
cans. As indicated in the discussion of Sec. 75.1900, the term ``safety 
can'' is defined in the final rule as a metal container intended for 
storage, transport or dispensing of diesel fuel with a nominal capacity 
of no more than 5 gallons, listed or approved by a nationally 
recognized independent testing laboratory. Paragraph (f)(1) of this 
section reiterates the 5-gallon capacity limitation, and paragraph 
(f)(2) requires that safety cans be equipped with a flexible or rigid 
tubular nozzle attached to a valved spout. Paragraph (f)(3) requires 
that safety cans be provided with a vent valve designed to open and 
close simultaneously and automatically with the opening and closing of 
the pouring valve. Finally, paragraph (f)(4) requires that safety cans 
be designed so that they will safely relieve internal pressure when 
exposed to fire. These requirements will reduce the likelihood of 
diesel fuel spills and afford appropriate protection for miners, in 
response to commenters who were concerned about the use of safety cans 
to store and transport diesel fuel.

[[Page 55452]]

Section 75.1905  Dispensing of Diesel Fuel
    This section addresses the dispensing of diesel fuel, and has been 
revised from the proposal to clarify the various ways that diesel fuel 
may be safely dispensed. Paragraph (a) provides that diesel-powered 
equipment may be refueled only from safety cans, from tanks on diesel 
fuel transportation units, or from stationary tanks. These requirements 
are intended to control the circumstances under which diesel fuel is 
dispensed underground, minimizing the opportunities for spills or 
leakage, and in response to commenters who expressed concern about fuel 
spillage underground.
    Paragraph (b) contains requirements for the dispensing of diesel 
fuel from tanks, except for the dispensing of fuel from safety cans. 
Design specifications for safety cans are included in Sec. 75.1904(f) 
of the final rule, which requires nozzles, spouts, and vent valves on 
safety cans.
    The requirements of paragraph (b)(1) apply when gravity feed is 
used as a means of dispensing diesel fuel. Although in developing the 
proposed rule MSHA contemplated that gravity feed would be used as a 
method for dispensing fuel, the proposal did not specifically refer to 
it. Some commenters questioned whether this omission should be 
interpreted as a prohibition of gravity feed fuel dispensing. In 
response to these comments, MSHA has clarified that gravity feed is a 
permissible method of dispensing fuel. However, because gravity feed 
presents the same potential as a powered pump for a loss of fuel from 
an unattended hose, the final rule prohibits a latch-open device when 
gravity feed is the method of dispensing.
    Paragraph (b)(2) is identical to the proposal and requires that a 
manual pump used to dispense diesel fuel have a hose equipped with a 
nozzle containing a self-closing valve. No comments were received on 
this aspect of the proposal, and it has been adopted unchanged.
    Paragraphs (b)(3) (i) through (iii) require that, when a powered 
pump is used to dispense fuel, it be equipped with an accessible 
emergency shutoff switch for each nozzle, and that the hose be equipped 
with a self-closing valve without a latch-open device, and with an 
anti-siphoning device. These requirements have been adopted, with some 
minor changes, from the proposal. Specifically, the final rule 
clarifies that an accessible emergency shutoff switch be provided for 
``each nozzle'', and adds a requirement for an anti-siphoning device. 
These modifications recognize that fuel piping systems may be installed 
underground that do not transport fuel from the surface, but from one 
location to another in the mine itself. These additional requirements 
are intended to prevent the leakage or pumping of the contents of a 
tank into the mine in the event of a broken or leaking pipe or hose. An 
accessible emergency shutoff switch is required for each nozzle under 
the final rule to permit quick action by mine personnel in the case of 
a leaking pipe or hose or in the event of fire during refueling. An 
anti-siphoning device prevents the inadvertent siphoning of fuel from a 
tank connected to the piping system, and is responsive to commenters' 
concerns regarding the hazards of fuel leaks and spills underground.
    Commenters recommended that an inline fuse be required as near as 
possible to the pump's power source to deenergize the electrical system 
in the event of an electrical short circuit. This comment has not been 
adopted in the final rule, because the circuit protection specified in 
existing Sec. 75.518 is sufficient to prevent or detect a short 
circuit. In addition, other existing electrical safety requirements in 
part 75 apply to electrical components associated with diesel fuel 
handling and storage, and provide adequate protection from electrical 
hazards.
    Paragraph (c) prohibits the use of compressed gas in dispensing 
diesel fuel. This prohibition is identical to what was proposed and 
received no comments. The use of compressed gas to dispense diesel fuel 
would require not only a special tank but also an emergency venting 
system for pressurized tanks, and would still present a hazard. If a 
leak developed in the pressurized tank or its associated piping, 
relatively large amount of fuel could be spilled onto the mine floor, 
creating a serious fire hazard. This prohibition has therefore been 
retained in the final rule.
    Paragraph (d), like the proposal, prohibits diesel fuel from being 
dispensed to the fuel tank of diesel-powered equipment while the 
equipment engine is running. This prohibition is derived from MSHA's 
review of Canadian fire accident data, which reveals that 10 fires 
occurred during refueling. Failure to shut off the engine may have 
contributed to these fires. This prohibition is also consistent with 
Sec. 75.1916(d) of the final rule, which forbids unnecessary engine 
idling, and reduces exposure of miners to exhaust emissions.
    Several commenters recommended that permissible diesel equipment be 
excluded from this prohibition because it is designed to be explosion-
proof. These commenters also stated that shutting down the equipment 
should be avoided because of the difficulty in restarting it, and that 
in some cases a trained mechanic would be needed to restart the engine.
    MSHA does not agree that permissible equipment should be excluded 
from this requirement. Although permissible diesel equipment is 
equipped with engine surface temperature controls that would prevent 
the ignition of diesel fuel if it is spilled on the equipment, air 
quality considerations support the adoption of this requirement for 
permissible as well as nonpermissible equipment. Not shutting down a 
machine engine during refueling serves no purpose other than 
convenience, and the diesel exhaust produced contributes unnecessarily 
to contaminant levels. The fact that engines may be difficult to 
restart does not justify exempting permissible equipment from this 
requirement. Equipment that is difficult to restart is in need of 
service or repair. The final rule therefore does not exempt permissible 
equipment from the prohibition against refueling of diesel equipment 
while the equipment engine is running.
    Paragraph (e), which requires that powered pumps be shut off when 
fuel is not being dispensed, has been added to the final rule to 
address concerns about loss of fuel as a result of broken or leaking 
pipes. This requirement is intended to minimize the likelihood of fuel 
spills in the underground mine environment.
Section 75.1905-1  Diesel Fuel Piping Systems
    Section 75.1905-1 has been added to the final rule to address 
requirements for diesel fuel piping systems. The requirements in the 
proposal governing fuel piping systems were included in the same 
section as proposed requirements for fuel transfer. MSHA has concluded 
that dispensing requirements and design and construction requirements 
for piping systems are sufficiently unique that they are more 
appropriately addressed in a separate standard.
    Underground fuel piping systems can be very complex and may require 
specialized expertise for their design and installation. Mine operators 
should ensure that an engineering evaluation, including a fault 
analysis, is performed in developing a fuel piping system.
    One commenter recommended that piping of diesel fuel should be 
allowed only in shaft mines, from the surface vertically to permanent 
underground

[[Page 55453]]

storage areas, and that the piping should be contained in its own 
borehole to isolate it from ignition sources. Safety considerations do 
not warrant restricting fuel piping systems to shaft mines. MSHA and 
industry experience, including an analysis of accident reports, does 
not reveal any increased hazard with the use of piping systems in slope 
mines. In the final rule, MSHA has removed the reference to vertical 
pipelines to clarify that this section applies to all mines.
    Paragraph (a) of this section of the final rule adopts the proposed 
requirement that diesel fuel piping systems from the surface to be 
designed and operated as dry systems, unless an automatic shutdown is 
incorporated that prevents accidental loss or spillage of fuel and that 
activates an alarm system. The phrase ``from the surface'' has been 
added to the final rule to clarify that only piping systems from the 
surface are governed by the requirements of this paragraph. MSHA is 
aware that some mines have installed horizontal piping systems that do 
not originate at the surface. Because these horizontal systems 
typically cannot be operated as dry systems, the rule specifies that 
these systems would not be affected by this requirement. No location is 
specified for the alarm in the final rule, to allow mine operators 
flexibility in determining where the alarm will be most effective in 
alerting mine personnel.
    Compliance with the requirement of this paragraph mandates a well 
designed piping system, and may require a double wall system. Except 
for the comment suggesting that piping of diesel fuel underground be 
limited to shaft mines, MSHA received no other comments on this 
provision, and the proposed requirement has been adopted in the final 
rule without change.
    Paragraphs (b)(1) through (b)(4) address requirements for piping, 
valves, and fittings. These requirements are unchanged from the 
proposal, and constitute generally accepted design specifications. This 
standard requires that all piping, valves, and fittings be: (1) Capable 
of withstanding working pressures and stresses; (2) capable of 
withstanding four times the static pressure; (3) compatible with diesel 
fuel; and (4) maintained in a manner which prevents leakage.
    Paragraph (c) requires pipelines to have manual shutoff valves 
installed at the surface filling point, and at the underground 
discharge point. This requirement is the same as the proposal, except 
that the proposal used the term ``vertical'' to describe pipelines. For 
the reasons discussed in the introduction to this section, the term 
``vertical'' has been eliminated to clarify that this section applies 
to all underground coal mines.
    Paragraphs (d) and (e), like the proposal, include requirements for 
shutoff valves on fuel lines. Paragraph (d) provides that if fuel lines 
are not buried in the ground, shutoff valves must be located every 300 
feet. Paragraph (e) requires that shutoff valves be installed at each 
branch line where the branch line joins the main line. One commenter 
recommended that automatic shutoff valves be required in these two 
situations, stating that they provide for minimal loss of fuel and 
maximum safety in the case of a pipeline rupture or leak. MSHA does not 
believe that automatic shutoff valves are necessary when the additional 
benefits are balanced with other provisions in this final rule. The 
commenter's suggestion has therefore not been adopted in the final 
rule.
    Paragraph (f) is a new provision in the final rule and requires 
that an automatic means be provided to prevent unintentional transfer 
of fuel from the surface into the permanent underground diesel fuel 
storage facility. This requirement has been added to address the 
concerns of some commenters that were prompted by a specific diesel 
fuel spill caused by malfunctioning components in a diesel fuel piping 
system. Additionally, many commenters were generally concerned about 
possible fire and other hazards that could result from diesel fuel 
spills and leaks, particularly when piping systems are used. This 
paragraph responds to those comments by requiring a fail-safe piping 
system, ensuring that necessary protection is provided to miners.
    Paragraph (g) provides that diesel fuel piping systems from the 
surface can only be used to transport fuel directly to stationary tanks 
or diesel fuel transportation units in a permanent underground diesel 
fuel storage facility. This requirement has been renumbered and has 
been revised from the proposal to respond to commenters who recommended 
strict control of the use of safety cans and stated that dispensing 
fuel from a piping system directly into diesel equipment fuel tanks 
would create a fire hazard. This paragraph is intended to prohibit 
filling safety cans and equipment fuel tanks directly from a piping 
system and further minimize hazards associated with fuel spills.
    Under this paragraph a fuel piping system from the surface may 
terminate underground only in a permanent fuel storage facility, which 
must be equipped with features such as a fire suppression system and a 
means of containing a fuel spill. Because temporary fuel storage areas 
are not required to have these features, they would not provide 
adequate fire protection for a situation where a significant amount of 
fuel is lost in a spill from a piping system.
    Paragraph (h), like the proposal, requires that when boreholes are 
used the diesel fuel piping system cannot be located in a borehole with 
electric power cables. This will minimize the likelihood of fire by 
diesel fuel coming into contact with potential ignition sources.
    Paragraph (i) requires that diesel fuel piping systems located in 
entries not be located on the same side of the entry as electric cables 
or power lines. It also requires that guarding be provided when piping 
systems cross electric cables or power lines. The final rule has been 
modified from the proposal to acknowledge that, in some cases, a 
pipeline must cross over power lines, depending upon the mine's layout. 
The standard addresses any hazards presented by the intersection of 
pipelines and electric cables or power lines by requiring that guarding 
be provided.
    Paragraph (j) requires that piping systems be protected to prevent 
physical damage. Commenters supported this provision, and it is 
unchanged from the proposal.
Section 75.1906  Transport of Diesel Fuel
    This section of the final rule has been retitled and reorganized to 
reflect MSHA's approach to diesel fuel storage and handling in this 
final rule. The word ``containers'' is removed from the title to 
reflect that only two types of vessels are allowed to transport and 
dispense diesel fuel--safety cans and tanks. This section of the final 
rule is responsive to commenters who: expressed concerns about the wide 
and uncontrolled use of safety cans in underground coal mines; 
recommended limited section storage of diesel fuel; stated that fire 
suppression systems were not needed on the tank used to transport fuel; 
and noted the need for clarification of the requirement for portable 
fire extinguishers on diesel fuel transportation units.
    Several commenters stated that the proposed rule was vague and 
confusing. Their comments were directed to the use of the terms 
``containers,'' ``safety cans,'' ``tanks,'' and ``fuel transportation 
units.'' As indicated in the preamble discussion for Sec. 75.1900, MSHA 
has included definitions in the final rule for the terms ``safety 
cans,'' ``diesel fuel tank,'' and ``diesel fuel transportation unit'' 
to provide additional clarification

[[Page 55454]]

for the fuel handling and storage requirements in the final rule. The 
term ``container'' has not been defined because it has been eliminated 
from the final rule.
    Several commenters recommended that the use of small containers and 
cans be restricted because they are prone to leak when transported or 
used to dispense fuel. In support of their recommendation, these 
commenters cited instances of mine floors being saturated with fuel. 
Other commenters urged that safety cans be allowed for transport of 
small quantities of diesel fuel, and stated that prohibiting their use 
would be unwarranted. As stated earlier in the discussion for this 
section, the final rule has been revised to require that safety cans be 
listed or approved by a nationally recognized independent testing 
laboratory. This aspect of the final rule will provide miners with 
protection against leakage and spillage during dispensing operations, 
while recognizing the practical need to transport small quantities of 
diesel fuel.
    Paragraph (a) of this section of the final rule requires diesel 
fuel to be transported only by diesel fuel transportation units or in 
safety cans. This requirement is intended to ensure that diesel fuel is 
transported only in vessels designed for that purpose. The proposal 
would have required diesel fuel to be transported in specially designed 
containers. A commenter recommended substituting the term ``combustible 
liquid'' in place of the term ``diesel fuel'', stating that there are 
Department of Transportation specifications for containers that 
transport combustible liquids. The final rule responds to commenters by 
limiting the transport of diesel fuel to safety cans, which must be 
listed or approved by a nationally recognized independent testing 
laboratory, or by diesel fuel transportation units, which must be 
equipped with a tank designed for the transport of diesel fuel.
    MSHA recognizes that safety can use must be carefully controlled. 
Paragraph (b) of this section of the final rule allows only one safety 
can to be transported on a vehicle at any time, and the can must be 
protected from damage during transport. All other safety cans must be 
stored in permanent underground fuel storage facilities. This provision 
is revised from the proposal to be responsive to commenters who cited 
problems with misuse of small cans and recommended that they be 
strictly controlled. Commenters further stated that in some mines there 
was no designated area for storage of safety cans. The requirements 
that have been added to the final rule are intended to ensure safe 
transport of safety cans. The final rule does not require that single 
safety cans, which are secured and protected on a vehicle, be removed 
for storage in permanent facilities when the vehicle is left 
unattended. This aspect of the final rule will allow for emergency 
refueling, while at the same time provide a degree of control over the 
use of safety cans.
    Paragraphs (c) and (d) require that leaking safety cans be promptly 
removed from the mine, and that safety cans and tanks on diesel fuel 
transportation units be conspicuously marked. These marking 
requirements are consistent with marking requirements for permanent 
fuel storage facilities and temporary fuel storage areas in 
Sec. 75.1903(b)(3) of the final rule. The inclusion of marking 
requirements for safety cans and tanks in the final rule is responsive 
to several commenters who suggested that signs should be placed on 
mobile equipment identifying tanks and cans used for diesel fuel 
storage. This is also a prudent fire protection practice.
    Paragraphs (e) and (f) establish requirements for the 
transportation of tanks on fuel transportation units. As mentioned 
earlier, the final rule does not use the term ``container''. Paragraph 
(e) provides that diesel fuel transportation units must not transport 
more than 500 gallons of diesel fuel at one time. Paragraph (f) 
requires tanks on diesel fuel transportation units to be permanently 
fixed to the units and have a total capacity of no greater than 500 
gallons. Under the proposal, containers used for the transport of 
diesel fuel could not exceed a capacity of 500 gallons, and would have 
been required to be permanently fixed to the transportation unit. One 
commenter recommended that the maximum tank capacity be limited to 250 
gallons, reasoning that less fuel would reduce the fire hazard. The 
interrelated precautions of the final rule are designed to protect 
against a fire involving a diesel fuel transportation unit. Reducing 
the unit's fuel capacity to 250 gallons would not add significantly to 
the protection against fire, and would increase the frequency with 
which the unit would need to be refilled. However, paragraph (e) is 
intended to limit the amount of fuel transported by a single trip, 
either on rails or rubber tires, to 500 gallons. Paragraph (f) will 
ensure that the fuel tank is not removed from the vehicle for transport 
separately, thereby exposing the tank to possible damage, and also 
offers some protection for the tank from the vehicle frame.
    Paragraph (g) requires non-self-propelled diesel fuel 
transportation units equipped with electric components for dispensing 
fuel that are connected to a source of electrical power be provided 
with a fire suppression device that meets the requirements of existing 
Secs. 75.1107-3 through 75.1107-6, Secs. 75.1107-8, and Sec. 75.1107-
16. The proposed requirement would have required a fire suppression 
system meeting the requirements of proposed Sec. 75.1911 on all diesel 
fuel transportation units, not only on those with electrical 
components.
    Commenters were opposed to a requirement for fire suppression 
systems on all diesel fuel transportation units, stating that a 
trailer-mounted fuel tank did not need a fire suppression system since 
it had no ignition source, and should not be treated any differently 
than tanks transporting other combustible materials. These commenters 
believed that the fire extinguishers required under the proposal would 
provide adequate fire protection in temporary fuel storage areas.
    MSHA agrees with commenters that fuel tanks alone, without an 
ignition source, do not present a significant fire hazard. However, 
fire protection for fuel tanks must be provided when a potential 
ignition source exists. An ignition source is present on the diesel 
fuel transportation unit when electrical power is provided to the 
dispensing pump on the unit from either an electric-powered machine or 
the mine electrical system. The final rule therefore requires fire 
protection for non-self-propelled diesel fuel transportation units with 
electrical components for dispensing fuel that are connected to a 
source of electrical power. Diesel fuel transportation units with 
electrical devices other than those used for dispensing fuel, such as 
lights, do not present a significant fire hazard and do not need to be 
protected by a fire suppression system. This fire suppression device 
requirement would also apply when the transportation unit's dispensing 
pump is powered by its own batteries or an off-board generator.
    The final rule requires a fire suppression device meeting the 
requirements of existing Sec. 75.1107, instead of Sec. 75.1911 under 
the proposal, because the fire protection provided by Sec. 75.1107 is 
suitable for electrical installations, and therefore appropriate for 
electrical components of fuel transportation units. A fire suppression 
system under Sec. 75.1911 is designed to protect diesel-powered 
equipment, and,

[[Page 55455]]

unlike existing Sec. 75.1107, does not require that the mine electric 
power supply to the fuel transportation unit be shut off when the fire 
suppression system is actuated, an important safety feature that 
prevents reignition of the fire.
    Paragraph (h) requires diesel fuel transportation units and 
vehicles transporting safety cans to have at least two multipurpose, 
dry chemical type (ABC) fire extinguishers. The fire extinguishers must 
be listed or approved by a nationally recognized independent testing 
laboratory, and have a 10A:60B:C or higher rating. There must be at 
least one fire extinguisher located on each side of the vehicle. The 
proposal would have required that fire extinguishers be provided on 
each end of a fuel transportation unit when diesel fuel was transported 
in containers other than safety cans. Locating fire extinguishers on 
the side is consistent with the requirements of Sec. 75.1911(e) of the 
final rule for the location of fire suppression system actuators. The 
type and size of extinguisher are the same as required by 
Sec. 75.1903(b)(1) and (b)(2) for permanent underground diesel fuel 
storage facilities and temporary underground diesel fuel storage areas.
    Paragraph (i) requires that diesel fuel transportation units be 
parked in permanent underground diesel fuel storage facilities or 
temporary underground fuel storage areas when not in use. Under the 
proposal, ``unattended'' diesel fuel transportation units would have 
been required to be parked only in fixed or mobile fuel storage 
facilities. Some commenters objected to this requirement, and urged 
MSHA to provide a more workable rule that would allow transportation 
units to be parked, consistent with the Advisory Committee's 
recommendation that MSHA establish requirements for the temporary 
parking of diesel transportation vehicles. Some commenters also stated 
that ``unattended'' was an ambiguous term.
    The term ``unattended'' has been eliminated from the final rule. 
Instead, the final rule provides that diesel fuel transportation units 
that are ``not in use'' must be parked either in permanent storage 
facilities or temporary storage areas. The phrase ``not in use'' means 
that the unit is not being trammed or used to dispense fuel or 
lubricants or waiting to refuel another piece of equipment. It does not 
mean that the unit operator must be within 500 feet or within the line 
of sight of the fuel transportation unit, as long as the operator is 
performing an activity associated with the operation of the unit. This 
may occur, for example, while the operator is locating the next unit of 
equipment to be refueled. This requirement is intended to control the 
locations of diesel fuel transportation units to minimize fire hazards 
associated with their use.
    Paragraph (j), like the proposal, applies the requirements of 
existing Sec. 75.1003-2 when the distance between a diesel fuel 
transportation unit and an energized trolley wire at any location is 
less than 12 inches. Section 75.1003-2 sets forth specific precautions 
to be followed when off-track equipment is being moved in areas where 
energized trolley wires are present. MSHA received no comments on this 
aspect of the proposal and it has been adopted into the final rule 
unchanged. This requirement is intended to minimize the risk of 
ignition and fire when a diesel fuel transportation unit is in close 
proximity to a bare energized trolley wire. The sparks and heat from an 
electrical short circuit could ignite residual fuel on the 
transportation unit and fire may then spread to the larger volume of 
fuel stored on the transportation unit.
    Paragraph (k) prohibits the transport of diesel fuel on or with 
mantrips, or on conveyor belts. This requirement has been revised from 
the proposal, which would have prohibited transport of diesel fuel on 
conveyor belts, to include within the prohibition the transport of 
diesel fuel on mantrips, in response to several commenters who 
expressed concern about transportation of diesel fuel on personnel 
carriers because of the inherent hazards associated with that practice. 
This requirement applies to equipment being used as personnel carriers, 
but does not apply to such equipment when it is used for purposes other 
than transporting miners in the mine. This requirement also does not 
apply to diesel fuel contained in the fuel tank of a diesel-powered 
personnel carrier.
    Paragraph (l) requires that, as of 12 months after the publication 
date of the final rule, diesel fuel must be stored and handled in 
accordance with the requirements of Secs. 75.1902 through 75.1906 of 
this part. Twelve months will provide sufficient time for mine 
operators to make any necessary changes to their fuel handling, 
transportation, and storage practices underground, such as fuel tank 
retrofits or construction of fuel storage facilities. The requirements 
of Sec. 75.1903 (c) and (d) take effect sooner, because they address 
safe welding practices in or near diesel fuel storage areas, and mine 
operators should not need any additional time to come into compliance 
with these provisions.
 Section 75.1907  Diesel-Powered Equipment Intended For Use In 
Underground Coal Mines.
    This section establishes a schedule for compliance with the final 
rule's equipment-related requirements, including requirements for 
approved engines and power packages, fire suppression systems, and 
safety-related requirements for nonpermissible equipment in 
Secs. 75.1909 and 75.1910. The concept of a time schedule to allow for 
conversion or replacement of diesel-powered equipment currently in use 
to comply with the new requirements of the final rule was recommended 
by the Diesel Advisory Committee. The Committee also recommended that 
equipment newly introduced underground after a fixed date meet the new 
requirements.
    Under the compliance schedule of this section, 30 days after the 
rule's publication date all diesel-powered equipment used where 
permissible electric equipment is required must be approved under part 
36. This section also establishes a compliance schedule for Part 36-
approved equipment, to comply with certain surface temperature limits 
within 6 months, and be provided with a fire suppression system and 
brakes that meet certain standards within 36 months of the rule's 
publication. Part 36-approved equipment is also required to have a 
particulate index and a dilution air quantity determined under subpart 
E of part 7 within 12 months of the rule's publication date. 
Permissible diesel-powered equipment that is manufactured 3 years after 
the date of publication of the final rule or later and used in 
underground coal mines must incorporate a power package approved under 
subpart F of part 7 of the final rule. This section of the final rule 
also requires nonpermissible diesel-powered equipment, with the 
exception of the special category of ambulances and firefighting 
equipment under Sec. 75.1908(d), to be equipped with the machine safety 
features set forth in Secs. 75.1909 and 75.1910 within 36 months of the 
publication date of the final rule.
    The overall approach taken in the final rule for equipment safety 
features is different from that of the proposal, in response to 
commenters and for reasons explained in detail in the preamble for 
parts 7 and 36. The proposed rule would have required approval of fully 
assembled permissible equipment under subpart H of part 7, and approval 
of fully assembled nonpermissible

[[Page 55456]]

equipment under subpart I of part 7. A limited class of light-duty 
nonpermissible equipment would have been established that did not 
require fully assembled machine approval, but which would have been 
equipped with specific machine safety features set forth as mandatory 
standards in proposed Sec. 75.1909. Under proposed Sec. 75.1907, 
specific deadlines, up to 60 months after the rule's effective date, 
would have been set for compliance with the equipment-related 
requirements of the final rule for both permissible and nonpermissible 
equipment, including limited class and stationary unattended equipment. 
Additionally, the proposal would have allowed a mine operator to apply 
for MSHA approval for continued use of diesel-powered locomotives 
without required subpart F or G power packages. MSHA would have been 
authorized to grant such approval if approved power packages suitable 
for specific mine conditions and locomotive design were not available, 
recognizing that the current state of technology might make compliance 
difficult or impossible.
    The proposed rule took the approach of phasing in the different 
equipment-related requirements, depending on how long MSHA determined 
mine operators and manufacturers would need to obtain the necessary 
equipment or make the necessary retrofits, including time needed to 
obtain MSHA approval for the appropriate machine components. 
Specifically, the proposed rule would have allowed a longer period of 
time for equipment to be provided with approved engines and power 
packages than it would have allowed for other equipment-related 
requirements, for such features as brakes, fuel systems, and electrical 
components. Different time frames would have been allowed under the 
proposal to take into account the time needed for the MSHA approval 
process as well as the technical difficulties associated with 
retrofitting equipment with approved power packages and engines.
    As discussed in the preamble to part 7 of the final rule, the final 
rule does not adopt the approach of fully assembled machine approval 
under subparts H and I of part 7 contemplated by the proposal and 
addressed in the concurrent advance notice of proposed rulemaking. 
Instead, part 36 has been expanded to specifically provide for approval 
of diesel-powered equipment used in areas of underground coal mines 
where permissible electric equipment is required. Fully assembled 
machine approval is not required under the final rule for any category 
of nonpermissible equipment. The compliance time frames of this section 
of the final rule reflect this change in approach.
    The time frames in this section are based on an estimation of the 
useful life of existing diesel-powered equipment, the reasonable time 
needed to convert or retrofit existing equipment, and the commercial 
availability of suitable replacement equipment. The time frames in this 
section are intended to provide mine operators with a reasonable period 
of time to make determinations of the expected remaining useful life of 
diesel-powered machines in use in their mines and the cost of necessary 
machine modifications, and to compare this information with the 
replacement cost of equipment that complies with the requirements of 
the final rule.
    One commenter rebuilt a diesel-powered truck to convert it to a 
personnel carrier that met the equipment safety requirements of the 
proposed rule for self-propelled limited class nonpermissible 
equipment, and submitted a written summary documenting the conversion 
into the rulemaking record. This information generally demonstrated 
that compliance would be facilitated if equipment-related requirements 
were phased in by equipment type, rather than phasing in specific 
requirements across all equipment types. In short, once an equipment 
rebuild is initiated, it is easier to perform all machine feature 
modifications at the same time.
    One commenter asserted generally that mine operators and equipment 
manufacturers could bring diesel-powered equipment into compliance with 
the requirements of the final rule within 12 months. Although MSHA 
agrees, and the final rule reflects, that some requirements can be met 
within a year, compliance with other requirements, will reasonably 
involve more time.
    As explained in greater detail elsewhere in the preamble, the final 
rule requires specific safety features on both permissible and 
nonpermissible diesel-powered equipment. These requirements apply to 
nonpermissible diesel-powered equipment in Secs. 75.1909 and 75.1910, 
and will be applied to permissible diesel-powered equipment during the 
MSHA approval process under part 36.
    The final rule does not require nonpermissible equipment to be 
provided with power packages, which would have been required under the 
proposal. Neither does it require fully assembled machine approval for 
nonpermissible equipment. Power packages would have provided this 
equipment with, among other things, surface temperature controls for 
the equipment. As discussed elsewhere in the preamble, commenters were 
divided on this issue. Some commenters believed not only that 
temperature controls were necessary to adequately address the fire 
hazards presented by diesel-powered equipment underground, but also 
recommended that all diesel-powered equipment be approved under part 36 
as permissible, and provided with the explosion-proof features required 
on such equipment. Other commenters strenuously opposed a requirement 
for approved power packages on nonpermissible equipment, stating that 
surface temperature controls were not needed on equipment operated 
outby the face, and that fire protection features, such as fire 
suppression systems, in conjunction with other machine safety features 
would provide an appropriate margin of safety. These commenters stated 
that a power package requirement for nonpermissible equipment would 
have the effect of eliminating many useful pieces of equipment from 
mines that could not be retrofitted with power packages or would not be 
manufactured with them.
    The final rule does not require approved power packages on outby 
equipment, except when the equipment discharges its exhaust directly 
into a return air course, as provided under Sec. 75.1909. Proposed 
subpart G, which would have established an approval program for power 
packages for nonpermissible equipment, has not been adopted in the 
final rule. Instead, nonpermissible equipment is required under 
Sec. 75.1909(a)(10) to be provided with a means to prevent the spray 
from ruptured hydraulic or lubricating oil lines from being ignited by 
contact with engine exhaust system component surfaces. This requirement 
recognizes that the hazards of high surface temperatures on diesel-
powered equipment can be controlled in a number of ways in addition to 
the methods contemplated under proposed subpart G. MSHA has concluded 
that the requirement of paragraph (a)(10), along with the other safety 
features required for control of fuel sources on diesel-powered 
equipment, provides effective fire prevention on nonpermissible diesel-
powered equipment. The approach of the final rule allows mine operators 
and manufacturers the flexibility to improve existing methods and to 
develop new methods of meeting the performance goals of the final rule 
requirements.
    Paragraph (a) of this section of the final rule adopts the proposed 
requirement that within 30 days of the date of publication of the final 
rule, all

[[Page 55457]]

diesel-powered equipment used where permissible electrical equipment is 
required be approved under part 36. Part 36 approval ensures that the 
equipment is explosion-proof, and that equipment used in areas of the 
mine where methane is likely to accumulate and where there may be 
combustible quantities of coal dust and other materials will not cause 
a fire or an explosion. All underground coal mines using diesel 
equipment already have the approved equipment necessary to comply with 
this requirement, in most cases because the mine's ventilation plan 
specifically requires it. This requirement therefore goes into effect 
30 days after publication of the final rule, providing necessary 
protections for miners working underground.
    Paragraph (b) establishes a time schedule under which equipment 
approved under part 36 is required to be provided with additional 
safety features. Paragraph (b)(1) requires the equipment to be provided 
with a safety component system that limits surface temperatures to 
those specified in subpart F of part 7. This requirement is essentially 
identical to that of the proposal, which would have required that part 
36-approved equipment be provided with a power package that limits 
surface temperatures to those specified in subpart F. In the final 
rule, the equipment is required to have a ``safety component system'' 
that limits the surface temperatures rather than a ``power package'' 
specified under the proposal. Existing permissible equipment has been 
approved under the current version of part 36, which uses the term 
``safety component system'' to refer to those devices added to the 
engine to control surface temperatures of the exhaust system. The term 
``power package'' used in the final rule includes those devices, which, 
with the engine, comprises the ``power package.'' Power packages are 
approved under subpart F of part 7 of the final rule. As discussed 
elsewhere in this preamble, part 36 has been specifically revised to 
provide for approval of diesel-powered machines used in underground 
coal mines. Part 36 now references subparts E and F of part 7 of the 
final rule, and requires equipment approved under part 36 for use in 
coal mines to be equipped with a power package approved under subpart 
F. Subpart F limits the maximum surface temperature to less than 
302 deg. F (150 deg. C). Until promulgation of this final rule, the 
maximum surface temperature of the engine and exhaust system components 
under part 36 was 400 deg. F (204 deg. C). To date, only one engine and 
safety component system used in part 36-approved equipment has a 
surface temperature above 302 deg. F, and the equipment on which the 
system is installed is not used in coal mines. Consequently, compliance 
with this requirement within six months of the publication of the final 
rule should present no compliance difficulties for mine operators or 
manufacturers. This requirement will ensure that permissible equipment 
in underground coal mines will have surface temperatures below 302 deg. 
F, minimizing the chance that combustibles such as diesel fuel, float 
coal dust, and hydraulic fluid will be ignited by high surface 
temperatures.
    Paragraph (b)(2) requires that, as of 36 months after the final 
rule is published, equipment approved under part 36 be provided with an 
automatic or manual fire suppression system that meets the requirements 
of Sec. 75.1911, and be provided with a portable fire extinguisher. A 
fire suppression system is required on permissible equipment in 
addition to surface temperature controls to address fire hazards 
created by other machine system malfunctions. The fire suppression 
system on permissible equipment may be either manual or automatic. 
Under the proposal, part 36-approved equipment would have been required 
to have a fire suppression system that met the requirements of 
Sec. 75.1911. The requirements of proposed Sec. 75.1911 provided only 
for automatic fire suppressions systems. For reasons explained in 
greater detail in the preamble discussion to Sec. 75.1911, automatic 
fire suppression is not required on permissible diesel-powered 
equipment. This is because all equipment approved under part 36 is 
provided with surface temperature controls, which reduce the risk of 
fire. The final rule includes the additional requirement that the 
equipment be provided with at least one portable multipurpose dry 
chemical type ABC fire extinguisher having a 10A:60B:C rating or 
higher. The fire extinguisher must be located within easy reach of the 
equipment operator and be protected from damage by collision. This 
requirement has been added in response to the recommendation of a 
commenter. MSHA has concluded that requiring equipment to be provided 
with a portable fire extinguisher is a good fire prevention practice, 
and this recommendation has therefore been adopted in the final rule, 
superseding the requirement in part 36 for a fire extinguisher with a 
much lower firefighting rating. This requirement is consistent with the 
fire extinguisher requirements for nonpermissible equipment in the 
final rule.
    MSHA had proposed a 6-month compliance deadline for installation of 
fire suppression systems on part 36-approved equipment, but has 
concluded that a 36-month time frame is needed for mine operators to 
obtain MSHA approval of field modifications on approved equipment, and 
for equipment manufacturers to process approval applications to permit 
installation of fire suppression systems on permissible equipment. The 
Agency intends to promptly process approval applications for 
modification of machines to aid compliance with this requirement.
    Paragraph (b)(3) has been added to the final rule to require that, 
as of 36 months after the publication date of the final rule, equipment 
approved under part 36 be provided with brake systems that meet the 
requirements of Sec. 75.1909(b)(7), (b)(8), (b)(9), (c), (d), and (e). 
These brake requirements have been added to ensure that permissible 
equipment meets at least the same braking requirements as 
nonpermissible equipment under the final rule. All existing part 36 
equipment is already equipped with service brake systems that meet the 
requirements of Sec. 75.1909(b)(8), (b)(9), and (d). The requirements 
of Sec. 75.1909(c) have been developed from requirements for automatic 
emergency parking brakes on electric equipment in Sec. 75.523-3. A 
number of commenters supported the application of these requirements to 
diesel-powered equipment, and they have been applied to permissible 
equipment under the final rule. Some existing part 36-approved 
equipment will require minor modifications to comply with the 
requirements of Sec. 75.1909(c). Section 75.1909(b)(7) essentially 
requires independent service brake systems for the front and rear 
wheels of vehicles. This is a well-recognized safety feature that is 
warranted for part 36-approved diesel-powered equipment as well as for 
nonpermissible equipment covered by Sec. 75.1909. Although the majority 
of part 36-approved equipment is already provided with this feature, a 
limited number of machines will require modification. Because some mine 
operators will need to obtain field modifications and equipment 
manufacturers must obtain MSHA approval of design modifications, a 36-
month compliance time is appropriate and is provided for in the final 
rule.
    Section 75.1909 of the final rule requires that nonpermissible 
diesel-powered equipment be equipped with a supplemental brake system, 
which provides substantially the same features as would be provided by 
the automatic emergency parking brakes specified in

[[Page 55458]]

Sec. 75.523-3. Section 75.1909(e) requires setting of the supplemental 
brake system when the operator is not at the controls of the equipment, 
except during the movement of disabled equipment. Because part 36-
approved equipment is provided with a supplemental brake system under 
the final rule, the requirement for setting of the supplemental brake 
has also been applied to this equipment.
    Paragraph (b)(4) requires that equipment approved under part 36 
have a particulate index and a dilution air quantity determined in 
accordance with part 7, subpart E within 12 months of the publication 
date of the final rule. The types of engines that are affected by this 
requirement are installed in permissible face equipment that is 
currently approved under part 36. Because of where and how this 
equipment is used, it significantly affects the air quality where 
miners work and travel. Diesel-powered face equipment includes haulage 
equipment and roof bolters, which are typically used in the confined 
environment in the production area of the face and operated almost 
continuously over the course of a shift. The contribution of diesel 
exhaust from this equipment into the mine atmosphere can be significant 
and can adversely affect the health conditions for miners working in 
and around the area where the equipment is being operated. Under new 
requirements in Sec. 75.325 of the final rule, minimum ventilating air 
quantities are established for areas where diesel-powered equipment 
operates. These minimum quantities are derived from the approval plate 
ventilating air quantity for the equipment that is operating. 
Consequently, ventilating air quantities must be calculated for these 
engines so that the minimum air quantity requirements can be 
implemented. As mentioned elsewhere in this preamble, the particulate 
index will not be used to determine the minimum ventilating air 
quantity for the engine, but will be available for informational 
purposes.
    There are only four engines models used in the majority of part 36-
approved equipment used in underground coal mines. These engines are 
typically of older design, and it is uncertain whether the engine 
manufacturers will seek approval for their engine designs under subpart 
E of part 7. As a result, MSHA intends to determine dilution air 
quantities and particulate indices for these engines in accordance with 
part 7, subpart E, whether or not the manufacturers seek a subpart E 
approval for their engines. MSHA will make this information available 
to mine operators, which must be applied and implemented within 12 
months of the date of the final rule's publication. This time frame is 
consistent with the 12-month effective date for compliance with the 
ventilation requirements of Sec. 75.325(k) of the final rule that apply 
where diesel-powered equipment is operated.
    Paragraph (b)(5) requires that permissible diesel-powered equipment 
that is manufactured 36 months or more after the publication date of 
the final rule and used in an underground coal mine incorporate a power 
package approved under part 7, subpart F. Under the proposal, only 
``new'' diesel-powered equipment approved under subpart H or I or 
meeting the requirements of Secs. 75.1909 and 1910 could be introduced 
into underground coal mines 60 months after the effective date of 
Sec. 75.1907. This meant that both new permissible and nonpermissible 
equipment (that did not fall into the limited class or was not used as 
stationary unattended equipment) introduced in an underground coal mine 
after the deadline would have had to receive a full machine approval. 
One commenter recommended that the proposed 60-month delayed effective 
date be changed to 12 months. Another commenter suggested that the 
language be clarified to state that existing part 36 approvals remain 
valid.
    The time frame for compliance has been reduced to 36 months in 
recognition of the fact that the final rule does not require full 
machine approval of all permissible and nonpermissible equipment, as 
contemplated by the proposal. Three years should be sufficient for 
equipment manufacturers to obtain approval for and incorporate subpart 
F power packages into the permissible diesel-powered equipment they 
manufacture. Part 36-approved equipment manufactured before the 
relevant date may continue to be used in accordance with its approval 
indefinitely.
    Paragraph (c) requires nonpermissible diesel-powered equipment to 
comply with Secs. 75.1909 and 75.1910 within 36 months of the 
publication date of the rule. Under the final rule nonpermissible 
equipment, which is used in areas where permissible electric equipment 
is not required, does not need full machine approval by MSHA. However, 
under Sec. 75.1909(a)(1) nonpermissible equipment must be equipped with 
an engine approved under subpart E of part 7. The final rule did not 
adopt the proposed establishment of a limited class of nonpermissible 
light-duty equipment, for reasons explained in detail in the preamble 
to Sec. 75.1908. Instead, the final rule establishes two categories of 
nonpermissible equipment, heavy-duty and light-duty. Under paragraph 
(c) of this section of the final rule, equipment in both categories 
must be provided with the safety features set forth in Secs. 75.1909 
and 75.1910. These features include engines approved under subpart E of 
part 7, fire suppression systems, brakes, and electrical protections. 
Several commenters stated that approved engines, power packages, or 
surface temperature controls are unnecessary for nonpermissible 
equipment, while other commenters considered surface temperature 
controls necessary.
    The final rule's equipment safety requirements for nonpermissible 
diesel-powered equipment are intended to ensure that the equipment will 
not present a fire hazard and that gaseous diesel exhaust emissions and 
particulate emissions are addressed.
    A compliance time of 24 months was proposed, and one commenter 
recommended a 12-month compliance time. The final rule allows 36 months 
for nonpermissible equipment to comply with the requirements of 
Secs. 75.1909 and 75.1910. Included in these sections is a requirement 
that nonpermissible equipment be provided with an engine approved under 
subpart E of part 7. It is expected that this requirement will require 
the longest time period for compliance, as engine manufacturers must 
first obtain MSHA approval of appropriate engines. The 36-month time 
frame allows some models of nonpermissible equipment currently in use 
in underground coal mines to reach the end of its useful life and to be 
replaced with equipment that meets these requirements, rather than 
being retrofitted with a new engine and the other features required by 
Secs. 75.1909 and 75.1910.
    The final rule does not adopt the proposed provision allowing mine 
operators to seek MSHA approval for the extended use of diesel-powered 
locomotives because of the unavailability of approved power packages 
suitable for the mine conditions or for the locomotive's design. This 
provision recognized that certain types of diesel locomotives might not 
have been able to be retrofitted to meet all of the applicable 
equipment-related requirements. Because the final rule does not require 
approved power packages for nonpermissible equipment, a process for 
MSHA approval of extended use of nonpermissible locomotives without 
approved power packages is no longer

[[Page 55459]]

necessary, and has consequently not been adopted in the final rule.
Section 75.1908  Nonpermissible Diesel-Powered Equipment; Categories
    This section of the final rule establishes three categories of 
nonpermissible diesel-powered equipment: heavy-duty equipment, which is 
defined as equipment that is used for such tasks as cutting or moving 
rock or coal, drilling or bolting, or moving longwall components; 
light-duty equipment, which includes any other nonpermissible equipment 
that is not heavy-duty; and a special category for ambulances and fire 
fighting equipment. Because nonpermissible equipment is used in areas 
of the mine where methane is not likely to accumulate, it is not 
required to be explosion-proof. However, all nonpermissible equipment, 
with the exception of ambulances and other emergency equipment 
described under paragraph (d), is required to have an engine approved 
under subpart E of part 7, which sets engine performance and exhaust 
emissions requirements.
    The requirements that apply to nonpermissible equipment under the 
final rule vary according to the equipment's category. Most 
importantly, the equipment category determines which equipment safety 
features are required under Secs. 75.1909 and 75.1910 of the final 
rule. One of the most important distinctions between heavy-and light-
duty equipment under the final rule is that heavy-duty equipment is 
required to have an automatic fire suppression system under 
Sec. 75.1909, while light-duty equipment may be provided with either a 
manual or automatic system. Additionally, heavy-duty nonpermissible 
equipment is subject to the weekly undiluted exhaust emissions test 
under Sec. 75.1914(g) of the final rule, and must also be included in 
the air quantity calculation for multiple units of diesel-powered 
equipment under Sec. 75.325(g). These provisions do not apply to light-
duty equipment.
    The final rule is a significant departure from the proposal, in 
response to a majority of commenters who were opposed to the proposed 
criteria for the equipment categories. The proposal would have 
established a special category of nonpermissible ``limited class'' 
equipment. Limited class equipment under the proposal would have been 
equipment weighing less than 6,000 pounds and equipped with an engine 
of less than 90 horsepower. Equipment with a hydraulic system could not 
be included in the limited class, although MSHA stated in the preamble 
to the proposal that this restriction was not intended to apply to 
hydraulic systems used in brake units or automotive-style power assist 
units. Additionally, the equipment engine could not be turbocharged. 
Portable equipment that fell into this class was limited to welders and 
compressors. The proposal also allowed altitude compensation devices to 
be used with limited class equipment.
    Although limited class equipment under the proposal would have been 
required to have an engine approved under subpart E of part 7, the 
machine as a whole would not have been approved by MSHA. Instead, 
limited class equipment would have been required to be equipped with 
the safety features in proposed Sec. 75.1909. All other nonpermissible 
equipment would have been required to have a subpart F or G approved 
``power package,'' which would have included an approved engine with 
additional components to prevent the ignition of methane or combustible 
materials, such as surface temperature controls. Additionally, it was 
MSHA's intention, reflected in the advance notice of proposed 
rulemaking published with the proposal, to require whole machine 
approval of all nonpermissible equipment, except equipment that fell 
into the limited class defined under the proposal.
    The equipment categories in the proposed rule were based upon the 
Diesel Advisory Committee recommendation that fire prevention features, 
including surface temperature controls and fire suppression systems, be 
required on all outby equipment. However, the Committee recognized that 
much of the light-duty equipment in use in mines was not specifically 
designed for mining and might not be available with surface temperature 
controls. The Committee therefore concluded that a limited class of 
light-duty equipment could be safely operated if it was equipped with 
fire prevention and protection features in lieu of surface temperature 
controls, such as fire suppression devices, reduction of the potential 
for fuels to contact hot surfaces, and reduction of potential ignition 
sources. Equipment in this limited class would be expected to operate 
on a light-duty cycle, and would not reach high temperatures or would 
reach high temperatures for a limited period of time, with a 
significantly reduced potential for fire.
    Commenters expressed widely varying views on this aspect of the 
proposal. Most commenters supported the concept of a distinct class of 
equipment with less extensive safety requirements, but many stated that 
the criteria in the proposal for limited class equipment were 
unnecessarily restrictive, and that the class should be significantly 
broadened to include many more types of equipment, such as light-duty 
manned personnel and material haulage equipment. A number of commenters 
indicated that the equipment that they would consider light-duty 
equipment in their mines exceeded either the weight or horsepower 
restrictions of the proposal.
    Other commenters were of the opinion that fire suppression systems 
were an acceptable substitute for surface temperature controls, and 
strongly supported a significant expansion of the equipment falling 
into the limited class and therefore not required to have a power 
package that would provide such controls. A number of commenters also 
indicated that much of the equipment currently in use in mines that did 
not fall into the proposed limited class would have to be replaced, 
because it would be impossible to retrofit the equipment to provide the 
required surface temperature controls. Other commenters were concerned 
that limitations based on existing equipment designs could discourage 
the development of new technology.
    One commenter was generally opposed to the creation of a limited 
class that was not required to have surface temperature controls, 
because the commenter believed that this would present an unacceptable 
fire hazard. This commenter stated that heat sensors that triggered 
engine shutdown or fire suppression were not acceptable substitutes for 
surface temperature controls.
    A number of commenters were opposed to the limitation on equipment 
weight, stating that weight had no relationship to the hazards 
presented by the equipment, and that the 6,000-pound restriction was 
arbitrary. One commenter stated that although weight in some cases 
could be an indicator of duty cycle and the potential for higher 
equipment operating temperatures and resulting fires, requirements for 
fire suppression and automatic engine shutdown when engine temperature 
reaches a specified limit would adequately address these concerns. 
Another commenter stated that most diesel equipment that exceeds 6,000 
pounds is not used in heavy-duty applications such as coal production 
but is considered light-duty equipment.
    Some commenters were particularly concerned about the safety impact 
of the weight limitation on railmounted equipment, pointing out that 
weight is needed to provide traction. These commenters stated that 
although some

[[Page 55460]]

rail-mounted equipment would fall below the proposed horsepower 
limitation, the weight of most rail-mounted equipment significantly 
exceeds 6,000 pounds, and that it would be neither practical nor 
feasible to modify existing outby track equipment to meet the proposed 
limited class criteria. Because of this concern, one commenter 
suggested that outby rail-mounted equipment be addressed in a separate 
category, without a weight restriction.
    Several commenters also stated that the safety features that would 
be required on limited class equipment under proposed Sec. 75.1909 
would add to the vehicle weight, making the 6,000-pound restriction 
even more unrealistic in those commenters' opinion. One commenter 
estimated that equipment retrofits for safety features and for mine-
worthiness would increase equipment weight by at least 50 percent. 
Another commenter suggested that the proposed weight limitation would 
result in overloading equipment units because of light construction. 
Some suggested that the weight limitation for limited class equipment 
be increased to 7,500 or 8,500 pounds; others recommended that the 
limit be increased to 14,000 to 15,000 pounds, to permit units to be 
manufactured with heavy steel to withstand collisions. One commenter 
recommended that the weight limitation be reduced to 4,000 pounds for 
self-propelled equipment.
    A number of commenters were also opposed to the 90-horsepower 
limitation, stating that engine horsepower was no more an indication of 
whether equipment was heavy-duty or light-duty than was equipment 
weight. However, one commenter recommended that the limitation be 
reduced to less than 70 horsepower.
    Commenters were also concerned about the prohibition against 
hydraulic systems on limited class equipment. Several commenters stated 
that there was no basis for excluding equipment with hydraulic systems 
from the limited class, except for the fact that hydraulic fluid could 
present a fire hazard. These commenters suggested that equipment with 
hydraulic systems that utilized fire-resistant hydraulic fluid should 
be permitted. Some of these commenters also suggested that equipment 
with hydraulic systems should be eligible for the limited class 
category if the equipment is equipped with a fire-suppression system. 
Other commenters stated that equipment with hydraulic systems had not 
been shown to be less safe than equipment without such systems. Some 
pointed out that hydraulic systems facilitate the handling of supplies 
and materials, making the job easier and safer. These commenters also 
believed that prohibiting hydraulic systems on limited class equipment 
would preclude other equipment features that enhance safety, such as 
power take-offs, automatic transmissions, and hydrostatic drive units.
    Commenters were also opposed to the prohibition against 
turbocharged engines for limited class equipment. This restriction was 
included in the proposal because of the concern about the potential 
ignition of combustible materials on the hot exhaust system surfaces 
that are characteristic of turbocharged engines. Commenters stated that 
turbochargers have served as an effective means of yielding greater 
horsepower from smaller engines and should be allowed on limited class 
equipment, and that the exhaust components could be encased in 
protective insulating material to eliminate any fire hazard.
    A number of commenters expressed concern that manufacturers of 
equipment that was not specifically designed for use in mines would not 
seek MSHA approval for their equipment because the share of the market 
for mining applications was too small to warrant the expense of 
developing power packages.
    A number of commenters stated that inclusion of equipment in a 
limited class should depend on how the equipment is being used rather 
than on factors such as size and weight. Some of these commenters 
suggested that light- duty equipment include equipment that does not 
move rock, coal, or longwall shields. Other commenters advocated that 
all diesel-powered equipment, including limited class equipment, be 
designed to be explosion-proof and be approved by MSHA under part 7. 
These commenters felt that establishing a limited class of light-duty 
equipment would allow mine operators to use equipment with inferior 
means of fire prevention.
    One commenter recommended that a determination of the equipment 
included in the limited class should be based on MSHA's evaluation of 
diesel equipment fire experience in other industries and in other 
countries as to which types of equipment do and do not pose a 
significant fire hazard. In response to this comment, MSHA acquired 
accident reports from the Ministry of Labor, Province of Ontario, 
Canada, containing detailed information of fires on diesel-powered 
equipment in underground mines in Ontario for the years 1984 through 
1992. This information was carefully analyzed to determine which 
machine safety features and what type of equipment design are needed to 
prevent fires on diesel-powered equipment used in underground coal 
mines. An analysis of the Ontario fire data reveals that equipment used 
in heavy-duty type activities, such as hauling rock or coal or moving 
longwall components, presents a significant fire hazard and requires 
suitable fire prevention and protection features.
    Consistent with these conclusions and also with the recommendations 
of a number of commenters, paragraphs (a)(1) through (a)(5) of this 
section of the final rule specify what constitutes heavy-duty 
equipment. Heavy-duty nonpermissible equipment includes equipment that 
cuts or moves rock or coal; equipment that performs drilling or bolting 
functions; equipment that moves longwall components; self-propelled 
diesel fuel transportation units and lube units; and machines used to 
transport portable fuel transportation units or lube units. These 
machines are intended to move rock or coal or other heavy loads, such 
as longwall components, or move large quantities of combustible diesel 
fuel as a normal part of their duty cycle. Locomotives used to 
transport rock or coal and portable diesel fuel transportation units or 
lube units would also be in the heavy-duty equipment category under the 
final rule. Graders would also be considered heavy-duty equipment, 
because they are used to move rock or coal.
    Equipment falling within the heavy-duty equipment category under 
paragraph (a) is typically used for extended periods during a shift on 
a continuous, rather than intermittent, basis. This is in contrast to 
equipment that is used for limited periods during a shift, such as 
mantrips or supply vehicles. Heavy-duty equipment under the final rule 
also moves heavy loads or performs considerable work as in the case of 
drilling machines. Equipment used to haul longwall components is 
typically operated at a consistently accelerated pace under an 
extremely heavy load. Fuel transportation units and lube units 
generally are larger machines specially designed to transport and 
dispense diesel fuel, hydraulic fluid, grease, oil, and other 
combustible materials. This equipment also operates under a heavy load 
and typically moves constantly around a section during the course of a 
shift, refueling equipment as needed. Equipment that performs drilling 
and bolting functions generally has an engine that runs at a high rate 
of speed and powers large hydraulic systems. Under the final rule 
heavy-duty

[[Page 55461]]

equipment must be provided with an automatic fire suppression system, 
addressing the additional fire risks resulting from the way this 
equipment is used. Heavy-duty equipment also produces greater levels of 
gaseous contaminants, and under the final rule is therefore subject to 
weekly undiluted exhaust emissions tests under Sec. 75.1914(g), and is 
included in the air quantity calculation for ventilation of diesel-
powered equipment under Sec. 75.325(g).
    Under paragraph (b) light-duty equipment is defined as any other 
diesel-powered equipment that does not meet the criteria of paragraph 
(a). This is in contrast to the approach taken in the proposed rule 
establishing a limited class of light-duty equipment. Light-duty 
equipment under the final rule may include, but is not limited to, 
forklifts used to carry supplies, rock dusting machines, tractors not 
used to move rock or coal, supply trucks, water trucks, personnel 
carriers, jeeps, scooters, golf carts, and pickup trucks. The equipment 
may be rubber-tired, crawler-mounted, or rail-mounted.
    Under the final rule two machines of the same model could fall into 
different equipment categories, depending on how they are used. For 
example, a load-haul-dump unit used to move rock or coal would be 
considered heavy-duty equipment, while an identical machine used 
exclusively to move supplies would be a light-duty machine, subject to 
different requirements. Although these machines are of the same design, 
they do not present the same risk of fire because of the way they are 
used. They also do not produce the same quantities of exhaust 
contaminants: machines that are operated for extended periods of time 
under heavy load generate more contaminants than machines that are not.
    Equipment that is classified as light-duty may not be used, even 
intermittently, to perform the functions listed in paragraphs (a)(1) 
through (a)(5). This is because equipment that performs heavy-duty 
functions poses an increased fire risk, resulting in the need for an 
automatic fire suppression system, as required under Sec. 75.1909 for 
heavy-duty equipment. On the other hand, heavy-duty equipment may be 
used to perform light-duty work.
    The proposed restriction of portable limited class equipment to 
compressors and welders has not been adopted in the final rule. 
Although one commenter did support this restriction, most commenters 
were opposed to it, stating that it was arbitrary and unjustified as 
well as impractical. One commenter stated that the proposed restriction 
would require major replacement of diesel-powered portable equipment, 
either by electric-powered machines or by diesel equipment furnished 
with power packages. Other commenters suggested that attended diesel 
generators be added to the limited class because they presented safety 
concerns that were no greater than for welders and compressors.
    In response to these comments, any type of attended portable 
diesel-powered equipment may be light-duty under the final rule, so 
long as it does not perform any of the functions listed in paragraph 
(a). As discussed more fully above, the distinction between light-duty 
and heavy-duty equipment has less significance under the final rule 
than it would have had under the proposal, since neither light-duty nor 
heavy-duty nonpermissible equipment will be required to have a surface 
temperature-controlled power package or be subject to fully assembled 
machine approval.
    One commenter suggested that the term ``attended'' be defined in 
the final rule, and paragraph (c) specifies that attended diesel-
powered equipment for purposes of subpart T includes: any machine or 
device that is operated by a miner; and any machine or device that is 
mounted in the direct line of sight of a job site located within 500 
feet of such machine or device, which job site is occupied by a miner.
    This definition of ``attended'' is largely derived from the 
definition of ``attended'' in existing Sec. 75.1107-1 applicable to 
electric-powered equipment, although it has been tailored to address 
safety concerns unique to diesel-powered equipment, such as the fact 
that fires on diesel-powered equipment, unlike fires on electrical 
equipment, do not smolder for a very long time and therefore are less 
likely to be discovered before flaming and spreading. For this reason 
and unlike equipment under Sec. 75.1107-1, attended equipment under 
paragraph (c) must be continuously attended while it is operating, 
regardless of whether it is during a production shift. Also unlike 
equipment under Sec. 75.1107-1, attended equipment under paragraph (c) 
does not need to be attended by the person assigned to operate it. The 
definition of ``attended'' in this section permits prompt operator 
action in the event of a fault or fire on a diesel-powered machine. As 
discussed elsewhere in this preamble, the category of ``stationary 
unattended'' equipment has not been adopted in the final rule, and 
under Sec. 75.1916(e) all diesel-powered equipment must be attended 
when operated.
    Paragraph (d) establishes a special equipment category for diesel-
powered ambulances and fire fighting equipment, which may be used 
underground only in accordance with the fire fighting and evacuation 
plan required under existing Sec. 75.1101-23. This special category was 
included in the proposal under Sec. 75.1907(b), but has been included 
in this section of the final rule with the other categories of 
nonpermissible equipment. Equipment that falls into this category is 
not required to have an approved engine or power package, or to comply 
with the requirements of Secs. 75.1909 and 75.1910. Instead, such 
equipment must be used in accordance with the fire fighting and 
evacuation plan required under existing Sec. 75.1101-23.
    This provision was addressed by only a few commenters, who 
supported the establishment of a special class of diesel-powered 
equipment for emergency use, and has been adopted essentially unchanged 
from the proposal. The equipment under this paragraph may be used only 
during emergencies and the fire drills specified in the fire-fighting 
and evacuation plan. Very little equipment that is currently in use 
falls into this category. Mines that do have such equipment must 
provide MSHA with revised fire fighting and evacuation plans that 
adequately address the use of this equipment.
Sections 75.1909 and 1910  Design and Performance Requirements for 
Nonpermissible Diesel-Powered Equipment
    Overview. Sections 75.1909 and 75.1910 of the final rule set forth 
the design and performance requirements that apply to nonpermissible 
diesel-powered equipment, except for the special category of emergency 
equipment established under Sec. 75.1908(d) of the final rule. Section 
75.1909 requires, among other things, nonpermissible diesel-powered 
equipment to be provided with engines approved under subpart F of part 
7, fire suppression systems, fuel systems, and brakes. For ease of 
reference, electrical system requirements, which were proposed under 
Sec. 75.1909, have been adopted in the final rule in Sec. 75.1910.
    As explained in greater detail in the preamble discussion for 
Sec. 75.1908 of the final rule, the proposal would have established a 
``limited class'' of light-duty equipment, which, although required to 
have an approved engine, was not otherwise subject to MSHA approval. 
Instead, limited class equipment would have been governed by the design 
and performance requirements set forth in proposed

[[Page 55462]]

Sec. 75.1909. This scheme was consistent with the recommendations of 
the Diesel Advisory Committee. Nonpermissible equipment that did not 
meet the criteria of the limited class would have been subject to fully 
assembled machine approval under subpart I of part 7, and would also 
have been required to be equipped with a power package approved under 
subpart G of part 7. Power packages provide the equipment with safety 
features such as surface temperature controls, exhaust temperature 
controls, and safety shutdown capability.
    Although the proposal anticipated fully assembled machine approval 
of both permissible and nonpermissible diesel-powered equipment, MSHA 
specifically solicited comments on whether nonpermissible diesel-
powered equipment should be approved by MSHA in an advance notice of 
proposed rulemaking published on the same day as the proposed rule. 
Many commenters to the proposal and to the advance notice were strongly 
opposed to fully assembled machine approval for nonpermissible 
equipment, stating that it was neither necessary for safety nor 
consistent with MSHA's approach to electrical equipment. These 
commenters stated that approval of nonpermissible diesel equipment 
would create significant technical hurdles and place unnecessary 
financial burdens on mine operators, without any justification from a 
safety perspective. These commenters recommended that the final rule 
set performance-oriented safety requirements for nonpermissible 
equipment in mandatory standards in part 75, and that the safety 
features that were proposed for the limited class of light-duty 
equipment in Sec. 75.1909 be applied to all nonpermissible equipment.
    Many commenters were also opposed to the proposed requirement that 
most nonpermissible equipment have a power package approved under 
subpart F or G of part 7. Commenters stated that the protections 
afforded by a power package were unnecessary for equipment operated in 
areas of the mine where methane is not likely to accumulate, and that 
much of the nonpermissible diesel-powered equipment currently in use 
would have to be either scrapped or significantly retrofitted to comply 
with the proposed requirements, at tremendous expense. Several 
commenters pointed out that it would be impossible to retrofit some 
types of equipment because of design limitations.
    Other commenters supported full machine approval and power packages 
for all nonpermissible equipment, and further recommended that all 
diesel-powered equipment in underground mines be permissible and 
equipped with the explosion-proof equipment features required in areas 
of the mine where coal is extracted and where higher methane levels are 
a concern.
    The final rule responds to commenters opposed to full machine 
approval for nonpermissible equipment, and does not adopt the proposed 
requirement for power packages on most nonpermissible equipment. It 
should be noted, however, that all nonpermissible equipment, with the 
exception of emergency equipment under Sec. 75.1908(d), is required to 
have an engine approved under subpart E of part 7.
    In evaluating whether an approval program for nonpermissible 
diesel-powered equipment was warranted in the final rule, MSHA 
considered whether the machine safety features set forth in proposed 
Sec. 75.1909 for the limited class of light-duty equipment could be 
modified to provide adequate protection for heavy-duty equipment. This 
review revealed that many requirements in proposed Sec. 75.1909 could 
be applied directly to heavy-duty equipment without revision, while 
other proposed requirements could be made suitable with slight 
revisions.
    The safety features proposed in Sec. 75.1909 for limited class 
equipment have been adopted in the final rule in Secs. 75.1909 and 
75.1910 to cover equipment that is larger and more powerful than what 
would have been covered under the proposed rule. This is in response to 
a number of commenters who believed that these proposed requirements 
should be applied to both heavy-duty and light-duty equipment, in lieu 
of a full machine approval program. In general, the proposed 
requirements have not been substantially changed in the final rule, 
although the final rule does adopt several additional requirements for 
heavy-duty equipment based on requirements in part 36 or developed from 
existing part 75 requirements applicable to electric-powered machines. 
Other additions or revisions have been made in response to comments 
received on proposed Sec. 75.1909 and in response to the advance notice 
of proposed rulemaking.
Section 75.1909  Nonpermissible Diesel-Powered Equipment--Design and 
Performance Requirements
    Section 75.1909 establishes design and performance requirements for 
diesel-powered equipment used where nonpermissible electric equipment 
is permitted, with the exception of the special category of equipment 
under Sec. 75.1908(d). The requirements of this section are consistent 
with the recommendation of the Advisory Committee that such equipment 
be provided with fire suppression system and fuel and electrical system 
protection. All nonpermissible equipment, with the exception of the 
special category of emergency equipment under Sec. 75.1908(d), is also 
required to be provided with an approved engine within the time frames 
established in Sec. 75.1907 of the final rule.
     Paragraph (a)(1), like the proposal, requires that nonpermissible 
diesel-powered equipment be equipped with an engine approved under 
subpart E of part 7. The final rule also requires that the engine be 
equipped with an air filter and an air filter service indicator. The 
air filter must be sized and the service indicator set in accordance 
with the engine manufacturer's recommendations.
     Some commenters stated that approved engines were not necessary on 
outby equipment. Other commenters recommended that all equipment used 
in outby areas be provided not only with an approved engine, but also 
with a permissible power package approved under subpart F of part 7.
     The final rule adopts the proposed requirement that nonpermissible 
equipment be provided with an approved engine. Engines approved under 
subpart E of part 7 must meet specific gaseous emission standards and 
be provided with an approval plate indicating the quantity of 
ventilating air needed to dilute gaseous contaminants to acceptable 
levels. These requirements not only place limits on the quantity of 
gaseous contaminants that an approved engine may produce, they also 
provide a scheme for control of those contaminants through effective 
ventilation. Commenters expressed serious concern over unhealthful 
exhaust emissions from diesel equipment in outby areas that may 
significantly affect the quality of air that miners breathe. In 
response to these concerns, the final rule takes a comprehensive 
approach in addressing health hazards presented by diesel exhaust, and 
requires clean-burning engines, approved by MSHA under subpart E of 
part 7, on all diesel-powered machines, including nonpermissible 
equipment. Engines installed in this equipment must therefore meet the 
emissions standards established in subpart E of part 7.
     The final rule does not adopt the suggestion of commenters who 
supported requiring all diesel equipment in underground coal mines

[[Page 55463]]

to be permissible. The explosion- proof features provided by a subpart 
F power package are not needed for outby equipment, because the 
equipment operates in areas of the mine where methane is not expected 
to accumulate. Electrical equipment without explosion-proof features 
has been operated safely in outby locations for many years.
     The requirement that the engine be equipped with an air filter and 
an air filter service indicator has been added in response to 
commenters'' statements that clogged air filters were the single most 
frequent cause of smoky engines, resulting in the production of 
disproportionate quantities of carbon monoxide and diesel particulate. 
These components are typically supplied as part of the equipment, and 
the air filter service indicator will enable the equipment operator and 
maintenance personnel to ensure that the air filter is in good 
condition. Both the size of the air filter and the setting of the air 
filter service indicator are best determined by the engine 
manufacturer, and the final rule requires that these be determined in 
accordance with the engine manufacturer's recommendations.
    Paragraph (a)(2) has been added to the final rule and requires that 
nonpermissible equipment be provided with at least one portable 
multipurpose dry chemical type (ABC) fire extinguisher, listed or 
approved by a nationally recognized independent testing laboratory, and 
having a 10A:60B:C or higher rating. The extinguisher must be located 
within easy reach of the equipment operator and be protected from 
damage. This requirement has been added to the final rule in response 
to a commenter who supported requiring two chemical fire extinguishers 
accessible to each end of the unit and protected from external damage. 
MSHA agrees with this recommendation, which is consistent with good 
fire prevention practices and which will provide additional fire 
protection on diesel-powered machines. One rather than two fire 
extinguishers has been required, however, because one extinguisher, 
accessible to the operator and protected from damage, is adequate for 
virtually all diesel-powered equipment. As discussed elsewhere in the 
preamble, this equipment is also required to be equipped with either an 
automatic or manual fire suppression system, depending on the equipment 
category.
     Paragraph (a)(3) has been adopted from the proposal, and requires 
that the equipment's fuel system be specifically designed for diesel 
fuel, and that it meet specific additional criteria. One commenter 
recommended that this provision be revised to require a fuel system 
``specifically designed and constructed to minimize the possibility of 
a fire in case of a collision or refueling''. The commenter stated that 
fuel tanks on most light-duty equipment, such as pickup trucks, already 
meet certain standards, and that it would be unwise from a safety 
standpoint to modify these tanks. The final rule has not been revised 
in response to this comment. The fuel system requirements in the final 
rule are designed to address safety hazards presented by the use of 
diesel equipment in the underground mine environment, and nonspecific 
concerns about retrofitting equipment do not outweigh the protections 
afforded by the fuel system criteria included in the final rule. 
However, a fuel system that meets applicable industry standards would 
be acceptable so long as it also meets the criteria in paragraphs 
(a)(3)(i) through (xi).
     Paragraph (a)(3)(i) provides that the fuel system must have a fuel 
tank and fuel lines that do not leak. The proposed rule, unlike the 
final rule, would have required that the fuel tank be of ``leakproof 
construction.'' Several commenters stated that the term ``leakproof 
construction'' was ambiguous and needed to be defined in the final 
rule, or be revised to provide for construction that was ``designed to 
prevent leaks''. Rather than providing a definition for ``leakproof 
construction'' and specifying design or construction requirements to 
protect against leakage, the final rule sets a performance standard and 
simply requires that the fuel tank and fuel lines not leak, allowing 
mine operators the flexibility to determine how to best comply with 
this requirement. Fuel lines have been included in this requirement 
under the final rule, in response to commenters who were concerned 
about fire hazards presented by leaking fuel lines on diesel-powered 
equipment coming into contact with hot engine surfaces.
     Paragraph (a)(3)(ii) adopts the proposed requirement that the fuel 
tank be substantially constructed and protected against damage by 
collision. Commenters generally supported this requirement. The tank 
may be protected from damage by collision by being located within the 
frame components of the machine, or be constructed of material that is 
sufficiently sturdy so that the tank will not be damaged by collision 
with other vehicles or with the mine roof, rib, or floor. It should be 
noted that although the term ``tank'' is used in the singular here and 
in other paragraphs of this section, the final rule is not intended to 
limit the number of tanks on equipment. Several models of pickup trucks 
are manufactured with dual fuel tanks, and this configuration is 
acceptable under the final rule.
     Paragraph (a)(3)(iii) requires that the fuel system be provided 
with a vent opening that maintains atmospheric pressure in the tank, 
and which is designed to prevent fuel from splashing out. The proposed 
rule would have required that the size of the vent prevent fuel from 
splashing out of the vent opening. This requirement has been modified 
slightly in the final rule to specify that the design rather than the 
size of the vent opening must prevent fuel from splashing out, in 
response to commenters who advocated requirements that were more 
performance-oriented. This minor revision will allow mine operators 
increased flexibility in satisfying this requirement. MSHA anticipates 
that the vent provided in the fuel filler cap will satisfy this 
requirement.
     Paragraph (a)(3)(iv) requires a self-closing filler cap on the 
fuel tank. The proposed rule would have required either a tethered cap 
or a self-closing cap. The final rule requires a self-closing fuel cap 
that will serve to minimize fuel spillage, and responds to commenters'' 
serious concerns about the hazards of fuel spillage.
    Paragraph (a)(3)(v) requires that the fuel tank, filler and vent be 
located so that any leaks or spillage during refueling will not contact 
hot surfaces. This requirement has been revised from the proposed rule, 
which would have required that these components be located to prevent 
fuel from contacting hot engine surfaces. The final rule has been 
revised from the proposal because of the application of the 
requirements of this section to all nonpermissible diesel-powered 
equipment, not just equipment falling in the proposed limited class. 
This modification recognizes that there are additional machine 
components, particularly on larger heavy-duty equipment, now falling 
under this requirement that reach temperatures that could ignite diesel 
fuel. For example, brake components can reach temperatures that are as 
high as engine temperatures.
    Paragraph (a)(3)(vi) requires that fuel line piping be either: 
steel-wire reinforced; synthetic elastomer-covered hose suitable for 
use with diesel fuel that has been tested and has been determined to be 
fire-resistant by the manufacturer; or metal. The proposal would have 
required metal fuel line piping. Several commenters stated that 
requiring fuel line piping to be made of metal was too restrictive. 
Several of these commenters stated that metal fuel

[[Page 55464]]

lines could deteriorate over time as a result of machine vibration, and 
that there were fuel lines made of other materials that were superior 
in strength and performance to metal lines. The final rule has been 
revised from the proposal to address these concerns. Synthetic 
elastomer-covered hose must be of a type that is suitable for use with 
diesel fuel, and must have been tested and determined to be fire-
resistant by the manufacturer, using any one of a number of fire-
resistance tests. Such tests have been developed by a number of 
organizations, including Underwriters Laboratories, The Society of 
Automotive Engineers, and the U.S. Coast Guard. MSHA's tests for flame-
resistance specified in regulations at part 18 would also be 
appropriate. This will ensure that material used for diesel fuel lines 
will have adequate fire-resistance in the underground coal mine 
environment.
    Paragraph (a)(3)(vii) adopts the proposed requirement that fuel 
line piping be clamped. One commenter stated that this requirement, 
along with the requirement that primary fuel lines be located so that 
fuel line leaks do not contact hot surfaces, would limit machine design 
flexibility. This commenter recommended that these requirements be 
revised to provide that the manufacturer's design provide maximum 
protection from damage. The final rule does not adopt this suggestion. 
The requirements identified by the commenter are intended to address 
potential hazards on diesel equipment, particularly fire hazards. The 
fact that there may be some resulting limitations on machine design, 
alone, does not warrant the elimination of requirements that address 
specific hazards.
    Paragraph (a)(3)(viii), like the proposal, requires primary fuel 
lines to be located such that leaks do not contact hot surfaces. The 
fuel lines referred to in this paragraph are the supply and return 
lines connecting the fuel tank to the engine, not those lines that are 
integral to the engine and installed by the engine manufacturer, such 
as the lines connecting the injector pump to the injectors. Several 
commenters supported this requirement, pointing to the potential for 
fire resulting from leaking fuel dripping on hot exhaust components. 
One commenter recommended that the engine be designed to shut down in 
the event of a leaking fuel line. This comment has not been adopted in 
the final rule, in part because MSHA is unaware of any existing 
technology that would provide such a function. Additionally, such a 
requirement is not necessary, given the fuel system design criteria 
under this section in conjunction with the weekly equipment inspections 
required by Sec. 75.1914 of the final rule. These requirements together 
adequately address the potential hazard created by leaking fuel lines.
    Paragraph (a)(3)(ix) requires fuel lines to be separated from 
electrical wiring and protected from damage in ordinary use. This 
requirement has been adopted from the proposal, and was supported by 
several commenters, who mentioned incidents where fuel lines were 
exposed to damage. Separation of fuel and electrical lines can 
generally be easily accomplished. On machines where both electrical 
lines and fuel lines are routed through a machine articulation joint, 
fuel lines must be bundled separately from electrical lines and must be 
positioned so that fuel leaks will not contact electrical lines.
    Paragraph (a)(3)(x) requires that a manual shutoff valve be 
installed in the fuel system as close as practicable to the tank. The 
language of the final rule has been modified from the proposal, which 
would have required the valve to be located ``near'' the tank. This 
change is made in response to a commenter who stated that valves 
located ``near'' the tank would not necessarily be easily accessible to 
the equipment operator or other mine personnel when the fuel supply 
needs to be shut off in an emergency or for maintenance. The commenter 
recommended that this aspect of the proposal be revised to require 
shutoff valves as close as practicable to the tank, and the final rule 
adopts this comment.
    Paragraph (a)(3)(xi) adopts the proposed requirement that equipment 
be provided with fuel filter(s) and a water separator. The final rule 
substitutes the term ``water separator'' for the term ``water 
strainer'' used in the proposal. The terms mean the same thing, but 
``water separator'' is more commonly used and more widely understood. 
Although commenters generally supported this requirement, one commenter 
stated this requirement should be eliminated because fuel filters and 
water separators were not necessary. MSHA disagrees with this 
commenter, and the proposed requirement has been included in the final 
rule. Fuel filters filter out particulate matter in fuel, thereby 
reducing diesel exhaust emissions as well as slowing engine wear. Water 
separators filter out water in the fuel, and minimize fuel system 
corrosion. Several commenters recommended that the proposed requirement 
be revised to permit the use of a single device that functions as both 
a fuel filter and a water separator. Such combination devices will 
satisfy the requirements of this section. The final rule has not been 
revised, however, because the language as proposed and as adopted in 
the final rule does not preclude the use of a combination fuel filter/
water separator.
    The proposed requirement for a fuel tank drain plug has not been 
adopted in the final rule. Although the drain plug is usually provided 
on larger mining equipment, it is typically not provided on light-duty 
equipment such as pickup trucks. Although a drain plug is a convenient 
feature for persons performing equipment maintenance, it is not 
necessary from a strict safety standpoint. For these reasons, a fuel 
tank drain plug is not required under the final rule.
    Paragraph (a)(4) adopts the requirement of the proposal for a 
sensor to monitor the temperature and provide a visual warning of an 
overheated cylinder head on air-cooled engines. This feature is 
necessary because it reduces potential fire hazards on air-cooled 
engines. While such sensors do not completely eliminate the hazards of 
hot surface temperatures, they do provide additional protection by 
warning the equipment operator of overheating. The proposed rule would 
have required a temperature sensor to be located in the engine 
compartment that would automatically activate an intake air shutdown 
device to stop the engine before the engine compartment temperature 
exceeded the actuation temperature of the fire suppression system. This 
requirement has not been adopted in the final rule. Although commenters 
generally supported the concept behind this requirement, they had 
varied concerns about its application and impracticality from a 
technological standpoint. One commenter stated that this requirement 
could create a safety hazard because the engine could be shut off 
unexpectedly. Since loss of steering and braking could result, this 
commenter recommended that the engine be shut off only upon actuation 
of the fire suppression system. Several commenters stated that use of 
manual fire suppression systems on equipment was incompatible with this 
requirement.
    MSHA agrees that this proposed requirement could have resulted in 
the equipment losing control of the machine in the case of unexpected 
engine shutdown, and the engine should only be shut down upon actuation 
of the fire suppression system. The automatic engine shutdown under the 
proposal would have been triggered before the engine temperature 
exceeded the actuation temperature of the fire suppression system. 
Section 75.1911(d)

[[Page 55465]]

of the final rule already requires fire suppression systems for diesel-
powered equipment to provide for automatic engine shutdown, and a 
redundant requirement for automatic engine shutdown at a lower 
temperature is not necessary. An increase in the engine compartment 
temperature may reflect an engine malfunction, such as loss of engine 
coolant, but does not necessarily indicate a safety hazard. Linking 
engine shutdown to the engine compartment temperature would have 
provided protection against engine damage rather than addressing a 
discrete safety hazard. Equipment manufacturers routinely provide 
gauges in the equipment operator's compartment that indicate engine 
faults. Equipment operators will be alerted by this warning system and 
will then be able to shut the engine down, if appropriate. For these 
reasons, the proposed requirement for automatic engine shutdown based 
on engine compartment temperature has not been adopted in the final 
rule.
    Paragraph (a)(5) requires that guarding be provided to protect 
fuel, hydraulic, and electric lines when such lines pass near rotating 
parts and to protect the lines in the event of shaft failure. This 
requirement is intended to prevent leaks and short circuits caused by 
fuel, hydraulic, and electric lines abrading against rotating parts. 
Rotating parts include machine components such as pulleys, belts, fans, 
and shafts. This requirement is similar to that of the proposal, 
although the proposed rule had specified that ``adequate guarding'' be 
provided and did not include protection for hydraulic lines or 
protection in case of shaft failure. The word ``adequate'' is redundant 
in this context and has not been adopted in the final rule. The 
reference to ``hydraulic lines'' was not included in the proposal 
because no hydraulic systems were permitted on the limited class of 
equipment for which the requirement was proposed. Under the final rule 
these requirements apply to larger equipment with hydraulic systems, 
and protection for hydraulic lines has therefore been added. Guarding 
to protect against shaft failure has also been added to the final rule 
to address the design features of the larger equipment now governed by 
these requirements. MSHA has received reports of several fires ignited 
by broken shafts that damaged hydraulic and electrical lines.
    One commenter supported this requirement, while another commenter 
believed that it was unnecessary. A third commenter recommended that 
the engine compartment be shielded by metal from hydraulic components. 
Protection for fuel, hydraulic, and electrical lines is an essential 
element in preventing fires. The final rule does not specify what 
method must be used to comply with this requirement, because a number 
of different methods, including guarding, shielding as recommended by 
the commenter, or relocation of fuel, hydraulic or electrical lines, 
can provide adequate protection.
    Paragraph (a)(6) has been added to the final rule and requires that 
hydraulic tanks, fillers, vents, and lines be located so that any 
spillage or leaks will not contact hot surfaces. This requirement has 
been added to the final rule to supplement the guarding of hydraulic 
lines in paragraph (a)(5) and is supported by the Ontario fire accident 
data, which show that leaking hydraulic lines contribute to fires. This 
requirement was not included in the proposal because, as explained in 
the discussion of paragraph (a)(5), hydraulic systems would not have 
been permitted on the limited class of light-duty equipment to which 
the requirement would have applied under the proposal. This requirement 
will ensure that spills and leaks of combustible hydraulic fluid do not 
contact hot equipment surfaces. This requirement can be satisfied by 
relocation of machine components, or by directing spills and leaks away 
from hot surfaces by means of splash guards or other such devices.
    Paragraph (a)(7) requires that reflectors or warning lights which 
can be readily seen in all directions be mounted on equipment. This 
requirement was generally supported by commenters and is adopted 
unchanged from the proposal. A determination of whether the reflectors 
or warning lights can be ``readily seen'' must be based on the unique 
mine conditions, and must take into account such things as equipment 
size in relation to the mine entry and undulating mine terrain.
    Paragraph (a)(8) has been added to the final rule in response to 
comments, and requires that a means be installed on the equipment to 
direct exhaust gas away from the equipment operator and persons on 
board the machine. This requirement is intended to provide for the 
discharge of exhaust gases away from persons on the machine to the 
greatest extent practicable, minimizing their exposure to excessive 
levels of unhealthful diesel exhaust contaminants. The exhaust pipe 
must direct the flow away from any area where a machine operator or a 
passenger could be located. Exhaust pipes that extend straight up and 
that would allow the exhaust to flow back over the equipment operator 
as the machine moves forward, such as on some agricultural and 
commercial equipment, are unacceptable under the final rule. This 
requirement is added to the final rule in response to the 
recommendation of two commenters, one of whom noted that exhaust gases 
can build up in the operator's compartment of a machine.
    Paragraph (a)(9) has been added to the final rule in response to a 
commenter and as a result of the expansion of the class of equipment 
subject to the requirements of this section. This paragraph requires 
that a means be provided to prevent unintentional free and uncontrolled 
descent of personnel-elevating work platforms. Personnel-elevating work 
platforms normally are equipped with hydraulic systems and would 
consequently not have been eligible for inclusion in the category of 
limited class equipment under the proposed rule. This requirement is 
currently applied to equipment approved under existing part 36. 
Hydraulically operated personnel-elevating platforms meeting the 
applicable American National Standards Institute criteria for 
personnel-elevating platforms (i.e., ANSI A92.2 and A.92.5) would be 
acceptable. This requirement also applies to work platforms which 
utilize other methods to raise the platform, such as wire ropes. The 
machine must be provided with a specific feature that prevents the free 
and uncontrolled descent of the platform in the event of a failure in 
the lifting system, such as a ruptured hydraulic hose or broken wire 
rope. In such a situation, the platform must descend at a rate which 
will not endanger miners located on or below the platform.
    Paragraph (a)(10) has been added to the final rule and requires 
that all nonpermissible equipment be provided with a means to prevent 
the spray from ruptured hydraulic or lubricating oil lines from being 
ignited by contact with engine exhaust system component surfaces. This 
requirement achieves the goal of the limitation of surface temperatures 
in proposed subpart G of part 7, which is not adopted in the final 
rule, and recognizes that high surface temperatures on diesel-powered 
equipment can be controlled in ways other than the water-jacketing of 
hot engine components contemplated under proposed subpart G. The 
requirement of this paragraph, in conjunction with other requirements 
in the final rule for control of fuel sources on diesel-powered 
machines, will provide effective fire prevention on nonpermissible 
diesel-powered equipment used underground.
    The requirements of this paragraph are performance-oriented, and 
are

[[Page 55466]]

intended not only to allow flexibility in compliance but also to 
accommodate new technology developed in the future. One method of 
achieving compliance with this requirement is through the use of a 
water-cooled manifold. A safety component system certified under part 
36 or a power package approved under subpart F of part 7 of the final 
rule also satisfies the requirement of this paragraph.
    Non-absorbent insulating materials are also available for use on 
mining equipment to reduce the surface temperature of diesel exhaust 
system components. Such materials, which were first developed for 
diesel-powered military vehicles, are impervious to hydraulic fluid, 
lubricating fluids, and diesel fuel, and have been successfully used on 
mining equipment in the United States and Canada. Use of these 
materials can reduce surface temperatures of exhaust components to less 
than 300  deg.F, and may also be used to prevent contact of hydraulic 
fluid and lubricating oil with hot surfaces. The goal of applying the 
insulating material is to substantially reduce the surface area of the 
exhaust system that is at elevated temperatures, because of the direct 
relationship between the area of a hot surface and the likelihood of 
ignition of a spray of hydraulic fluid. A large area of exhaust 
component, which includes the turbocharger, at a high temperature is 
more likely to ignite a spray.
    The use of shielding or partitions to isolate hydraulic components 
from the engine would also satisfy the requirement of this paragraph, 
preventing the fluid from contacting the engine in the event of a leak. 
One commenter retrofitted a diesel-powered machine to provide shielding 
of the engine.
    Paragraph (b) sets forth additional requirements for self-propelled 
nonpermissible diesel-powered equipment, which are specifically 
designed for equipment that moves under its own power, as opposed to 
equipment that is towed. Paragraph (b)(1) has been added to the final 
rule and requires a means to ensure that no stored hydraulic energy 
that will cause machine articulation is available after the engine is 
shut down. As discussed elsewhere in the preamble, requirements 
relating to hydraulic systems were not included in the proposal because 
the affected equipment could not have hydraulic systems. This 
requirement is intended to eliminate accidents where an equipment 
operator inadvertently activates the steering controls on articulated 
vehicles when entering or exiting the operator's compartment. In many 
articulated machine designs, personnel must enter the equipment 
operator's compartment through the articulation area. If the 
articulation joint were to close as the operator entered the 
compartment, the operator could be crushed. This requirement will also 
protect miners who encounter a machine that has been shut down and who 
may accidentally activate the control levers. Under the final rule, the 
stored hydraulic energy does not have to be dissipated instantly. The 
time permitted for dissipation of the stored energy will depend on the 
machine design and the amount of movement the machine is capable of 
after shutdown.
    Paragraph (b)(2) has been added to the final rule in response to a 
specific comment that equipment should only be able to start in 
neutral. This paragraph requires equipment to be provided with a 
neutral start feature which ensures that engine cranking torque will 
not be transmitted through the powertrain and cause machine movement on 
vehicles utilizing fluid power transmissions. MSHA agrees with the 
commenter that this requirement is necessary, because some types of 
diesel-powered equipment may be started with the transmission in gear. 
This could result in power being delivered to the driving wheels of the 
machine before the equipment operator is in control of the vehicle, 
endangering both the operator and miners working in the vicinity of the 
equipment. Equipment must be designed such that its transmission is in 
either neutral or park before the starter will crank the engine.
    For machines with steering wheels, brake pedals, and accelerator 
pedals, paragraph (b)(3) requires that the controls be arranged 
consistent with standard automobile orientation. This requirement has 
been added in response to a commenter who was concerned that equipment 
operators could become confused in the operation of equipment controls. 
Under this paragraph the brake pedal must be on the left and the 
accelerator must be on the right when the operator is facing the 
controls. Clockwise rotation of the steering wheel must turn the 
machine to the right, and counter-clockwise rotation of the steering 
wheel must turn the machine to the left. For machines with seating 
perpendicular to the direction of travel, the forward direction of 
travel and the automobile orientation of the controls are to be defined 
with respect to the front end of the equipment. For machines where the 
operator changes seats depending on the direction of travel, the 
machine control movements should also change accordingly, to retain the 
automobile orientation.
    Paragraph (b)(4), like the proposal, requires self-propelled 
equipment to be provided with an audible warning device conveniently 
located near the operator. Such a device could be a horn or bell, and 
must be capable of being heard over the operation of the machine by 
miners in the area. Commenters were generally supportive of this 
provision.
    Paragraph (b)(5) requires that lights be provided and maintained on 
both ends of the equipment. Equipment normally operated in both 
directions must be equipped with headlights for both directions. The 
proposal would have required self-propelled equipment to be provided 
with headlights, tail lights, and back-up lights. The requirement in 
the final rule is derived from the proposal but has been revised to 
better address typical lighting configurations on all types of 
nonpermissible equipment, not only the limited class of equipment that 
would have been affected under the proposal. For equipment such as 
ramcars, headlights on each end of the machine would be required, but 
not tail lights or back-up lights. For pickup trucks, headlights and 
back-up lights installed as original equipment would satisfy this 
requirement. The lights required by this paragraph are in addition to 
the warning lights or reflectors required by paragraph (a)(7) of this 
section.
    Under the proposal lights would have been required to be 
``protected from accidental damage''. The final rule requires instead 
that lights be ``maintained'', in response to a commenter who 
questioned what was meant by ``protected from accidental damage.'' 
Under the final rule equipment lights must be kept in working order, 
and replaced if they burn out or are damaged.
    Although most commenters generally agreed with the proposed 
requirement, one commenter supported a requirement for back-up alarms 
or other means to alert miners to a change in the direction that 
equipment is moving. Although a back-up alarm may be appropriate on 
some equipment, an alarm on equipment that normally operates in both 
directions is not advisable because the alarm would be set off on a 
regular basis, defeating its effectiveness as a warning system. This 
suggestion has therefore not been adopted in the final rule.
    Paragraph (b)(5) also requires equipment that normally operates in 
both directions to be equipped with headlights for both directions. One 
commenter recommended that lights be designed for operation in both

[[Page 55467]]

directions at once. This commenter noted that normally the light switch 
allows the lights to be on in only one direction and that it would be 
beneficial to observe the load while traveling in the other direction. 
Although this feature may be appropriate under some circumstances, it 
would provide no significant safety benefit and is not warranted for 
inclusion as a general machine feature. In many mines, the fact that 
lights are illuminated in only one direction at a time allows other 
miners in the vicinity to determine the equipment's direction of 
movement and provides some safety benefit. Illumination of both sets of 
lights at the same time would eliminate this capability, and this 
suggestion has therefore not been adopted in the final rule.
    Paragraph (b)(6) requires that self-propelled nonpermissible 
equipment be provided with service brakes that act on each wheel of the 
vehicle and that are designed such that failure of any single 
component, except the brake pedal or similar actuation device, does not 
result in a complete loss of service braking capability. This paragraph 
requires two separate brake systems and ensures that, in the event of 
the failure of one braking system, the other system can bring the 
machine to a controlled stop. The only common component permitted in 
the two systems is the brake pedal or a similar device, such as a lever 
or button that is actuated by the equipment operator. This requirement 
has been adopted from the proposal with slight revisions to specify 
that the service brakes ``act on each wheel'' instead of ``for each 
wheel''. This will allow the use of axle brakes, which act on all of 
the wheels on that axle. This requirement prohibits drive line brakes 
in which failure of a single drive shaft or chain results in the loss 
of all braking capability. A split brake system with two completely 
independent hydraulic circuits with an automotive-type dual piston 
master cylinder complies with this requirement.
    The proposal provided that failure of one ``brake line'' must not 
result in a complete loss of service braking capability. This language 
has been changed to provide that failure of any ``single component'' 
must not result in a complete loss of service braking capability, to 
conform the requirement to the expanded range of equipment that is 
governed by this requirement under the final rule.
    The brake pedal or other interface between the equipment operator 
and the braking system is excluded from this requirement. If the pedal 
is connected to more than one link to activate the brake systems, those 
links must provide for independent actuation of the brake systems in 
the event of the failure of one of the links. Drive line brakes are not 
adequate because of the frequent failure of universal joints. The 
failure of the universal joint could result in the loss of all braking 
ability if a second brake system is not provided. Most agricultural 
equipment and some commercial equipment used in mines, such as high 
lifts or backhoes, may need a retrofit of their braking systems to 
comply with this requirement.
    Several commenters supported this requirement and recommended two 
braking systems independent of each other in all working aspects. Other 
commenters noted that a single brake system would be adequate for 
tractor-type vehicles because they travel at speeds of less than 15 
mph. MSHA disagrees that the low speeds of this type of equipment 
eliminates the need for two brake systems. Failure of an equipment's 
brake system in the confined area of an underground coal mine could 
result in serious injury or death, even at speeds of 15 mph or less. 
The final rule therefore does not incorporate this comment. Other 
commenters were of the opinion that the brake systems should not be 
separate for each wheel. This recommendation has been incorporated into 
the language of the final rule.
    Paragraph (b)(7) has been adopted unchanged from the proposal and 
requires self-propelled nonpermissible equipment to be provided with 
service brakes that can safely bring the fully loaded vehicle to a 
complete stop on the maximum grade on which it is operated. No stopping 
distance or braking force is specified in the final rule, to allow 
flexibility in equipment design and usage. Compliance with this 
requirement is highly site-dependent because of the variation in mine 
grades. The mine operator is responsible for ensuring that equipment 
with adequate grade-holding ability is used at a particular location. 
Commenters generally supported this requirement.
    Paragraph (b)(8) has been added to the final rule and requires that 
no device that traps a column of fluid to hold the brake in the applied 
position be installed in any brake system, unless the trapped column of 
fluid is released when the operator is no longer in contact with the 
brake activation device. This requirement prohibits the installation of 
``park'' brakes devices which rely on a trapped column of fluid, and 
has been included in response to the suggestion of commenters. The use 
of such devices can present serious hazards, and are prohibited. 
Because the temperature of hydraulic brake fluid increases due to 
usage, a column of fluid trapped at a sufficient pressure will 
initially apply the brakes sufficiently to hold the machine stationary. 
However, as the fluid cools it contracts, lowering the pressure and 
possibly releasing the brakes. These devices are not permitted even as 
supplemental devices, because of the risk that equipment operators 
would use them as park brakes even if another park brake is provided. 
Several fatal accidents have been attributed to use of these devices, 
also called ``mico lock braking systems''.
    This requirement does not apply to normal automotive-type service 
brakes which trap a column of fluid, as long as the operator is 
applying pressure to the foot pedal. This requirement also does not 
preclude the use of hydrostatic drive wheel motors that are designed 
and maintained to function as service brakes. These wheel motors do not 
necessarily lose their service braking ability if the fluid cools or if 
minimal leakage occurs. The wheel motors can act to maintain continuous 
pressure in the braking circuit. Although hydrostatic wheel motors can 
function as adequate service brakes, these systems do not provide 
adequate parking brake capability. For the wheel motor to maintain 
pressure in the braking circuit, the wheel must turn slightly, thereby 
permitting the machine to move very slowly down the grade. This 
movement is insignificant during the short period of time the service 
brakes are applied. However, if wheel motors are used as parking 
brakes, the machine can move a significant distance when the equipment 
operator is away from the machine. This can endanger miners who may be 
working near the machine in the confined area of the mine.
    Paragraph (c) has been added to this section of the final rule to 
specifically address self-propelled nonpermissible heavy-duty diesel-
powered equipment meeting the requirements of Sec. 75.1908(a), except 
rail-mounted equipment. These requirements have been added to the final 
rule in response to the additional types of equipment that are now 
subject to the requirements of this section. Heavy-duty equipment that 
hauls rock, coal, or longwall components or transports large quantities 
of diesel fuel are governed by these safety requirements, and must be 
provided with a supplemental braking system that meets specified 
criteria. The criteria for these braking systems were developed from 
the criteria contained in Sec. 75.523-3, applicable to automatic 
emergency parking brakes on similar

[[Page 55468]]

types of electrical equipment. There was widespread support for 
applying these braking requirements to diesel-powered equipment, in 
comments submitted in response to the advance notice of proposed 
rulemaking addressing equipment approval and machine safety features. 
Although there was a difference of opinion among these commenters as 
far as whether these braking requirements should be incorporated as 
part of an equipment approval program, commenters did agree that they 
be included as machine features either in an approval program or as 
mandatory safety standards in part 75. Commenters also recommended that 
there should be separate brake requirements for rail-mounted equipment. 
The Agency agrees with these comments, and has concluded that existing 
brake requirements in Secs. 75.1404 and 75.1404-1, which apply to both 
electric and diesel-powered rail-mounted equipment, provide sufficient 
protection. Rail-mounted equipment has therefore been specifically 
excluded from this requirement under the final rule.
    Existing Sec. 75.523-3 specifies different requirements for two 
types of electric-powered equipment: haulage equipment and all other 
equipment. Electric-powered haulage equipment is very similar in 
function to the heavy-duty diesel-powered equipment subject to this 
requirement. Paragraphs (c)(1) through (c)(5) of this section of the 
final rule closely track the brake system requirements for electric 
haulage equipment in existing Sec. 75.523-3, with the exception of the 
requirement that the brake be engaged by an emergency deenergization 
device or panic bar. A panic bar is appropriate for only some types of 
permissible diesel-powered equipment, and will be addressed during the 
part 36 approval process. Panic bars are not required for 
nonpermissible diesel-powered equipment. Under the final rule, self-
propelled nonpermissible heavy-duty diesel-powered equipment, except 
rail-mounted equipment, is required to have a supplemental braking 
system that: (1) Engages automatically within 5 seconds of shutdown of 
the engine; (2) safely brings the equipment when fully loaded to a 
complete stop on the maximum grade where it is operated; (3) holds the 
equipment stationary, despite any contraction of brake parts, 
exhaustion of any nonmechanical source of energy, or leakage; (4) 
releases only by a manual control that does not operate any equipment 
function; (5) has a means in the equipment operator's compartment to 
apply the brakes manually without the engine operating, and a means to 
release and reengage the brakes without the engine operating; and (6) 
has a means to ensure that the supplemental braking system is released 
before the equipment can be trammed, and is designed to ensure that the 
brake is fully released at all times when the equipment is trammed.
    Paragraph (c)(6) has been added to the final rule and requires that 
the supplemental braking system have a means to ensure that the system 
is released before the equipment can be trammed. It further requires 
that the system be designed to ensure the brake is fully released at 
all times while the equipment is trammed. This requirement is added to 
the final rule to address the hazard of dragging brakes, which were the 
cause of numerous fires reported in the Ontario fire data analyzed by 
MSHA in response to a commenter's recommendation. Some manufacturers 
install a lever on the transmission gear selector to ensure that the 
supplemental brakes are released. This lever automatically releases the 
brake when the operator shifts the transmission into gear.
    Paragraph (d) applies to self-propelled nonpermissible light-duty 
diesel-powered equipment meeting the requirements of Sec. 75.1908(b), 
except rail-mounted equipment. This provision, which has been adopted 
from the proposal, requires that the equipment be provided with a 
parking brake that holds the fully loaded equipment stationary on the 
maximum grade on which it is operated despite any contraction of the 
brake parts, exhaustion of any nonmechanical source of energy or 
leakage. This requirement was developed from existing Sec. 75.523-3(d), 
which addresses parking brakes for electric-powered equipment other 
than haulage equipment, which is similar to the equipment in the light-
duty category under Sec. 75.1908(b) of the final rule.
    A parking brake meeting the requirements of paragraph (d), rather 
than the supplemental brake system required for heavy-duty equipment 
under paragraph (c), is adequate for light-duty equipment, which is 
typically used for transportation or moving of supplies on an 
intermittent basis.
    Paragraph (e) has been added to the final rule as a result of the 
inclusion of requirements for supplemental and park brake systems under 
paragraphs (c) and (d) of this section. This paragraph requires that 
the supplemental and park brake systems required by paragraphs (c) and 
(d) be applied when the equipment operator is not at the controls of 
the equipment, except during movement of disabled equipment. This 
requirement was developed from existing Sec. 75.523-3(e), and requires 
the machine operator to set the brakes when not at the controls. 
However, this provision is not intended to suggest that it would be a 
safe practice for the operator to apply the brake and leave the machine 
with the engine running.
    Paragraph (f) has been added to the final rule as a result of 
MSHA's review of the Ontario fire data, and requires self-propelled 
personnel-elevating work platforms be provided with a means to ensure 
that the parking braking system is released before the equipment can be 
trammed, and that the platforms be designed to ensure the brake is 
fully released at all times while the equipment is trammed. MSHA's 
review of the Ontario fire data revealed a high number of personnel-
elevating vehicle fires caused by dragging brakes. The final rule 
applies the same requirement to personnel-elevating vehicles in this 
paragraph as applies to self-propelled heavy-duty nonpermissible 
equipment under paragraph (c)(6).
    Paragraph (g) has been added to the final rule and requires that 
any nonpermissible equipment that discharges its exhaust directly into 
a return air course be provided with a power package approved under 
subpart F of part 7. The basis for this requirement is the possibility 
that the return air course may contain high levels of methane, which 
could be drawn into the machine's exhaust system as it cools after 
engine shutdown. This creates the potential for ignition of the methane 
by the hot surfaces of the diesel engine. As a result, the final rule 
requires equipment which discharges its exhaust directly into the 
return to be furnished with the fire and explosion protection provided 
by a subpart F power package. Equipment without a subpart F power 
package must discharge its exhaust into intake air.
    Under the proposed rule all nonpermissible equipment, with the 
exception of a limited class of light-duty equipment, would have been 
required to be equipped with a power package approved under either 
subpart F or G of part 7. Subpart F power packages are equipped with 
spark arresters and flame arresters, which significantly reduce the 
likelihood that equipment will ignite explosive levels of methane. 
Because the final rule does not require power packages on 
nonpermissible equipment, this requirement has been added to the final 
rule to ensure that nonpermissible equipment that discharges it exhaust 
directly into a return air course, which could contain explosive levels 
of

[[Page 55469]]

methane, will not create an explosion hazard.
    Paragraph (h) requires that self-propelled nonpermissible heavy-
duty equipment meeting the requirements of Sec. 75.1908(a) be provided 
with an automatic fire suppression system meeting the requirements of 
Sec. 75.1911. Paragraph (i) requires that self-propelled nonpermissible 
light-duty equipment meeting the requirements of Sec. 75.1908(b) be 
provided with a manual or automatic fire suppression system meeting the 
requirements of Sec. 75.1911. Under the proposed rule, all 
nonpermissible equipment would have been required to be provided with 
an automatic fire suppression system.
    As explained in greater detail in the preamble discussion for 
Sec. 75.1911 of the final rule, some commenters supported automatic 
fire suppression systems for all types of equipment, while others 
expressed support for automatic fire suppression systems on portable or 
unattended equipment but were strongly opposed to requiring automatic 
fire suppression on all types of nonpermissible diesel-powered 
equipment. These commenters stated that automatic fire suppression 
systems were much more difficult to maintain, and were unnecessary for 
equipment that was attended by an equipment operator. These commenters 
suggested that mine operators should have the option of installing 
either manual or automatic systems on self-propelled equipment, stating 
that the equipment operator is in the best position to detect machine 
fires, and would be able to actuate a manual fire suppression system 
more easily than an automatic system. Other commenters stated that it 
might be difficult for an equipment operator to actuate a manual system 
depending on the size and type of the fire, expressing concern that an 
equipment operator could be overcome by the effects of a fire or 
explosion and not be able to manually extinguish the fire.
    As discussed more fully under Sec. 75.1911 of the preamble, the 
Ontario fire accident data indicates that heavy-duty diesel-powered 
equipment, such as the type specified in Sec. 75.1908(a) of the final 
rule, presents a much greater fire hazard than light-duty equipment. 
Although light-duty equipment still presents some fire risk, a 
manually-actuated fire suppression system provides adequate protection 
if the equipment is attended and provided with additional safety 
features for protection of fuel, hydraulic, and electrical systems 
under this section and Sec. 75.1910 of the final rule. As noted 
elsewhere in this preamble, Sec. 75.1916(d) of the final rule requires 
all diesel-powered equipment to be attended while it is being operated.
    An automatic fire suppression system is needed on equipment that 
presents a greater fire risk. Good fire fighting practice demands that 
a fire be suppressed as early as possible, and several reports of fire 
indicate that the rapid growth of a fire prevented the equipment 
operator from actuating the manual fire suppression system. Automatic 
systems respond quickly to fire without operator intervention, and are 
needed on equipment that operates frequently for long periods of time 
under high load, presenting an increased fire risk. Compressors and 
other non-self-propelled equipment also operate for long periods of 
time under high load. This results not only in high engine temperatures 
but also increases the possibility of mechanical failure, presenting 
ignition and fuel sources. To address these hazards, automatic fire 
suppression systems meeting the requirements of Sec. 75.1911 of the 
final rule are required under paragraph (h) for self-propelled heavy-
duty nonpermissible equipment, and under paragraph (j)(3) for both 
heavy-duty and light-duty equipment that is not self- propelled. 
Paragraph (i) provides that self-propelled light-duty nonpermissible 
equipment may be provided with either a manual or an automatic system 
that meets the requirements of Sec. 75.1911.
    Paragraph (j) requires nonpermissible diesel-powered equipment that 
is not self-propelled to be provided with features in addition to those 
listed in paragraph (a). These features include a means to prevent 
inadvertent movement of the equipment when parked, safety chains or 
other suitable secondary connections on equipment that is being towed, 
and, as discussed above, an automatic fire suppression system meeting 
the requirements of Sec. 75.1911. A requirement for automatic fire 
suppression for non-self-propelled equipment has been retained in the 
final rule in recognition of the fact that non-self-propelled equipment 
is typically operated under load for extended periods of time, 
resulting in the need for automatic rather than manual fire suppression 
to address the additional fire risks. MSHA intends that automatic fire 
suppression systems be provided for those machines, such as 
compressors, welders, and generators, that may have some limited 
capacity for self- propulsion but which essentially function as 
portable equipment, i.e., where the equipment operator performs a 
function some distance from the machine while the equipment is running.
    The proposal would have required a means to prevent inadvertent 
movement as well as safety chains or other connections for equipment 
being towed, but would have required a fire extinguisher instead of an 
automatic fire suppression system. The proposal would also have 
required the equipment to be provided with a sensor to monitor 
equipment operation that would stop the engine when an equipment 
malfunction would result in the creation of a hazard.
    The proposed requirement for sensors to monitor the operation of 
portable equipment has not been adopted in the final rule. Several 
commenters expressed confusion as to what these devices were intended 
to monitor, and suggested that this requirement be eliminated because 
it was vague and ambiguous. The proposed requirement was intended to 
ensure that general safety devices supplied as original equipment 
features, such as low oil sensors or high temperature sensors, were 
maintained in proper working condition. However, MSHA has concluded 
that it would be extremely difficult to develop a standard that is any 
more specific than what was proposed that would be suitable for the 
variety of monitors and sensors that may be installed on equipment. In 
light of these circumstances, and in light of the fact that all 
equipment used in underground coal mines is required to be maintained 
in safe operating condition under existing Sec. 75.1725, this 
requirement has not been adopted in the final rule.
    A number of commenters recommended that additional equipment safety 
features be required in the final rule that were not included in the 
proposal. Several commenters expressed concern about limited visibility 
from the operator's compartment on certain types of large diesel-
powered equipment. The final rule does not adopt these commenters' 
recommendations. Although this concern is addressed to some extent by 
Sec. 75.1916 of the final rule, which requires that mines using diesel-
powered equipment establish and follow standardized traffic rules, MSHA 
has concluded that the issue of operator equipment design and 
visibility should be addressed in the context of all types of 
equipment, not only diesel-powered equipment. Specific provisions on 
operator visibility have therefore not been included in the final rule.

[[Page 55470]]

Section 75.1910  Nonpermissible Diesel-Powered Equipment; Electrical 
System Design and Performance Requirements
    This section addresses electrical system requirements for 
nonpermissible diesel-powered equipment. These requirements were 
proposed in Sec. 75.1909 with other equipment safety requirements that 
would have applied to a limited class of nonpermissible light-duty 
equipment, but in the final rule are included separately in 
Sec. 75.1910.
    Faulty equipment electrical systems have frequently been the cause 
of equipment fires, and the requirements of this section address the 
hazards associated with these systems. Although commenters generally 
supported the proposed requirements, one commenter suggested that these 
requirements not be adopted in the final rule, because some equipment 
is designed for highway use and meets safety standards that have been 
developed by the industry over many years. The commenter asserted that 
changing the design of those machines' electrical systems would have an 
adverse impact on machine safety. MSHA is aware that electrical systems 
on certain types of diesel-powered equipment, such as utility vehicles, 
personnel carriers, and ambulances, are designed to meet safety 
standards for highway use. However, this final rule expands the scope 
of the limited class of equipment to include types of equipment that 
would not meet the requirements for highway use. Additionally, because 
of the significant hazards presented by a fire in an underground mine, 
additional safeguards for electrical systems on equipment employing 
storage batteries and integral charging systems are warranted, given 
the fact that a number of electrical accidents have been attributed to 
faults in these systems. The analysis of the Ontario fire accident data 
revealed that 43 percent of the fires were attributable to electrical 
system faults. Almost half of these were related to the engine starting 
and charging systems. Changes in machine design to comply with the 
requirements in this section are necessary to enhance safety. For these 
reasons, the final rule retains these special provisions.
    The requirements included under this section of the final rule 
apply only to those electrical circuits and components associated with, 
or connected to, electrical systems utilizing storage batteries and 
integral charging systems. It should be noted, as indicated in the rule 
itself, that these requirements do not apply to equipment that falls 
within the special category of emergency equipment under 
Sec. 75.1908(d) of the final rule. The requirements in this section 
would apply, for example, to circuits for instrument panel gages and 
machine lights on most equipment utilizing storage batteries and 
integral charging systems. Accordingly, electrical systems on 
nonpermissible diesel-powered equipment without storage batteries and 
charging systems are not governed by the requirements of this section. 
Additionally, the requirements of this section do not apply to 
electrical circuits and components on equipment that is not directly 
connected to or otherwise powered from a separate electrical system 
utilizing storage batteries and an integral charging system. Both types 
of systems should be designed and maintained in compliance with 
existing safety standards in part 75 for underground coal mines.
    Several commenters suggested that the proposed electrical system 
requirements not be adopted in the final rule, and instead that the 
final rule provide that electrical systems on diesel-powered equipment 
comply with existing part 75 electrical safety standards for 
nonpermissible equipment. Some of these commenters also suggested that 
more performance-oriented standards be developed for electrical 
circuits and components associated with storage batteries and charging 
systems.
    Performance-oriented requirements have been adopted where 
appropriate in the final rule to allow flexibility in design and to 
facilitate future development of new and improved technology. Instead 
of simply applying existing requirements to this equipment, as 
suggested by some commenters, many of the requirements of this section 
have been derived from existing MSHA electrical safety standards in 
part 75 but have been tailored to apply to diesel-powered equipment.
    It should be noted that MSHA does not consider the continuous on-
board recharging of the battery on this equipment, which typically 
power auxiliary features such as headlights, to be the type of battery-
charging contemplated by existing Sec. 75.340.
    Paragraph (a) addresses overload and short circuit protection of 
electric circuits and components and, like the proposal, requires that 
such protection be provided in accordance with existing Secs. 75.518 
and 75.518-1. The references to the existing sections have been 
retained in the final rule in response to commenters' suggestions that 
such references would minimize confusion over what the standard 
requires.
    Paragraphs (b) and (c) are adopted from the proposal and were 
developed from existing approval requirements for electrical systems on 
other types of diesel-powered equipment. Paragraph (b) requires that 
each electric conductor from the battery to the starting motor be 
provided with short circuit protection, and requires that the short 
circuit protective device be placed as near as practicable to the 
battery terminals. Paragraph (c) requires that each branch circuit 
conductor connected to the main circuit between the battery and the 
charging generator be provided with circuit protection. When complied 
with, these requirements will provide all electric conductors and 
circuits with circuit protection and will minimize the hazards of fire 
due to circuit failure.
    Paragraph (d), like the proposal, requires that a main circuit-
interrupting device be provided in the electrical system so that power 
may be disconnected from the equipment, at or near the battery 
terminals, in the event of an emergency. The device must be located as 
close as practicable to the battery terminals and be designed to 
operate within its electrical rating without damage. This paragraph 
also requires that the device not automatically reset after being 
actuated, and that magnetic devices be mounted in such a manner to 
preclude closing by gravity. This requirement reduces the possibility 
of a fire in the event of a short circuit protective device 
malfunction. The proposal would have provided that a manually operated 
controller, such as a rheostat, would not be acceptable as a service 
switch. This provision has not been included in the final rule because 
it is redundant and adds nothing of substance to the paragraph. 
Manually operated controllers are not typically used on diesel-powered 
equipment, and would be prohibited in any case by the language in the 
final rule.
    Under the final rule circuit-interrupting devices must be designed 
not to automatically reset after being actuated. If the circuit has 
been interrupted it is most likely due to some fault in the system, and 
an automatic reset would defeat the purpose behind the device. These 
devices must also be operational within their electrical rating without 
damage, because otherwise they could self-destruct. Magnetic circuit-
interrupting devices are required to be mounted in a manner that 
prevents gravity from closing the contacts to prevent a premature or 
undesirable activation of electric circuits. The requirements of this 
paragraph ensure proper design and installation of circuit-interrupting 
devices.

[[Page 55471]]

    The proposed rule would have included the additional requirement 
that circuit-interrupting devices and other controls be designed so 
that they could be operated without opening any compartment in which 
they were enclosed. This proposed provision has not been adopted in the 
final rule, in response to commenters who advocated performance-
oriented requirements. The proposal would also have required that 
circuit-interrupting devices meet the requirements of existing 
Sec. 75.520, which simply requires that all electric equipment be 
provided with switches or other controls that are safely designed, 
constructed, and installed. This reference adds little or nothing of 
substance to the requirements of this paragraph, and has not been 
adopted in the final rule.
    Paragraph (e) adopts the proposed requirement that each motor and 
charging generator be protected from overload by an automatic 
overcurrent device. This requirement is necessary to ensure proper 
deenergization of circuits and equipment in the event of overcurrent 
conditions such as arcing and motor overheating, and, when complied 
with, will minimize resulting fire hazards. The final rule also adopts 
the proposed provision that one device will be acceptable when two 
motors of the same rating operate simultaneously and perform virtually 
the same duty.
    The requirements of paragraph (f), like the proposal, address 
conductor size and capacity. Proper selection of circuit conductors of 
adequate size and current carrying capacity and with insulation 
compatible with the circuit voltage depends on the environmental 
conditions under which the conductors will be used. Conductor size and 
capacity are also important in minimizing overload and short circuit 
conditions which could cause a fire. The final rule adopts the proposed 
requirements that each ungrounded conductor have insulation compatible 
with the impressed voltage, and that insulation materials be resistant 
to deterioration from engine heat and oil. The final rule, like the 
proposal, also requires that electric conductors meet the requirements 
of existing Secs. 75.513 and 75.513-1, except for electrical conductors 
for starting motors, which must only comply with the performance-
oriented requirements of Sec. 75.513. Existing Sec. 75.513 provides 
that all electric conductors shall be sufficient in size and have 
adequate current carrying capacity and be of such construction that a 
rise in temperature resulting from normal operation will not damage the 
insulating material. Existing Sec. 75.513-1 provides that an electric 
conductor is not of sufficient size to have adequate current carrying 
capacity if it is smaller than provided for in the National Electric 
Code of 1968.
    Existing Secs. 75.513 and 75.513-1 were developed for electrical 
equipment used in outby locations, but they are also suitable for 
application to all nonpermissible diesel- powered equipment. Greater 
flexibility is provided for electric conductors for starting motors, 
which are not required to meet the size and carrying capacity 
requirements under Sec. 75.513-1, but must only comply with the 
performance requirements of Sec. 75.513. This is because the conductor 
size requirements in the 1968 National Electric Code are determined 
based on the motor running at maximum load, with no allowance for the 
type of duty. The conductor sizes specified in the Code would therefore 
not be appropriate for starting motors, which typically run for only a 
very short period of time.
    Several commenters objected to the requirement in the proposed rule 
that conductors for equipment or accessories added to a vehicle's 
electrical system after manufacture not be smaller than No. 14 AWG in 
size, stating that some components were not readily available with wire 
sizes compatible with this requirement. In response to this comment and 
in light of the requirements that have been adopted in the final rule, 
which will provide adequate protection, the proposed size restriction 
on certain conductors is not adopted in the final rule.
    Since damaged or defective conductors or components may present 
potential fire hazards, paragraphs (g) and (h) address the protection 
of electric circuits and components. Paragraph (g), like the proposal, 
requires all wiring to have adequate mechanical protection to prevent 
damage to the cable that might result in short circuits. Paragraph (h) 
adopts the proposed requirement that sharp edges and corners be removed 
at all points where there is a possibility for damaging wires, cables, 
or conduits by cutting or abrasion. The insulation of the cables within 
a battery box is also required to be protected against abrasion. These 
paragraphs ensure that circuits are physically protected and secured 
from movement or displacement caused by vibration, as well as from 
cutting or abrasion. The proposed rule would have included the 
additional requirements that wiring have adequate electrical protection 
to prevent cable damage, and that wiring be installed in accordance 
with existing Sec. 75.515, as applicable. The reference to electrical 
protection in the proposal was determined to be redundant, and has not 
been adopted in the final rule. The reference to existing Sec. 75.515 
in the proposal has also not been adopted in the final rule, because it 
simply restates requirements already included in the final rule.
    Paragraph (i) requires electrical connections and splices to be 
electrically and mechanically efficient, in addition to having adequate 
insulating properties. Insulating material would be required in 
applications where space is limited and where the possibility exists of 
arcs striking metal walls or parts. These precautions minimize fire 
hazards from improper or loose connections and splices as well as 
insufficient electrical clearances, which could cause a fire due to 
conductor overheating or electrical arcing. In response to comments, 
specific references to bolted connectors and to existing Sec. 75.514 
have been deleted and replaced with more performance-oriented 
requirements.
    Paragraph (j) of the final rule, like the proposal, requires 
storage batteries to be secured in place to prevent undue movement and 
protected from external damage. Batteries not protected from damage by 
their location on the equipment are required to be housed in a battery 
box.
    Paragraphs (k) through (o) of the final rule set forth requirements 
for battery box construction, and are adopted from the proposal with 
slight revision. These requirements provide for a substantially 
constructed battery enclosure and address battery insulation, 
ventilation, and chemical reaction from electrolyte. A number of 
commenters suggested that more performance-oriented requirements be 
adopted for battery box construction. However, the proposed design 
specifications have been retained in the final rule because they set 
forth the minimum construction requirements needed to protect a battery 
from external damage. One commenter related an incident where a battery 
case had deteriorated, resulting in arcing and sparking between the 
battery terminal and the frame of the machine. Other reports of fires 
from the Ontario fire accident data indicate that a number of fires had 
been caused by batteries that were not secured in place or adequately 
protected from external damage. The minimum design and construction 
requirements for battery boxes in the final rule are necessary to 
reduce these types of hazards.
    Paragraph (k) provides that the battery box, including the cover, 
must be constructed of steel with a minimum thickness of \1/8\ inch, or 
of a material other than steel that provides equivalent strength. One 
commenter specifically

[[Page 55472]]

cited the proposed \3/16\-inch thickness requirement as an example of 
an unnecessary design requirement. This requirement has been changed to 
\1/8\-inch minimum thickness to conform to existing part 7 requirements 
for battery boxes containing batteries no greater than 1,000 pounds. 
Thinner battery box cross sections would not provide adequate 
protection for the battery and could result in a fire or explosion.
    Paragraph (l) provides that battery-box covers must be lined with a 
flame-resistant insulating material permanently attached to the 
underside of the cover, unless equivalent protection is provided. 
Battery-box covers must also be provided with a means for securing them 
in a closed position. At least \1/2\-inch of air space must be provided 
between the underside of the cover and the top of the battery, 
including terminals. Paragraph (m) requires battery boxes to be 
provided with ventilation openings to prevent the accumulation of 
flammable or toxic gases or vapors within the battery box. The size and 
locations of openings for ventilation must prevent direct access to 
battery terminals. Paragraph (n) requires the battery to be insulated 
from the battery-box walls and supported on insulating materials. 
Insulating materials that may be subject to chemical reaction with 
electrolyte must be treated to resist such action. Finally, paragraph 
(o) requires drainage holes in the bottom of each battery box.
    Stationary unattended diesel-powered equipment. The Diesel Advisory 
Committee recommended that stationary unattended diesel-powered 
equipment be prohibited where permissible electric equipment is 
required, and that stationary unattended equipment used elsewhere in 
the mine be provided with the fire prevention features required for 
electrical installations and mobile diesel-powered equipment. The 
Committee recommended that stationary unattended equipment be equipped 
with specific machine features, such as surface temperature controls, 
an automatically and manually actuated fire suppression system, an 
engine shutdown device, and a means to shut down the engine from the 
surface. The Committee also recommended that stationary unattended 
equipment be housed in a fireproof enclosure ventilated to a return air 
course.
    Section 75.1910 of the proposed rule incorporated the 
recommendations of the Advisory Committee for stationary unattended 
equipment. Specifically, proposed Sec. 75.1910 would have prohibited 
stationary unattended diesel-powered equipment in areas of the mine 
where permissible electric equipment was required or in the primary 
escapeway. Stationary unattended equipment located in other areas of 
the mine would have been required to have a diesel power package 
approved under subpart F or G of part 7. Additional safety features 
were proposed for this equipment, including fuel system requirements, 
limitations on storage of the equipment fuel supply, and a methane 
monitor that would shut down the engine in the presence of 1.0 percent 
concentration of methane.
    A number of commenters were concerned that the proposed rule dealt 
with stationary unattended diesel-powered equipment differently than 
existing standards addressed unattended electrical equipment, and 
imposed unnecessary restrictions. These commenters stated that it was 
excessive to require approved power packages on equipment when the 
equipment is already housed in a noncombustible enclosure, vented to a 
return air course, protected by an automatic fire suppression system, 
and equipped with a device that shuts down the equipment and sounds an 
alarm at an attended surface location. Several commenters stated that 
unattended electric equipment, which they believed presented similar 
ignition sources, was not required to have methane monitors, and that 
such monitors were not necessary, given the outby locations where 
stationary nonpermissible equipment would operate.
    Other commenters favored a complete prohibition of unattended 
diesel equipment in underground coal mines, stating that diesel 
equipment presented too great a fire hazard to allow it to be operated 
unattended, even with the imposition of rigid safety requirements. One 
commenter referred to the 1984 Wilberg Mine disaster, where a fire 
started by an unattended electrical compressor killed 27 miners. In the 
alternative, these commenters recommended that extensive additional 
requirements be imposed on stationary unattended equipment, including a 
requirement that the equipment be permissible, and that the enclosure 
housing the equipment meet a 2-hour fire resistance test.
    One commenter stated that there should be clarification of what 
constitutes ``stationary'' versus ``portable'' equipment. The commenter 
pointed out that some types of equipment, such as compressors, are 
portable because they are capable of being transported by rail or 
otherwise carried, but that the equipment can also be placed in a 
remote location and operated there for an indefinite period of time.
    In considering these comments, MSHA reviewed data to determine the 
types of equipment that would be affected by the proposed requirements 
for stationary unattended equipment. This review revealed that there 
were approximately 200 pieces of equipment that were currently being 
operated either as stationary unattended equipment or as portable 
attended equipment. Equipment such as air compressors, generators, mine 
sealant machines, hydraulic power units, rock dusters, water spray 
units, and welders fell into this category. Water spray units are used 
to wash mining equipment; mine sealant machines apply sealants to 
stoppings or mine surfaces; hydraulic power units are used to operate 
certain special purpose tools; rock dusters are used to apply rock dust 
to mine surfaces; and diesel-powered welders are used where electric 
power is not readily available. An operator must be present to perform 
the main function of all of these types of equipment, i.e., welding, 
rock dusting, etc.
    MSHA's review also revealed that diesel-powered generators are 
typically used to provide electrical power to move equipment with 
electric motors from place to place in the mine. An equipment operator 
is also in attendance when this type of equipment is being used. 
Finally, MSHA's review also indicated that diesel-powered compressors 
are used in a manner similar to hydraulic power units, with an operator 
in attendance, to provide a source of compressed air to operate tools 
such as pneumatic hammers and drills.
    From this review, MSHA has concluded that diesel-powered equipment 
is not commonly operated unattended in a permanent location, but 
instead is operated with a person in close proximity. The final rule 
includes a definition of what constitutes attended diesel-powered 
equipment in Sec. 75.1908, which provides that the equipment must 
either be operated by a miner, or located within 500 feet of a job site 
where a miner is located. Essentially all of the diesel-powered 
equipment currently operated in underground coal mines is ``attended'' 
under the final rule's definition. In light of this determination, and 
also in light of the serious concerns expressed by some commenters 
about the possible fire hazards presented by unattended diesel-powered 
equipment operating underground, Sec. 75.1916(d) of the final rule 
prohibits the operation of unattended diesel-powered equipment in 
underground coal mines.

[[Page 55473]]

Consequently, the proposed requirements addressing the operation of 
stationary unattended diesel-powered equipment are not adopted in the 
final rule.
    As a result of the final rule's prohibition against operation of 
unattended diesel-powered equipment in underground coal mines, 
conforming amendments are necessary to several existing standards, 
primarily to delete unnecessary references to unattended diesel-powered 
equipment. Existing Sec. 75.360 lists the locations where preshift 
examiners must examine for hazardous conditions, test for methane and 
oxygen deficiency, and determine if the air is moving in the proper 
direction. The final rule deletes from these locations the reference in 
Sec. 75.360(b)(7) to ``where unattended diesel equipment is to 
operate.'' Additionally, existing Sec. 75.380(f)(3)(i) included a 
prohibition against operation in the primary escapeway of unattended 
diesel equipment without an automatic fire suppression system. This 
reference is deleted by the final rule.
    Finally, existing Sec. 75.344 deals with the use of air compressors 
underground, including unattended diesel compressors. The final 
ventilation rule that was published in October 1989 made clear that the 
application of the requirements of Sec. 75.344 to diesel compressors 
would be removed when the final rule for diesel equipment was 
promulgated. [54 FR 40950]. The reference to diesel compressors in 
paragraph (d) of Sec. 75.344 is therefore removed by the final rule.
Section 75.1911--Fire Suppression Systems For Diesel-Powered Equipment 
And Fuel Transportation Units
    Section 75.1911 of the final rule establishes requirements for the 
design, installation, and maintenance of fire suppression systems used 
on diesel-powered equipment and fuel transportation units in 
underground coal mines. Under the final rule, both permissible and 
nonpermissible diesel-powered equipment is required to be equipped with 
fire suppression systems. The requirement for installation of fire 
suppression systems on permissible diesel-powered equipment is 
contained in the final rule at Sec. 75.1907(b)(2),and for 
nonpermissible equipment at Sec. 75.1909 (h), (i), and (j)(3). 
Nonpermissible diesel-powered equipment typically includes scoops, 
personnel carriers, and pickup trucks.
    The Diesel Advisory Committee recommended that fire suppression 
systems be required on certain types of diesel-powered equipment, in 
addition to surface temperature controls, to address fire hazards 
created by other machine system malfunctions such as brake components 
overheating, severing of a fuel line or hydraulic line, and electric 
component short-circuiting. The Committee made a number of 
recommendations regarding the application of fire suppression systems 
to specific types of equipment such as nonpermissible equipment, 
limited class equipment, and stationary equipment. The proposed rule 
included design, installation and maintenance requirements for fire 
suppression systems on diesel-powered equipment and fuel transportation 
units. These requirements would have been applicable to approved 
equipment, limited class equipment, and fuel transportation units, both 
self-propelled and towed.
    Commenters to the proposed rule generally accepted the need for 
fire suppression systems on diesel-powered equipment operated in 
underground coal mines. However, comments varied on what the 
requirements for fire suppression systems should be. Some commenters 
recommended that only manufacturer's requirements for design, 
installation and maintenance be used. Other commenters suggested a more 
detailed approach and recommended that the final rule outline specific 
requirements for fire suppression systems.
    Fire suppression systems are necessary on diesel-powered equipment, 
including fuel transportation units, because of the numerous fuel 
sources, including diesel fuel, hydraulic fluid, and combustible 
material, and several potential ignition sources, such as hot exhaust 
components, dragging brakes, and electrical wiring on this type of 
equipment. Accident reports describe machine fires caused by hot 
exhaust components, dragging brakes and shorted electrical components 
igniting diesel fuel, hydraulic fluid, brake fluid, lube oil, and other 
combustible materials, such as electrical insulating material.
    Fire suppression systems are designed to extinguish fires quickly, 
in their incipient stage, and to reach all locations where a fire may 
occur. This is important for diesel-powered equipment because a fire 
must be extinguished quickly before fuel sources can further propagate 
a fire. For example, if a fire is not extinguished at an early stage, 
leaking diesel fuel or hydraulic fluid can fuel a fire and result in an 
increase in the intensity and size of the fire. Also, promptly 
extinguishing a fire prevents reignition through the contact of hot 
surfaces created by the fire with leaked or spilled diesel fuel or 
hydraulic fluid. Fixed fire suppression systems also offer two 
advantages over portable fire extinguishers: fast attack and 
application of the suppressant to difficult-to-reach areas on and under 
diesel machines where fires may occur.
    An automatic fire suppression system uses a supplemental detection 
device to sense an early warning of a fire. The fire detection system, 
which is generally actuated by either smoke or heat, automatically 
sends a signal to the system for the discharge of suppressant agent. 
Manual fire suppression systems require a person to actuate the fire 
suppression system by either pushing a button or throwing a switch to 
discharge the fire suppressant agent to the hazard. Both automatic and 
manual fire suppression systems utilize a network of piping and nozzles 
to allow suppressant agent to be released and distributed directly at a 
predetermined fire hazard.
    Under the final rule, fire suppression systems are required to 
provide fire suppression and, if an automatic system is installed, fire 
detection for the engine, transmission, hydraulic pumps and tanks, fuel 
tanks, exposed brake units, air compressors, battery areas and other 
areas as necessary. The final rule also requires that automatic fire 
suppression systems include audible and visual alarms to warn of fires 
or system faults and automatic engine shutdown in the event of a fire. 
In addition, the final rule requires all fire suppression systems to be 
tested and maintained in accordance with manufacturer's 
recommendations. Finally, the rule establishes certain recordkeeping 
requirements for faulty fire suppression systems that are found during 
inspection and testing.
    Paragraph (a) of this section of the final rule provides that the 
fire suppression system required by Secs. 75.1907 and 75.1909 must be a 
multipurpose dry chemical type (ABC) fire suppression system listed or 
approved by a nationally recognized independent testing laboratory and 
appropriate for installation on diesel-powered equipment and fuel 
transportation units.
    The proposed rule would have required an automatic multipurpose dry 
powder type fire suppression system suitable for its intended 
application and listed or approved by a nationally recognized 
independent testing laboratory on diesel-powered equipment and portable 
diesel-powered equipment and fuel transportation units. The proposal 
would have further established fire suppression requirements for 
approved equipment, limited class equipment, and fuel transportation 
units, both self-propelled and towed.

[[Page 55474]]

    Commenters expressed support for automatic fire suppression systems 
on portable or unattended diesel-powered equipment. A number of 
commenters, however, stated that automatic fire suppression systems are 
not needed on self-propelled diesel-powered equipment, because this 
type of equipment is attended by an equipment operator. These 
commenters suggested that mine operators should have the option of 
providing either manual or automatic fire suppression systems on self-
propelled diesel-powered equipment, stating that the equipment operator 
is in the best position to detect incipient fires on the machine and is 
able to actuate a manual fire suppression system more easily than an 
automatic system. Some commenters stated that automatic fire 
suppression systems are not necessary on mobile diesel-powered 
equipment because this type of equipment will already be required to 
have fire protection and shutdown features. Commenters also stated that 
automatic systems can require extra maintenance and are susceptible to 
vibration, which can cause them to discharge unexpectedly. In addition, 
commenters stated that automatic fire suppression systems should not be 
required on vehicles with surface temperature controls, such as 
permissible vehicles, because compatible permissible systems were not 
available at the time of the proposal.
    Other commenters supported the proposal for automatic fire 
suppression systems on all types of diesel-powered equipment. In 
testimony before the Diesel Advisory Committee, equipment manufacturers 
and mine operators endorsed the use of automatic fire suppression 
systems on several types of diesel-powered equipment and gave examples 
of current applications. Other commenters to the proposal observed that 
it might be difficult for an equipment operator to actuate a manual 
system depending on the type and size of a fire. These commenters 
expressed concern that an equipment operator could be overcome by the 
effects of a fire or explosion and not be able to manually extinguish 
the fire. Some commenters also expressed concern that a manually-
actuated system would be ineffective for a fire that started after the 
equipment had been shut off and the equipment operator had left the 
area.
    Paragraph (a) of this section of the final rule does not adopt the 
proposed requirement for installation of an automatic fire suppression 
system on all mobile diesel-powered equipment. Instead, the final rule 
establishes requirements for both manual and automatic fire suppression 
systems. The type of fire suppression system required for installation 
on diesel-powered equipment is specified in Sec. 75.1907(b)(2) for 
permissible equipment, and Sec. 75.1909 (h), (i), and (j)(3) for 
nonpermissible equipment.
    The Ontario fire accident data indicated that heavy-duty diesel-
powered equipment of the type defined in the final rule at 
Sec. 75.1908(a) presents a much greater fire hazard than light-duty 
equipment defined under the final rule at Sec. 75.1908(b). The data 
showed that heavy-duty diesel-powered equipment, which includes 
equipment that cuts or moves rock or coal, equipment that performs 
drilling or bolting functions, and fuel transportation units, had 247 
fires (85 percent) of the total number of fires. Heavy-duty equipment 
frequently works under load and can develop large areas of hot engine 
surfaces. This equipment is prone to mechanical breakdown, especially 
hydraulic hose and electrical cable failure, creating a serious risk 
that the equipment will develop both an ignition source and provide a 
source of fuel for a fire.
    By contrast, light-duty diesel-powered equipment, which under the 
final rule includes supply vehicles, maintenance vehicles, personnel 
carriers, and other equipment not used to move rock or coal, accounted 
for 43 (15 percent) of the total number of fires. Light-duty equipment 
is not used in the actual mining process and is generally not worked 
very hard and typically used only intermittently during a shift. While 
over a third of the fires on heavy-duty equipment were started by hot 
engine surfaces, fewer than 10 percent of the fires on light-duty 
equipment were started by hot engine surfaces. Fires related to the 
electrical system accounted for 60 percent of the light-duty equipment 
fires. Electrical fires tend to smolder and provide more time for 
action to be taken to extinguish the fires than do diesel fires.
    Although light-duty equipment still poses a fire risk, this risk 
can be adequately addressed by fire suppression systems which take into 
account the manner in which light-duty equipment is used and the types 
of fires that typically occur on it. The final rule, therefore, does 
not adopt the proposal that automatic fire suppression systems be 
installed on all diesel machines.
    A manually-actuated fire suppression system provides adequate 
protection on light-duty self-propelled equipment. This type of 
equipment is attended by its operator at all times that it is operating 
as required by Sec. 75.1916(d) of the final rule. As discussed by 
several commenters to the proposal, it has been their experience that a 
well-maintained manually-actuated fire suppression system is 
appropriate if the equipment is attended. These commenters stated that 
manually-actuated fire suppression systems are adequate in conjunction 
with additional protective features for fuel, hydraulic, and electrical 
systems, to provide fire protection on outby diesel-powered equipment. 
In addition to a manual fire suppression system, protective features 
for fuel, hydraulic, and electrical systems are required on both heavy-
duty and light-duty nonpermissible equipment under Secs. 75.1909 and 
75.1910 of the final rule.
    Automatic fire suppression systems are necessary on equipment that 
poses a higher fire risk. This includes heavy-duty equipment, which 
presents an increased fire hazard as discussed above. It also includes 
equipment for which the operator is not immediately present at the 
controls of the machine at all times it is operated, such as 
compressors. Good fire fighting practice requires that the fire be 
attacked as early as possible. Further, several reports indicate that 
the rapid growth of fire prevented the equipment operator from 
actuating the manual fire suppression system. Automatic systems provide 
a fast response without operator intervention. Compressors and other 
non-self-propelled equipment frequently operate for long periods of 
time under high load. This results in sustained high engine surface 
temperatures, which can provide an ignition source for a fire and 
increase the likelihood of a a mechanical failure providing a fuel 
source for a fire. Also, the individual operating the compressor may be 
some distance from the machine, and would not be able to promptly 
actuate the fire suppression system. To address these hazards, the 
final rule adopts the proposed requirement for automatic fire 
suppression systems for heavy-duty and non-self-propelled equipment.
    One commenter to the proposal stated that the requirement in 
paragraph (a) that the ``system be suitable for the intended 
application'' was ambiguous and could be subject to different 
interpretations. This commenter stated that the term ``suitable'' could 
refer to a system that is suitable for a particular type of fire (class 
B flammable or combustible liquid fire) or it could mean that the 
system has a sufficient capacity to extinguish a fire on a particular 
piece of equipment. Other commenters recommended that the final rule 
specify the capacity of the fire suppression system.
    The final rule responds to commenters' concerns by requiring that

[[Page 55475]]

fire suppression systems be multipurpose dry chemical type (ABC) fire 
suppression systems listed or approved by a nationally recognized 
independent testing laboratory, and appropriate for installation on 
diesel-powered equipment. The final rule does not adopt the language 
``suitable for the intended application.''
    The capacity and suitability of fire suppression systems for 
protecting against specific fire hazards are specified as part of the 
listing or approval by the nationally recognized independent testing 
laboratory. The nationally recognized independent testing laboratory 
system listing or approval does not necessarily designate the system 
for a specific type of equipment, such as fuel transportation units or 
even diesel-powered equipment. Instead, the listing or approval uses a 
more general description such as mobile mining equipment or vehicle 
protection. Listing or approval by a nationally recognized independent 
testing laboratory ensures that a fire suppression system is properly 
designed for a particular type of fire protection hazard by putting the 
system through a series of specific performance tests. The system must 
also meet rigid design requirements in order to gain approval or 
listing.
    Fire suppression systems should be installed by a qualified 
individual following the installation and maintenance instructions in 
the system manufacturer's installation manual. The sizing of a fire 
suppression system is dependent on the number of nozzles needed to 
adequately cover all of the fire hazard areas that have been 
identified. The number of dry chemical canisters required will be 
proportional to the number of hazard areas that must be covered by the 
nozzles. This information can be obtained from the installation manual 
that is part of the listing or approval documentation. Other 
installation considerations, such as proper location and guarding of 
nozzles and other system components to prevent damage, are addressed in 
the system's installation manual. In addition to the installation 
requirements in the manual, follow-up maintenance and inspection 
procedures are provided.
    Also modified in this section from the proposal is the term 
``chemical'' replacing the term ``powder'' and the addition of the 
letter references ``ABC'' for the three classes of fire. These 
modifications are made in response to commenters' requests for 
clarification and to incorporate more appropriate terminology.
    A multipurpose dry chemical type system is capable of suppressing 
the three classes (ABC) of fires on diesel-powered equipment. A class A 
fire refers to fires of combustible solid materials such as paper, 
rubber, textiles, and cloth, and would typically involve such items as 
tires, hosing or seats on diesel-powered equipment. A class B fire on 
diesel-powered equipment would involve diesel fuel. Class C fires 
involve electrical components, and could include such components as 
lights, pumps, and components of the control panel on diesel-powered 
equipment. A multipurpose dry chemical type agent is specifically 
designed to extinguish ABC class fires.
    Paragraph (a)(1) of the final rule, like the proposal, requires 
that the fire suppression system be installed in accordance with the 
manufacturer's specifications and the limitations of the nationally 
recognized independent testing laboratory listing or approval. 
Commenters generally expressed support for this aspect of the proposal. 
This requirement ensures that the system is installed within the limits 
defined by the listing or approval organization and as specified by the 
fire suppression system manufacturer. Since the system already is 
performance-tested to a specific standard and in certain 
configurations, it must be installed within these parameters to be 
effective.
    Paragraph (a)(2) adopts the requirement from the proposal that the 
fire suppression system be installed in a protected location or guarded 
to minimize physical damage from routine vehicle operations. No 
specific comments were received on this aspect of the proposal. In 
order for fire suppression systems to work properly, they must not be 
subjected to damage from the mining environment. Damage to any part of 
the fire suppression system can result in a malfunction of the entire 
system and in the system not responding to a fire. For example, a rock 
fall can pinch a hose or crush a sensor and create faults that can 
disable either the entire system or a portion of the system that covers 
a certain area of the machine.
    Paragraph (a)(3), like the proposal, requires that the suppressant 
agent distribution tubing or piping be secured and protected against 
damage, including pinching, crimping, stretching, abrasion, and 
corrosion, and that the discharge nozzles be positioned and aimed for 
maximum fire suppression effectiveness in the protected areas. No 
specific comments were received on this aspect of the proposal. During 
the normal operation of diesel-powered equipment in the confined space 
of a coal mine, a fire suppression system can become damaged from 
collision or nozzles positioned at a specific predetermined location 
can be redirected away from a fire hazard.
    Paragraph (a)(4), like the proposal, requires that fire suppression 
nozzles also be protected against the entrance of foreign materials. No 
specific comments were received on this aspect of the proposal. The 
openings in the nozzles used on multipurpose dry chemical fire 
suppression systems can be as small as \1/8\ of an inch. If material 
such as mud, coal dust, or rock dust enters the nozzle, it can prevent 
the chemical agent from discharging entirely, or alter the pattern and 
coverage of fire suppressant.
    Paragraph (b) of the final rule requires fire suppression and, if 
the system is automatic, fire detection for certain coverage areas on 
diesel-powered equipment. Under the final rule, the coverage areas 
include the engine (including the starter), transmission, hydraulic 
pumps and tanks, fuel tanks, exposed brake units, air compressors and 
battery areas on diesel-powered equipment and electric panels or 
controls used on fuel transportation units. This requirement ensures 
that fire detection and fire suppression are provided with coverage for 
key areas of diesel-powered equipment and fuel transportation units.
    Although the listing or approval generally describes areas on 
equipment that pose a fire hazard, it does not specifically identify 
which hazards must be covered by fire suppression. The final rule's 
requirement for specific fire suppression coverage for certain areas on 
diesel-powered equipment is supported by the Ontario fire data. The 
data showed that engine fires accounted for 99 (34 percent) of the 
total number of fires on diesel-powered equipment. Included in engine 
fires were 10 compressor fires, 27 hydraulic system fires, 11 
transmission fires, and 7 fuel tank fires. The Ontario fire data also 
indicate 32 battery fires and 55 brake fires.
    The scope of paragraph (b) is expanded to include the starting 
mechanism on diesel-powered equipment. This responds to commenters' 
recommendations that foreign fire data be evaluated to establish 
criteria for fire protection on diesel-powered equipment. The Ontario 
fire accident data indicate that starters, starter solenoids, and the 
wiring associated with these components present a fire hazard. The data 
showed 21 (17 percent) of the electrical fires on self-propelled 
diesel-powered equipment were caused by starter circuits. Also, the 
proposal included the engine compartment as an area to be

[[Page 55476]]

covered by the fire suppression system. The specific reference to the 
starter area in the final rule clarifies that the starter area of the 
engine compartment be covered by the fire suppression system.
    The proposed rule specified fire suppression system coverage areas 
for various types of limited class equipment. Because of the different 
fire hazards presented by the various types of equipment listed in the 
proposal, separate provisions in proposed paragraph (b)(1) were 
included. In the final rule the limited class category of light-duty 
equipment is expanded to include a range of equipment types, beyond the 
types defined in the proposal, and the requirements for coverage areas 
have been combined.
    Proposed paragraph (b)(2) has not been adopted in the final rule to 
the extent that it would have specified coverage areas around fuel 
transportation units in response to commenters' statements that fuel 
tanks by themselves do not constitute a fire hazard, and only need 
coverage if an associated ignition source is present. Proposed 
paragraph (b)(3), which would have required fire suppression coverage 
for fuel containers and electric panels or controls used during fuel 
transfer operations on fuel transportation units, has not been adopted 
because the term ``container'' is no longer used in the final rule. The 
phrase ``during fuel transfer operations'' was not adopted from the 
proposal to eliminate the inference that only electric panels or 
controls used during fuel transfer operations must have coverage. Under 
the final rule, electrical components installed on fuel transportation 
units must be covered by fire suppression systems. However, a vehicle's 
instrument panel located in the operator's compartment of the machine 
would not be considered ``electrical panels and controls.'' Expelling 
fire suppressant in the operator's compartment would create other 
hazards for the equipment operator such as a cloud of fire suppressant 
which could limit visibility.
    Paragraph (c), like the proposal, requires that automatic fire 
suppression systems include audible and visual alarms to warn of fires 
or system faults. No specific comments were received on this aspect of 
the proposed rule. This requirement provides a means for immediate 
notification of the equipment operator, both audibly and visually, when 
the system detects a fire on the machine or a problem with the fire 
detection device. The audible and visual indication of fire detection 
can alert the equipment operator of the imminent discharge of the 
chemical agent and the engine shutdown required by paragraph (d).
    Paragraph (d) of the final rule adopts the proposed requirement 
that the fire suppression system provide for automatic engine shutdown. 
The final rule also provides that if the fire suppression system is 
automatic, engine shutdown and discharge of suppressant agent may be 
delayed for a maximum of 15 seconds after the fire is detected by the 
system. Commenters expressed support for this aspect of the proposed 
rule.
    The engine shutdown requirement is intended to prevent an engine 
from continuing to run once the system has been actuated, either 
automatically or manually. This will prevent the engine from pumping 
diesel fuel or hydraulic fluid through a leaking fuel line or hydraulic 
hose, fueling the fire that the fire suppression system is attempting 
to extinguish. Since fire suppression systems are designed to suppress 
fires in their incipient stages, the contribution of additional fuel to 
the fire may render the system ineffective. The Ontario accident data 
included a number of machine fires where the engine continued to feed 
the fire with diesel fuel or hydraulic fluid, reducing the 
effectiveness of the system's ability to suppress the fire. In 
addition, the engine shutdown feature prevents the engine cooling fan 
from dispersing the fire suppressant agent before it extinguishes the 
fire. A maximum of 15 seconds delay between the time of fire detection 
and actuation provides a limited period of time for the equipment 
operator to stop and exit the machine before the machine engine shuts 
down.
    Paragraph (e) of the final rule adopts the proposed requirement 
that the fire suppression system be operated by at least two manual 
actuators. One actuator must be located on each side of the equipment, 
and if the equipment is provided with an operator's compartment, one 
actuator must be located in the compartment within easy reach of the 
equipment operator.
    Several commenters expressed the opinion that two manual actuators 
were unnecessary on small units of diesel equipment, such as tractors, 
when the second actuator would have to be installed in close proximity 
to the engine. Another commenter urged that actuators be separated from 
each other by a means of a check valve or other device to allow the 
system to operate even if there is an open line in the actuation 
circuit.
    Two actuators for a fire suppression system are important to afford 
ample opportunity to initiate the system, even on small units of 
diesel-powered equipment. For example, if only one actuator were 
located on the side of a piece of equipment, the equipment operator 
might be unable to access the actuator due to the confined spaces in an 
underground coal mine, or because the fire ignited in the same location 
as the actuator. The final rule requirement for two manual actuators is 
also consistent with existing Sec. 75.1107 for dry chemical fire 
suppression systems for electric equipment.
    The final rule does not include a requirement for a check valve 
between the actuators for fire suppression systems. This is part of the 
system design and is more appropriately addressed by the system 
manufacturer and the listing or approving nationally recognized 
independent testing laboratory.
    Paragraph (f) adopts the proposed requirement that the fire 
suppression system must remain operative in the event of engine 
shutdown, equipment electrical system failure, or failure of any other 
equipment system. No specific comments were received on this aspect of 
the proposed rule. This requirement is intended to ensure that the 
functioning of the system is not dependent on any external power 
source, such as an engine-driven alternator, vehicle battery, or the 
proper operation of any other machine system.
    Paragraph (g), like the proposal, requires that the electrical 
components of each fire suppression system installed on diesel-powered 
equipment used where permissible electric equipment is required be 
permissible or intrinsically safe, and that such components be 
maintained in permissible or intrinsically safe condition. This 
provision requires that automatic fire suppression systems be certified 
or approved by MSHA under part 18.
    A number of commenters to the proposal stated that intrinsically 
safe vehicle-type automatic fire suppression systems were not 
available. Currently, however, two fire suppression system 
manufacturers have obtained approval under part 18 for their automatic 
fire suppression systems.
    Paragraph (h) adopts the requirement from the proposal that 
electrically operated detection and actuation circuits be monitored and 
provided with status indicators showing power and circuit continuity. 
If the system is not electrically operated, a means must be provided to 
indicate the functional readiness status of the detection system. These 
features notify the equipment operator or maintenance person of the 
functional readiness status of both the detection and actuation circuit 
and the power source. No specific comments

[[Page 55477]]

were received on this aspect of the proposed rule.
    Currently at least one manufacturer is marketing an automatic fire 
suppression system with these electrical features on both permissible 
and nonpermissible systems. There is also an automatic system which is 
not electrically operated and employs a pressurized cylinder to 
disperse the suppressant. A pressure gauge on the cylinder is 
considered sufficient to indicate the condition of the system.
    Paragraph (i) requires that each fire suppression system be tested 
and maintained in accordance with the manufacturer's recommended 
inspection and maintenance program and as required by the nationally 
recognized independent testing laboratory listing or approval. It also 
requires fire suppression systems to be visually inspected at least 
once each week by a person trained to make such inspections.
    The proposed rule would have required each fire suppression device 
to be visually inspected at the same interval by a person qualified to 
make such inspections. The proposal also would have required that each 
fire suppression device be tested and maintained in accordance with 
applicable requirements in Sec. 75.1100.
    Commenters to the proposal generally expressed support for required 
maintenance of fire suppression systems installed on diesel-powered 
equipment. Some commenters, however, recommended that a maintenance 
program specifically designed for fire suppression systems be developed 
at each mine. One commenter stated that a visual inspection of fire 
suppression systems on diesel-powered equipment would not be adequate 
and recommended that fire suppression systems be maintained in 
accordance with the manufacturer's guidelines by either outside 
entities qualified by the equipment manufacturer or through a program 
to qualify individuals at the mine. Another commenter to the proposal 
recommended that the manufacturer's inspection and maintenance program 
be referenced in lieu of the requirements in Sec. 75.1100. One 
commenter stated that automatic fire suppression systems are more 
difficult to maintain than manual systems, but that both types of 
systems should be inspected monthly and maintained semi-annually as a 
minimum. Another commenter expressed concern that certain critical 
internal components of a fire suppression system could be checked 
simply by a visual inspection.
    Under the final rule, the weekly visual inspection is not intended 
to be an in-depth inspection. The weekly visual inspection is intended 
to be a quick check to determine if defects, such as disconnected hose 
lines or altered nozzles, are readily apparent. The in-depth inspection 
takes place as part of the manufacturer's recommended testing and 
inspection procedure also required under the final rule. Fire 
suppression system manufacturers are most familiar with the design and 
operation of their systems and are best able to identify the components 
that need maintenance as well as the type and frequency of maintenance. 
Adequate maintenance is essential because of the importance of these 
systems in suppressing machine fires. Maintenance and testing 
requirements for fire suppression systems are included in the final 
rule in addition to the requirement for a weekly visual inspection.
    The manufacturer's inspection and maintenance procedures are 
typically spelled out in great detail in the manufacturer's manual and, 
depending on the operating environment, include the recommended 
inspection intervals. In addition, these inspection and maintenance 
procedures are evaluated as part of the system's approval or listing by 
a nationally recognized independent testing laboratory.
    The requirement in this paragraph is identical to the requirement 
in existing Sec. 75.1107-16(a). However, the fire suppression system 
requirements in Secs. 75.1107-3 through 75.1107-16 cannot be directly 
applied to diesel-powered equipment for several reasons. Any 
modification of these existing requirements by inserting the term 
``diesel-powered'' in the regulatory language would result in an 
extremely confusing regulation. Also, the fire hazards presented by 
diesel-powered equipment are different from those on electric-powered 
equipment, due to the close proximity of large quantities of hydraulic 
oils and fuels to the heated diesel engine exhaust. The single 
modification made to this paragraph was replacing the term ``device'' 
with the term ``system''. This was done because MSHA intends that the 
whole system be inspected and not just individual components of the 
system.
    Although automatic systems have additional components that must be 
inspected and maintained, properly trained maintenance personnel should 
have little difficulty satisfying these requirements. It is anticipated 
that the training of the personnel assigned to perform the testing and 
maintenance of fire suppression systems will be provided by the system 
manufacturer or distributor. Additionally, automatic fire suppression 
systems under the final rule are required to have a status monitoring 
feature to tell the equipment operator or maintenance personnel that a 
problem exists.
    Section 75.1915(b)(3)(iv) of the final rule requires that the 
training and qualification program for qualified persons working on 
diesel equipment address tests and maintenance of fire suppression 
systems. The qualified person conducting maintenance on fire 
suppression systems on diesel-powered equipment should have sufficient 
familiarity with the elements of the fire suppression system. A person 
``trained'' to perform inspections and tests required by paragraph (i) 
of this section of the final rule is not required to be a person 
qualified under Sec. 75.1915. However, the final rule intends that the 
person performing tests and inspections of fire suppression systems 
have sufficient knowledge to determine whether a fire suppression 
system is functioning properly. MSHA anticipates that since fire 
suppression systems are common to both electric and diesel equipment, 
the mine operator will work with either the fire suppression system 
manufacturer or distributor to ensure that personnel responsible for 
the maintenance of fire suppression systems are adequately trained.
    Paragraphs (j) of the final rule establishes recordkeeping 
requirements which address the inspection and maintenance requirements 
for fire suppression systems set forth in paragraph (i). Paragraph (j) 
of the final rule requires that persons performing inspections and 
tests of fire suppression systems record results of tests and 
inspections only when a fire suppression system does not meet the 
installation or maintenance requirements of this section. Under these 
circumstances, the person performing the inspection or test is required 
to record the equipment on which the fire suppression system did not 
meet the installation or maintenance requirements of this section, the 
defect found, and the corrective action taken. The final rule also 
requires that these records be kept either manually or electronically 
in a secured manner that is not susceptible to alteration. Paragraph 
(j)(3) requires that records be maintained at a surface location at the 
mine for one year and made available for inspection by an authorized 
representative of the Secretary and miners' representatives.
    The proposal would have required that a record be kept of all 
inspections and tests of fire suppression systems

[[Page 55478]]

and maintained at an appropriate location for each fire suppression 
device. One commenter to the proposal recommended that, in order to 
provide adequate maintenance of fire suppression systems, interested 
parties be allowed to view the results of visual inspections recorded 
in approved books. Another commenter recommended that records of 
inspections be maintained on the surface by the operator so that they 
would be available for MSHA verification. This commenter stated that 
maintaining separate records for inspections of fire suppression 
systems is an unnecessary burden for the mine operator. This commenter 
stated that records kept on computers, as pre-shift examinations and by 
normal maintenance inspections, would be adequate for documenting the 
inspections conducted on fire suppression systems.
    Office of Management and Budget guidance comments directed MSHA to 
reexamine the recordkeeping requirements in the proposal and 
recommended that the final rule require paperwork that was the least 
burdensome necessary. MSHA has done so, and the final rule does not 
adopt the proposal that all fire suppression system test and 
maintenance results be recorded. In response to commenters and 
consistent with other provisions of the final rule, paragraph (j) 
requires that records of inspections and tests be made only when a fire 
suppression system does not meet the installation or maintenance 
requirements of this section. This requirement is important because if 
a fire suppression system does not meet the installation or maintenance 
requirements of this section, the defect could be sufficiently serious 
to cause the system to fail in the event of a fire. This requirement is 
intended to ensure that records are maintained and made available to 
interested parties when a defect is found, and that the appropriate 
level of mine management is made aware of defects requiring corrective 
action.
    The final rule does not specify a particular way of recording the 
test and maintenance data, only that the records be located at the 
surface of the mine. The records of the inspections and tests must be 
made in a secure media not susceptible to alteration. A detailed 
discussion of the subject of acceptable record books and electronic 
records can be found under the heading ``Recordkeeping Requirements'' 
in the General Discussion section of this preamble.
    The final rule does not adopt the requirement from the proposed 
rule that records of inspections be maintained at an appropriate 
location near each fire suppression system. Instead, paragraph (k) of 
the final rule establishes the requirement recommended by a commenter 
that records of inspections and tests be maintained at a surface 
location at the mine. Storing records on the surface at the mine makes 
them more accessible to interested parties. Also in response to 
commenters, the final rule provides access to not only miners' 
representatives but to authorized representatives of the Secretary. 
This provision ensures that test and inspections of fire suppression 
systems are being made and, when a defect is found, that corrective 
action is taken.
    Records for inspection of diesel-powered equipment are also 
required under Sec. 75.1914(f)(2) of the final rule. However, the 
recordkeeping requirement under paragraph (j) is not intended to be 
duplicated. While Sec. 75.1914(f)(2) applies to diesel-powered 
equipment, some diesel fuel transportation units may be portable 
trailers with only electrical components and therefore would need to be 
covered under the recordkeeping requirement under paragraph (j) of this 
section. The only records required for fire suppression systems under 
this section of the final rule are for tests and maintenance required 
under paragraph (i).
    Paragraph (k) adopts the proposed requirement that all miners 
normally assigned in the active workings of the mine be instructed 
about the hazards inherent to the operation of fire suppression 
systems, and where appropriate, the safeguards available for each 
system. This requirement is intended to ensure that all miners working 
in areas where fire suppression systems operate are instructed in any 
inherent hazards and necessary precautions associated with the 
operation of these systems. The final rule modifies the proposal in 
that the term ``device'' has been replaced by the term ``system'' to 
clarify that this requirement applies to the entire fire suppression 
system, not merely a component of it.
    One commenter to the proposal agreed with the requirement that 
miners be trained in the hazards and safeguards of fire suppression 
systems, but recommended that such training be incorporated in the 
annual refresher training required under existing Sec. 75.1101-23 for 
the program of instruction, location and use of fire fighting 
equipment. Under the final rule, it is anticipated that the instruction 
on the hazards of fire suppression systems required by this paragraph 
will be part of the Sec. 75.1101-23 instruction.
    Paragraph (l) of this section of the final rule provides that, for 
purposes of existing Sec. 75.380(f), a fire suppression system 
installed on diesel-powered equipment and meeting the requirements of 
Sec. 75.1911 is equivalent to a fire suppression system meeting the 
requirements of Secs. 75.1107-3 through 75.1107-16.
    Section 75.380 addresses requirements for escapeways in bituminous 
and lignite mines. Section 75.380(f) specifies the equipment that can 
be used in the primary escapeway and the type of fire suppression 
system required to be installed on this equipment. Section 75.380(f)(4) 
requires that each piece of mobile equipment operated in primary 
escapeways, except for continuous miners and as provided in paragraphs 
(f)(5), (f)(6) and (f)(7) of the section, be equipped with a fire 
suppression system installed according to Secs. 75.1107-3 through 
75.1107-16 that is: (1) manually operated and attended continuously by 
a person trained in the system's function and use; or (2) a 
multipurpose dry chemical type capable of both automatic and manual 
activation. The requirement in Sec. 75.380(f)(4) for installation of a 
fire suppression system that meets the requirements of Secs. 75.1107-3 
through 75.1107-16 on equipment operating in the primary escapeway 
presents a potential conflict with the requirement for installation of 
a fire suppression system on diesel-powered equipment in Sec. 75.1911.
    As noted earlier, several commenters to the proposed rule believed 
that the requirements for fire suppression systems in Secs. 75.1107-3 
through 75.1107-16 should be made applicable to diesel-powered 
equipment. However, the requirements in Secs. 75.1107-3 through 
75.1107-16 make specific reference to electric equipment and components 
and are not practical for diesel-powered equipment. Any modification of 
these existing requirements by inserting the term ``diesel-powered'' in 
the regulatory language would result in an extremely confusing 
regulation.
    After a review of the issue, MSHA has determined that fire 
suppression systems installed on diesel-powered equipment meeting the 
requirements of Sec. 75.1911 afford at least equivalent protection to 
fire suppression systems meeting the requirements of Secs. 75.1107-3 
through 75.1107-16. Many of the requirements contained in 
Secs. 75.1107-3 through 75.1107-16 are similar to those in 
Sec. 75.1911. Both sections include requirements for: listed or 
approved fire

[[Page 55479]]

suppression systems; the capacity and size of fire suppression system 
hardware; a system design that will withstand the normal rigors of 
mining; compatibility of the extinguishing agent with the mine 
atmosphere; the system's ability to operate independently of an 
equipment power supply; sensor operability status indication; and the 
inclusion of manual actuators. Consequently, the final rule makes clear 
that fire suppression systems meeting the requirements of Sec. 75.1911 
will satisfy the requirements of Sec. 75.380(f)(4).
Section 75.1912  Fire Suppression Systems for Permanent Underground 
Diesel Fuel Storage Facilities
    This section of the final rule establishes requirements for the 
design, installation and maintenance of fire suppression systems at 
permanent underground diesel fuel storage facilities. Under the final 
rule, a permanent underground diesel fuel storage facility is defined 
as a facility designed and constructed to remain at one location for 
the storage or dispensing of diesel fuel, which does not move as mining 
progresses. Section 75.1903(a)(5) of the final rule requires that 
permanent underground diesel fuel storage facilities be equipped with 
an automatic fire suppression system that meets the requirements of 
Sec. 75.1912.
    The Diesel Advisory Committee recommended that automatic fire 
suppression systems be used to address potential fire hazards from 
ignition and fuel sources at permanent underground diesel fuel storage 
facilities. The proposed rule included design, installation and 
maintenance requirements for automatic fire suppression systems for 
diesel fuel storage areas and stationary diesel-powered equipment.
    Commenters to the proposed rule generally accepted the need for 
fire suppression systems at permanent underground diesel fuel storage 
facilities. However, comments varied on what the requirements for fire 
suppression systems should be. Some commenters recommended that only 
manufacturer's requirements for design, installation and maintenance be 
used. Other commenters recommended a more detailed approach and 
suggested that the final rule outline specific requirements for fire 
suppression systems.
    The storage of diesel fuel at permanent underground facilities 
presents a limited fire hazard when fuel is contained in diesel fuel 
tanks and safety cans constructed of noncombustible material. However, 
diesel fuel does present a fire hazard when it is spilled from a tank 
or leaked from a hose and comes into contact with an ignition source. 
Spills and leaks of diesel fuel at permanent underground storage 
facilities can occur when machinery is being refueled, when diesel fuel 
is being placed in or taken out of storage tanks, or when tanks are 
damaged or not properly maintained. Potential ignition sources at 
permanent underground storage facilities include a running diesel 
vehicle with hot surfaces or hot brake components, malfunctioning 
electric valves, or pumps used to dispense diesel fuel.
    Fire suppression systems are designed to extinguish fires quickly, 
in their incipient stage, and to reach all locations where a fire may 
occur. This is important at permanent underground diesel fuel storage 
facilities because a fire must be extinguished quickly before fuel can 
further propagate a fire. For example, if a fire is not extinguished at 
an early stage, leaking diesel fuel can fuel a fire and result in an 
increase of the intensity and size of the fire.
    Fixed fire suppression systems also offer two advantages over 
portable fire extinguishers: fast attack and application of the 
suppressant to difficult-to-reach areas where fires may occur. In 
addition, an automatic fire suppression system has the advantage of 
detecting and suppressing fires without a person in attendance. Because 
permanent underground diesel fuel storage facilities will not always be 
attended, it is necessary to require a means of electrically or 
mechanically detecting a fire as well as electrically or mechanically 
activating the fire suppression system upon fire detection. This is 
important since the potential hazard for mine personnel throughout the 
mine is significant if a fire in a diesel fuel storage facility could 
burn unnoticed.
    The proposed rule would have established requirements for fire 
suppression devices for permanent underground diesel fuel storage areas 
and stationary unattended diesel-powered equipment. Because 
Sec. 75.1916(d) of the final rule requires all diesel-powered equipment 
to be attended while operating, and because proposed requirements for 
stationary unattended equipment have not been adopted in the final 
rule, Sec. 75.1912 of the final rule has been modified to apply only to 
permanent underground diesel fuel storage facilities.
    A number of commenters to the proposal expressed concern with the 
requirements for fire suppression systems at permanent underground 
diesel fuel storage facilities. One commenter stated that since diesel 
fuel is a Class II combustible liquid, a diesel fuel storage station 
used and moved with a working section should be treated similar to a 
lubricating oil or grease storage station. This commenter expressed the 
view that requirements for limiting the quantity of diesel fuel in 
temporary storage and requiring portable fire extinguisher protection 
would be adequate safeguards. Another commenter expressed concern with 
the ability of a dry compound to suppress a fire over a long enough 
period of time to prevent re-ignition. This commenter stated that high 
volumes of ventilating air in a mine can blow dry compound away from 
the area it is attempting to protect before it can cool down a hot 
surface created by a fire.
    MSHA agrees with the commenter who stated that diesel fuel stored 
on and moved with a section should be treated as a Class II combustible 
liquid. The final rule addresses this comment by establishing the 
allowance for one temporary underground diesel fuel storage area for 
the short-term storage and dispensing of diesel fuel on each working 
section, which can move as mining progresses. A temporary underground 
diesel fuel storage area is defined under Sec. 75.1900 of the final 
rule as an area of the mine provided for the short-term storage of 
diesel fuel in a fuel transportation unit, which moves as mining 
progresses. These temporary underground diesel fuel storage areas are 
required to meet the requirements in Secs. 75.1902, 75.1903 and 75.1906 
of the final rule. All other diesel fuel storage areas will be treated 
as permanent storage facilities and must comply with all of the 
requirements for such facilities. Permanent diesel fuel storage 
facilities pose a higher risk of fire than oil and grease storage areas 
because diesel fuel is generally stored in much greater quantities in 
underground coal mines. In addition, diesel fuel has a lower flash 
point than either lubricating oil or grease and can be more easily 
ignited by a hot surface.
    Although permanent diesel fuel storage facilities are provided with 
ventilating air during normal operations, these facilities are required 
under Sec. 75.1903(a)(2) of the final rule to be equipped with either a 
self-closing door or a means for automatic enclosure upon actuation of 
the fire suppression system. This feature should prevent any 
ventilating air from affecting the suppressant agent.
    An automatic fire suppression system uses a supplemental detection 
device to provide an early warning of a fire. The fire detection 
system, which is generally activated by either smoke or heat,

[[Page 55480]]

automatically sends a signal to the system for the discharge of 
suppressant agent. Automatic fire suppression systems activate a 
network of piping and nozzles to allow suppressant agent to be released 
and distributed directly at a predetermined fire hazard.
    Under the final rule, automatic fire detection and fire suppression 
systems are required to provide fire suppression for all areas of a 
permanent underground diesel fuel storage facility. The final rule also 
requires that the system include audible and visual alarms to warn of 
fires or system faults and automatic electrical system shutdown in the 
event of a fire. In addition, the final rule requires all fire 
suppression systems to be tested and maintained in accordance with 
manufacturer's recommendations. Finally, the final rule establishes 
certain recordkeeping requirements for fire suppression systems that 
are found not to meet required specifications during inspection and 
testing.
    Paragraph (a) of this section of the final rule requires that a 
fire suppression system required by Sec. 75.1903(a)(5) be an automatic 
multipurpose dry chemical type (ABC) fire suppression system listed or 
approved as an engineered dry chemical extinguishing system by a 
nationally recognized independent testing laboratory and appropriate 
for installation at a permanent underground diesel fuel storage 
facility.
    The proposed rule would have required an automatic multipurpose dry 
powder type fire suppression system suitable for the intended 
application and listed or approved by a nationally recognized 
independent testing laboratory.
    A commenter to the proposal stated that this paragraph should 
require that ``an automatic fire suppression system suitable for the 
intended application shall be installed to protect the entire area 
inside the fire proof enclosure.'' This commenter believed that all of 
the necessary requirements for fire suppression systems were already 
addressed in existing part 75, and that it was unnecessary to identify 
protected coverage components inside the storage facility if the entire 
area is required to be protected. Another commenter stated that the 
requirement in the proposal that the ``system be suitable for the 
intended application'' was ambiguous and could be subject to different 
interpretations. This commenter stated that the term ``suitable'' could 
refer to a system that is suitable for a particular type of fire (class 
B or combustible liquid fire) or it could mean that the system has a 
sufficient capacity to extinguish a fire. This commenter also 
recommended that the final rule specify the capacity of fire 
suppression systems installed at permanent underground diesel fuel 
storage facilities.
    In response to commenters, MSHA evaluated whether the requirements 
for fire suppression systems in existing Sec. 75.1107 should be 
extended to apply to permanent underground diesel fuel storage 
facilities, but has concluded that such an extension would not be 
appropriate. The fire hazards that exist at permanent underground 
diesel fuel storage facilities are different from those on electric-
powered equipment, due to the storage of large quantities of diesel 
fuel in close proximity to ignition sources at these facilities. 
Additionally, because existing Sec. 75.1107 makes specific reference to 
electrical controls and components on electric-powered equipment, a 
modification of the existing requirements by inserting the term 
``permanent underground diesel fuel storage facility'' in the 
regulatory language would result in an extremely confusing regulation. 
Existing fire suppression requirements in part 75 have therefore not 
been applied to permanent underground fuel storage facilities.
    In response to commenters' suggestions, the final rule does not 
adopt the phrase ``suitable for the intended application'' from the 
proposal. Instead, the final rule includes the more specific language 
``listed or approved as an engineered dry chemical extinguishing system 
approved by a nationally recognized independent testing laboratory.'' 
This modification is intended to clarify that an automatic fire 
suppression system installed at a permanent underground diesel fuel 
storage facility must be listed or approved by a nationally recognized 
independent testing laboratory specifically for a fixed engineered dry 
chemical extinguishing system unit.
    The capacity and suitability of fire suppression systems for 
protecting against specific fire hazards are specified as part of the 
listing or approval by the nationally recognized independent testing 
laboratory. The listing or approval ensures that a fire suppression 
system is properly designed for a particular type of fire protection 
hazard by putting the system through a series of specific performance 
tests. The system must also meet rigid design requirements in order to 
gain listing or approval.
    Fire suppression systems should be installed by a qualified 
individual following the installation and maintenance instructions in 
the system manufacturer's installation manual. The sizing of a fire 
suppression system is dependent upon the number of nozzles needed to 
adequately cover the entire area of a permanent underground diesel fuel 
storage facility. The number of dry chemical canisters required will be 
proportional to the amount of area that must be covered by the nozzles. 
This information can be obtained from the installation manual that is 
part of the listing or approval documentation. Other installation 
considerations, such as proper location and guarding of nozzles and 
other system components to prevent damage, are addressed in the 
system's installation manual. In addition to the installation 
requirements, the manual includes provisions for follow-up maintenance 
and inspection procedures.
    One commenter to the proposal recommended that the term ``dry 
powder'' be deleted from paragraph (a) because this commenter believed 
that there were many equally effective systems, such as foam/water 
spray systems, available to protect against fire hazards. Another 
commenter stated that the terms ``listed'' and ``approved'' were not 
strong enough. This commenter stated that there was no way of verifying 
whether a system had been ``listed'' or ``approved'' and recommended 
that the term ``tested'' replace the term ``listed''.
    Although dry chemical is the most commonly used type of suppressant 
agent in the mining environment and is specifically referenced in 
paragraph (a) of the final rule, paragraph (a)(1) of the final rule 
allows for alternate types of fire suppression systems that are no less 
effective. In addition, the requirement that a system be listed or 
approved by a nationally recognized independent testing laboratory is 
more stringent than using the term ``tested''. Under the final rule, 
when a system is listed or approved by a nationally recognized 
independent testing laboratory, it means that the system has met 
performance and design requirements outlined in an industry standard in 
a certain configuration and for a specific function. Also, if a system 
has been listed or approved by a nationally recognized independent 
testing laboratory, it means that the system has met other requirements 
for inspection, maintenance, and quality control assurances.
    Also modified in this paragraph from the proposal is the term 
``chemical'' replacing the term ``powder'' and the addition of the 
reference ``ABC'' for the three classes of fire. These modifications 
were made in response to commenters' request for clarification and to 
incorporate more appropriate terminology.

[[Page 55481]]

    A multipurpose dry chemical type agent is the most commonly used 
and successfully applied type of suppressant agent in fire suppression 
systems in underground coal mines. This type of agent is specifically 
designed to extinguish ABC class fires. A class A fire refers to a fire 
of combustible solid materials such as paper, rubber, textiles, and 
cloth, and would involve such items as hosing at a permanent 
underground diesel fuel storage facility. A class B fire would include 
diesel fuel. Class C fires involve electrical components and could 
include such components as lights, pumps, and valves at permanent 
underground diesel fuel storage facilities.
    The term ``engineered'' was added to the final rule in response to 
commenters' concerns regarding the adequacy of a fire suppression 
system to address all of the fire hazards at a permanent underground 
diesel fuel storage facility. An engineered fire suppression system 
will ensure that all of the fire hazards are addressed since a 
representative from a fire suppression system manufacturer will go to 
the facility and evaluate all of the fire hazards. The evaluation by 
the system manufacturer representative also includes determining the 
appropriate coverage areas for the fire suppression system, the number 
and size of dry chemical canisters, the length of piping, and the 
number of nozzles.
    The proposed rule would have allowed the use of inert or halogenate 
gas suppressant agents in unoccupied and enclosed areas where the use 
of such suppressants would not pose a toxic hazard. One commenter to 
the proposal recommended that the use of inert or halogenate gas 
suppressant agents be prohibited because they create a toxic hazard. 
This requirement has not been included in the final rule because inert 
or halogenated gas fire suppression systems are considered an alternate 
type of fire suppression system that are addressed in paragraph (a)(1) 
of this section of the final rule. The potential toxic hazard presented 
by inert or halogenated gas suppressant agent will be evaluated by MSHA 
on a case-by-case basis as an alternate type system. In addition, 
typical inert gas agents such as halon 1211 and 1301 are no longer 
being marketed due to their reported contribution to the ozone 
depletion of the environment.
    Paragraph (a)(1) of the final rule adopts the provision from the 
proposal that alternate types of fire suppression systems be approved 
in accordance with Sec. 75.1107-13 of this part. This paragraph of the 
final rule is intended to allow the use of fire suppression systems 
other than dry chemical systems, so long as they provide substantially 
equivalent protection. Under the final rule, MSHA will evaluate 
alternate types of fire suppression systems, such as foam/water 
sprinkler-based systems, using the criteria set forth in existing 
Sec. 75.1107-13.
    One commenter to the proposal objected to this provision and stated 
that only the manufacturer who designs and constructs these systems 
will know the exact capabilities and limitations of the system. This 
commenter also stated that this requirement would result in the 
installation of inadequate fire suppression systems at permanent 
underground diesel fuel storage facilities, because the requirements in 
existing Sec. 75.1107-13 are applicable to fire suppression systems 
installed on equipment.
    Existing Sec. 75.1107-13 establishes criteria for the approval of 
alternate fire suppression devices. Under Sec. 75.1107-13, the 
appropriate MSHA district manager may approve any fire suppression 
system or device which provides substantially equivalent protection to 
what would be achieved through compliance with the standard.
    The final rule does not intend to allow alternate types of fire 
suppression systems that do not adequately address fire hazards at 
permanent underground diesel fuel storage facilities. Instead, all 
types of alternate fire suppression systems must be installed and 
operated in strict accordance with the system manufacturer's 
recommendations as specified in paragraph (a)(2) of this section of the 
final rule. Any type of fire suppression system that is not designed 
and constructed in accordance with industry standards for fire 
protection will be unacceptable.
    Paragraph (a)(2) of the final rule adopts the requirement from the 
proposal that the suppression system be installed in accordance with 
the manufacturer's specifications and the limitations of the nationally 
recognized independent testing laboratory listing or approval. One 
commenter to the proposal expressed the view that the term ``listing'' 
was not specific enough and recommended that the language ``independent 
testing'' be added. As explained earlier, a listing or approval by a 
nationally recognized independent testing laboratory is more stringent 
than the use of the term ``testing''. This comment has therefore not 
been adopted in the final rule.
    This requirement ensures that the system is installed within the 
limits defined by the listing or approval issued by the nationally 
recognized independent testing laboratory and as specified by the fire 
suppression system manufacturer. Since the system is performance-tested 
to a specific standard and in certain configurations, it must be 
installed within these parameters to be effective.
    Paragraph (a)(3) adopts the requirement from the proposal that the 
fire suppression system be installed in a protected location or guarded 
to prevent physical damage from routine operations. Damage to any part 
of the fire suppression system can result in a malfunction of the 
entire system and in the system not responding to fire hazards. For 
example, a rock fall can pinch a hose or crush a sensor and create 
faults that can disable the entire system or a portion of the system.
    One commenter stated that the proposed rule did not define what 
protections were necessary on fire suppression systems and suggested 
that the systems be fully protected from physical elements, including 
rib and roof falls. This commenter further stated that this protection 
is already provided for electrical circuit breakers under existing 
Sec. 75.901, and that this type of protection is even more vital for 
the protection of fire suppression systems.
    This comment has not been adopted in the final rule because the 
construction requirements for permanent underground diesel fuel storage 
facilities at Secs. 75.1902 and 75.1903 ensure that fire suppression 
systems will be protected from the general hazards of the mine 
environment. The installation requirements in this paragraph ensure 
that additional protection will be provided for specific system 
components.
    Paragraph (a)(4), like the proposal, requires that the suppressant 
agent distribution tubing or piping be secured and protected against 
damage, including pinching, crimping, stretching, abrasion, and 
corrosion. No specific comments were received on this aspect of the 
proposal. During the normal mining activity in and around a permanent 
underground diesel fuel storage facility, a fire suppression system can 
become damaged from collisions with mining equipment or from daily 
mining operations. This requirement ensures that fire suppression 
system components are kept in proper working order and that the entire 
system remains ready to discharge fire suppressant to the entire area 
of a permanent underground diesel fuel storage facility.
    Paragraph (a)(5) adopts the requirement from the proposal that fire 
suppression nozzles be protected against the entrance of foreign 
materials.

[[Page 55482]]

No specific comments were received on this aspect of the proposal. The 
nozzles used on multipurpose dry chemical fire suppression systems can 
be as small as \1/8\ of an inch. If material such as mud, coal dust, or 
rock dust enters the nozzle, it can prevent the chemical agent from 
discharging entirely, or alter the pattern and coverage of fire 
suppressant.
    Paragraph (b) of this section of the final rule requires that the 
fire suppression system provide automatic fire detection and automatic 
suppression for all areas within a permanent underground diesel fuel 
storage facility. The proposal would have required automatic fire 
detection and fire suppression for fuel storage tanks, containers, 
safety cans, pumps, electrical panels and control equipment in fuel 
storage areas. The requirement in the final rule responds to 
commenters'' recommendations that automatic fire detection and 
suppression be provided for all areas within a permanent underground 
diesel fuel storage facility enclosure.
    Although the listing or approval generally describes certain areas 
that may pose a fire hazard, it does not specifically identify which 
hazards must be covered by fire suppression. Fire suppression coverage 
for the entire area of a permanent underground diesel fuel storage 
facility is necessary because of the potential fire hazard created by 
numerous ignition and fuel sources. The proposed coverage of only 
certain specific hazards within a diesel fuel storage facility would 
have resulted in other potential hazards not being addressed. Under the 
proposal, it would have been possible for a fire to begin in one area 
of the facility that was not specifically covered by fire suppression. 
Under these circumstances, a fire could be difficult to contain if 
large quantities of leaked diesel fuel are present throughout the 
facility. The final rule requires the entire area of a diesel fuel 
storage facility to be covered because of the likely spread of a fire 
if a diesel fuel leak develops.
    Paragraph (c) of the final rule requires that audible and visual 
alarms to warn of fire or system faults be provided at the protected 
area and at a surface location which is continually monitored by a 
person when personnel are underground. The final rule also requires 
that, in the event of a fire, personnel be warned in accordance with 
the provisions set forth in Sec. 75.1101-23. This requirement is 
intended to provide a means for immediate notification of personnel in 
the area of a permanent underground diesel fuel storage facility when 
the fire suppression system detects a fire or identifies a problem with 
the system. The audible and visual indication of fire detection is 
important because it alerts personnel in and around the area of a 
permanent underground diesel fuel storage facility that a fire exists 
and that a chemical agent is being discharged. The requirement for 
audible and visual indication of fault detection is established in 
order to alert personnel working in and around diesel fuel storage 
facilities that a problem exists with the fire detection system so that 
the defect can be addressed.
    The proposal would have required that audible and visual alarms to 
warn of fire or system faults be provided at the protected area and at 
a surface location which is always staffed when personnel are 
underground who could be endangered by a fire. In addition, the 
proposal would have required that a means also be provided for warning 
all endangered personnel in the event of a fire.
    Several commenters to the proposal expressed concern over this 
requirement, stating that the requirement for visual and audible alarms 
at a surface location would be impractical for many small operators 
because it would result in operators maintaining a monitoring system to 
detect fires. These commenters recommended that fire suppression 
systems be examined regularly to determine system faults, and that 
audible and visual alerts should only be required at locations where 
miners are present. Another commenter stated that mines have become lax 
in responding to fire warnings. One commenter recommended that a formal 
procedure be established to warn personnel in the event of a fire, and 
that this procedure should be submitted to MSHA for approval and be 
included in the mine emergency fire fighting and evacuation plan and in 
the miners'' annual refresher training. Other commenters stated that 
the proposed phrase ``always staffed'' does not ensure that a qualified 
or responsible person will be designated to alert mine personnel 
underground in the event of a fire. One commenter suggested that the 
language ``always staffed'' be changed to ``someone who is qualified.''
    The continual monitoring by a person on the surface of fire 
detection and fire suppression system faults is not a burdensome 
requirement given the chance that a fire or system fault may otherwise 
go unnoticed. The early warning of a fire at a permanent underground 
diesel fuel storage facility is critical, due to the presence of 
numerous ignition sources and large quantities of diesel fuel. If 
communication is not available, fire fighting efforts can be hampered 
and the fire can spread. Also, if a program is not instituted to warn 
of a fire, personnel located in other areas of the mine can be put at 
risk of being cut off from escape. In addition, faults in fire 
suppression systems need to be identified and communicated to 
maintenance personnel so that system defects can be corrected. If an 
automatic fire suppression system is not functioning properly and a 
fire breaks out, it could result in a serious hazard since the fire 
would not be extinguished in its incipient stage. The inspection and 
maintenance requirements for fire suppression systems specified under 
the final rule should ensure the reliability of the system and minimize 
the occurrence of false alarms.
    The final rule responds to commenters by providing flexibility in 
the method used to alert mine personnel that a fire exists at a 
permanent underground diesel fuel storage facility. Under the final 
rule, when a fire is detected, personnel are to be warned in accordance 
with the provisions set forth in existing Sec. 75.1101-23. Section 
75.1101-23 requires that each operator of an underground coal mine 
adopt a program for the instruction of all miners in fire fighting and 
evacuation. The program of instruction is submitted to the appropriate 
MSHA district manager for approval on a mine-by-mine basis. By 
including the requirement for early warning of fires at permanent 
underground diesel fuel storage facility in Sec. 75.1101-23, the final 
rule allows this important communication provision to be developed by 
taking into consideration mine-specific conditions.
    This section of the final rule also requires that a person be 
assigned on the surface whose duties include receiving notification of 
fire detection and alerting underground personnel that a fire has been 
detected. The final rule does not specify any qualification or training 
for the person designated on the surface. However, the instruction of 
all mine personnel, including the designated person staffed at a 
surface location, is a critical element of an early warning fire 
response strategy and is the responsibility of the mine operator under 
Sec. 75.1101-23.
    Paragraph (d) of this section of the final rule requires that the 
fire suppression system deenergize all power to the diesel fuel storage 
facility when actuated except that required for automatic enclosure and 
alarms. This requirement was added to the final rule in response to 
commenters' concerns regarding reignition of fires caused by electrical 
failures. As stated earlier, fire

[[Page 55483]]

suppression systems are designed to suppress fires in their incipient 
stage. If the ignition source and fuel sources remain present after the 
fire suppression system has been actuated, the fire can reignite. 
Shutting off any unnecessary electrical power to the facility will 
remove a potential ignition source and reduce the likelihood that the 
fire will reignite.
    The Ontario accident data for fires on diesel equipment supports 
the need for shutting off ignition sources to prevent reignition. This 
hazard is just as significant for diesel fuel storage facilities, since 
potential electrical ignition sources are present with large quantities 
of diesel fuel. The final rule is also consistent with existing 
Sec. 75.1107-4, which requires that the electric power source to the 
protected equipment be disconnected when the fire suppression system is 
actuated.
    This requirement also applies to any fuel transportation unit 
located in a permanent diesel fuel storage facility that is equipped 
with an electric panel and controls directly connected to an electrical 
power source.
    Paragraph (e) of the final rule, like the proposal, requires that 
fire suppression systems at permanent underground diesel fuel storage 
facilities be equipped with two manual actuators. The final rule 
requires that at least one actuator be located within the fuel storage 
facility and at least one actuator be located a safe distance away from 
the facility in intake air, upwind of the storage facility. The final 
rule is intended to ensure that at least two manual actuators be 
provided in locations that are accessible to mine personnel working in 
or around a permanent diesel fuel storage facility. This requirement is 
similar to the fire extinguisher location requirements for underground 
fuel storage facilities and areas in Sec. 75.1903(b)(1) and (b)(2) of 
the final rule, which provide that at least one portable fire 
extinguisher be located outside of the storage facility or area upwind 
of the facility, in intake air, to enable miners to reach the actuator 
in the event of fire. To allow flexibility in complying with the 
requirements of this paragraph, what constitutes a ``safe distance from 
the facility'' has not been specified in the final rule. The location 
of the actuator outside the facility should be determined based on mine 
conditions and the particular usage of the facility.
    Commenters generally expressed support for this aspect of the 
proposal. One commenter recommended that a requirement be added to 
address manual application of water in lieu of manual actuators when 
sprinkler systems are used. Another commenter suggested that actuators 
be separated from each other, and specifically recommended that a check 
valve be used to ensure that one faulty actuator does not circumvent or 
defeat the use of the other actuator.
    The final rule specifically addresses only requirements for dry 
chemical fire suppression systems, and a water sprinkler type fire 
suppression system would be considered an alternate type of fire 
suppression system under paragraph (a)(1) of this section. As a result, 
the final rule does not adopt the suggestion that an additional 
requirement be added to address manual application when water sprinkler 
systems are used. In addition, the final rule does not include a 
requirement for a check valve between the actuators for fire 
suppression systems. This is considered part of the system design and 
is more appropriately addressed by the system manufacturer and the 
listing or approving nationally recognized independent testing 
laboratory.
    Paragraph (f) of the final rule adopts the requirement from the 
proposal that the fire suppression system remain operational in the 
event of an electrical system failure. No specific comments were 
received on this aspect of the proposal. This requirement is intended 
to ensure that the system will be functional if power from external 
sources is lost. The phrase ``engine shutdown'' has not been adopted 
from the proposal, because the phrase would have applied to fire 
suppression system requirements for unattended diesel- powered 
equipment. Because the final rule does not permit the operation of 
unattended diesel-powered equipment, this phrase is no longer 
necessary.
    Paragraph (g) adopts the requirement from the proposal that 
electrically operated detection and actuation circuits be monitored and 
provided with status indicators showing power and circuit continuity. 
The final rule also requires that automatic detection systems be 
provided with a means to indicate the functional readiness status of 
the detection system. This paragraph requires that the fire suppression 
system provide a means of notifying miners and maintenance personnel of 
the functional readiness status of both the detection and actuation 
circuit and the power source. This paragraph also requires that 
automatic systems not electrically operated provide a means of 
notifying the operator or maintenance person of the functional 
readiness of the system.
    This requirement is included in the final rule to ensure the 
continuity of electrical systems used to detect faults on fire 
suppression systems. This requirement will serve to alert miners and 
maintenance personnel when a fire suppression system is not in a state 
of readiness due to an electrical system fault. The continuity of the 
electrical system used to detect fires and actuate the system is 
important since an automatic system is based on early detection and 
automatic actuation.
    One commenter to the proposal stated that the fire suppression 
system should also be protected as specified in Sec. 75.1101-17, which 
requires that each dry powder chemical system be adequately sealed to 
protect all components of the system from moisture, dust, and dirt.
    The protection of the fire suppression system components from 
moisture and dust is adequately addressed by the requirements of 
paragraphs (a)(3), (a)(4) and (a)(5) of this section of the final rule. 
In addition, the listing or approval typically includes requirements 
for a dust shield and checks of the powder for dryness.
    Paragraph (h) of the final rule adopts the requirement from the 
proposed rule that each fire suppression system be tested and 
maintained in accordance with the manufacturer's recommended inspection 
and maintenance program and as required by the nationally recognized 
independent testing laboratory listing or approval, and be visually 
inspected at least once each week by a person trained to make such 
inspections.
    The proposed rule would have required each fire suppression device 
to be visually inspected at least once each week by a person qualified 
to make such inspections. The proposal also would have required that 
each fire detection device be tested and maintained in accordance with 
applicable requirements in Sec. 75.1100.
    Commenters to the proposal generally expressed support for 
maintenance of fire suppression systems installed at permanent 
underground diesel fuel storage facilities. A number of commenters, 
however, recommended that a maintenance program specifically designed 
for fire suppression systems be developed at each mine. One commenter 
to the proposal expressed concern over the requirement for weekly 
visual inspections of fire suppression systems at permanent underground 
diesel fuel storage facilities. This commenter recommended that there 
be frequent functional testing of the suppression systems to ensure 
that lines are not blocked or pinched. Another commenter stated that 
the proposal did not specify the types of tests that should be 
conducted on fire suppression systems at permanent underground

[[Page 55484]]

diesel fuel storage facilities. Other commenters expressed concern over 
the frequency of tests and inspections. These commenters recommended 
that detailed inspections and functional tests be conducted 
semiannually or quarterly. One commenter recommended that fire 
suppression systems be treated in the same manner as portable fire 
extinguishers and that inspections be conducted once a week and 
physically tested twice a year.
    Under the final rule, the weekly visual inspection is not intended 
to be an in-depth examination. The weekly visual inspection is intended 
to be a quick check to verify that there are no obvious defects, such 
as disconnected hose lines or altered nozzles. An in-depth inspection 
takes place as part of the manufacturer's recommended testing and 
inspection procedure also required under the final rule. Fire 
suppression system manufacturers are most familiar with the design and 
operation of their systems and are best able to identify the components 
that need maintenance, the type of maintenance needed, and the 
frequency of maintenance. Adequate maintenance is essential because of 
the importance of these systems in fire protection. The maintenance and 
testing requirements for fire suppression systems are in addition to 
the requirement set forth for a weekly visual inspection.
    The manufacturer's inspection and maintenance procedures are 
spelled out in great detail in the manufacturer's manual and include 
the recommended inspection intervals, which depend on the environment 
in which the system operates. In addition, these inspection and 
maintenance procedures are evaluated as part of the system's approval 
or listing by a nationally recognized independent testing laboratory.
    This paragraph is identical to the requirement in Sec. 75.1107-
16(a). As stated earlier, the fire suppression system requirements in 
Secs. 75.1107-3 through 75.1107-16 cannot be directly applied to diesel 
equipment because the fire hazards presented by diesel fuel are 
different from those on electric-powered equipment, due to the close 
proximity of large quantities of diesel fuel to potential ignition 
sources.
    Also modified in this paragraph is the replacement of the term 
``device'' with the term ``system''. This was done because MSHA intends 
that the whole system be inspected, not just individual components of a 
system.
    A person ``trained'' to perform the inspections and tests required 
by paragraph (h) of this section of the final rule is not required to 
be a qualified person under Sec. 75.1915. However, the final rule 
intends that the person performing tests and inspections of fire 
suppression systems have sufficient knowledge to determine whether a 
fire suppression system is functioning properly. MSHA anticipates that 
since fire suppression systems are common to both electric and diesel 
equipment, the mine operator will work with either the fire suppression 
system manufacturer or distributor to ensure that persons responsible 
for the maintenance of fire suppression systems are adequately trained.
    Paragraph (i) of the final rule establishes recordkeeping 
requirements for the inspection and maintenance requirements for fire 
suppression systems set forth in paragraph (h), and requires that 
persons performing inspections and tests of these systems record 
results of tests and inspections only when a system does not meet the 
installation or maintenance requirements of this section. Under these 
circumstances, the person performing the inspection or test is required 
to indicate the fuel storage facility where the fire suppression system 
did not meet the installation or maintenance requirements of this 
section, the defect found, and the corrective action taken. The final 
rule also requires that these records be kept either manually or 
electronically in a secured manner that is not susceptible to 
alteration. In addition, the final rule requires that records be 
maintained at a surface location at the mine for one year and made 
available for inspection by an authorized representative of the 
Secretary and by miners representatives.
    The proposal would have required that a record be kept of all of 
the inspections of fire suppression systems and maintained at an 
appropriate location for each fire suppression device. One commenter to 
the proposal recommended that the records required by this section be 
made available to all interested parties and that this information be 
centrally located on the surface of the specific mine.
    Office of Management and Budget guidance comments directed MSHA to 
reexamine the recordkeeping requirements in the proposal and 
recommended that the final rule require paperwork that was the least 
burdensome necessary. MSHA has done so, and the final rule does not 
adopt the proposal that all fire suppression system test and 
maintenance results be recorded. In response to commenters and 
consistent with other provisions of the final rule, paragraph (i) 
requires that records of inspections and tests be made only when a fire 
suppression system does not meet the installation or maintenance 
requirements of this section. This requirement is important because if 
a fire suppression system does not meet its listing or approval, the 
defect can be of a nature and seriousness that the system can fail when 
a fire begins. This requirement is intended to ensure that records are 
maintained and made available to interested parties when a defect is 
found, and that the appropriate level of mine management is made aware 
of defects requiring attention.
    The final rule does not specify a particular way of recording the 
test and maintenance data, only that it be located at the surface of 
the mine. The records of the inspections and tests must be made in a 
secure media not susceptible to alteration. A detailed discussion of 
the subject of acceptable record books and electronic records can be 
found under the heading ``Recordkeeping Requirements'' in the General 
Discussion section of this preamble.
    The final rule does not adopt the requirement from the proposed 
rule that records of inspections be maintained at an appropriate 
location near each fire suppression system. Instead, paragraph (i)(3) 
of this section of the final rule establishes the requirement 
recommended by a commenter that records of inspections and tests be 
maintained at a surface location at the mine. Storing records on the 
surface at the mine makes them more accessible to interested parties. 
Also in response to commenters, the final rule provides access not only 
to miners representatives but to authorized representatives of the 
Secretary. This provision ensures that test and inspections of fire 
suppression systems are being made and, when a defect is found, 
corrective action is taken.
    Paragraph (j) adopts the proposed requirement that all miners 
normally assigned in the active workings of the mine be instructed 
about the hazards inherent to the operation of fire suppression 
systems, and where appropriate, the safeguards available for each 
system. This requirement is intended to ensure that all miners working 
in areas where fire suppression systems operate are instructed in any 
inherent hazards and necessary precautions associated with the 
operation of these systems. The final rule modifies the proposal in 
that the term ``device'' has been replaced by the term ``system'' to 
clarify that this requirement applies to the entire system rather than 
to system components.
    One commenter to the proposal agreed with the requirement that 
miners be trained in the hazards and safeguards

[[Page 55485]]

of fire suppression systems, but recommended that such training be 
incorporated in the annual refresher training required under existing 
Sec. 75.1101-23 for the program of instruction, location and use of 
fire fighting equipment. Under the final rule, it is anticipated that 
the instruction on the hazards of fire suppression systems required by 
this paragraph will be part of the Sec. 75.1101-23 instruction.
Section 75.1913--Starting Aids
    This section addresses the storage and use of volatile fuel 
starting aids for diesel-powered equipment. The requirements of the 
final rule are similar to the requirements contained in the proposal, 
with some minor modifications. This section places limitations on the 
use and storage of volatile fuel starting aids underground, to minimize 
the risks of fire or explosion. Under the final rule, volatile fuel 
starting aids must be used in accordance with recommendations of the 
starting aid manufacturer, the engine manufacturer, and the machine 
manufacturer. The final rule also includes requirements for the storage 
of volatile fuel starting aids, and prohibits the use of starting aids 
under certain circumstances, such as in areas where permissible 
equipment is required or where 1.0 percent or greater concentration of 
methane is present. Connection of compressed oxygen or compressed 
flammable gases to diesel air-start systems is also prohibited.
    The Diesel Advisory Committee recognized that improper storage and 
handling of starting aids could present fire and explosion hazards in 
underground coal mines. The Committee therefore recommended that MSHA 
regulate the storage and use of starting aids. The proposed rule set 
forth limitations on the use of starting aids, to minimize the hazards 
associated with their use in the underground coal mine environment. The 
requirements of the final rule reflect MSHA's determination that 
volatile fuel starting aids can be safely used underground if 
appropriate precautions are taken.
    Volatile fuel starting aids, normally ethyl ether, facilitate the 
starting of diesel engines in cold temperatures. In very cold weather 
the compression ignition of diesel engines cannot easily reach the high 
temperature necessary to ignite diesel fuel. This makes it difficult, 
and in some cases impossible, to start the engine without special 
measures, such as the use of volatile fuel starting aids. Volatile fuel 
starting aids sprayed into a cold diesel engine help to start the 
engine because they ignite at a much lower temperature than diesel 
fuel. Starting aids that are ignited in a diesel engine will both heat 
up the cylinder walls of the engine and start the engine spinning, 
resulting in easier ignition of the diesel fuel.
    The use and storage of volatile fuel starting aids in underground 
coal mines present safety hazards, due to the starting aids' high 
volatility. When these substances are stored or used improperly, they 
can present a very real danger of fire or explosion, particularly in 
the underground coal mine environment.
    Commenters were divided on whether the use of starting aids should 
be permitted in underground coal mines. Some commenters recommended a 
complete prohibition of the use of volatile fuel starting aids 
underground, stating that starting aids are extremely flammable, have a 
very low flash point, and can be ignited by any source of heat in the 
mine. These commenters believed that there were already numerous 
potentials for fire in the underground coal mine environment, and that 
permitting the use of starting aids would introduce another unnecessary 
hazard into that environment. Some commenters believed that starting 
aids were used at some mines as a substitute for effective maintenance 
of diesel engines, and that a properly maintained engine should be able 
to start on its own, without the boost that a starting aid provides.
    Other commenters advocated allowing the use of starting aids but 
strictly controlling their use. Several commenters stated that starting 
aids were currently being used safely and effectively in their mines, 
and that any hazards arising from their use could be controlled by 
careful handling. These commenters stated that proper maintenance of 
diesel engines does not prevent starting difficulties in cold 
temperatures. One commenter observed that air temperatures at mines 
located at elevations of 9,000 or 10,000 feet can fall well below 
0 deg. F. Several commenters observed that a diesel-powered machine 
that has been shut down and has been sitting in cold weather, such as 
over a weekend, can be virtually impossible to start without the use of 
a starting aid.
    Some of the commenters who favored prohibiting the use of volatile 
fuel starting aids underground stated that starting aids sometimes were 
used as a substitute for effective maintenance. Although an engine that 
has not been properly maintained could in some cases be started more 
easily with starting aids, this fact alone does not compel the 
prohibition of volatile fuel starting aids in underground coal mines. 
The final rule requires regular maintenance and testing of diesel-
powered equipment, designed to ensure that the equipment is kept in 
good operating condition. Compliance with these requirements should 
eliminate any need to use starting aids as a replacement for effective 
equipment maintenance.
    Paragraph (a) of this section requires that volatile fuel starting 
aids be used in accordance with the recommendations of the starting aid 
manufacturer, the engine manufacturer, and the machine manufacturer. 
The proposed rule would have required that volatile fuel starting aids 
be used in accordance with the specific recommendations in the engine 
manufacturer's maintenance and operations manual.
    Several commenters noted that the written documentation from 
machine or engine manufacturers does not always address correct use of 
volatile fuel starting aids, and expressed their concern that starting 
aids could create serious hazards if not used in conformance with 
specific recommendations. In response to these comments, the final rule 
provides that starting aids must also be used in accordance with the 
recommendations of the starting aid manufacturer, ensuring that mine 
operators will at a minimum be guided by those instructions. Starting 
aid manufacturers are already required by Occupational Safety and 
Health Administration regulations to develop Material Safety Data 
Sheets (MSDS) for their products. To comply with this provision the 
mine operator should obtain an MSDS and any other product safety and 
use information prepared by the starting aid manufacturer on the safe 
use of that particular starting aid, and use the starting aid in 
accordance with those instructions.
    Because engine and machine manufacturers are in the best position 
to determine whether volatile fuel starting aids can be safely and 
effectively used with a particular engine or machine, the final rule 
also requires mine operators to use starting aids in accordance with 
any available recommendations from the engine and machine manufacturers 
on the safe use of starting aids. This requirement recognizes that 
volatile fuel starting aids can damage engine or machine components and 
result in the failure of machine safety devices or increase exhaust 
emissions. For example, a buildup of the starting aid in intake or 
exhaust components could result in an explosion. Use of starting aids 
in accordance with the recommendations of engine and machine 
manufacturers will minimize

[[Page 55486]]

any safety hazards and avoid damage to the engine or machine, such as 
damage to intake or exhaust components, especially on permissible 
equipment.
    Although the final rule is not intended to prohibit the use of 
starting aids if such information has not been developed by the machine 
or engine manufacturer, MSHA encourages diesel-powered engine and 
machine manufacturers who do not already do so to develop 
recommendations on the use of volatile fuel starting aids with the 
engines and machines they produce.
    Paragraph (b) requires that containers of volatile fuel starting 
aids be conspicuously marked to indicate their contents. This paragraph 
further requires that containers of volatile fuel starting aids that 
are not in use be stored in metal enclosures that are used only to 
store starting aids. The metal enclosures themselves are required to be 
conspicuously marked, secured, and protected from damage.
    The requirement that starting aid containers be conspicuously 
marked was not included in the proposal, but has been incorporated in 
the final rule in response to commenters' concerns over the serious 
dangers that could result if starting aids containers were damaged in 
any way. The container marking requirement is intended to prevent 
inadvertent damage to containers by ensuring that mine personnel are 
aware of the containers' contents. Labels that are affixed to the 
starting aid can by the starting aid manufacturer will satisfy the 
requirement for container marking.
    The final rule also requires that enclosures for containers of 
starting aids be made of metal, marked, secured, and protected from 
damage, and used only for the storage of starting aids. The proposed 
rule would have required only that starting aids be stored in a fire 
proof enclosure when not in use. The final rule includes additional 
requirements to address commenters' concerns that starting aid 
containers could be inadvertently damaged, resulting in the 
unintentional release of the highly flammable starting aid. These 
additional requirements are similar to the requirements in the final 
rule that apply to safety cans containing diesel fuel that are 
transported on vehicles. Because both volatile fuel starting aids and 
diesel fuel present a possible fire hazard, the final rule imposes 
similar precautions for the handling and storage of these substances. 
The final rule also prohibits any other items, such as tools, from 
being stored with volatile fuel starting aids. This prohibition 
responds to commenters' concerns that containers of volatile fuel 
starting aids could be damaged through contact with other items, 
resulting in the release of the starting aid and the creation of a 
potentially hazardous situation.
    Some commenters noted that the term ``fire proof enclosure'' used 
in the proposed rule was not defined anywhere in the regulations, and 
recommended the substitution of the term ``noncombustible''. Other 
commenters opposed the use of the term ``noncombustible'' because of 
their concern that a container that is simply noncombustible may not be 
substantial enough to protect starting aid containers. MSHA agrees with 
commenters who believe that the term ``fire proof'' is ambiguous, and 
also with commenters who oppose the substitution of the term 
``noncombustible'' for the term ``fire proof'' because containers that 
are ``noncombustible'' may not be sufficiently durable. The final rule 
therefore requires that containers of starting aids be stored when not 
in use in metal enclosures, which are not only noncombustible but also 
sturdy enough to protect the starting aid containers that are stored 
there.
    Paragraph (c) adopts the requirements of the proposal, and imposes 
specific restrictions on where and under what circumstances volatile 
fuel starting aids may be used in underground coal mines, to minimize 
any hazards presented by their use. Paragraph (c)(1) prohibits volatile 
fuel starting aids from being taken into or used in areas where 
permissible equipment is required. Volatile fuel starting aids can 
create flames that flame arresters, which are designed to provide 
protection against methane ignitions, cannot stop. Use of volatile fuel 
starting aids in an area where permissible equipment is required could 
lead to an ignition of any methane in the area. Use of starting aids in 
those areas is therefore forbidden in the final rule.
    Paragraph (c)(2) prohibits the use of volatile fuel starting aids 
in the presence of open flames or burning flame safety lamps, or when 
welding or cutting is taking place. As noted by several commenters, 
vapors from volatile fuel starting aids are easily ignited. The final 
rule requires that volatile starting aids be kept away from the 
potential ignition sources of open flames or welding or cutting. 
Starting aids are also prohibited in the presence of burning flame 
safety lamps. The gauze in a flame safety lamp, although safe for use 
in the presence of methane, will not prevent the propagation of the 
flame by the ether vapors given off by the starting aid. The final rule 
is intended to prohibit these ignition sources in the immediate 
vicinity of any area where volatile fuel starting aids are being used.
    Paragraph (c)(3) adopts the proposal to prohibit the use of 
volatile fuel starting aids in any area of the mine where 1.0 percent 
or greater concentration of methane is present. This requirement 
minimizes the possibility that starting aid vapors that have 
accidentally been ignited would spread to methane in the surrounding 
area. Permissible equipment may not prevent a flashback of fire that 
could ignite a methane atmosphere.
    The proposed rule would have prohibited the use of starting aids in 
areas of the mine where 1.0 percent or greater of methane is detected. 
The final rule has been clarified to reflect that volatile fuel 
starting aids must not be used where 1.0 percent or greater of methane 
is ``present'', thereby placing on the mine operator the responsibility 
of ensuring that methane levels are within acceptable limits before 
volatile fuel starting aids are used.
    Paragraph (d) imposes limitations on the use of compressed gases as 
starting aids for diesel-powered engines. The final rule adopts the 
proposal's prohibition of the connection of compressed oxygen or 
compressed flammable gases to diesel air-start systems. Commenters 
generally supported this restriction. The use of compressed oxygen in 
the presence of engine lubricants, which are normally in diesel air 
start-systems, presents an immediate danger of a fire. The final rule 
consequently forbids the use of compressed oxygen for this purpose. 
Additionally, the introduction of compressed flammable gases into the 
machine's compressed air system presents not only the same fire hazard 
as compressed oxygen, but also a danger of explosion from flammable 
gases being placed in close proximity to possible sparks from the 
diesel engine. The final rule therefore also prohibits the use of 
compressed flammable gases in diesel air-start systems. Nonflammable 
gases, such as nitrogen, are permitted for this purpose.
Section 75.1914 Maintenance Of Diesel-Powered Equipment
    Section 75.1914 sets forth maintenance, repair and testing 
requirements for diesel-powered equipment, and also indicates the level 
of training or qualification a person must have to perform these 
important tasks. The rule generally requires that diesel-powered 
equipment be maintained in safe and approved condition, and 
specifically requires weekly equipment examination, weekly testing and 
evaluation of gaseous

[[Page 55487]]

emissions, flushing and draining of scrubbers, and changing of air 
filters. A person must be qualified under Sec. 75.1915 to perform 
maintenance and repairs of approved and other specified features on 
diesel-powered equipment, and to conduct weekly equipment tests and 
examinations. However, the rule allows other functions required under 
this section to be performed by a person not qualified under 
Sec. 75.1915, so long as the person has been trained in the task.
    This section of the final rule recognizes that effective equipment 
maintenance is an indispensable element in reducing the health and 
safety hazards of diesel-powered equipment, and that adequate training 
of maintenance personnel is an important part of ensuring that such 
work is performed correctly. The purpose of the requirements of this 
section is to ensure that diesel-powered equipment is properly 
maintained so that it does not deteriorate through neglect, abuse, or 
normal use and result in a safety or health hazard to miners.
    Virtually all commenters to the proposed rule supported the need 
for maintenance requirements for diesel-powered equipment used in 
underground coal mines. Commenters agreed that regular maintenance and 
routine examination of equipment is essential, as the performance of 
even the best-designed equipment will decline over time without proper 
maintenance. Inadequate maintenance of diesel equipment can result in 
the creation of fire or explosion hazards, and the levels of harmful 
gaseous and particulate components in diesel exhaust can increase when 
equipment is poorly maintained.
    Several commenters to the proposed rule provided specific examples 
of the problems and hazards that result when maintenance personnel are 
poorly trained. Some commenters stated that inadequately trained 
personnel frequently failed to maintain diesel equipment in approved 
condition, causing the engines to deteriorate and resulting in 
increased levels of harmful exhaust gases. Commenters also reported 
that untrained persons were more likely than properly trained persons 
not only to allow safety systems to malfunction in the first place, but 
also to bypass the malfunctioning safety system in order to continue 
operating the machine, rather than to repair the system.
    Paragraph (a) of this section retains the language of the proposed 
rule and requires that all diesel-powered equipment used in underground 
coal mines be maintained in approved and safe condition or removed from 
service. Several commenters recommended that the word ``approved'' be 
deleted, in the belief that it would be acceptable to use permissible 
equipment in non-approved condition when the machine was being operated 
in an outby location.
    Paragraph (a) of the final rule prohibits the use of diesel 
equipment that is not in approved and safe condition. This prohibition 
includes the operation of permissible diesel-powered equipment in outby 
areas when an approved feature has been disabled. There are several 
reasons that this requirement has been adopted in the final rule. Many 
types of approved diesel equipment are extremely mobile, moving easily 
from areas of the mine where permissible equipment is required to areas 
where it is not, and there is nothing to distinguish a piece of diesel-
powered equipment that has not been maintained in permissible condition 
from one that has. Both bear MSHA approval plates. Additionally, 
temperature sensors and other safety system components on diesel-
powered equipment can be permanently damaged by exposure to high 
temperature exhaust gas when the equipment is not maintained in 
approved condition and a safety system is bypassed. The final rule 
therefore requires that equipment be maintained not only in safe 
condition but also in approved condition.
    Paragraph (b) requires that maintenance and repairs of approved 
features, and the features required by Secs. 75.1909 and 75.1910, be 
made only by a person qualified under Sec. 75.1915. The final rule 
retains the concept of the proposal that the maintenance and repair of 
certain features of diesel-powered equipment be performed by a 
qualified person. The majority of commenters supported mandatory 
training and some form of qualification for those individuals 
performing these functions because it would help to ensure that diesel 
equipment is adequately maintained and kept in good operating 
condition. The Diesel Advisory Committee also recommended that 
qualified persons be responsible for the more complicated systems on 
the machine, such as the approved components.
    A more extensive level of training is needed to ensure that persons 
working on more complex equipment features are adequately skilled. 
Additionally, MSHA machine approval requirements are largely 
performance-oriented, and equipment manufacturers consequently have 
significant latitude in designing their equipment to satisfy MSHA's 
permissibility requirements. Because a variety of equipment designs 
could accomplish the safety objectives mandated by an MSHA approval, 
approved equipment does not always conform to easily recognizable 
standards, and the ability to perform maintenance and repair work on 
the more complex features of diesel-powered equipment requires a 
comprehensive understanding of the equipment's design. The final rule 
therefore adopts the requirement of the proposal that persons 
performing work on certain specified features of diesel-powered 
equipment be qualified under Sec. 75.1915, which requires completion of 
a training program developed by the mine operator.
    The proposed rule specified only that ``approved features'' must be 
maintained and repaired by a person qualified under Sec. 75.1915, and 
did not include within its scope ``features required by Secs. 75.1909 
and 75.1910'' as does paragraph (b) of the final rule. However, the 
scope of this requirement under the final rule is essentially the same 
as it would have been under the proposed rule. Under the proposed rule, 
all nonpermissible equipment, with the exception of a limited class of 
light-duty equipment and stationary unattended equipment, would have 
been subject to a whole machine approval under part 7. Because the 
final rule does not require whole machine approval of nonpermissible 
equipment, and instead requires that this equipment be provided with 
the safety features set forth in Secs. 75.1909 and 75.1910, essentially 
the same features must be maintained and repaired by a qualified person 
under the final rule as would have been required under the proposal.
    Paragraph (c) of the final rule requires that the water scrubber 
system on diesel-powered equipment be drained and flushed, by a person 
who is trained to perform this task, at least once during each shift 
that the equipment is operated. The proposed rule contained the same 
requirement for flushing scrubbers, but did not specify what type of 
training was required for the person performing the task.
    The rationale behind the requirement for flushing and draining is 
that routine cleaning of scrubbers, which cool equipment exhaust gases 
and act as flame arresters, is essential to prevent a buildup of solid 
exhaust particles and sludge in the scrubber. This condition can 
eventually block internal passages of the scrubber, impairing the 
scrubber's effectiveness and compromising safety in the mine. The 
Advisory Committee also recommended that MSHA require mine operators to 
change scrubber water on a regular basis.
    Commenters generally supported regular draining and flushing of

[[Page 55488]]

scrubber systems, although some commenters questioned whether the rule 
should specify the point in the shift when draining and flushing must 
be done. Commenters also questioned what level of qualification was 
necessary as a prerequisite to performing this task. The consensus of 
the Advisory Committee was that routine maintenance, such as changing 
scrubber water, could be performed by a person who is not certified, 
and that task training would be sufficient in those situations.
    MSHA agrees that draining and flushing of the scrubber is a 
relatively straightforward task, and that the comprehensive training 
required for qualification under Sec. 75.1915 is unnecessary to ensure 
that persons perform this task competently. The final rule therefore 
clarifies MSHA's intention that scrubber draining and flushing need not 
be done by a person qualified under Sec. 75.1915, only that the person 
be trained to perform the task. MSHA expects that the draining and 
flushing of the water scrubber system will typically be performed by 
the machine operator.
    In response to the proposed requirements for scrubber maintenance, 
some commenters stated that the final rule should specify that scrubber 
systems must be drained and flushed at the beginning of the shift. 
These commenters were concerned that if the rule did not specifically 
require draining and flushing at the beginning of the shift, MSHA could 
not issue a citation for violation of this standard until the end of 
the shift, making enforcement difficult. Other commenters advocated 
that the final rule require the scrubber system to be drained and 
flushed at the end of the shift, allowing mine operators to perform the 
task as part of the routine maintenance to prepare the machine for the 
next shift.
    MSHA has carefully considered the comments on this issue, and has 
chosen to retain the language of the proposed rule in the final rule, 
which simply requires scrubber systems to be flushed and drained once 
during each shift that the equipment is operated, without specifying 
when during the shift the task must be performed. This is consistent 
with MSHA's intention to afford mine operators reasonable flexibility 
in performing the maintenance required by the final rule. However, MSHA 
recommends that mine operators perform scrubber maintenance at about 
the same point during every shift, thereby ensuring that scrubbers are 
flushed and drained every 8 to 10 hours (depending on the length of the 
shift) during the equipment's operation.
    Paragraph (d) requires that the intake air filter be replaced or 
serviced either when the intake air pressure drop device indicates that 
it is necessary, or when the engine manufacturer's maximum allowable 
air pressure drop level is exceeded. The final rule also requires that 
this replacement or servicing be done by a person who is trained to 
perform the task.
    Maintenance of diesel machine air filters is an important element 
of overall equipment maintenance. Air filters screen the air taken in 
by the machine for combustion. Over time, the filters load up with dust 
and dirt, restricting air flow and making the engine work harder to 
pull in the same amount of air. As the engine works harder, greater 
quantities of engine emissions are produced, adversely affecting the 
quality of the air that miners breathe. Research and experience 
indicate that air restrictions have a negative effect on emission 
generation, specifically carbon monoxide and diesel particulate.
    The proposed rule would have required filter replacement or 
servicing when the filter was ``dirty'' as well as when the machine's 
intake air pressure drop device indicated that it was necessary. The 
proposed rule would not have required, as does the final rule, filter 
maintenance when the manufacturer's maximum allowable air pressure drop 
level is exceeded.
    Commenters generally supported the requirements of this paragraph, 
and several stated that dirty air filters were frequently to blame when 
engines began to produce increased levels of carbon monoxide. However, 
several commenters objected to mandatory filter replacement and 
servicing when the filter was ``dirty'', pointing out that the term 
``when dirty'' was ambiguous. Commenters stated that air filters catch 
dirt continually, and are therefore ``dirty'' to some degree at all 
times. MSHA agrees with commenters on this issue, and has concluded 
that the use of the term ``when dirty'' could create uncertainty for 
mine operators in complying with the provision. The requirement that 
filters be replaced or serviced ``when dirty'' has therefore not been 
adopted in the final rule.
    The final rule does adopt the requirement of the proposed rule that 
air filters be replaced or serviced when the intake air pressure device 
indicates that it is necessary. Intake air pressure devices monitor the 
air pressure across the filter. As the air filter loads up with dust 
and dirt the pressure drop across the filter will increase, and at a 
certain point the intake air pressure device will signal that the 
filter is sufficiently blocked by dirt to require servicing or 
replacement.
    Not all types of diesel-powered equipment are presently equipped 
with intake air pressure devices. Under the proposed rule, air filters 
without air pressure devices would have been required to be changed or 
serviced ``when dirty''. However, as discussed above, that provision 
has not been included in the final rule. One commenter to the proposed 
rule stated that service indicators specified by the manufacturer are 
sufficient for determining when an air filter should be changed. A 
service indicator is simply the manufacturer's specification of the 
drop in pressure across the air filter, reflected by the air pressure 
gauge on the machine, indicating that the air filter must be serviced 
or replaced. MSHA agrees that service indicators provide an objective 
and measurable method of determining the need for air filter servicing 
for machines without intake air pressure devices. The final rule has 
therefore been modified to provide that air filters must be replaced or 
serviced when the engine manufacturer's maximum allowable air pressure 
drop level is exceeded.
    The proposal did not specify the level of training or qualification 
required for the person performing air filter maintenance under this 
paragraph, and commenters questioned whether MSHA intended that this 
task be performed by a person qualified under Sec. 75.1915. Commenters 
generally stated that air filter maintenance did not need to be 
conducted by a qualified person, only by someone who has been trained 
to perform the task. This view is consistent with the consensus of the 
Advisory Committee that simple maintenance activities, such as changing 
air filters, could be performed by miners who are not qualified or 
certified. Accordingly, the final rule specifies that air filter 
maintenance must be performed by a person who has received training in 
the task.
    Paragraph (e) requires that mobile diesel-powered equipment that is 
to be used during a shift be visually examined by the equipment 
operator before being placed in operation, and that equipment defects 
that affect safety be reported to the mine operator. This requirement 
is identical to that of the proposed rule, and was supported by 
commenters.
    MSHA intends that the examinations required under this paragraph 
consist of the equipment operator conducting a check of the equipment 
before operating it to verify that the machine has no obvious safety 
defects, such as fuel leaks, loose batteries, or accumulations of 
combustible materials on the

[[Page 55489]]

machine. The language of the final rule has been changed slightly to 
require that the equipment be ``visually examined'' rather than 
``inspected'', to better convey the nature of the examination. Such an 
examination will provide a regular check on some of the more 
conspicuous equipment problems. This paragraph also requires that 
observed defects be reported promptly to the mine operator, which could 
be a responsible management official, such as a superintendent or 
foreman. The word ``promptly'' has been included in the final rule to 
clarify that safety defects observed during this check should be 
directed to a responsible management official in a timely manner.
    Paragraph (f) provides that all diesel-powered equipment must be 
examined and tested weekly by a person qualified under Sec. 75.1915. 
Commenters generally agreed with the concept of mandatory equipment 
examination at regular intervals, although several commenters stated 
that only diesel equipment that was in use should be subject to 
required examinations, advocating revision of the rule to reflect that 
only equipment ``in service'' is subject to weekly examination.
    Although MSHA understands the basis for these commenters' concerns, 
MSHA has concluded that inserting the term ``in service'' in the final 
rule could be misinterpreted by some mine operators to exclude 
equipment from the weekly examination requirement that the Agency does 
not intend to exclude. For example, some operators may consider 
equipment to be out of service if it has not been operated for an 
extended period, even though the equipment remains in the mine and 
could be operated at any time. MSHA takes a very broad view of what 
equipment is ``in service,'' regarding all equipment not located in 
maintenance shops or surface storage areas as being ``in service'' and 
subject to weekly examination and testing. MSHA has therefore not 
adopted the change advocated by commenters.
    Although commenters supported the concept of regular examination 
and testing of diesel-powered equipment, there was no clear consensus 
on how regularly equipment must be examined. A few commenters who 
raised the issue of the frequency of required equipment examinations 
referred to maintenance schedules for diesel-powered equipment in place 
at their mines, with examination intervals of one week, two weeks, or 
every 150 hours of equipment operation. Other commenters stated that 
examination requirements for diesel- powered equipment should be 
similar to those for electrical equipment. The latter comment is 
consistent with the unanimous recommendation of the Advisory Committee 
that diesel-powered equipment be maintained on the same basis as 
electrical equipment.
    MSHA has concluded that testing and examination of diesel-powered 
equipment on a weekly basis will ensure that equipment is being 
maintained in safe and healthful condition. Weekly examination of 
electrical equipment in underground coal mines has been required and 
has served as an effective check for adequate equipment maintenance for 
more than 20 years. Weekly examinations have consequently become an 
accepted element of routine equipment maintenance in the coal mining 
industry. Diesel equipment and electrical equipment in the underground 
coal mine environment present many of the same hazards. Paragraph (f) 
therefore provides for weekly testing and examination of diesel-powered 
equipment by a person qualified under Sec. 75.1915.
    Several commenters stated that the weekly examinations under 
paragraph (f) should be required only for approved components. Neither 
the proposed rule nor the final rule contains this limitation. The 
proposal would have specified that the weekly examinations be conducted 
in accordance with approved checklists, which are lists developed, with 
the assistance of MSHA, by an equipment manufacturer who is seeking 
MSHA approval. The proposal would have required fully assembled machine 
MSHA approval of all diesel-powered equipment, except for a ``limited 
class'' of light-duty nonpermissible equipment and stationary 
unattended equipment. The final rule requires full machine approval 
only for permissible equipment; nonpermissible equipment must only be 
provided with an approved engine. MSHA nonetheless believes that 
certain machine features, although not subject to MSHA approval, should 
be inspected as part of the regular examination.
    Paragraph (f)(1) requires that examinations and tests be conducted 
in accordance with approved checklists and manufacturers' maintenance 
manuals. These checklists are to be used in conjunction with checklists 
and instructions included in manufacturers' maintenance manuals.
    Commenters supported the use of checklists for examinations and 
tests of diesel-powered equipment. One commenter advocated that 
maintenance requirements be stated in general terms to accommodate new 
equipment design and improved technology in the future. MSHA agrees 
with this comment, and the use of equipment-specific permissibility/
approval checklists and equipment manufacturers' maintenance manuals 
should achieve this result. MSHA would also consider a mine operator to 
be in compliance with this provision if the operator developed its own 
checklist format based on and consistent with the manufacturers' 
maintenance manuals.
    Equipment manufacturers, with the assistance of MSHA, currently 
develop such checklists as part of the MSHA approval process. These 
checklists are designed to provide specific guidance to mine operators 
in verifying that approved equipment is in approved condition. 
Permissibility checklists are used to determine whether maintenance or 
repair is needed to bring the equipment back into approved condition; 
manufacturers' maintenance manuals complement these checklists by 
providing mine operators with specific instructions on how to conduct 
the necessary maintenance or repair. MSHA intends that the approved 
checklists referred to in this paragraph for diesel-powered equipment 
under part 7 will be similar to the permissibility checklists used for 
part 36-approved machines.
    Commenters supported the use of checklists for examinations and 
tests of diesel-powered equipment. One commenter advocated that 
equipment maintenance requirements be stated in general terms to 
accommodate new equipment design and future technological improvements. 
MSHA believes that the use of equipment-specific permissibility/
approval checklists should achieve this result, and has included 
language in the final rule that provides for the use of equipment-
specific manufacturers' maintenance manuals in conjunction with the 
approved checklists in conducting necessary maintenance. MSHA would 
also consider a mine operator to be in compliance with this provision 
if operators developed their own checklist formats based on and 
consistent with the manufacturer's maintenance manuals.
    Paragraph (f)(2) requires that persons performing weekly 
examinations and tests of diesel-powered equipment under this paragraph 
shall make a record when the equipment is not in approved or safe 
condition. The record must include the equipment that is not in 
approved or safe condition, the defect found, and the corrective action 
taken. This requirement has been adopted with modification from the 
proposed rule. Under the proposed rule, a record of all weekly 
equipment examinations would have been required, and recordkeeping

[[Page 55490]]

would not have been limited to those examinations that disclosed a 
defect. Under the final rule the recordkeeping burden has been reduced, 
consistent with efforts to reduce the paperwork burdens placed on the 
regulated public.
    Commenters generally supported the concept of recording of 
examinations, and a number of commenters provided information on the 
type of records of equipment examination that were maintained at their 
mines. The record required by this paragraph may be entered or recorded 
by the qualified person who performed the examination, or by a 
responsible mine official, such as a foreman or superintendent.
    Paragraph (g) requires the mine operator to develop and implement 
written standard operating procedures for weekly testing and evaluation 
of undiluted exhaust emissions from diesel-powered equipment used where 
permissible electrical equipment is required, and from heavy-duty 
diesel-powered equipment as defined in Sec. 75.1908(a), in use 
underground. The paragraph also requires that specific aspects of the 
testing and evaluation process be addressed in the procedures. The 
final rule differs from the proposal in that the proposal would have 
required emission testing of all diesel-powered equipment underground, 
while the final rule narrows the requirement for such testing to 
permissible and heavy-duty nonpermissible equipment. The final rule 
also differs slightly from the proposal in the type of training 
required for the person who tests and evaluates the exhaust emissions.
    The proposed emission testing requirements elicited the most 
controversy among commenters of all of the requirements in this 
section. Some commenters acknowledged that emission testing could be 
useful in monitoring the general operating condition of a diesel engine 
in identifying diesel equipment that needs maintenance. These 
commenters nonetheless expressed serious concern that a standardized 
in-mine test for undiluted exhaust emissions had not yet been devised, 
and until such a test was developed there would be no consistency in 
test results. These commenters recommended that emission test 
requirements not be included in the final rule. In response to these 
comments, the final rule limits required undiluted exhaust emission 
testing to permissible equipment and to heavy-duty nonpermissible 
equipment, as defined under Sec. 75.1908(a). In-mine tests for diesel 
exhaust emissions have in fact been developed for these types of 
equipment. Permissible equipment and heavy-duty nonpermissible 
equipment are also typically the types of equipment that operate under 
load for extended periods of time, and consequently generate high 
levels of emissions relative to other types of equipment. Regular 
testing of the exhaust emissions of this equipment will help to ensure 
that this equipment is properly maintained.
    A number of commenters supplied extensive information on emissions 
tests that had been developed and were being conducted at their mine, 
stating that such tests provided a valuable indication of engines that 
were in need of maintenance. Some commenters who supported the 
requirement for emissions testing in the proposed rule nonetheless 
recommended different testing intervals, ranging from two times per 
shift to once a month. One commenter stated that an emissions test 
frequency of one time per month was appropriate for light-duty 
equipment, while another commenter recommended that emissions be tested 
each week by a person qualified under Sec. 75.1915, and during each 
shift by the equipment operator. The final rule adopts the proposed 
requirement for weekly exhaust emissions testing, consistent with the 
weekly examinations and testing requirement of paragraph (f). A weekly 
testing interval is of sufficient frequency to ensure that 
deteriorating engines are identified and serviced before they create a 
potential health hazard for miners in the area.
    A number of commenters questioned where the exhaust gas should be 
sampled, some stating that they sampled diluted exhaust gas either in 
the equipment operator's compartment or at a significant distance from 
the tailpipe, such as 2 or 3 feet, and in one case 10 feet away. 
Several commenters stated that emissions test should be taken no more 
than 3 inches from the exhaust pipe if a particulate probe is not 
provided, because greater distances will not provide meaningful 
results. One commenter found that testing 2 feet away from the exhaust 
was very unreliable, and that the test results would depend on which 
way the machine was facing. Another commenter believed that test 
procedures used by some mine operators were intended to circumvent the 
goal of testing, which is to gauge engine performance and identify 
equipment that needs maintenance. Other commenters stated that while 
samples taken in the operator's compartment or away from the tailpipe 
can provide valuable information, inconsistent dilution prevents such 
samples from giving the most accurate indication of engine condition. 
One commenter's experience has shown that samples taken directly from 
the exhaust tailpipe provide a more accurate analysis of engine 
performance, and that samples drawn further away are influenced too 
much by the variables of mine ventilation. MSHA agrees with the 
commenters who are concerned about these variables, not least among 
them mine ventilation, that can dilute and distort emission samples 
that are taken any distance away from the machine tailpipe. A 
significantly diluted sample may fail to indicate declining engine 
performance and may not trigger the necessary corrective maintenance, 
thereby exposing miners to unhealthy levels of gaseous emissions. In 
response to these concerns, MSHA has concluded that adopting the 
requirement in the proposal for sampling of the undiluted exhaust 
emissions is the best way to ensure that the measurements will provide 
an accurate indication of deteriorating engine performance. The final 
rule specifically requires the testing of undiluted exhaust emissions, 
which means that emission samples required must be taken directly from 
the tailpipe, not at any distance away.
    Paragraph (g) specifies that the person performing the weekly 
testing and evaluation of exhaust emissions be trained to perform the 
task. The person is not required to be qualified under Sec. 75.1915, 
but does have to be adequately trained. This is a slight modification 
from the proposed rule, which would have required the person conducting 
emissions tests to demonstrate to a person qualified under Sec. 75.1915 
the capability to perform the tests. MSHA has concluded that the 
requirement in the proposed rule that the training be conducted by a 
qualified person is an unnecessary limitation. Mine operators have the 
responsibility of ensuring that persons who perform such tasks are 
adequately instructed in the activity. An important part of carrying 
out that responsibility is making sure that the persons conducting task 
training have the requisite knowledge and experience. Accordingly, the 
final rule simply requires that persons who test and evaluate emissions 
receive the necessary task training.
    Paragraph (g)(1) requires that the emissions testing procedures 
developed by the mine operator include a method for achieving a 
repeatable loaded engine operating condition for each type of 
equipment, and is identical to what was proposed. Most commenters 
stated that a loaded engine test was not feasible for all types of 
equipment, specifically diesel machines equipped with clutches. Several 
commenters emphasized the difficulty of analyzing

[[Page 55491]]

the exhaust emissions of a loaded engine without exposing miners to the 
danger of sudden equipment movement. Other commenters stated that valid 
samples could not be obtained if the engine were not under load. In 
response to these commenters, and as discussed above, the final rule 
limits the requirement for exhaust testing to permissible equipment and 
heavy-duty nonpermissible equipment. These types of equipment are 
generally not equipped with clutched transmissions, and therefore do 
not present the problems identified by commenters that would exist with 
loaded engine tests for diesel equipment with clutches. As mentioned 
earlier, MSHA has developed loaded engine test procedures for the 
equipment subject to testing under the final rule.
    Paragraph (g)(2) requires that the procedures for weekly testing 
and evaluation of the undiluted exhaust emissions of diesel engines 
specify sampling and analytical methods that include calibration of 
instrumentation capable of accurately detecting carbon monoxide in the 
expected concentrations. Commenters indicated that instruments are 
available and currently being used for accurate emissions testing. 
Several commenters stated that testing should not be limited to carbon 
monoxide, stating that they were currently testing for other gases, 
such as sulfur dioxide and the oxides of nitrogen. Other commenters 
were of the opinion that carbon monoxide concentrations were the best 
indicator of engine performance.
    After consideration of all comments, MSHA has concluded that 
sampling for carbon monoxide alone is sufficient for determining a 
change in engine performance that may reflect a need for maintenance. 
Data indicates that carbon monoxide increases the most among the 
exhaust gases when an engine is poorly maintained, and is the best 
indicator that an engine needs attention. See, Report of the Bureau of 
Mines, U.S. Department of the Interior, ``Relationship of Underground 
Diesel Engine Maintenance to Emissions'' (December 1983). Sampling for 
nitrogen dioxide is required by Sec. 70.1900 of the final rule. This 
will ensure that miners are not exposed to contaminants at levels above 
the applicable limits.
    Paragraph (g)(3) requires that the procedures for emissions testing 
and evaluation include evaluation and interpretation of the emission 
test results. Commenters generally supported this requirement, and 
several commenters provided information on their evaluation and 
interpretation of results. This provision has been adopted unchanged 
from the proposed rule.
    Paragraph (g)(4), like the proposal, requires that the testing 
procedures developed by the operator specify the concentration or 
changes in concentration of carbon monoxide that will indicate a change 
in engine performance. The paragraph also provides that concentrations 
of carbon monoxide shall not exceed 2500 parts per million, which is 
the limit for carbon monoxide established in the test procedures for 
Category B engines in subpart E of part 7 of the final rule. This 
aspect of the proposal received little comment, and has been adopted 
without change in the final rule.
    Paragraph (g)(5) requires that the testing and evaluation 
procedures address the maintenance of records that are necessary to 
track engine performance. Commenters supported this requirement and 
indicated that some mines are already maintaining emissions records. 
The proposed rule would have required that the procedures address 
``maintenance and retention of necessary records''. MSHA has added 
language to this paragraph to eliminate any ambiguity that might have 
been created by the term ``necessary records'', by specifying the 
purpose of the records required under this paragraph. MSHA has also 
eliminated the reference in the proposed rule to the ``retention'' of 
records, and has chosen instead to address retention of records in a 
new paragraph (h) in this section, discussed below.
    Paragraphs (h)(1) and (h)(2) provide that records required by 
paragraphs (f)(2) and (g)(5) of this section must be recorded in a 
secure book that is not susceptible to alteration, or recorded 
electronically in a computer system that is secure and not susceptible 
to alteration. The records must be retained at a surface location for 
at least 1 year and made available for inspection by an authorized 
representative of the Secretary and by miners' representatives.
    The proposed rule did not address the availability of or access to 
records under this section. One commenter recommended that records of 
weekly examination be accessible to miners' representatives. MSHA 
agrees with this comment, and has revised the paragraph to provide 
miners' representatives with access to records. The final rule also 
requires such access for authorized representatives of the Secretary, 
to allow MSHA inspectors to review records to verify that examinations 
and tests required under this section have been conducted.
    The final rule does not specify a particular way of making records, 
only that they are to be recorded in a manner that is not susceptible 
to alteration. A detailed discussion on the issue of recordkeeping and 
electronic records can be found under ``Recordkeeping Requirements'' in 
the General Discussion section of this preamble.
    The proposed rule would have required that the emission testing 
procedures under paragraph (g) include the designation of training of 
the individual who performs the tests. This requirement has not been 
adopted in the final rule. Instead, as discussed earlier, the rule 
imposes a performance-based requirement that emissions testing and 
evaluation under this paragraph be conducted by a person who has been 
trained to perform the task. Mine operators are consequently 
responsible for ensuring that individuals who test and evaluate 
emissions receive the training necessary to ensure their competence. 
The ability of these persons to discharge their responsibilities is of 
much greater concern to MSHA than the training they receive to achieve 
it, and the final rule reflects this emphasis.
    Finally, several commenters recommended that this section include a 
requirement for regular examination of fire suppression systems. 
Examination of fire suppression systems is not addressed here, but 
instead is dealt with in Sec. 75.1911 of the final rule, which provides 
that equipment fire suppression systems be visually inspected at least 
once each week, and be tested and maintained in accordance with the 
manufacturer's recommended inspection and maintenance program.
    Paragraph (i) provides that diesel-powered equipment must be 
maintained in accordance with this part beginning 12 months after the 
date of publication of the final rule. This time is allowed for the 
development of a training and qualification program under Sec. 75.1915 
and for the training of individuals who perform work on diesel-powered 
equipment. MSHA recognizes that the resources available for training in 
particular geographical areas may be limited in some cases, and that 
competent trainers may be in significant demand as mine operators 
prepare to comply with the requirements of the final rule. A one-year 
delayed effective date for the requirements of this section should 
afford the mining community sufficient time to prepare for compliance.

[[Page 55492]]

Section 75.1915  Training And Qualification Of Persons Working On 
Diesel-Powered Equipment
    This section of the final rule requires a training and 
qualification program for persons who perform maintenance, repairs, 
examinations and tests on diesel-powered equipment, as required by 
Sec. 75.1914. These critical tasks must be performed correctly for 
diesel equipment to be maintained in safe condition with acceptable 
levels of emissions. The final rule sets minimum, performance-based 
requirements for training and qualification programs, and requires 
successful completion of such a program for a person to be qualified to 
perform diesel maintenance, repairs, examinations, and tests.
    The final rule differs from the proposed rule in several respects: 
it does not require the training and qualification programs to be 
approved by MSHA; it does not specify an interval for retraining; it 
clarifies that the rule does not require MSHA approval of instructors 
who provide training; and it eliminates the use of the term ``diesel 
mechanic''.
    Paragraph (a) of this section of the final rule provides that in 
order to be qualified to perform maintenance, repairs, examinations, 
and tests on diesel-powered equipment, as required by Sec. 75.1914, a 
person must complete a training and qualification program which meets 
the requirements of the section. A qualified person is required to be 
retrained when necessary to maintain the ability to perform all 
assigned maintenance, repairs, examinations, and tests. The final rule 
does not require, as would have the proposed rule, that MSHA approve 
training and qualification programs developed under this section.
    Although there was virtually universal agreement among commenters 
that some form of training was essential for persons working on diesel 
equipment, commenters disagreed about the need for a formal training 
and qualification program and the necessity of MSHA review and approval 
of such programs. Some commenters were of the opinion that persons 
working on diesel equipment should be formally qualified, and that 
diesel training programs for qualification should meet strict minimum 
standards and be subject to approval by MSHA. One commenter stated that 
if strict training requirements were not included in the standard, the 
necessary training would not be provided.
    Other commenters opposed requiring a formal program with specific 
requirements, advocating as an alternative performance-oriented 
standards that could be adapted to a mine's specific needs. One 
commenter stated that a formal qualification scheme was unnecessary, 
and that diesel maintenance training should be provided on an as-needed 
basis in the same manner as task training under part 48. Another 
commenter maintained that the benefits realized from a formal 
qualification program would not justify the additional administrative 
burdens of such a program. The Office of Management and Budget guidance 
comments directed MSHA to reexamine whether all of the information 
proposed to be submitted to MSHA for approval of training and 
qualification programs had practical utility and imposed the least 
burden on mine operators.
    Numerous other commenters, while supporting the establishment of 
procedures to qualify persons to perform work on diesel equipment, were 
opposed to the proposed requirement that MSHA approve training and 
qualification programs. Many commenters indicated that very good diesel 
equipment maintenance training is already being provided by mine 
operators as well as equipment manufacturers, without MSHA review or 
approval. In contrast, other commenters maintained that training 
programs should meet the approval of all interested parties, including 
MSHA and the representative of miners, to ensure that the training is 
adequate. The Diesel Advisory Committee had unanimously recommended 
that MSHA require persons performing work on approved diesel equipment 
features be trained and tested for competency, and that the training 
and testing be approved by MSHA.
    After careful consideration of all of these views and comments, 
MSHA has concluded that a basic structure for training and 
qualification programs for persons performing certain work on diesel 
equipment is necessary. Properly trained persons are fundamental to 
adequate maintenance of diesel-powered equipment. To meet this 
objective, MSHA believes minimum criteria for the training and 
qualification of these persons are essential. Paragraph (a) therefore 
provides that to be qualified to perform diesel equipment maintenance, 
repairs, examinations, and tests, as required by Sec. 75.1914, a person 
must successfully complete a training and qualification program meeting 
the requirements of the section.
    The proposal that MSHA review and approve training and 
qualification programs is not adopted in the final rule. MSHA's paper 
review of training and qualification programs, as proposed, could 
provide an initial check of the quality of the program. Such a review 
would not, however, ensure that the program is successful in its 
implementation. Rather than expending Agency resources on the review 
and approval of diesel training programs, MSHA will direct those 
resources toward verification of the effectiveness of training and 
qualification programs in their execution. Similarly, mine operators 
and training providers can focus on the development and administration 
of their training and qualification programs rather than on procedures 
to gain MSHA approval. The rulemaking record contains a number of well-
designed diesel training plans already in effect, demonstrating that 
the mining community has the expertise needed to develop and implement 
effective training programs. MSHA will closely monitor the 
effectiveness of the training programs implemented under this section.
    Paragraph (a) also requires retraining when needed. The proposed 
rule would have required qualified persons to undergo retraining every 
12 months. Some commenters to the proposed rule opposed the 
establishment of a specific requirement for annual retraining, stating 
that the mining industry needed performance-oriented standards that 
could be adapted to mine-specific needs for maintenance and training. 
Other commenters stated that an annual retraining requirement was 
necessary to ensure that persons working on diesel-powered equipment 
maintained the necessary knowledge and expertise over time.
    MSHA considers retraining to be an important part of any training 
program. The final rule, however, does not mandate retraining at 
specified intervals. MSHA has concluded that mine operators should 
tailor the frequency of retraining to the conditions and practices at 
each mine, to ensure that all persons who work on diesel-powered 
equipment maintain the requisite level of expertise. Factors that could 
affect the timing of retraining include the frequency with which the 
qualified person works on specific pieces of diesel equipment; newly 
developed techniques for performing the required inspections and tests; 
and any modifications that may have been made to the equipment since 
the last training. Frequent retraining may be necessary at some mines 
to ensure that qualified persons retain sufficient skill and knowledge 
to perform their jobs effectively. At other mines where conditions are 
less changeable, retraining at greater intervals may be appropriate.

[[Page 55493]]

    Paragraph (a) of the final rule also eliminates the term ``diesel 
mechanic'', was used in the proposal to identify those persons 
qualified to perform maintenance and repairs of approved features of 
diesel equipment. Many commenters to the proposed rule objected to the 
use of the term, stating that it would result in the creation of a new 
job title or classification. MSHA did not intend to establish a new job 
classification through the use of the term ``diesel mechanic'', and 
concludes from the comments that its use would result in confusion. The 
term ``diesel mechanic'' has therefore not been adopted in the final 
rule.
    Finally, the phrase ``examinations and tests'' has been included in 
paragraph (a) of the final rule, reflecting that a person qualified 
under this section would be authorized to conduct weekly examinations 
and tests of diesel-powered equipment under Sec. 75.1914(f), in 
addition to maintenance and repairs of such equipment under 
Sec. 75.1914(b).
    Paragraph (b) provides a basic structure for training and 
qualification programs, but is intended at the same time to provide 
mine operators with sufficient latitude in developing their programs. 
MSHA believes that training and qualification programs will be most 
effective if they are tailored to specific mining conditions and 
equipment in use at the mine, as well as to the skill levels and 
experience of the persons being trained.
    A number of commenters reported that they already have training and 
qualification programs in place at their mines, and provided 
descriptions and documentation of these programs. Many of these 
programs utilize training at off-site facilities, such as community 
colleges and technical and trade schools. Commenters also indicated 
that mining equipment manufacturers are typically called upon to 
provide training. These programs generally include classroom training 
modules as well as hands-on in-mine training on specific pieces of 
equipment. Commenters stated that the duration of training programs 
could be from three days to eight weeks. The length of the program was 
generally dependent upon how much diesel-powered equipment was used at 
the mine, as well as on the previous experience and skill level of the 
persons being trained.
    MSHA anticipates that local community colleges and technical 
schools will assist mine operators in developing the training and 
qualification programs required under this section. Commenters 
indicated that this type of assistance is already being provided to 
mine operators in a number of areas of the country.
    Paragraph (b)(1) requires that training courses be presented by a 
competent instructor, in contrast to the proposed rule, which would 
have required that courses for training and retraining be conducted by 
either a qualified diesel mechanic or ``other instructor determined by 
MSHA to be qualified.'' Several commenters objected to this aspect of 
the proposal, based on their belief that the proposal required some 
type of formal approval by MSHA before anyone other than a qualified 
person could conduct diesel training under this section. A number of 
other commenters believed that such approval would only add an 
unnecessary procedural hurdle to providing training. Contrary to the 
understanding of such commenters, MSHA did not intend by the proposal 
to approve training instructors. The language of the final rule has 
been clarified to provide that courses may be presented by a competent 
instructor. A competent instructor under paragraph (b)(1) could be a 
person qualified under Sec. 75.1915, an instructor from a trade school 
or college, or a person experienced in diesel maintenance, such as a 
representative of an equipment or engine manufacturer, or even the 
chief of maintenance at the mine, provided that the instructor has the 
necessary technical expertise.
    Paragraph (b)(2) of the final rule provides that the training and 
qualification program must be sufficient to prepare or update a 
person's ability to perform all assigned tasks with respect to diesel-
powered equipment maintenance, repairs, examinations, and tests. This 
paragraph incorporates the requirements of proposed paragraphs (e)(2) 
and (e)(3), except that it substitutes the term ``person'' for the term 
``diesel mechanic,'' for the reasons stated in the discussion of 
paragraph (a) of this section. Several commenters were opposed to the 
requirement in proposed paragraph (e)(3) that courses in the training 
program address each piece of diesel-powered equipment in use at the 
mine, stating that this could be an unnecessary burden at mines that 
operate a variety of types of diesel-powered equipment. These 
commenters stated that if an individual never worked on certain pieces 
of equipment, requiring that individual to receive training on all 
equipment in use at the mine would be unnecessary.
    MSHA did not intend proposed paragraph (e)(3) to require that each 
qualified person be trained on all types of diesel-powered equipment in 
use in the mine, only those pieces of diesel-powered equipment the 
qualified person actually works on. However, the language of proposed 
paragraph (e)(3) could be interpreted to require that the courses in 
the training program cover all pieces of diesel equipment in use at the 
mine.
    MSHA agrees with the commenters that training should be tailored to 
the duties and responsibilities of the individual qualified person. The 
language in the final rule has therefore been clarified to reflect this 
concept. A qualified person is not required to be trained on a 
particular type of equipment, unless he or she performs work on it. 
However, a person who is untrained on a particular type of equipment is 
not a qualified person with respect to that equipment, and may not 
perform maintenance, repairs, and tests required to be conducted by a 
qualified person. Finally, MSHA anticipates that training will address 
equipment by model and not by individual machine, unless machines at 
the mine with the same model number differ because of field changes or 
other special features. In such cases training would need to take into 
account any significant differences among machines.
    While MSHA's intent is to promote flexibility in the implementation 
of training and qualification programs, the final rule does specify 
minimum topics of instruction for these programs. Paragraphs (b)(3)(i) 
through (b)(3)(vii) of the final rule set forth the specific areas of 
instruction that must be covered by a training and qualification 
program. Commenters were generally in agreement with the areas of 
instruction required under the proposed rule, and the language of the 
final rule is virtually the same as what was proposed''.
    Paragraph (b)(3)(i) requires that training programs address the 
``requirements of subpart T of this part''. Several commenters 
recommended that the phrase ``as applicable'' be added to this 
requirement, to eliminate the need for training to address requirements 
that may not be directly applicable at the specific mine. This 
recommendation is not adopted in the final rule. MSHA believes that a 
person qualified under this section should have, at a minimum, basic 
familiarity with the scope of subpart T and the diesel-powered 
equipment safety standards. However, MSHA does not intend that this 
aspect of the final rule require exhaustive coverage of requirements 
that have no application to the mine in question. The well-designed, 
mine-specific training program contemplated by this section will focus 
on the requirements that are the most relevant. For example, if a mine 
does not store diesel fuel underground, qualified persons working

[[Page 55494]]

at that mine would not be expected to have extensive knowledge of the 
requirements of the standards governing fuel storage. Qualified persons 
should nonetheless be aware that subpart T contains provisions that 
address underground fuel storage.
    Paragraph (b)(3)(ii) is virtually identical to proposed paragraph 
(e)(4)(ii), and requires that the training program address the use of 
power package or machine checklists to conduct tests to ensure that 
diesel equipment is in approved and safe condition, with acceptable 
emission levels. Some commenters reported that maintenance of the 
permissibility features of approved equipment was often neglected, and 
emphasized the importance of using only trained personnel to evaluate 
these features. This requirement is intended to ensure that training 
addresses the evaluation of the equipment's permissibility features. 
Several commenters also questioned the meaning of the term ``safe 
operating condition''. The term has been changed to ``safe condition'' 
to conform to the terminology in Sec. 75.1914. MSHA intends that ``safe 
condition'' used in this paragraph means that the equipment has been 
maintained in compliance with subpart T of this part and does not 
present a hazard to miners. Finally, the language of this paragraph has 
been slightly revised to delete the term ``appropriate'' from the 
phrase ``to conduct appropriate tests'', because it is unnecessary and 
redundant.
    Paragraph (b)(3)(iii) of this section is identical to proposed 
paragraph (e)(4)(iii), and requires that the training program cover the 
proper maintenance of approved features and the correct use of 
appropriate maintenance manuals, including machine adjustments, 
service, and assembly. Paragraph (b)(3)(iii) is different from 
paragraph (b)(3)(ii) in that it addresses proper maintenance of 
equipment, while paragraph (b)(3)(ii) addresses tests to ensure 
permissibility.
    Paragraph (b)(3)(iv) of the final rule requires that training under 
this section address tests and maintenance of fire suppression system 
on diesel-powered equipment. The final rule uses the phrase ``fire 
suppression system'' rather than ``fire protection system,'' which was 
used in the proposed rule, to conform the language of the final rule to 
terminology that is more commonly in use. The purpose of this 
requirement is to ensure that a qualified person has sufficient 
familiarity with the elements of fire suppression systems used on 
diesel equipment.
    Paragraph (b)(3)(v) of this section requires that fire and ignition 
sources and their control and elimination, including cleaning the 
equipment, be addressed by the training program. The phrase ``including 
cleaning of the equipment'' has been added in response to comments 
emphasizing the importance of frequent cleaning of equipment to prevent 
the accumulation of combustible materials such as oil, grease and float 
coal dust and thereby reduce the risk of fire. This requirement is 
consistent with and is intended to reinforce compliance with 
Sec. 75.400, which has been revised in this final rule to specifically 
prohibit accumulations of combustible material on diesel-powered 
equipment.
    Paragraph (b)(3)(vi) of this section requires that the training 
program address safe fueling procedures and maintenance of the 
equipment's fuel system. The importance of proper refueling procedures 
is illustrated by the analysis of the Canadian fire accident data in 
the discussion of Sec. 75.1908. These data show that the failure to 
follow proper refueling procedures resulted in several fires.
    Paragraph (b)(3)(vii), like the proposal, requires that the 
training program address maintenance and testing of the engine's intake 
air system. A number of commenters reported that failure to replace 
dirty intake air filters was the most frequent cause of excessive 
levels of smoke and carbon monoxide from otherwise properly adjusted 
engines.
    Proposed paragraph (e)(4)(viii) would have required the training 
course to address tests and maintenance of the engine shutdown device. 
Because engine shutdown devices are in fact components of permissible 
equipment, training covering these devices will already be required by 
paragraphs (b)(3) (ii) and (iii) of this section, discussed above. The 
language of proposed paragraph (e)(4)(viii) has therefore not been 
included in the final rule.
    Proposed paragraph (e)(4)(ix) would have given the district manager 
the authority to require the training program to cover additional 
subjects necessary to address specific health and safety needs. This 
provision has not been adopted in the final rule, which is designed to 
be more performance-oriented. As discussed above, the requirements of 
this section are intended to result in the development of training 
programs that are tailored to the specific needs of each mine, 
including the equipment being used and the skill levels of the persons 
receiving the training. Failure to address mine-specific health and 
safety needs in the training program may result in MSHA determining 
that a mine operator is not in compliance with Sec. 75.1915. 
Additionally, the proposed rule would have required MSHA approval of 
training programs and would have provided a framework for the exercise 
of district manager authority under proposed paragraph (e)(4)(ix). As 
discussed above, the final rule does not require MSHA approval of 
training programs. For these reasons, this proposed provision has not 
been adopted in the final rule.
    Paragraph (b)(4) requires the training and qualification program to 
include an examination that requires demonstration of the ability to 
perform all assigned tasks with respect to diesel equipment 
maintenance, repairs, examinations, and tests. There is no specific 
requirement that the examination be in writing, although an examination 
that effectively assesses competence will most likely include a written 
test as well as a practical portion that allows a hands-on evaluation 
of a person's abilities. Under the proposed rule, a minimum score of 80 
percent would have been required on any written portion of a 
qualification examination. Although some commenters supported the 
concept, MSHA has concluded that mandating a minimum score is 
unnecessary when a written portion is not a required part of the 
examination. Further, such a specific requirement is at odds with the 
performance-oriented approach of this paragraph. The requirement for a 
minimum score has therefore been omitted from the final rule.
    Paragraph (b)(5) requires that the training and qualification 
program be in writing, and contain a description of the course content, 
materials, and teaching methods to be used for initial training and 
retraining. The language of this paragraph is substantially the same as 
proposed paragraph (d)(1), except that the word ``approved'' has been 
omitted. As discussed above, the program will not be subject to MSHA 
approval under the final rule.
    The requirements of proposed paragraphs (d)(2) and (d)(3) have not 
been adopted in the final rule. Specifically, proposed paragraph (d)(2) 
would have required that the training and qualification program include 
a copy of the examination, to allow MSHA to review the examination as 
part of the approval process. Because the final rule does not require 
MSHA approval, and also because a written examination is not required, 
a copy of the examination does not need to be included as part of the 
program.
    Proposed paragraph (d)(3) would have required that the program 
include a description of the evaluation program to be used for 
retraining to assess the knowledge, skills, and ability of the

[[Page 55495]]

qualified person. This requirement has not been included in the final 
rule, consistent with MSHA's intention to measure the effectiveness of 
training and qualification programs by how well diesel-powered 
equipment is being maintained at the mine, rather than by the adequacy 
of a written program. Consequently, the final rule does not require a 
retraining evaluation program, but MSHA expects that mine operators 
will closely monitor the maintenance of diesel equipment at their 
mines, and will ensure that qualified persons receive the necessary 
retraining.
    Paragraph (c) of this section requires the mine operator to 
maintain a copy of the training and qualification program required by 
this section and a record of the names of all persons qualified under 
the program. Paragraph (c)(1) requires that the record of the names of 
qualified persons be made in a manner that is not susceptible to 
alteration or recorded electronically in a computer system that is 
secure and not susceptible to alteration. Under paragraph (c)(2), the 
training and qualification program and the record of qualified persons 
must be kept at a surface location of the mine and made available for 
inspection by an authorized representative of the Secretary and by 
miners' representatives. Paragraph (c) incorporates, with certain 
revisions, the requirements originally proposed in Secs. 75.1916 (i) 
and (j). Proposed Secs. 75.1916 (i) and (j) would have required a list 
of current instructors also to be included in the training and 
qualification program and, in addition to the names of all qualified 
persons, the dates of qualification and the date of the last 
retraining. MSHA has removed these additional recordkeeping 
requirements from the final rule, consistent with the Agency's 
intention to gauge the adequacy of training and retraining by how 
effectively diesel-powered equipment at the mine is maintained. The 
final rule does not specify a particular method for maintaining the 
record of qualified persons, only that it is not susceptible to 
alteration. A detailed discussion of recordkeeping and electronic 
records can be found under the heading ``Recordkeeping Requirements'' 
in the General Discussion section of this preamble.
    Finally, the proposed rule specified procedures in Sec. 75.1916 for 
MSHA's administration of training and qualification programs. Among 
other things, the proposed rule set forth a process for MSHA review and 
approval of the training and qualification program required under 
Sec. 75.1915, and established procedures for the revocation of 
individual qualifications. Because MSHA will not be formally reviewing 
and approving training and qualification programs, procedural 
requirements for review and approval are unnecessary. Consequently, the 
provisions proposed in Sec. 75.1916 have not been retained in the final 
rule, with the exception of the requirements of proposed 
Secs. 75.1916(i) and (j), as discussed above.
Section 75.1916 Operation Of Diesel-Powered Equipment
    Section 75.1916 addresses speed limits and other traffic 
restriction on roadways in underground coal mines where diesel-powered 
equipment is operated. This section also prohibits unnecessary idling 
of diesel-powered equipment, as well as the operation of unattended 
diesel-powered equipment.
    The Diesel Advisory Committee advocated MSHA regulation of 
operating conditions of diesel-powered equipment, recommending proposal 
of a rule that addressed speed limits, road conditions, and operator 
control of vehicles. This section is intended to ensure that diesel-
powered equipment underground is operated in a safe manner, and 
requires that operating speeds of diesel-powered equipment be 
consistent with conditions in the mine, and that operators of diesel-
powered equipment maintain full control of the equipment when it is in 
motion. Standardized traffic rules, including speed, signals, and 
warning signs, are required to be established at each mine and 
followed.
    The final rule recognizes that the safe operating speed for a 
particular piece of diesel-powered equipment depends greatly on the 
specific mining conditions and the type of equipment being operated, 
and as a result the final rule does not establish a universal speed 
limit for diesel-powered equipment operated in underground coal mines. 
Finally, idling of mobile diesel-powered equipment is prohibited, 
except as required in normal mining operations. Operation of unattended 
diesel-powered equipment is also prohibited under this section.
    Several commenters recommended elimination of the requirements of 
this section, stating that the proposed standards were too vague and 
could result in inconsistent enforcement. Some of these commenters 
suggested reducing the proposed requirements of this section to a 
single requirement that the mine operator establish traffic rules, 
appropriate for the specific mine conditions at each mine, that address 
speed and operator control of equipment. A number of commenters also 
pointed out that existing Sec. 75.1403 gives MSHA the authority to 
regulate hazards arising from the transportation of men and materials 
at underground coal mines. These commenters believed that 
transportation hazards were already adequately covered under 
Sec. 75.1403, and that additional regulation was therefore unnecessary.
    The existing authority to issue safeguards under Sec. 75.1403 does 
not make the requirements of this section unnecessary. Section 75.1403 
authorizes an MSHA inspector to issue a ``safeguard notice'' when the 
inspector determines that a transportation hazard exists at a mine and 
the hazard is not already addressed by a mandatory standard. The 
``safeguard notice'', issued by an MSHA inspector to the mine operator, 
identifies the nature of the hazard and establishes requirements based 
on the actual conditions or practices that constitute a transportation 
hazard at the particular mine. After the mine operator is given a 
reasonable time to come into compliance with the requirements set forth 
in the safeguard notice, the safeguard has the force and effect of a 
mandatory standard at the mine and can be enforced as such. Sections 
75.1403-1 through 75.1403-11 contain criteria to guide inspectors in 
issuing safeguards, covering a wide range of potential transportation 
hazards, such as clearance distances on belt conveyors and track 
haulage roads, brakes on hoists and elevators, and safety gates for 
entrances to shafts and slopes.
    Safeguards are not a substitute for the mandatory requirements in 
Sec. 75.1916. Although some of the topics covered in this section, such 
as speed limits and roadway conditions, are included as safeguard 
criteria in Secs. 75.1403-1 through 75.1403-11, the criteria are not 
enforceable unless and until they have been incorporated in a safeguard 
notice, after an MSHA inspector has determined that a hazard exists. In 
contrast, the requirements of this section of the final rule apply at 
all underground coal mines where diesel-powered equipment is used. In 
addition, safeguard criteria are intended to be tailored to the unique 
conditions and practices at an individual mine, while the requirements 
in this section are general in nature, although mine operators are 
given the flexibility to set traffic rules appropriate for the 
conditions at their mines. The final rule therefore does not reflect 
the opinion of some commenters that the requirements under this section 
are unnecessary.
    The requirements of this section specifically govern the manner and 
conditions under which diesel-powered

[[Page 55496]]

equipment operates in underground coal mines, and recognize that 
diesel-powered equipment tends to be much larger and more powerful, and 
to have the ability to travel at much greater speeds than electric-
powered equipment. Some types of diesel-powered equipment used in 
underground coal mines, such as pickup trucks, are designed for use on 
highways, and can travel at speeds in excess of 60 miles per hour 
(mph). In comparison, a typical piece of mobile rubber-tired battery-
powered equipment will have a top speed of less than 10 mph. The 
potential traffic hazards are therefore significantly greater in the 
operation of diesel-powered equipment, and there is a resulting need 
for the minimum requirements set by the final rule at mines where 
diesel-powered equipment is operated.
    Paragraph (a) of this section adopts the requirements of the 
proposal and provides that operating speeds of diesel-powered equipment 
must be consistent with the type of equipment being operated, the 
conditions of roadways, grades, clearances, visibility, and other 
traffic. Under this paragraph diesel-powered equipment must be operated 
at all times at safe speeds, which in many cases will be slower than 
the maximum speed limit set in the mine-wide traffic rules established 
under paragraph (c).
    Some commenters recommended that the rule specify a maximum speed 
limit, such as 15 mph or 25 mph, that would apply at all underground 
coal mines. These commenters stated that a standardized speed limit 
would promote compliance because the rules would be the same at all 
mines everywhere. A few of these commenters recommended that equipment 
be fitted with gear reduction ratios that would make it mechanically 
impossible for equipment to be operated at speeds above the limit. 
Other commenters opposed the establishment of a universal speed limit 
for all mines, stating that safe speeds were highly dependent on 
variable mining conditions, and that a speed that is prudent under one 
set of circumstances could be quite unsafe, even reckless, under 
another.
    The requirements of this paragraph recognize that certain mine 
conditions and equipment characteristics must be taken into account in 
determining the speed at which equipment can be safely operated. Mine 
conditions have been a contributing factor in many traffic accidents. 
Adverse conditions that can negatively impact equipment safety include 
steep grades and slippery mine surfaces, which decrease the 
effectiveness of equipment brakes. Particularly large diesel-powered 
machines, which can take up nearly an entire mine entry, can present 
significant limitations in visibility for the equipment operator, whose 
line of vision is below the machine frame. Consequently, the equipment 
operator has several large blind spots where other pieces of equipment 
and mine personnel cannot be seen. Large haulage units operating in the 
same area as small pieces of diesel-powered equipment can create 
particularly dangerous traffic patterns. The proposed rule would have 
required roadways to be kept as free as practicable from bottom 
irregularities or other conditions that could affect control of the 
equipment. A number of commenters recommended elimination of this 
paragraph, noting that the proposed rule would require standardized 
traffic rules and could be used to address concerns about roadway 
conditions. Other commenters supported this proposed requirement, 
citing the dangers that can result from poorly maintained roads.
    Although MSHA agrees that keeping mine roads free from bottom 
irregularities, debris, and wet or muddy conditions is important to 
safe operation of diesel-powered equipment, the requirements of 
paragraphs (a), (b), and (c) of this section of the final rule are 
sufficient to address concerns about adverse road conditions. The 
requirements of proposed paragraph (a), which would have required 
roadway maintenance, have therefore not been adopted in the final rule.
    Under the requirements of the final rule, vehicle speed must take 
into account roadway conditions and other factors that affect safe 
equipment operation. Equipment operators are required to maintain full 
control of their equipment, and traffic rules must be established and 
followed at each mine where diesel-powered equipment is operated.
    Paragraph (b) also adopts the requirements of the proposal and 
provides that equipment operators must maintain control of mobile 
diesel-powered equipment while it is in motion. Commenters generally 
supported this requirement, which recognizes that there may be cases 
where the roadway conditions, posted operating speed, and traffic rules 
are adequate but other factors interfere with the equipment operator's 
ability to exercise full control over the equipment. For example, the 
rule would prohibit the operator from carrying tools or supplies in the 
operator's compartment that interfere with the operator's ability to 
control the equipment. Additionally, equipment controls must be free of 
any debris which could obstruct safe operation. Operator inattention 
could also constitute a violation of this requirement if the 
inattention causes unsafe operation of the equipment.
    Paragraph (c) requires that standardized traffic rules, including 
speed limits, signals, and warning signs, be established and followed 
at each mine. Under this provision, the mine operator must develop 
mine-wide traffic rules to address hazards arising from the operation 
of diesel-powered equipment, and ensure that mine employees are aware 
of the rules and comply with them. This is consistent with the 
suggestions of several commenters, who supported simplifying the 
proposed rule requirements by a single provision that mine operators 
establish safe operating rules appropriate for mine conditions. The 
requirements in the final rule are similar to those of the proposal, 
except that the final rule provides that traffic rules must be 
``followed'', and does not adopt the proposed requirement that the 
rules be ``posted.'' Mine operators have the responsibility to take 
whatever steps are necessary to ensure that their employees are 
familiar with the mine's traffic rules and follow them. Although 
posting of traffic rules can serve as a means for mine operators to 
facilitate compliance, it is not specifically required under the final 
rule.
    Commenters who advocated a standardized maximum speed limit at all 
underground coal mines, in response to proposed paragraph (b), renewed 
this recommendation in their comments to this paragraph. For the 
reasons discussed above, the final rule does not impose a universal 
speed limit. Some commenters suggested that simply requiring the 
establishment of a mine-wide speed limit would eliminate the need for 
other traffic rules. MSHA disagrees that restrictions on speed alone 
will eliminate potential traffic hazards. The traffic rules required 
under this paragraph are intended to address other factors that affect 
safe operation of diesel-powered equipment, such as changes in mining 
conditions.
    Some commenters recommended that MSHA provide criteria for mine 
operators to use in establishing mine traffic rules, and that operators 
develop traffic plans, consistent with these criteria, that are 
reviewed and approved by MSHA. The final rule does not adopt this 
recommendation. Although MSHA's review of a mine's traffic rules could 
provide a preliminary check on the adequacy of the rules, such a review 
will not ensure that they have been effectively implemented. The final 
rule reflects MSHA's conclusion that both mine operator and Agency 
resources are

[[Page 55497]]

better spent ensuring that traffic rules are being followed. However, 
if an MSHA inspector determines that an operator's traffic rules fail 
to adequately address the mine's traffic hazards, MSHA will require 
revision of the traffic rules.
    This paragraph also requires that the traffic rules be followed. 
The language in the proposed rule did not specifically require that the 
rules be ``followed,'' although MSHA believes that most commenters 
understood that the rules must be obeyed. To eliminate any possible 
ambiguity or misunderstanding, the rule has been clarified to 
specifically require that the rules be complied with.
    One commenter recommended that mine operators be required to 
investigate and file reports of mine traffic accidents in specific 
circumstances, such as where an injury occurs or where a certain amount 
of damage is sustained. MSHA regulations at part 50 already require 
mine operators to investigate and report certain accidents to MSHA, as 
well as to report to MSHA all occupational injuries and illnesses. MSHA 
has concluded that there is no compelling reason why traffic accidents 
and injuries should be treated differently from other types of mining 
accidents and injuries. The final rule therefore does not adopt this 
comment.
    Paragraph (d) prohibits idling of mobile diesel-powered equipment, 
except as required in normal mining operations. This prohibition has 
been added to the final rule in response to the concerns of some 
commenters, who observed that engines are excessively idled most 
frequently in areas where it is impractical to increase air quantities. 
This results in high levels of exhaust contaminants in these areas of 
the mine, and increases the risks of miner overexposure. The final rule 
addresses this problem by prohibiting unnecessary engine idling. The 
intent of this provision is that equipment parked at any location, 
including the loading point, will be shut down if it is not being used 
to do work.
    Paragraph (e) has been added to the final rule and prohibits the 
operation of unattended diesel-powered equipment. The proposal would 
have prohibited portable limited class equipment from being operated 
unattended. This prohibition is consistent with the decision not to 
adopt the proposed requirements for stationary unattended equipment 
into the final rule, and is explained in detail in the preamble 
discussion of stationary unattended equipment.
Amendment of Certain Part 75 Standards
    MSHA's part 75 sets forth mandatory safety standards for each 
underground coal mine. The final rule amends existing Secs. 75.342, 
75.400, 75.1710 and 75.1710-1 to extend their application to diesel-
powered equipment, requiring the installation of methane monitors on 
certain types of diesel-powered equipment, prohibiting accumulation of 
combustible materials on diesel-powered equipment in active workings of 
underground coal mines, and requiring diesel-powered face equipment and 
shuttle cars to be equipped with substantially constructed cabs or 
canopies. Although these existing standards specifically apply to 
electric equipment, the hazards that these standards are designed to 
address are independent of the power source of the equipment.
    The requirements of these four mandatory safety standards have 
applied to electric-powered equipment for a number of years, and have 
been extremely effective in protecting miners from the hazards of 
fires, explosions, and roof falls. The Diesel Advisory Committee 
recommended that MSHA review its existing standards to determine 
whether any existing safety requirements should be made applicable to 
diesel-powered equipment.
    In the preamble to the proposed rule, MSHA solicited comments on 
extending the applicability of certain listed standards to diesel-
powered equipment. The standards listed in the proposal included 
Sec. 75.313 (now Sec. 75.342, methane monitors); Sec. 75.400 
(accumulation of combustible materials); Sec. 75.400-2 (cleanup 
programs); Secs. 75.523, 75.523-1, and 75.523-2 (emergency 
deenergization of self-propelled equipment); Sec. 75.1107-1 (fire 
suppression devices); and Secs. 75.1710 and 75.1710-1 (cabs and 
canopies on face equipment). MSHA also solicited comments on whether 
any other part 75 standards that were not listed should be made 
applicable to diesel-powered equipment.
    Commenters expressed general support for extending requirements for 
methane monitors, brakes, and cabs and canopies to diesel-powered 
equipment. Some commenters expressed the view that all equipment safety 
features on diesel-powered equipment should be addressed under part 75. 
One commenter suggested that all requirements in part 75, particularly 
Secs. 75.500 through 75.524 (applicable to battery- and electric-
powered equipment), be applied to diesel-powered equipment. Other 
commenters stated that all necessary equipment safety features should 
be required as part of the equipment approval process, rather than as 
standards under part 75.
    The final rule retains MSHA's longstanding approach of including in 
part 75 general equipment safety requirements such as methane monitors, 
prohibitions against accumulation of combustible materials, and cabs 
and canopies. The approach of requiring general safety features in part 
75 has been effective in protecting miners in underground coal mines 
where electric-powered equipment is in use. As discussed below, the 
safety hazards addressed by the standards amended in the final rule are 
the same regardless of the equipment's power source.
    By including these equipment safety requirements in part 75, mine 
operators will have the flexibility to improve safety by making machine 
modifications based on specific conditions at each mine. For example, 
the selection of an appropriate cab or canopy for a machine is 
dependent on mine height and entry width.
Section 75.342 Methane Monitors.
    Methane monitors automatically shut down permissible electric 
mining equipment used to extract or load coal when methane 
concentrations around the equipment reach 2.0 percent. Permissible 
diesel equipment can create the same explosion hazard as permissible 
electric equipment if operated in the presence of high concentrations 
of methane. Also, under certain conditions, a diesel engine can ingest 
methane from the mine atmosphere, resulting in uncontrolled 
acceleration of the diesel engine during start up or operation, and 
produce an ignition of methane in the area.
    Methane monitors are recognized as a critical link in the safety 
protections designed to prevent mine explosions. These monitors are 
normally mounted on equipment that operates in the face area, providing 
the first warning that methane gas is accumulating in potentially 
dangerous quantities.
    The final rule requires methane monitors on all diesel-powered face 
cutting machines, continuous miners, longwall face equipment, loading 
machines, and other diesel-powered equipment used to extract or load 
coal in the working place. By applying the methane monitor requirements 
of existing Sec. 75.342 to diesel-powered equipment, miners working 
around such equipment will be protected from fire and explosion hazards 
to the same degree as miners working in areas where similar electric-
powered equipment is in use.

[[Page 55498]]

Section 75.400 Accumulation of Combustible Materials
    The final rule requires that coal dust, loose coal, and other 
combustible materials be cleaned up and not permitted to accumulate in 
active workings or on electric equipment therein. The hazards of a mine 
fire or explosion in an underground coal mine are similar for diesel-
powered and electric-powered equipment. Coal dust can produce a ready 
fuel source when combined with the lubricating and hydraulic oils used 
in diesel-powered equipment and can start a fire if it comes into 
contact with ignition sources on the equipment. As discussed elsewhere, 
diesel-powered equipment that is not equipped with surface temperature 
controls, such as outby equipment, may have engine and exhaust surfaces 
above the ignition temperature of coal dust. Accumulations of coal dust 
can also contribute to the propagation and severity of mine fires and 
explosions. Because diesel equipment uses large quantities of diesel 
fuel and hydraulic fluid, once a fire starts it can quickly spread due 
to the close availability of these fuel sources on a diesel machine. A 
large fire can then ensue and spread in the mine. By adding the term 
``diesel-powered'' to Sec. 75.400, MSHA intends that the longstanding 
prohibition against the accumulation of combustible materials will now 
be explicitly applied to diesel-powered equipment.
Sections 75.1710 and 75.1710-1--Cabs and Canopies.
    The final rule amends Sec. 75.1710 to require diesel-powered face 
equipment and shuttle cars to be equipped with substantially 
constructed cabs or canopies to protect miners operating such equipment 
from roof falls and rib and face rolls. The final rule also applies the 
installation requirements for cabs and canopies in Sec. 75.1710-1 to 
diesel-powered equipment.
    Cabs and canopies provide very effective protection to equipment 
operators from the hazards of roof and rib falls and in collisions with 
the mine roof and ribs. Since 1972, approximately 250 miner fatalities 
have been prevented by cabs and canopies installed on electric 
equipment. Some mine operators have recognized the clear safety 
benefits of cabs and canopies and have installed these devices on the 
diesel-powered self-propelled face equipment in their mines. By 
specifically extending the existing requirements in these sections to 
diesel-powered self-propelled face equipment, including shuttle cars, 
the operators of all such equipment will be afforded the same 
protection that is currently provided for operators of electric 
equipment.
    Several standards identified in the proposal as possible subjects 
for revision have not been amended in this final rule. Section 75.400-
2, which requires the establishment of a cleanup program for the 
removal of accumulations prohibited under Sec. 75.400, has not been 
specifically amended to include the term ``diesel-powered equipment.'' 
Existing Sec. 75.400-2 does not make reference to a particular type of 
equipment, either diesel- or electric-powered. The standard simply 
requires that a program be established for the cleanup and removal of 
combustible materials. Therefore, Sec. 75.400-2 already applies to 
diesel-powered equipment and amending the standard is unnecessary.
    MSHA also solicited comments in the proposed rule on whether the 
requirements of Secs. 75.523, 75.523-1 and 75.523-2 should be applied 
to diesel-powered equipment. These standards protect equipment 
operators from pinning and crushing injuries by requiring self-
propelled electric face equipment to be equipped with panic bars, which 
quickly deenergize the tramming motors in the event of an emergency. 
The existing standards do not require panic bars if the equipment is 
provided with a substantially constructed cab or canopy in accordance 
with Sec. 75.1710-1, or if other devices approved by MSHA are installed 
to quickly deenergize the tramming motor in the event of an emergency.
    Because Secs. 75.523, 75.523-1, and 75.523-2 make specific 
reference to the interrelationship among electric motors, electrical 
control components, cabs, emergency parking brakes, and panic bars, 
these standards cannot be readily adapted to diesel-powered equipment. 
An MSHA study of diesel-powered face equipment accidents occurring from 
1984 to 1995 found that this type of equipment is manufactured with a 
substantially constructed operator's compartment which provides the 
same protection as a cab. The study also found no pinning or crushing 
accidents of the type that would have been prevented by a panic bar on 
diesel equipment. Since this type of diesel equipment will be evaluated 
under part 36, the approval process can ensure that the protection 
features provided on diesel equipment will provide at least the same 
protection as that provided by a panic bar on electrical equipment. The 
final rule, therefore, does not amend Sec. 75.523 to require panic bars 
or the equivalent on diesel-powered equipment.
    The proposed rule also solicited comment on the applicability of 
existing Sec. 75.1107-1, which requires fire suppression devices on 
certain attended and unattended underground electric equipment, to 
diesel-powered equipment. The fire hazards presented by diesel-powered 
equipment are different from those on electric-powered equipment, due 
to the close proximity of large quantities of hydraulic oils and fuels 
to the heated diesel engine exhaust. Because effective fire suppression 
systems are essential for the safe operation of diesel-powered 
equipment, specific requirements for fire suppression systems on 
diesel-powered equipment are addressed in the final rule at 
Sec. 75.1911.
Derivation Table
    The following table lists final standard section numbers and 
corresponding section numbers of existing standards from which they are 
derived.

------------------------------------------------------------------------
               New sections                       Existing sections     
------------------------------------------------------------------------
Part 7--Subpart E.........................  New, Parts 7, 32, 36        
7.81......................................  New                         
7.82......................................  New, 36.2, 7.2              
7.83......................................  New, 36.6, 7.3              
7.84......................................  New, 32.4(f), 36.26(b),     
                                             36.44, 75.322              
7.85 through 7.87.........................  New                         
7.88......................................  New, 75.322                 
7.89......................................  New                         
7.90......................................  New, 36.11                  
7.91 and 7.92.............................  New                         
Part 7--Subpart F.........................  New, Parts 7, 18, 36        
7.95......................................  New                         
7.96......................................  New, 36.2, 7.2              
7.97......................................  New, 36.6, 7.3              
7.98......................................  New, Part 36--Subpart B     
7.99......................................  New                         
7.100 and 7.101...........................  New, 36.46                  
7.102 and 7.103...........................  New, 36.47                  
7.104.....................................  New, 36.46                  
7.105.....................................  New, 7.6, 36.11             
7.106.....................................  New, 7.8(b)                 
7.107.....................................  New, 7.52                   
7.108 and 7.109...........................  New                         
Part 36...................................  Partly new, Part 31         
36.1......................................  Partly new                  
36.2(e)...................................  Partly new                  
36.2(f)...................................  Partly new, 36.2(h)         
36.6 (b)(2) through (b)(4)................  Partly new                  
36.9(a)...................................  Partly new                  
36.20(b)..................................  Partly new                  
36.20(c)..................................  New                         
36.21.....................................  Partly new                  
36.43(a)..................................  Partly new                  
36.48(b)..................................  Partly new                  
70.1900(a)................................  New, 75.100, 75.362         
70.1900 (a)(1) through (b)(3).............  New                         
70.1900(c)................................  New, 75.322, 75.325(j)      

[[Page 55499]]

                                                                        
70.1900(d)................................  New, 75.363                 
70.1900 (d)(1) through (e)................  New                         
75.325 (f) through (h)....................  New, Part 32                
75.325 (i) and (j)........................  New, Part 32, 75.322        
75.325(k).................................  New, Part 32, 75.371        
75.342 (b)(2) and (c).....................  Partly new                  
75.360(b)(7)..............................  Partly new                  
75.371(r).................................  Partly new                  
75.371 (kk) through (oo)..................  New                         
75.371(pp)................................  New, 75.322                 
75.400....................................  Partly new                  
75.1710 and 75.1710-1.....................  Partly new                  
Part 75--Subpart T........................  New, Part 32                
75.1900...................................  New, 75.301                 
75.1901(a)................................  New, 36.2(i)                
75.1901(b)................................  New                         
75.1901(c)................................  New, 40 CFR 79              
75.1902...................................  New                         
75.1903(a)(1).............................  New, 75.301, 75.340         
75.1903 (a)(2) and (a)(3).................  New                         
75.1903(a)(4).............................  New, 75.333(e), 75.340      
75.1903 (a)(5) through (a)(7).............  New                         
75.1903(b)(1).............................  New, 75.1100-2(f)           
75.1903 (b)(2) through (d)(6).............  New                         
75.1904...................................  New                         
75.1905...................................  New                         
75.1906 (a) through (f)...................  New                         
75.1906(g)................................  New, 75.1107-3 through      
                                             75.1107-6, 75.1107-8       
                                             through 75.1107-16         
75.1906 (h) and (i).......................  New                         
75.1906(j)................................  New, 75.1000-3              
75.1906 (k) and (l).......................  New                         
75.1907...................................  New                         
75.1908...................................  New                         
75.1909 (a)(1) through (a)(3)(i)..........  New                         
75.1909 (a)(3)(ii)........................  New, 36.27(a)(1)            
75.1909 (a)(3)(iii) through (a)(3)(ix)....  New                         
75.1909 (a)(3)(x).........................  New, 36.27(c)               
75.1909 (a)(3)(xi) through (b)(3).........  New                         
75.1909(b)(4).............................  New, 36.28                  
75.1909(b)(5).............................  New, 36.33(b)               
75.1909 (b)(6) through (b)(8).............  New, 36.29                  
75.1909(c)................................  New, 75.523-3, 75.1404,     
                                             75.1404-1                  
75.1909(c)(1).............................  New, 75.523-3(b)(2)         
75.1909(c)(2).............................  New, 75.523-3(b)(3)         
75.1909(c)(3).............................  New, 75.523-3(b)(4)         
75.1909(c)(4).............................  New, 75.523-3(b)(5)         
75.1909(c)(5).............................  New, 75.523-3(c)            
75.1909(c)(6).............................  New                         
75.1909(d)................................  New, 75.523-3(d)            
75.1909(e)................................  New, 75.523-3(e)            
75.1909(f)................................  New, 36.29                  
75.1909 (g) through (j)...................  New                         
75.1910(a)................................  New, 75.518, 75.518-1       
75.1910 (b) through (e)...................  New                         
75.1910(f)................................  New, 75.513, 75.513-1       
75.1910 (g) and (h).......................  New, 75.515                 
75.1910(i)................................  New, 75.514                 
75.1910(j)................................  New                         
75.1910(k)................................  New, 7.44(a)(1)             
75.1910(l)................................  New, 7.44 (d), (e), and (m) 
75.1910(m)................................  New, 7.44(f)                
75.1910(n)................................  New, 7.44(h)                
75.1910(o)................................  New, 7.44(g)                
75.1911 (a) through (k)...................  New                         
75.1911(l)................................  New, 75.380(f), 75.1107-3   
                                             through 75.1107-16         
75.1912(a)(1).............................  New, 75.1107-13             
75.1912 (a)(2) through (b)................  New                         
75.1912(c)................................  New, 75.1101-23             
75.1912(d)................................  New, 75.1107-4              
75.1912 (e) through (g)...................  New                         
75.1912(h)................................  New, 75.1107-16             
75.1912(i)................................  New                         
75.1912(j)................................  New, 75.1101-23             
75.1913...................................  New                         
75.1914...................................  New                         
75.1915...................................  New                         
75.1916(a)................................  New, 75.380(d), 75.1403     
75.1916 (b) through (e)...................  New                         
------------------------------------------------------------------------

Distribution Table

    The following table lists section numbers of existing standards 
which contain provisions that were used in the development of the 
listed final standards.

------------------------------------------------------------------------
             Existing sections                      New sections        
------------------------------------------------------------------------
7.2.......................................  7.82, 7.96                  
7.3.......................................  7.83, 7.97                  
7.6.......................................  7.105                       
7.8(b)....................................  7.106                       
7.44(a)(1)................................  75.1910(k)                  
7.44 (d) and (e)..........................  75.1910(l)                  
7.44(f)...................................  75.1910(m)                  
7.44(g)...................................  75.1910(o)                  
7.44(h)...................................  75.1910(n)                  
7.44(m)...................................  75.1910(l)                  
7.44(a)(1)................................  75.1910(k)                  
7.52......................................  7.107                       
Part 31...................................  Part 36                     
Part 32...................................  Part 7--Subpart E, 75.325   
                                             (f) through (k), and Part  
                                             75--Subpart T              
32.4(f)...................................  7.84                        
Part 36--Subpart B........................  7.98                        
36.2......................................  7.82, 7.96                  
36.2(h)...................................  36.2(f)                     
36.2(i)...................................  75.1901(a)                  
36.6......................................  7.83, 7.97                  
36.11.....................................  7.90, 7.105                 
36.26(b)..................................  7.84                        
36.27(a)(1)...............................  75.1909(a)(3)(ii)           
36.27(c)..................................  75.1909(a)(3)(x)            
36.28.....................................  75.1909(b)(4)               
36.29.....................................  75.1909 (b)(6) through      
                                             (b)(8) and (f)             
36.33(b)..................................  75.1909(b)(5)               
36.44.....................................  7.84                        
36.46.....................................  7.100, 7.101, 7.104         
36.47.....................................  7.102, 7.103                
75.100....................................  70.1900(a)                  
75.301....................................  75.1900, 75.1903(a)(1)      
75.322....................................  7.84, 7.88, 70.1900(c),     
                                             75.325 (i) and (j),        
                                             75.371(pp)                 
75.325 (g) and (i)........................  75.371(r)                   
75.325(j).................................  70.1900(c)                  
75.333(e).................................  75.1903(a)(4)               
75.340....................................  75.1903 (a)(1) and (a)(4)   
75.362....................................  70.1900(a)                  
75.363....................................  70.1900(d)                  
75.371....................................  75.325(k)                   
75.380(d).................................  75.1916(a)                  
75.380(f).................................  75.1911(l)                  
75.513 and 75.513-1.......................  75.1910(f)                  
75.514....................................  75.1910(i)                  
75.515....................................  75.1910 (g) and (h)         
75.518 and 75.518-1.......................  75.1910(a)                  
75.523-3..................................  75.1909(c)                  
75.523-3(b)(2)............................  75.1909(c)(1)               
75.523-3(b)(3)............................  75.1909(c)(2)               
75.523-3(b)(4)............................  75.1909(c)(3)               
75.523-3(b)(5)............................  75.1909(c)(4)               
75.523-3(c)...............................  75.1909(c)(5)               
75.523-3(d)...............................  75.1909(d)                  
75.523-3(e)...............................  75.1909(e)                  
75.1000-3.................................  75.1906(j)                  
75.1100-2(f)..............................  75.1903(b)(1)               
75.1101-23................................  75.1912 (c) and (j)         
75.1107-3 through 75.1107-16..............  75.1911(l)                  
75.1107-3 through 75.1107-6 and 75.1107-8   75.1906(g)                  
 through 75.1107-16.                                                    
75.1107-4.................................  75.1912(d)                  
75.1107-13................................  75.1912(a)(1)               
75.1107-16................................  75.1912(h)                  
75.1403...................................  75.1916(a)                  
75.1404 and 75.1404-1.....................  75.1909(c)                  
40 CFR 79.................................  75.1901(c)                  
------------------------------------------------------------------------

III. Paperwork Reduction Act

    The information collection requirements contained in this rule have 
been submitted to the Office of Management and Budget (OMB) for review 
under the Paperwork Reduction Act of 1995 (44 U.S.C. 3501-3520), as 
implemented by OMB in regulations at 5 CFR 1320. No person may be 
required to respond to, or may be subjected to a penalty for failure to 
comply with, these information collection requirements until they have 
been approved by OMB and MSHA has displayed the assigned OMB control 
number. The OMB control number, when assigned, will be announced by 
separate notice in the Federal Register.

[[Page 55500]]

    The final rule addresses comments submitted to OMB and MSHA on the 
collection of information requirements in the proposed rule in the 
section-by-section discussions. In revising the requirements from those 
that appeared in the proposed rule, MSHA has evaluated the necessity 
and usefulness of the collection of information; reevaluated MSHA's 
estimate of the information collection burden, including the validity 
of the underlying methodology and assumptions; and minimized the 
information collection burden on respondents to the extent possible. 
This final rule also provides for the use of electronic storage and 
maintenance of records.
    Tables 1 through 4 show the distribution of information collection 
burden hours imposed by the requirements of the final rule. Tables 1 
and 2 pertain to manufacturers, Table 3 pertains to small mine 
operators, and Table 4 pertains to large mine operators.

                                             Table 1.--Estimated Annual New Burden Related to Manufacturers                                             
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                                 Operating              
                                                                                                       Number of     Capital        and                 
                          Detail                              Number of     Hours per     Number of    responses      costs     maintenance  Total hours
                                                             respondents    response      responses       per       annualized     costs                
                                                                                                       respondent   (rounded)    (rounded)              
--------------------------------------------------------------------------------------------------------------------------------------------------------
                     Part 7--Subpart E                                                                                                                  
                                                                                                                                                        
New Eng. (Perm.) \1\......................................           1.5       43                1.5            1           $0           $0           65
New Eng. (Perm.) \2\......................................           1.5        0.5              1.5            1            0           75            1
New Eng. (Nonperm.) \3\...................................           2.5       34                2.5            1            0            0           85
New Eng. (Nonperm.) \4\...................................           2.5        0.5              2.5            1            0          100            1
Existing Eng. (Nonperm.) \5\..............................          16          5               16              1          425            0           80
New Eng. (Nonperm.) \6\...................................           1         34.5              1              1            0        2,600           35
Existing Eng. (Nonperm.) \7\..............................           1         34.5              1              1          200            0           35
7.90......................................................         148          0.1667         148              1            0          450           24
                                                                                                                                                        
                     Part 7--Subpart F                                                                                                                  
                                                                                                                                                        
New Pow. Pack. (Perm.) \8\................................           1.5       43                1.5            1            0            0           65
Existing Pow. Pack. (Perm.) \9\...........................          33         12               33              1        2,100            0          396
7.105.....................................................          20          0.1667          20              1            0           75            3
                                                           ---------------------------------------------------------------------------------------------
    Total Increases.......................................  ............  ............  ............  ...........        2,725        3,300         790 
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ New diesel-powered engine models used in permissible equipment will require a maximum fuel:air ratio test and a gaseous ventilation rate test under 
  part 7, subpart E, instead of under existing part 36. Burden hours are shifted from existing part 36 to part 7, subpart E. The annual estimated       
  application costs of $4,850 are currently being incurred by manufacturers under part 36. Under the final rule, such costs will continue to be incurred
  under part 7, subpart E, instead of under part 36. There are no new compliance costs.                                                                 
\2\ New diesel-powered engine models used in permissible equipment that would have received part 36 approval will require a particulate index test.     
\3\ New diesel-powered engine models used in nonpermissible equipment that would have received part 32 approval will require a maximum fuel air ratio   
  test and a gaseous ventilation rate test under part 7, subpart E, instead of under part 32. As a result of this rule, part 32 is deleted and burden   
  hours related to the tests on such engine models are shifted from deleted part 32 to part 7, subpart E. The annual estimated application costs of     
  $6,375 are currently being incurred by manufacturers under part 32. Under the final rule, such costs will continue to be incurred under part 7,       
  subpart E, instead of under part 32. There are no new compliance costs.                                                                               
\4\ New diesel-powered engine models used in nonpermissible equipment that would have received part 32 approval will require a particulate index test.  
\5\ Existing diesel-powered engine models used in nonpermissible equipment that have part 32 approval will require a one time particulate index test.   
\6\ New diesel-powered engine models used in nonpermissible equipment that would not have received part 32 approval will require a maximum fuel air     
  ratio test, a gaseous ventilation rate test, and a particulate index test.                                                                            
\7\ Existing diesel-powered engine models used in nonpermissible equipment that do not have part 32 approval will require a one time maximum fuel air   
  ratio test, a gaseous ventilation rate test, and a particulate index test.                                                                            
\8\ New diesel-power package models used in permissible equipment will require approval under part 7, subpart F, instead of under part 36. Burden hours 
  related to such approvals are shifted from part 36 to part 7, subpart F. The annual estimated application costs of $4,850 are currently being incurred
  by manufacturers under part 36. Under the final rule, such costs will continue to be incurred under part 7, subpart F, instead of under part 36. There
  are no new compliance costs.                                                                                                                          
\9\ Diesel-power package models used in permissible equipment and previously approved under part 36 could be reapproved and used to comply with the     
  requirement for a diesel power package pursuant to part 7, subpart F.                                                                                 


                                       Table 2.--Estimated Annual Decrease in Burden Related to Manufacturers \1\                                       
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                       Number of                 Operation              
                                                              Number of     Hours per     Number of    responses     Capital        and                 
                          Detail                             respondents    response      responses       per         costs     maintenance  Total hours
                                                                                                       respondent   annualized     costs                
--------------------------------------------------------------------------------------------------------------------------------------------------------
                          Part 36                                                                                                                       
                                                                                                                                                        
New Eng. (Perm.) \2\......................................          1.5           43            1.5             1           $0           $0           65
New Pow. Pack. (Perm.) \3\................................                                                                                              
                                                                    1.5           43            1.5             1            0            0           65
                          Part 32                                                                                                                       
                                                                                                                                                        
New Eng. (Nonperm.) \4\...................................          2.95          34.5          2.95            1            0            0          102
                                                           ---------------------------------------------------------------------------------------------
    Total Decreases.......................................  ............  ............  ............  ...........  ...........  ...........         232 
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Burden hours in this chart were developed and approved under the Paperwork Reduction Act of 1980 (PRA 80). PRA 80 did not require costs to be       
  reported with burden hours. Thus no compliance costs are noted in this table.                                                                         
\2\ New diesel-powered engine models used in permissible equipment will be approved under part 7, subpart E, instead of part 36.                        
\3\ Diesel-power package models used in permissible equipment will be approved under part 7, subpart F, instead of part 36.                             

[[Page 55501]]

                                                                                                                                                        
\4\ New diesel-powered engine models used in nonpermissible equipment will be approved under part 7, subpart E, instead of part 32.                     


                    Table 3.-- Estimated Annual New Burden for Small Underground Coal Operators That Use Diesel-Powered Equipment \1\                   
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                                 Operation              
                                                                                                       Number of     Capital        and                 
                          Detail                              Number of      Hours per    Number of    responses      costs     maintenance  Total hours
                                                             respondents     response     responses       per       annualized     costs                
                                                                 \2\                                   respondent   (rounded)    (rounded)              
--------------------------------------------------------------------------------------------------------------------------------------------------------
Sec.  75.363.............................................             10         0.10            100           10       $2,100       $3,800           10
Sec.  75.370.............................................             15         0.1667           15            1            0          100            3
Sec.  75.1901(a).........................................              8         0.05            160           20            0          100            8
Sec.  75.1904(b)(4)(i)...................................             15         0.0333           20            1          <25 0="" 1="" sec.="" 75.1911="" (i)&(j)="" \3\................................="" 15="" 0.3333="" 212="" 14="" 0="" 1,835="" 71="" sec.="" 75.1911="" (i)&(j)="" \4\................................="" 15="" 1.0833="" 11=""><1 0="" 915="" 12="" sec.="" 75.1912="" (h)&(i)="" \5\................................="" 15="" 0.5833="" 20="" 1="" 0="" 300="" 12="" sec.="" 75.1912="" (h)&(i)="" \6\................................="" 15="" 1.0833="" 2=""><1 0="" 100="" 2="" sec.="" 75.1914="" (f)(1)&(h).................................="" 15="" \7\="" 1.1857="" 500="" 33="" 0="" 15,400="" 593="" sec.="" 75.1914="" (f)(2)&(h).................................="" 15="" 0.0833="" 500="" 33="" 0="" 1,100="" 42="" sec.="" 75.1914(g)&(h)="" \8\.................................="" 15="" 2="" 30="" 2="" 150="" 0="" 60="" sec.="" 75.1914="" (g)&(h)="" \9\................................="" 1="" 2="" 1="" 1="" 0="" 50="" 2="" sec.="" 75.1914="" (g)(5)&(h).................................="" 15="" 0.25="" 1,480="" 98="" 3,150="" 16,650="" 370="" sec.="" 75.1915(a).........................................="" 15="" 5="" 30="" 2="" 400="" 0="" 150="" sec.="" 75.1915="" (b)(5)&(c)="" \8\.............................="" 15="" 10="" 15="" 1="" 400="" 0="" 150="" sec.="" 75.1915="" (b)(5)&(c)="" \9\.............................="" 1="" 3="" 1="" 1="" 0="" 125="" 3="" ----------------------------------------------------------------------------------------------="" total................................................="" ..............="" ............="" ...........="" ...........="" 6,225="" 40,475="" 1,489="" --------------------------------------------------------------------------------------------------------------------------------------------------------="" \1\="" small="" mines="" are="" those="" that="" employ="" 19="" or="" fewer="" people.="" \2\="" respondents="" are="" the="" number="" of="" small="" mines.="" \3\="" section="" 75.1911(j)="" requires="" a="" record="" of="" sec.="" 75.1911(i)="" weekly="" exams="" which="" find="" defects.="" \4\="" section="" 75.1911(j)="" requires="" a="" record="" of="" sec.="" 75.1911(i)="" manufacturer="" recommended="" exams="" which="" find="" defects.="" \5\="" section="" 75.1912(i)="" requires="" a="" record="" of="" sec.="" 75.1912(h)="" weekly="" exams="" which="" find="" defects.="" \6\="" section="" 75.1912(i)="" requires="" a="" record="" of="" sec.="" 75.1912(h)="" manufacturer="" recommended="" exams="" which="" find="" defects.="" \7\="" represents="" a="" weighted="" average="" of="" hours="" based="" upon="" different="" exam="" hours="" for="" different="" types="" of="" equipment.="" \8\="" reflects="" burden="" hours="" that="" will="" occur="" in="" the="" first="" year="" of="" implementation="" of="" the="" provision.="" \9\="" reflects="" burden="" hours="" that="" will="" occur="" annually,="" after="" the="" first="" year="" of="" implementation="" of="" the="" provision.="" table="" 4.--estimated="" annual="" new="" burden="" for="" large="" underground="" coal="" operators="" that="" use="" diesel-powered="" equipment="">1                     
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                                 Operating              
                                                                                                       Number of     Capital        and                 
                           Detail                              Number of     Hours per    Number of    responses      costs     maintenance  Total hours
                                                               respondent    responses    responses       per       annualized     costs                
                                                                   2                                   respondent   (rounded)    (rounded)              
--------------------------------------------------------------------------------------------------------------------------------------------------------
Sec.  75.363................................................          100        0.1834        1,000           10      $20,950      $40,825          184
Sec.  75.370................................................          158        0.3333          158            1            0        1,975           52
Sec.  75.1901(a)............................................           79        0.05          1,975           25            0        1,000           99
Sec.  75.1904(b)(4)(i)......................................          158        0.0333          494            3          250            0           16
Sec.  75.1911 (i) & (j) 3...................................          158        0.3333       14,810           94            0      128,340        4,936
Sec.  75.1911 (i) & (j) 4...................................          158        1.0833          592            4            0       51,335          641
Sec.  75.1912 (h) & (i) 5...................................          158        0.5833          100           <1 0="" 1,525="" 58="" sec.="" 75.1912="" (h)="" &="" (i)="">6...................................          158        1.0833            4           <1 0="" 350="" 5="" sec.="" 75.1914="" (f)(1)="" &="" (h)..................................="" 158="">7 0.6234       35,975          227            0      583,150       22,428
Sec.  75.1914 (f)(2) & (h)..................................          158        0.0833       35,975          227            0       77,925        2,997
Sec.  75.1914 (g) & (h) 8...................................          158        2               711            4        3,725            0        1,422
Sec.  75.1914 (g) & (h) 9...................................            5        2              22.5            4            0        1,700           45
Sec.  75.1914 (g)(5) & (h)..................................          158        0.25         52,350          331       33,100      460,225       13,088
Sec.  75.1915(a)............................................          158        5             1,264            8            0      236,000        6,320
Sec.  75.1915 (b)(5) & (c) 8................................          158       16               158            1        6,600            0        2,528
Sec.  75.1915 (b)(5) & (c) 9................................            5       16                 5            1            0        3,000           80
                                                             -------------------------------------------------------------------------------------------
    Total...................................................  ...........  ............  ...........  ...........       64,625    1,587,350      54,899 
--------------------------------------------------------------------------------------------------------------------------------------------------------
1 Large mines are those that employ 20 or more people.                                                                                                  
2 Respondents are the number of large mines.                                                                                                            
3 Section 75.1911(j) requires a record of Sec.  75.1911(i) weekly exams which find defects.                                                             
4 Section 75.1911(j) requires a record of Sec.  75.1911(i) manufacturer recommended exams which find defects.                                           
5 Section 75.1912(i) requires a record of Sec.  75. 1912(h) weekly exams which find defects.                                                            
6 Section 75.1912(i) requires a record of Sec.  75. 1912(h) manufacturer recommended exams which find defects.                                          
7 Represents a weighted average of hours based upon different exam hours for different types of equipment.                                              
8 Reflects burden hours that will occur in the first year of implementation of the provision.                                                           
9 Reflects burden hours that will occur annually, after the first year of implementation of the provision.                                              


[[Page 55502]]

IV. Executive Order 12866 and Regulatory Flexibility Analysis

    Under E.O. 12866 [58 FR 51735, October 4, 1993] the Agency must 
determine whether the regulatory action is ``significant'' and subject 
to OMB review.
    E.O. 12866 defines ``significant regulatory action'' as one that is 
likely to result in a rule that may: (1) Have an annual effect on the 
economy of $100 million or more or adversely affect in a material way 
the economy, a sector of the economy, productivity, competition, jobs, 
the environment, public health or safety, or state, local, or tribal 
governments or communities; (2) create a serious inconsistency or 
otherwise interfere with an action taken or planned by another agency; 
(3) materially alter the budgetary impact of entitlements, grants, user 
fees, or loan programs or the right and obligations of recipients 
thereof; or (4) raise novel legal or policy issues arising out of legal 
mandates, the President's priorities, or the principles set forth in 
the Executive Order.
    OMB determined that this rule for diesel-powered equipment in 
underground coal mines is a ``significant regulatory action'' because 
MSHA's diesel particulate rulemaking for all mines has been designated 
``significant'' by the Agency. Although the diesel particulate 
rulemaking is separate and distinct from this final rule, OMB concluded 
that there is a sufficient enough relationship with this final rule to 
warrant its designation as significant. As such, MSHA has submitted 
this final rule to OMB for review.
    As required by E.O. 12866, the Agency determined costs and benefits 
associated with this final rule and has prepared a Final Regulatory 
Impact Analysis (RIA) and a Final Regulatory Flexibility Analysis 
(RFA). The RFA assesses benefits and costs of, and potentially 
effective and reasonably feasible alternatives to, the planned 
regulatory action. The RIA and RFA are available electronically and on 
request from MSHA through the address listed in the contact section at 
the beginning of this document. It is summarized below.

Benefits

    The final rule establishes comprehensive and integrated 
requirements governing diesel-powered equipment used in underground 
coal mines. Compliance with the rule will minimize fire, explosion, 
fuel handling, and fuel storage hazards. The health hazards of diesel 
engine exhaust are addressed by design, performance, and maintenance 
standards for diesel engines. Other safety hazards associated with the 
use of diesel-powered equipment in underground coal mines are also 
addressed.
    The final rule includes tests and specifications for MSHA approval 
of diesel engines. Clean operating engines will reduce miners' exposure 
to harmful emissions in the confined underground mine environment. The 
final rule sets test procedures and limits on the concentrations of 
carbon monoxide and oxides of nitrogen, and establishes the quantity of 
ventilating air necessary to dilute these exhaust contaminants to safe 
levels. The rule also contains tests and specifications for approval of 
diesel engine components, to ensure that diesel engines are fire and 
explosion-proof.
    The final rule also requires diesel-powered equipment to be 
equipped with certain safety features. These safety features will 
result in reduced fire hazards and lower the risk of accidents 
involving diesel-powered equipment. For example, the final rule 
requires diesel-powered equipment to have basic safety features, such 
as brakes and lights; fire protection features, including fuel, 
hydraulic, and electrical system protections; and properly designed, 
installed, and maintained fire suppression systems. In addition, the 
rule extends to diesel-powered equipment safety measures that already 
apply to electric-powered equipment that are proven to protect miners 
from cave-ins, such as cabs and canopies, and from explosions, such as 
methane monitors.
    The final rule provides for a systematic approach to the clean and 
safe operation of diesel-powered equipment. To accomplish this, the 
final rule sets standards for ventilation of diesel-powered equipment, 
and for routine sampling of toxic exhaust gases in the workplace, and 
requires the use of low sulfur diesel fuel to minimize emissions. It 
also requires that maintenance be performed by trained personnel to 
keep diesel equipment in proper operating condition.
    To ensure that the hazards associated with diesel fuel usage in the 
underground mine environment are properly controlled, the final rule 
includes requirements for the underground storage, transportation, and 
dispensing of diesel fuel. Design, tank capacity, and dispensing 
requirements are set for diesel fuel storage, as well as safety 
precautions and construction requirements for underground storage 
facilities and areas, including automatic fire suppression systems. 
These provisions will reduce the risk of fires involving diesel fuel.
    The final rule also extends several longstanding safety 
requirements for electric equipment to diesel-powered equipment. The 
final rule requires certain diesel equipment to be installed with 
methane monitors, providing miners with critical protection against 
methane explosions. The final rule also requires cabs and canopies to 
be installed on certain diesel-powered equipment, protecting miners 
from the dangers of roof and rib falls in the underground mine 
environment.

Cost of Compliance

    The compliance costs associated with the standards directly impact 
two industry groups: manufacturers of diesel-powered mining equipment 
and operators of underground coal mines. Part 7, subparts E and F 
relate to manufacturer costs and parts 70 and 75 relate to operator 
costs. The total compliance costs of the rule are estimated to be about 
$10.35 million per year, of which mine operators will incur about $10.3 
million per year and manufacturers will incur about $50,000 per year.
    The per-year cost of $10.3 million for mine operators consists of 
$4.9 million of annualized cost plus $5.4 million of annual costs. Of 
the $10.3 million, large mine operators will incur about $10.1 million, 
which consists of $4.8 million of annualized costs and $5.3 million of 
annual costs. Of the $10.3 million, small mine operators will incur 
about $210,800, which consists of $92,300 of annualized costs and 
$118,500 of annual costs. The per-year compliance costs for large and 
small mine operators is shown by section in Table 5.
    Manufacturers will incur costs of approximately $50,450 per year. 
The $50,450 consists of $15,900 of annualized costs and $34,550 of 
annual costs. The per-year compliance costs for manufacturers is shown 
by section in Table 6.

[[Page 55503]]



                                          Table 5.--Underground Coal Mine Compliance Costs for Diesel Equipment                                         
                                                                   [Dollars  x  1,000]                                                                  
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                       Large and small mines                    Large mines                        Small mines          
                                               ---------------------------------------------------------------------------------------------------------
                   Standard                                                                                             (G) total                       
                                                 (A) total       (B)        (C)      (D) total       (E)        (F)       [Col.        (H)        (I)   
                                                 [col. B+C]  annualized    annual    [col. E+F]  annualized    annual      H+I]    annualized    annual 
--------------------------------------------------------------------------------------------------------------------------------------------------------
70.1900.......................................      ($59.7)       $80.9   ($140.6)      ($77.7)       $75.8   ($153.5)      $18.0        $5.1      $12.9
75.325........................................       589.0          0       589.0        589.0          0       589.0         0           0          0  
75.1902.......................................        39.7         39.7       0           37.6         37.6       0           2.1         2.1        0  
75.1903.......................................        68.5         51.5      17.0         58.2         44.7      13.5        10.3         6.8        3.5
75.1904.......................................        32.7         32.7       0           31.2         31.2       0           1.5         1.5        0  
75.1905.......................................         2.4          2.4       0            2.3          2.3       0           0.1         0.1        0  
75.1906.......................................       251.8        173.5      78.3        244.7        168.8      75.9         7.1         4.7        2.4
75.1907.......................................     1,610.3      1,596.6      13.7      1,589.6      1,576.4      13.2        20.7        20.2        0.5
75.1909.......................................     3,028.0      2,532.9     495.1      2,971.2      2,487.6     483.6        56.8        45.3       11.5
75.1910.......................................       117.4        117.4       0          116.1        116.1       0           1.3         1.3        0  
75.1911.......................................     1,221.3          0     1,221.3      1,203.2          0     1,203.2        18.1         0         18.1
75.1912.......................................        20.0          0        20.0         16.5          0        16.5         3.5         0          3.5
75.1913.......................................         9.5          9.5       0            9.4          9.4       0           0.1         0.1        0  
75.1914.......................................     2,769.3         40.1   2,729.2      2,700.0         36.8   2,663.2        69.3         3.3       66.0
75.1915.......................................       573.9        155.4     418.5        572.3        153.9     418.4         1.6         1.5        0.1
75.1916.......................................         8.7          8.7       0            8.4          8.4       0           0.3         0.3        0  
                                               ---------------------------------------------------------------------------------------------------------
      Total...................................    10,282.8      4,841.3   5,441.5     10,072.0      4,749.0   5,323.0       210.8        92.3      118.5
--------------------------------------------------------------------------------------------------------------------------------------------------------


 Table 6.--Estimated Manufacturers Compliance Costs Associated With the 
   Regulations for Diesel-Powered Equipment in Underground Coal Mines   
------------------------------------------------------------------------
                                            Manufacturers costs         
                                  --------------------------------------
             Standard               (A) total       (B)                 
                                    [col. B+C]   annualized   (c) annual
------------------------------------------------------------------------
Part 7--Subpart E................      $42,650      $12,200      $30,450
Part 7--Subpart F................        7,800        3,700        4,100
                                  --------------------------------------
      Total Part 7...............       50,450       15,900       34,550
------------------------------------------------------------------------

Regulatory Flexibility Certification

    The Regulatory Flexibility Act requires that agencies developing 
regulatory standards evaluate and, where possible, include compliance 
alternatives that minimize any impact that would adversely affect small 
businesses. The use of diesel-powered equipment presents similar health 
and safety hazards in both large and small mining operations, and small 
mines will benefit from the requirements in the final rule. MSHA, 
therefore, has not exempted small mines from any provision of the final 
rule.
    Regulatory relief is not warranted because the final rule will not 
impose a substantial cost increase for small mines. MSHA has determined 
that these provisions will not have a significantly adverse impact upon 
a substantial number of small entities.

Small Business Regulatory Enforcement Fairness Act

    MSHA has determined that this final rule is not a ``major rule'' 
requiring prior approval by the Congress and the President under the 
Small Business Regulatory Enforcement Act of 1996 (5 U.S.C. Sec. 801 et 
seq.) (SBREFA), because it is not likely to result in: (1) an annual 
effect on the economy of $100 million or more; (2) a major increase in 
costs or prices for consumers, individual industries, federal, state, 
or local government agencies, or geographic regions; or (3) significant 
adverse effects on competition, employment, investment, productivity, 
innovation, or on the ability of United States-based enterprises to 
compete with foreign enterprises in domestic and export markets.
    The Agency will send copies of the final rule, preamble, and 
regulatory flexibility analysis to the President of the Senate, the 
Speaker of the House, and the General Counsel of the General Accounting 
Office.

V. Unfunded Mandates Reform Act of 1995

    Title II of the Unfunded Mandates Reform Act of 1995, Pub.L. 104-4, 
requires each federal agency to assess the effects of federal 
regulatory actions on state, local, and tribal governments and the 
private sector, other than to the extent such actions merely 
incorporate requirements specifically set forth in a statute. For 
purposes of the Unfunded Mandates Reform Act of 1995, as well as E.O. 
12875, this rule does not include any federal mandate that may result 
in increased expenditures by either State, local, and tribal 
governments, or increased expenditures by the private sector of more 
than $100 million on the private sector.

VI. Electronic Availability of Rulemaking Documents

    Electronic copies of the preamble and final rule, and the 
Regulatory Impact Analysis and Regulatory Flexibility Analysis are 
available on the Internet at the U.S. Department of Labor, Mine Safety 
and Health Administration's World Wide Web home page at http://
www.msha.gov. Instructions for accessing regulatory documents and 
information are as follows:
    From MSHA's home page select the menu item entitled ``Statutory and 
Regulatory Information.'' This will direct the search to the Statutory 
and Regulatory menu page. Then select the menu item entitled ``Federal 
Register Documents.'' This will direct the search

[[Page 55504]]

to the menu page for Federal Register Documents. The type of documents 
listed are proposed rules, final rules, meetings (Advisory Committees), 
Information Collection Requests, petitions for modifications, proposed 
policies, and miscellaneous notices. Select the menu item desired. To 
return to MSHA's home page, use the icon at the bottom of the page or 
the ``Back Button'' provided by your browser.

List of Subjects

30 CFR Part 7

    Diesel-powered equipment, Mine safety and health, Reporting and 
recordkeeping requirements.

30 CFR Parts 31 and 32

    Reporting and recordkeeping requirements, Research, Underground 
coal mines.

30 CFR Part 36

    Mine safety and health.

30 CFR Parts 70 and 75

    Diesel-powered equipment, Incorporations by reference, Mine safety 
and health, Underground coal mines, Reporting and recordkeeping 
requirements.

    Dated: October 15, 1996.
J. Davitt McAteer,
Assistant Secretary for Mine Safety and Health.

    Accordingly, chapter I of title 30, Code of Federal Regulations is 
amended as follows:

PART 7--TESTING BY APPLICANT OR THIRD PARTY

    1. The authority citation for part 7 continues to read as follows:

    Authority: 30 U.S.C. 957.

    2. New subparts E and F are added to part 7 to read as follows:

Subpart E--Diesel Engines Intended for Use in Underground Coal Mines

Sec.
7.81  Purpose and effective date.
7.82  Definitions.
7.83  Application requirements.
7.84  Technical requirements.
7.85  Critical characteristics.
7.86  Test equipment and specifications.
7.87  Test to determine the maximum fuel-air ratio.
7.88  Test to determine the gaseous ventilation rate.
7.89  Test to determine the particulate index.
7.90  Approval marking.
7.91  Post-approval product audit.
7.92  New technology.

Subpart E--Diesel Engines Intended for Use in Underground Coal 
Mines


Sec. 7.81  Purpose and effective date.

    Subpart A general provisions of this part apply to this subpart E. 
Subpart E establishes the specific engine performance and exhaust 
emission requirements for MSHA approval of diesel engines for use in 
areas of underground coal mines where permissible electric equipment is 
required and areas where non-permissible electric equipment is allowed. 
It is effective November 25, 1996.


Sec. 7.82  Definitions.

    In addition to subpart A definitions of this part, the following 
definitions apply in this subpart.
    Brake Power. The observed power measured at the crankshaft or its 
equivalent when the engine is equipped only with standard auxiliaries 
necessary for its operation on the test bed.
    Category A engines. Diesel engines intended for use in areas of 
underground coal mines where permissible electric equipment is 
required.
    Category B engines. Diesel engines intended for use in areas of 
underground coal mines where nonpermissible electric equipment is 
allowed.
    Corrosion-resistant material. Material that has at least the 
corrosion-resistant properties of type 304 stainless steel.
    Diesel engine. Any compression ignition internal combustion engine 
using the basic diesel cycle where combustion results from the spraying 
of fuel into air heated by compression.
    Exhaust emission. Any substance emitted to the atmosphere from the 
exhaust port of the combustion chamber of a diesel engine.
    Intermediate speed. Maximum torque speed if it occurs between 60 
percent and 75 percent of rated speed. If the maximum torque speed is 
less than 60 percent of rated speed, then the intermediate speed shall 
be 60 percent of the rated speed. If the maximum torque speed is 
greater than 75 percent of the rated speed, then the intermediate speed 
shall be 75 percent of rated speed.
    Low idle speed. The minimum no load speed as specified by the 
engine manufacturer.
    Maximum torque speed. The speed at which an engine develops maximum 
torque.
    Operational range. All speed and load (including percent loads) 
combinations from the rated speed to the minimum permitted engine speed 
at full load as specified by the engine manufacturer.
    Particulates. Any material collected on a specified filter medium 
after diluting exhaust gases with clean, filtered air at a temperature 
of less than or equal to 125 deg. F (52 deg. C), as measured at a point 
immediately upstream of the primary filter. This is primarily carbon, 
condensed hydrocarbons, sulfates, and associated water.
    Percent load. The fraction of the maximum available torque at an 
engine speed.
    Rated horsepower. The nominal brake power output of a diesel engine 
as specified by the engine manufacturer with a specified production 
tolerance. For laboratory test purposes, the fuel pump calibration for 
the rated horsepower must be set between the nominal and the maximum 
fuel tolerance specification.
    Rated speed. Speed at which the rated power is delivered, as 
specified by the engine manufacturer.
    Steady-state condition. Diesel engine operating condition which is 
at a constant speed and load and at stabilized temperatures and 
pressures.
    Total oxides of nitrogen. The sum total of the measured parts per 
millions (ppm) of nitric oxide (NO) plus the measured ppm of nitrogen 
dioxide (NO2).


Sec. 7.83  Application requirements.

    (a) An application for approval of a diesel engine shall contain 
sufficient information to document compliance with the technical 
requirements of this subpart and specify whether the application is for 
a category A engine or category B engine.
    (b) The application shall include the following engine 
specifications--
    (1) Model number;
    (2) Number of cylinders, cylinder bore diameter, piston stroke, 
engine displacement;
    (3) Maximum recommended air inlet restriction and exhaust 
backpressure;
    (4) Rated speed(s), rated horsepower(s) at rated speed(s), maximum 
torque speed, maximum rated torque, high idle, minimum permitted engine 
speed at full load, low idle;
    (5) Fuel consumption at rated horsepower(s) and at the maximum 
rated torque;
    (6) Fuel injection timing; and
    (7) Performance specifications of turbocharger, if applicable.
    (c) The application shall include dimensional drawings (including 
tolerances) of the following components specifying all details 
affecting the technical requirements of this subpart. Composite 
drawings specifying the required construction details may be submitted 
instead of individual drawings of the following components--

[[Page 55505]]

    (1) Cylinder head;
    (2) Piston;
    (3) Inlet valve;
    (4) Exhaust valve;
    (5) Cam shaft--profile;
    (6) Fuel cam shaft, if applicable;
    (7) Injector body;
    (8) Injector nozzle;
    (9) Injection fuel pump;
    (10) Governor;
    (11) Turbocharger, if applicable;
    (12) Aftercooler, if applicable;
    (13) Valve guide;
    (14) Cylinder head gasket; and
    (15) Precombustion chamber, if applicable.
    (d) The application shall include a drawing showing the general 
arrangement of the engine.
    (e) All drawings shall be titled, dated, numbered, and include the 
latest revision number.
    (f) When all necessary testing has been completed, the following 
information shall be submitted:
    (1) The gaseous ventilation rate for the rated speed and 
horsepower.
    (2) The particulate index for the rated speed and horsepower.
    (3) A fuel deration chart for altitudes for each rated speed and 
horsepower.


Sec. 7.84  Technical requirements.

    (a) Fuel injection adjustment. The fuel injection system of the 
engine shall be constructed so that the quantity of fuel injected can 
be controlled at a desired maximum value. This adjustment shall be 
changeable only after breaking a seal or by altering the design.
    (b) Maximum fuel-air ratio. At the maximum fuel-air ratio 
determined by Sec. 7.87 of this part, the concentrations (by volume, 
dry basis) of carbon monoxide (CO) and oxides of nitrogen (NOX) in 
the undiluted exhaust gas shall not exceed the following:
    (1) There shall be no more than 0.30 percent CO and no more than 
0.20 percent NOX for category A engines.
    (2) There shall be no more than 0.25 percent CO and no more than 
0.20 percent NOX for category B engines.
    (c) Gaseous emissions ventilation rate. Ventilation rates necessary 
to dilute gaseous exhaust emissions to the following values shall be 
determined under Sec. 7.88 of this part:

Carbon dioxide.........................  -5000 ppm                      
Carbon monoxide........................  -50 ppm                        
Nitric oxide...........................  -25 ppm                        
Nitrogen dioxide.......................  -5 ppm                         
                                                                        

A gaseous ventilation rate shall be determined for each requested speed 
and horsepower rating as described in Sec. 7.88(b) of this part.
    (d) Fuel deration. The fuel rates specified in the fuel deration 
chart shall be based on the tests conducted under paragraphs (b) and 
(c) of this section and shall ensure that the maximum fuel:air (f/a) 
ratio determined under paragraph (b) of this section is not exceeded at 
the altitudes specified in the fuel deration chart.
    (e) Particulate index. For each rated speed and horsepower 
requested, the particulate index necessary to dilute the exhaust 
particulate emissions to 1 mg/m3 shall be determined under 
Sec. 7.89 of this part.


Sec. 7.85  Critical characteristics.

    The following critical characteristics shall be inspected or tested 
on each diesel engine to which an approval marking is affixed--
    (a) Fuel rate is set properly; and
    (b) Fuel injection pump adjustment is sealed, if applicable.


Sec. 7.86  Test equipment and specifications.

    (a) Dynamometer test cell shall be used in determining the maximum 
f/a ratio, gaseous ventilation rates, and the particulate index.
    (1) The following testing devices shall be provided:
    (i) An apparatus for measuring torque that provides an accuracy of 
2.0 percent based on the engine's maximum value;
    (ii) An apparatus for measuring revolutions per minute (rpm) that 
provides an accuracy of 2.0 percent based on the engine's 
maximum value;
    (iii) An apparatus for measuring temperature that provides an 
accuracy of 4 deg. F (2 deg. C) of the absolute value 
except for the exhaust gas temperature device that provides an accuracy 
of 27 deg. F (15 deg. C);
    (iv) An apparatus for measuring intake and exhaust restriction 
pressures that provides an accuracy of 5 percent of 
maximum;
    (v) An apparatus for measuring atmospheric pressure that provides 
an accuracy of 0.5 percent of reading;
    (vi) An apparatus for measuring fuel flow that provides an accuracy 
of 2 percent based on the engine's maximum value;
    (vii) An apparatus for measuring the inlet air flow rate of the 
diesel engine that provides an accuracy of 2 percent based 
on the engine's maximum value; and
    (viii) For testing category A engines, an apparatus for metering in 
1.0 0.1 percent, by volume, of methane (CH4) into the 
intake air system shall be provided.
    (2) The test fuel specified in Table E-1 shall be a low volatile 
hydrocarbon fuel commercially designated as ``Type 2-D'' grade diesel 
fuel. The fuel may contain nonmetallic additives as follows: Cetane 
improver, metal deactivator, antioxidant, dehazer, antirust, pour 
depressant, dye, dispersant, and biocide.

               Table E-1.--Diesel Test Fuel Specifications              
------------------------------------------------------------------------
              Item                     ASTM              Type 2-D       
------------------------------------------------------------------------
Cetane number..................  D613             40-48.                
Cetane index...................  D976             40-48.                
Distillation range:                                                     
    IBP  deg.F.................  D86              340-400.              
        ( deg.C)...............  ...............  (171.1-204.4).        
    10 pct. point,  deg.F......  D86              400-460.              
        ( deg.C)...............  ...............  (204.4-237.8).        
    50 pct. point,  deg.F......  D86              470.540.              
        ( deg.C)...............  ...............  (243.3-282.2).        
    90 pct. point,  deg.F......  D86              560-630.              
        ( deg.C)...............  ...............  (293.3-332.2).        
    EP,  deg.F.................  D86              610-690.              
        ( deg.C)...............  ...............  (321.1-365.6).        
Gravity,  deg.API..............  D287             32-37.                
Total sulfur, pct..............  D2622            0.03-0.05.            
Hydrocarbon composition:                                                
    Aromatics, pct.............  D1319            27 minimum.           
    Paraffins, naphthenes,       D1319            Remainder.            
     olefins.                                                           

[[Page 55506]]

                                                                        
Flashpoint, minimum,  deg.F....  93               130.                  
    ( deg.C)...................  ...............  (54.4).               
Viscosity, centistokes.........  445              2.0-3.2.              
------------------------------------------------------------------------

    (3) The test fuel temperature at the inlet to the diesel engine's 
fuel injection pump shall be controlled to the engine manufacturer's 
specification.
    (4) The engine coolant temperature (if applicable) shall be 
maintained at normal operating temperatures as specified by the engine 
manufacturer.
    (5) The charge air temperature and cooler pressure drop (if 
applicable) shall be set to within 7 deg. F(4 deg. C) and 
0.59 inches Hg (2kPa) respectively, of the manufacturer's 
specification.
    (b) Gaseous emission sampling system shall be used in determining 
the gaseous ventilation rates.
    (1) The schematic of the gaseous sampling system shown in Figure E-
1 shall be used for testing category A engines. Various configurations 
of Figure E-1 may produce equivalent results. The components in Figure 
E-1 are designated as follows--
    (i) Filters--F1, F2, F3, and F4;
    (ii) Flowmeters--FL1, FL2, FL3, FL4, FL5, FL6, and FL7;
    (iii) Upstream Gauges--G1, G2, and G5;
    (iv) Downstream Gauges--G3, G4, and G6;
    (v) Pressure Gauges--P1, P2, P3, P4, P5, and P6;
    (vi) Regulators--R1, R2, R3, R4, R5, R6, and R7;
    (vii) Selector Valves--V1, V2, V3, V4, V6, V7, V8, V15, and V19;
    (viii) Heated Selector Valves--V5, V13, V16, and V17;
    (ix) Flow Control Valves--V9, V10, V11 and V12;
    (x) Heated Flow Control Valves--V14 and V18;
    (xi) Pump--Sample Transfer Pump;
    (xii) Temperature Sensor--(T1);
    (xiii) Dryer--D1 and D2; and
    (xiv) Water traps--WT1 and WT2.
    (A) Water removal from the sample shall be done by condensation.
    (B) The sample gas temperature or dew point shall be monitored 
either within the water trap or downstream of the water trap and shall 
not exceed 45 deg. F (7 deg. C).
    (C) Chemical dryers are not permitted.

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[[Page 55508]]

    (2) The schematic of the gaseous sampling system shown in Figure E-
2 shall be used for testing category B engines. Various configurations 
of Figure E-2 may produce equivalent results. The components are 
designated as follows--
    (i) Filters--F1, F2, F3, and F4;
    (ii) Flowmeters--FL1, FL2, FL3, and FL4;
    (iii) Upstream Gauges--G1, and G2;
    (iv) Downstream Gauges--G3, and G4;
    (v) Pressure Gauges--P1, P2, P3, and P4;
    (vi) Regulators--R1, R2, R3, and R4;
    (vii) Selector Valves--V1, V2, V3, V4, V6, and V7;
    (viii) Heated Selector Valves--V5, V8, and V12;
    (ix) Flow Control Valves--V9, V10, V11;
    (x) Heated Flow Control Valves--V13;
    (xi) Pump--Sample Transfer Pump;
    (xii) Temperature Sensor--(T1); and
    (xiii) Water traps--WT1 and WT2.
    (A) Water removal from the sample shall be done by condensation.
    (B) The sample gas temperature or dew point shall be monitored 
either within the water trap or downstream of the water trap and shall 
not exceed 45  deg.F (7  deg.C).
    (C) Chemical dryers are not permitted.
    (3) All components or parts of components that are in contact with 
the sample gas or corrosive calibration gases shall be corrosion-
resistant material.

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[[Page 55510]]

    (4) All analyzers shall obtain the sample to be analyzed from the 
same sample probe.
    (5) CO and CO2 measurements shall be made on a dry basis.
    (6) Calibration or span gases for the NOX measurement system 
shall pass through the NO2 to NO converter.
    (7) A stainless steel sample probe shall be straight, closed-end, 
multi-holed, and shall be placed inside the exhaust pipe.
    (i) The probe length shall be at least 80 percent of the diameter 
of the exhaust pipe.
    (ii) The inside diameter of the sample probe shall not be greater 
than the inside diameter of the sample line.
    (iii) The heated sample line shall have a 0.197 inch (5 mm) minimum 
and a 0.53 inch (13.5 mm) maximum inside diameter.
    (iv) The wall thickness of the probe shall not be greater than 
0.040 inch (1 mm).
    (v) There shall be a minimum of 3 holes in 3 different radial 
planes sized to sample approximately the same flow.
    (8) The sample probe shall be located in the exhaust pipe at a 
minimum distance of 1.6 feet (0.5 meters) or 3 times the diameter of 
the exhaust pipe, whichever is the larger, from the exhaust manifold 
outlet flange or the outlet of the turbocharger. The exhaust gas 
temperature at the sample probe shall be a minimum of 158 deg. F 
(70 deg. C).
    (9) The maximum allowable leakage rate on the vacuum side of the 
analyzer pump shall be 0.5 percent of the in-use flow rate for the 
portion of the system being checked.
    (10) General analyzer specifications.
    (i) The total measurement error, including the cross sensitivity to 
other gases, (paragraphs (b)(11)(ii), (b)(12)(iii), (b)(13)(iii), and 
(b)(13)(iv) of this section), shall not exceed 5 percent of 
the reading or 3.5 percent of full scale, whichever is 
smaller. For concentrations of less than 100 ppm the measurement error 
shall not exceed 4 ppm.
    (ii) The repeatability, defined as 2.5 times the standard deviation 
of 10 repetitive responses to a given calibration or span gas, must be 
no greater than 1 percent of full scale concentration for 
each range used above 155 parts per million (ppm) or parts per million 
equivalent carbon (ppmC) or 2 percent of each range used 
below 155 ppm (or ppmC).
    (iii) The analyzer peak to peak response to zero and calibration or 
span gases over any 10 second period shall not exceed 2 percent of full 
scale on all ranges used.
    (iv) The analyzer zero drift during a 1-hour period shall be less 
than 2 percent of full scale on the lowest range used. The zero-
response is the mean response, including noise, to a zero gas during a 
30-second time interval.
    (v) The analyzer span drift during a 1-hour period shall be less 
than 2 percent of full scale on the lowest range used. The analyzer 
span is defined as the difference between the span response and the 
zero response. The span response is the mean response, including noise, 
to a span gas during a 30-second time interval.
    (11) CO and CO2 analyzer specifications.
    (i) Measurements shall be made with nondispersive infrared (NDIR) 
analyzers.
    (ii) For the CO analyzer, the water and CO2 interference shall 
be less than 1 percent of full scale for ranges equal to or greater 
than 300 ppm (3 ppm for ranges below 300 ppm) when a CO2 span gas 
concentration of 80 percent to 100 percent of full scale of the maximum 
operating range used during testing is bubbled through water at room 
temperature.
    (12) For NOX analysis using a chemiluminescence (CL) analyzer 
the following parameters shall apply:
    (i) From the sample point to the NO2 to NO converter, the 
NOX sample shall be maintained between 131 deg. F (55 deg. C) and 
392 deg. F (200 deg. C).
    (ii) The NO2 to NO converter efficiency shall be at least 90 
percent.
    (iii) The quench interference from CO2 and water vapor must be 
less than 3.0 percent.
    (13) For NOX analysis using an NDIR analyzer system the 
following parameters shall apply:
    (i) The system shall include a NO2 to NO converter, a water 
trap, and a NDIR analyzer.
    (ii) From the sample point to the NO2 to NO converter, the 
NOX sample shall be maintained between 131 deg. F (55 deg. C) and 
392 deg. F (200 deg. C).
    (iii) The minimum water rejection ratio (maximum water 
interference) for the NOX NDIR analyzer shall be 5,000:1.
    (iv) The minimum CO2 rejection ratio (maximum CO2 
interference) for the NOX NDIR analyzer shall be 30,000:1.
    (14) When CH4 is measured using a heated flame ionization 
detector (HFID) the following shall apply:
    (i) The analyzer shall be equipped with a constant temperature oven 
that houses the detector and sample-handling components.
    (ii) The detector, oven, and sample-handling components shall be 
suitable for continuous operation at temperatures of 374 deg. F 
(190 deg. C)  18 deg. F (10 deg. C).
    (iii) The analyzer fuel shall contain 40  2 percent 
hydrogen. The balance shall be helium. The mixture shall contain 
 1 part per million equivalent carbon (ppmC), and 
 400 ppm CO.
    (iv) The burner air shall contain < 2="" ppmc="" hydrocarbon.="" (v)="" the="" percent="" of="" oxygen="" interference="" shall="" be="" less="" than="" 5="" percent.="" (15)="" an="" ndir="" analyzer="" for="" measuring="">4 may be used in place 
of the HFID specified in paragraph (b)(14) of this section and shall 
conform to the requirements of paragraph (b)(10) of this section. 
Methane measurements shall be made on a dry basis.
    (16) Calibration gas values shall be traceable to the National 
Institute for Standards and Testing (NIST), ``Standard Reference 
Materials'' (SRM's). The analytical accuracy of the calibration gas 
values shall be within 2.0 percent of NIST gas standards.
    (17) Span gas values shall be traceable to NIST SRM's. The 
analytical accuracy of the span gas values shall be within 2.0 percent 
of NIST gas standards.
    (18) Calibration or span gases for the CO and CO2 analyzers 
shall have purified nitrogen as a diluent. Calibration or span gases 
for the CH4 analyzer shall be CH4 with purified synthetic air 
or purified nitrogen as diluent.
    (19) Calibration or span gases for the NOX analyzer shall be 
NO with a maximum NO2 concentration of 5 percent of the NO 
content. Purified nitrogen shall be the diluent.
    (20) Zero-grade gases for the CO, CO2, CH4 , and NOX 
analyzers shall be either purified synthetic air or purified nitrogen.
    (21) The allowable zero-grade gas (purified synthetic air or 
purified nitrogen) impurity concentrations shall not exceed  
1ppm C,  1 ppm CO,  400 ppm CO2, and 
 0.1 ppm NO.
    (22) The calibration and span gases may also be obtained by means 
of a gas divider. The accuracy of the mixing device must be such that 
the concentration of the diluted calibration gases are within 2 
percent.
    (c) Particulate sampling system shall be used in determining the 
particulate index. A schematic of a full flow (single dilution) 
particulate sampling system for testing under this subpart is shown in 
Figures E-3 and E-4.
    (1) The dilution system shall meet the following parameters:
    (i) Either a positive displacement pump (PDP) or a critical flow 
venturi (CFV) shall be used as the pump/mass measurement device shown 
in Figure E-3.

[[Page 55511]]

    (ii) The total volume of the mixture of exhaust and dilution air 
shall be measured.
    (iii) All parts of the system from the exhaust pipe up to the 
filter holder, which are in contact with raw and diluted exhaust gas, 
shall be designed to minimize deposition or alteration of the 
particulate.
    (iv) All parts shall be made of electrically conductive materials 
that do not react with exhaust gas components.
    (v) All parts shall be electrically grounded to prevent 
electrostatic effects.
    (vi) Systems other than full flow systems may also be used provided 
they yield equivalent results where:
    (A) A seven sample pair (or larger) correlation study between the 
system under consideration and a full flow dilution system shall be run 
concurrently.
    (B) Correlation testing is to be performed at the same laboratory, 
test cell, and on the same engine.
    (C) The equivalency criterion is defined as a  5 
percent agreement of the sample pair averages.
    (2) The mass of particulate in the exhaust shall be collected by 
filtration. The exhaust temperature immediately before the primary 
particulate filter shall not exceed 125 deg. F (52.0 deg. C).
    (3) Exhaust system backpressure shall not be artificially lowered 
by the PDP, CFV systems or dilution air inlet system. Static exhaust 
backpressure measured with the PDP or CFV system operating shall remain 
within  0.44 inches Hg (1.5 kPa) of the static pressure 
measured without being connected to the PDP or CFV at identical engine 
speed and load.
    (4) The gas mixture temperature shall be measured at a point 
immediately ahead of the pump or mass measurement device.
    (i) Using PDP, the gas mixture temperature shall be maintained 
within  10 deg. F (6.0 deg. C) of the average operating 
temperature observed during the test, when no flow compensation is 
used.
    (ii) Flow compensation can be used provided that the temperature at 
the inlet to the PDP does not exceed 122 deg. F (50 deg. C).
    (iii) Using CFV, the gas mixture temperature shall be maintained 
within  20 deg. F (11 deg. C) of the average operating 
temperature observed during the test, when no flow compensation is 
used.
    (5) The heat exchanger shall be of sufficient capacity to maintain 
the temperature within the limits required above and is optional if 
electronic flow compensation is used.
    (6) When the temperature at the inlet of either the PDP or CFV 
exceeds the limits stated in either paragraphs (c)(4)(i) or (c)(4)(iii) 
of this section, an electronic flow compensation system shall be 
required for continuous measurement of the flow rate and control of the 
proportional sampling in the particulate sampling system.
    (7) The flow capacity of the system shall be large enough to 
eliminate water condensation.

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[[Page 55514]]

    (8) The flow capacity of the PDP or CFV system using single 
dilution shall maintain the diluted exhaust at 125  deg.F (52.0 deg. C) 
or less immediately before the primary particulate filter.
    (9) The flow capacity of the PDP or CFV system using a double 
dilution system shall be sufficient to maintain the diluted exhaust in 
the dilution tunnel at 375 deg. F (191 deg. C) or less at the sampling 
zone.
    (10) The secondary dilution system shall provide sufficient 
secondary dilution air to maintain the double-diluted exhaust stream at 
125 deg. F (52.0 deg. C) or less immediately before the primary 
particulate filter.
    (11) The gas flow meters or the mass flow measurement 
instrumentation shall have a maximum error of the measured value within 
2 percent of reading.
    (12) The dilution air shall have a temperature of 77 deg. 
F9 deg. F (25 deg. C5 deg. C), and be--
    (i) Filtered at the air inlet; or
    (ii) Sampled to determine background particulate levels, which can 
then be subtracted from the values measured in the exhaust stream.
    (13) The dilution tunnel shall have the following specifications:
    (i) Be small enough in diameter to cause turbulent flow (Reynolds 
number greater than 4,000) and of sufficient length to cause complete 
mixing of the exhaust and dilution air;
    (ii) Be at least 3 inches (75 mm) in diameter; and
    (iii) Be configured to direct the engine exhaust downstream at the 
point where it is introduced into the dilution tunnel for thorough 
mixing.
    (14) The exhaust pipe length from the exit of the engine exhaust 
manifold or turbocharger outlet to the dilution tunnel shall not exceed 
a total length of 32 feet (10 m).
    (i) When the exhaust pipe exceeds 12 feet (4 m), then all pipe in 
excess of 12 feet (4 m) shall be insulated with a radial thickness of 
at least 1.0 inch (25 mm) and the thermal conductivity of the 
insulating material shall be no greater than 0.1 W/mK measured at 
752 deg. F (400 deg. C).
    (ii) To reduce the thermal inertia of the exhaust pipe, the 
thickness to diameter ratio shall be 0.015 or less.
    (iii) The use of flexible sections shall be limited to the length 
to diameter ratio of 12 or less.
    (15) The particulate sample probe shall--
    (i) Be installed in the dilution tunnel facing upstream, on the 
dilution tunnel centerline, and approximately 10 dilution tunnel 
diameters downstream of the point where the engine's exhaust enters the 
dilution tunnel; and
    (ii) Have 0.5 inches (12 mm) minimum inside diameter.
     (16) The inlet gas temperature to the particulate sample pump or 
mass measurement device shall remain a constant temperature of 
5 deg. F (3.0 deg. C) if flow compensation is not used.
    (17) The secondary dilution portion of the double dilution system 
shall have:
    (i) A particulate transfer tube shall have a 0.5 inch (12 mm) 
minimum inside diameter not to exceed 40 inches (1020 mm) in length 
measured from the probe tip to the secondary dilution tunnel has:
    (A) An inlet with the transfer tube facing upstream in the primary 
dilution tunnel, centerline, and approximately 10 dilution tunnel 
diameters downstream of the point where the engine's exhaust enters the 
dilution tunnel.
    (B) An outlet where the transfer tube exits on the centerline of 
the secondary tunnel and points downstream.
    (ii) A secondary tunnel that has a minimum diameter of 3.0 inches 
(75 mm), and of sufficient length to provide a residence time of at 
least 0.25 seconds for the double-diluted sample.
    (iii) Secondary dilution air supplied at a temperature of 77  deg.F 
 9 deg. F(25 deg. C5 deg. C).
    (iv) A primary filter holder located within 12.0 inches (300 mm) of 
the exit of the secondary tunnel.
    (18) The particulate sampling filters shall--
    (i) Be fluorocarbon-coated glass fiber filters or fluorocarbon-
based (membrane) filters and have a 0.3 m di-octylphthalate 
(DOP) collection efficiency of at least 95 percent at a gas face 
velocity between 35 and 80 cm/s.;
    (ii) Have a minimum diameter of 1.85 inches (47 mm), 1.46 inches 
(37 mm) stain diameter;
    (iii) Have a minimum filter loading ratio of 0.5mg/1075 mm \2\ 
stain area for the single filter method.
    (iv) Have minimum filter loading such that the sum of all eight (8) 
multiple filters is equal to the minimum loading value (mg) for a 
single filter multiplied by the square root of eight (8).
    (v) Be sampled at the same time by a pair of filters in series (one 
primary and one backup filter) so that:
    (A) The backup filter holder shall be located no more than 4 inches 
(100 mm) downstream of the primary filter holder.
    (B) The primary and backup filters shall not be in contact with 
each other.
    (C) The filters may be weighed separately or as a pair with the 
filters placed stain side to stain side.
    (D) The single filter method incorporates a bypass system for 
passing the sample through the filters at the desired time.
    (vi) Have a pressure drop increase between the beginning and end of 
the test of no more than 7.4 in Hg (25kPa).
    (vii) Filters of identical quality shall be used when performing 
correlation tests specified in paragraph (c)(1)(vi) of this section.
    (19) Weighing chamber specifications.
    (i) The temperature of the chamber (room) in which the particulate 
filters are conditioned and weighed shall be maintained to within 72 
deg.F5  deg.F (22  deg.C3  deg.C) during all 
filter conditioning and weighing.
    (ii) The humidity of the chamber (room) in which the particulate 
filters are conditioned and weighed shall be maintained to a dewpoint 
of 49  deg.F5  deg.F (9.5  deg.C3  deg.C) and a 
relative humidity of 45 percent 8 percent during all filter 
conditioning and weighing.
     (iii) The chamber (room) environment shall be free of any ambient 
contaminants (such as dust) that would settle on the particulate 
filters during their stabilization. This shall be determined as 
follows:
    (A) At least two unused reference filters or reference filter pairs 
shall be weighed within four (4) hours of, but preferably at the same 
time as the sample filter (pair) weighings.
    (B) The reference filters are to be the same size and material as 
the sample filters.
    (C) If the average weight of reference filters (reference filter 
pairs) changes between sample filter weighings by more than 
5.0 percent (7.5 percent for the filter pair 
respectively) of the recommended minimum filter loading in paragraphs 
(c)(18)(iii) or (c)(18)(iv) of this section, then all sample filters 
shall be discarded and the tests repeated.
    (20) The analytical balance used to determine the weights of all 
filters shall have a precision (standard deviation) of 20 g 
and resolution of 10 g. For filters less than 70 mm diameter, 
the precision and resolution shall be 2 g and 1 g, 
respectively.
    (21) All filters shall be neutralized to eliminate the effects of 
static electricity prior to weighing.


Sec. 7.87   Test to determine the maximum fuel-air ratio.

    (a) Test procedure.
    (1) Couple the diesel engine to the dynamometer and connect the 
sampling and measurement devices specified in Sec. 7.86.
    (2) Prior to testing, zero and span the CO and NOX analyzers 
to the lowest analyzer range that will be used during this test.
    (3) While running the engine, the following shall apply:

[[Page 55515]]

    (i) The parameter for the laboratory atmospheric factor, fa, 
shall be: 0.98fa1.02;
    (A) The equation is fa=(99/Ps) * ((Ta+273)/
298)0.7 for a naturally aspirated and mechanically supercharged 
engines; or
    (B) The equation is fa=(99/Ps)0.7* ((Ta+273)/
298) 1.5 for a turbocharged engine with or without cooling of the 
intake air.

    Where:
    Ps=dry atmospheric pressure (kPa)
    Ta=intake air temperature ( deg.C)
    (ii) The air inlet restriction shall be set within 10 
percent of the recommended maximum air inlet restriction as specified 
by the engine manufacturer at the engine operating condition giving 
maximum air flow to determine the concentration of CO as specified in 
paragraph (a)(6) of this section.
    (iii) The exhaust backpressure restriction shall be set within 
10 percent of the maximum exhaust backpressure as specified 
by the engine manufacturer at the engine operating condition giving 
maximum rated horsepower to determine the concentrations of CO and 
NOX as specified in paragraph (a)(6)of this section.
    (iv) The air inlet restriction shall be set within 10 
percent of a recommended clean air filter at the engine operating 
condition giving maximum air flow as specified by the engine 
manufacturer to determine the concentration of NOX as specified in 
paragraph (a)(6) of this section.
    (4) The engine shall be at a steady-state condition when the 
exhaust gas samples are collected and other test data is measured.
    (5) In a category A engine, 1.00.1 percent CH4 
shall be injected into the engine's intake air.
    (6) Operate the engine at several speed/torque conditions to 
determine the concentrations of CO and NOX, dry basis, in the raw 
exhaust.
    (b) Acceptable performance. The CO and NOX concentrations in 
the raw exhaust shall not exceed the limits specified in Sec. 7.84(b) 
throughout the specified operational range of the engine.


Sec. 7.88  Test to determine the gaseous ventilation rate.

    The test shall be performed in the order listed in Table E-2. The 
test for determination of the particulate index described in Sec. 7.89 
may be done simultaneously with this test.
    (a) Test procedure.
    (1) Couple the diesel engine to the dynamometer and attach the 
sampling and measurement devices specified in Sec. 7.86.
    (2) A minimum time of 10 minutes is required for each test mode.
    (3) CO, CO2, NOX, and CH4 analyzers shall be zeroed 
and spanned at the analyzer range to be used prior to testing.
    (4) Run the engine.
    (i) The parameter for fa shall be calculated in accordance 
with Sec. 7.87(a)(3).
    (ii) The air inlet and exhaust backpressure restrictions on the 
engine shall be set as specified in Secs. 7.87(a)(3) (iii) and (iv).
    (5) The engine shall be at a steady-state condition before starting 
the test modes.
    (i) The output from the gas analyzers shall be measured and 
recorded with exhaust gas flowing through the analyzers a minimum of 
the last three (3) minutes of each mode.
    (ii) To evaluate the gaseous emissions, the last 60 seconds of each 
mode shall be averaged.
    (iii) A 1.00.1 percent CH4, by volume, shall be 
injected into the engine's intake air for category A engines.
    (iv) The engine speed and torque shall be measured and recorded at 
each test mode.
    (v) The data required for use in the gaseous ventilation 
calculations specified in paragraph (a)(9) of this section shall be 
measured and recorded at each test mode.
    (6) Operate the engine at each rated speed and horsepower rating 
requested by the applicant according to Table E-2 in order to measure 
the raw exhaust gas concentration, dry basis, of CO, CO2, NO, and 
NO2, and CH4- exhaust (category A engines only).
    (i) Test speeds shall be maintained within 1 percent of 
rated speed or 3 RPM, which ever is greater, except for low 
idle which shall be within the tolerances established by the 
manufacturer.
    (ii) The specified torque shall be held so that the average over 
the period during which the measurements are taken is within 
2 percent of the maximum torque at the test speed.
    (7) The concentration of CH4 in the intake air shall be 
measured for category A engines.

                                         Table E-2.--Gaseous Test Modes                                         
                                                                                                                
                      Speed                                 Rated speed             Intermediate speed     Low- 
---------------------------------------------------------------------------------------------------------  idle 
                                                                                                           speed
                    % Torque                        100     75      50      10      100     75      50   -------
                                                                                                             0  
                                                                                                                
----------------------------------------------------------------------------------------------------------------

    (8) After completion of the test modes, the following shall be 
done:
    (i) Zero and span the analyzers at the ranges used during the test.
    (ii) The gaseous emission test shall be acceptable if the 
difference in the zero and span results taken before the test and after 
the test are less than 2 percent.
    (9) The gaseous ventilation rate for each exhaust gas contaminant 
shall be calculated as follows--
    (i) The following abbreviations shall apply to both category A and 
category B engine calculations as appropriate:

cfm--Cubic feet per min (ft3/min)
Exh--Exhaust
A--Air (lbs/hr)
H--Grains of water per lb. of dry intake air
J--Conversion factor
m--Mass flow rate (mass/hr)
TI--Intake air temperature ( deg. F)
PCAir--Percent Air
PCCH4--Percent CH4 (intake air)
UCH4--Unburned CH4
PCECH4--Percent Exhaust CH4

    (ii) Exhaust gas flow calculation for category B engines shall be 
(m Exh)=(A)+(m fuel).
    (iii) Fuel/air ratio for category B engines shall be (f/a)=(m fuel) 
/ (A).
    (iv) Methane flow through category A engines shall be determined by 
the following:

PCAir=100-PCCH4
Y=(PCAir)(0.289)+(PCCH4)(0.16)
Z=(0.16)(PCCH4)Y
mCH4=(A)(Z)(1-Z)


[[Page 55516]]


    (v) Exhaust gas flow calculation for category A engines shall be (m 
Exh)=(A)+(m fuel)+(m CH4)
    (vi) Unburned CH4 (lbs/hr) calculation for category A engines 
shall be mUCH4=(m Exh)(0.00552)(PCECH4)
    (vii) Fuel/air ratio for category A engines shall be (f/a)=((m 
fuel)+(m CH4)-(m UCH4))(A)
    (viii) Conversion from dry to wet basis for both category A and 
category B engines shall be:

(NO wet basis)=(NO dry basis)(J)
(NO2 wet basis)=(NO2 dry basis)(J)
(CO2 wet basis)=(CO2 dry basis)(J)
(CO wet basis)=(CO dry basis)(10-4)(J)

Where:

J=(f/a)(-1.87)+(1-(0.00022)(H))

    (ix) NO and NO2 correction for humidity and temperature for 
category A and category B engines shall be:

(NO corr)=(NO wet basis)(E)
(NO2 corr)=(NO2 wet basis)(E)

Where:

E=1.0+(R)(H-75)+(G)(TI-77)
R=(f/a)(0.044)-(0.0038)
G=(f/a)(-0.116)+(0.0053)

    (x) The calculations to determine the m of each exhaust gas 
contaminant in grams per hour at each test point shall be as follows 
for category A and category B engines:

(m NO)=(NO corr)(0.000470)(m Exh)
(m NO2)=(NO2 corr)(0.000720)(m Exh)
(m CO2)=(CO2 wet basis)(6.89)(m Exh)
(m CO)=(CO wet basis)(4.38)(m Exh)

    (xi) The calculations to determine the ventilation rate for each 
exhaust gas contaminant at each test point shall be as follows for 
category A and category B engines:

(cfm NO)=(m NO)(K)
(cfm NO2)=(m NO2)(K)
(cfm CO2)=(m CO2)(K)
(cfm CO)=(m CO)(K)

Where:
K=13,913.4 (pollutant grams/mole) (pollutant dilution value specified 
in Sec. 7.84(c)).

    (b) The gaseous ventilation rate for each requested rated speed and 
horsepower shall be the highest ventilation rate calculated in 
paragraph (a)(9)(xi) of this section.
    (1) Ventilation rates less than 20,000 cfm shall be rounded up to 
the next 500 cfm.
    Example: 10,432 cfm shall be listed 10,500 cfm.
    (2) Ventilation rates greater than 20,000 cfm shall be rounded up 
to the next 1,000 cfm.
    Example: 26,382 cfm shall be listed 27,000 cfm.


Sec. 7.89  Test to determine the particulate index.

    The test shall be performed in the order listed in Table E-3.
    (a) Test procedure.
    (1) Couple the diesel engine to the dynamometer and connect the 
sampling and measurement devices specified in Sec. 7.86.
    (2) A minimum time of 10 minutes is required for each measuring 
point.
    (3) Prior to testing, condition and weigh the particulate filters 
as follows:
    (i) At least 1 hour before the test, each filter (pair) shall be 
placed in a closed, but unsealed, petri dish and placed in a weighing 
chamber (room) for stabilization.
    (ii) At the end of the stabilization period, each filter (pair) 
shall be weighed. The reading is the tare weight.
    (iii) The filter (pair) shall then be stored in a closed petri dish 
or a filter holder, both of which shall remain in the weighing chamber 
(room) until needed for testing.
    (iv) The filter (pair) must be re-weighed if not used within 8 
hours of its removal from the weighing chamber (room).
    (4) Run the engine.
    (i) The parameter for fa shall be calculated in accordance 
with Sec. 7.87(a)(3).
    (ii) The air inlet and exhaust backpressure restrictions on the 
engine shall be set as specified in Secs. 7.87(a)(3) (iii) and (iv).
    (iii) The dilution air shall be set to obtain a maximum filter face 
temperature of 125 deg. F (52 deg. C) or less at each test mode.
    (iv) The total dilution ratio shall not be less than 4.
    (5) The engine shall be at a steady state condition before starting 
the test modes.
    (i) The engine speed and torque shall be measured and recorded at 
each test mode.
    (ii) The data required for use in the particulate index calculation 
specified in paragraph (a)(9) of this section shall be measured and 
recorded at each test mode.
    (6) A 1.00.1 percent CH4, by volume shall be 
injected into the engine's intake air for category A engines.
    (7) Operate the engine at each rated speed and horsepower rating 
requested by the applicant according to Table E-3 to collect 
particulate on the primary filter.
    (i) One pair of single filters shall be collected or eight multiple 
filter pairs shall be collected.
    (ii) Particulate sampling shall be started after the engine has 
reached a steady-state condition.
    (iii) The sampling time required per mode shall be either a minimum 
of 20 seconds for the single filter method or a minimum of 60 seconds 
for the multiple filter method.
    (iv) The minimum particulate loading specified in Secs. 7.86(c)(18) 
(iii) or (iv) shall be done.

                                       Table E-3.--Particulate Test Modes                                       
----------------------------------------------------------------------------------------------------------------
                      Speed                                 Rated speed             Intermediate speed     Low- 
---------------------------------------------------------------------------------------------------------  idle 
                                                                                                           speed
                    % Torque                        100     75      50      10      100     75      50   -------
                                                                                                             0  
----------------------------------------------------------------------------------------------------------------
Weighting factor................................    0.15    0.15    0.15     0.1     0.1     0.1     0.1    0.15
----------------------------------------------------------------------------------------------------------------

    (v) Test speeds shall be maintained within  percent of 
rated speed or 3 RPM, which ever is greater, except for low 
idle which shall be within the tolerances set by the manufacturer.
    (vi) The specified torque shall be held so that the average over 
the period during which the measurements are being taken is within 
2 percent of the maximum torque at the test speed.
    (vii) The modal weighting factors (WF) given in Table E-3 shall be 
applied to the multiple filter method during the calculations as shown 
in paragraph (a)(9)(iii)(B) of this section.
    (viii) For the single filter method, the modal WF shall be taken 
into account during sampling by taking a sample proportional to the 
exhaust mass flow for each mode of the cycle.
    (8) After completion of the test, condition and weigh the 
particulate filters in the weighing chamber (room) as follows:
    (i) Condition the filters for at least 1 hour, but not more than 80 
hours.

[[Page 55517]]

    (ii) At the end of the stabilization period, weigh each filter. The 
reading is the gross weight.
    (iii) The particulate mass of each filter is its gross weight minus 
its tare weight.
    (iv) The particulate mass (PF for the single filter method; 
PF,i for the multiple filter method) is the sum of the 
particulate masses collected on the primary and back-up filters.
    (v) The test is void and must be rerun if the sample on the filter 
contacts the petri dish or any other surface.
    (9) The particulate index for the mass particulate shall be 
calculated from the equations listed below--
    (i) The following abbreviations shall be:

cfm--Cubic feet per min (ft\3\ min)
PT--Particulate (gr/hr)
m mix--Diluted exhaust gas mass flow rate on wet basis (kg/hr)
m sample--Mass of the diluted exhaust sample passed through the 
particulate sampling filters (kg)
PF--Particulate sample mass collected on a filter (mg) at each 
test mode as determined in Table E-3.
Kp--Humidity correction factor for particulate
WF--Weighting factor
i-Subscript denoting an individual mode, i=1, . . . n
PI--Particulate Index (cfm)

    (ii) When calculating ambient humidity correction for the 
particulate concentration (PF part), the equation shall be:

Pfcorr=(Pf)(Kp)
Kp=1/(1+0.0133 * (H-10.71))

Where:

Ha=humidity of the intake air, g water per kg dry air
Ha=(6.220 * Ra * pa)/(pB-pa - Ra * 
10-2)
Ra=relative humidity of the intake air, %
pa=saturation vapor pressure of the intake air, kPa
pB=total barometric pressure, kPa

    (iii) When the multiple filter method is used, the following 
equations shall be used.
    (A) Mass of particulate emitted is calculated as follows:
    [GRAPHIC] [TIFF OMITTED] TR25OC96.004
    
    (B) Determination of weighted particulate average is calculated as 
follows:
[GRAPHIC] [TIFF OMITTED] TR25OC96.005

    (C) Determination of particulate index for the mass particulate 
from the average of the test modes shall be calculated as follows:
[GRAPHIC] [TIFF OMITTED] TR25OC96.006

    (iv) When the single filter method is used, the following equations 
shall be used.
    (A) Mass of particulate emitted:
    [GRAPHIC] [TIFF OMITTED] TR25OC96.007
    
Where:
[GRAPHIC] [TIFF OMITTED] TR25OC96.008

[GRAPHIC] [TIFF OMITTED] TR25OC96.009

    (B) Determination of particulate index for the mass particulate 
from the average of the test modes shall be as follows:
[GRAPHIC] [TIFF OMITTED] TR25OC96.010

    (v) When the effective weighting factor, WFE,i, for each 
mode is calculated for the single filter method, the following shall 
apply.
[GRAPHIC] [TIFF OMITTED] TR25OC96.011

    (B) The value of the effective weighting factors shall be within 
0.005 (absolute value) of the weighting factors listed in 
Table E-3.

[[Page 55518]]

    (b) A particulate index for each requested rated speed and 
horsepower shall be the value determined in paragraph (a)(9)(iii)(C) of 
this section for the multiple filter method or paragraph (a)(9)(iv)(B) 
of this section for the single filter method.
    (1) Particulate indices less than 20,000 cfm shall be rounded up to 
the next 500 cfm. Example: 10,432 cfm shall be listed 10,500 cfm.
    (2) Particulate indices greater than 20,000 cfm shall be rounded up 
to the nearest thousand 1,000 cfm. Example: 26,382 cfm shall be listed 
27,000 cfm.


Sec. 7.90   Approval marking.

    Each approved diesel engine shall be identified by a legible and 
permanent approval marking inscribed with the assigned MSHA approval 
number and securely attached to the diesel engine. The marking shall 
also contain the following information:
    (a) Ventilation rate.
    (b) Rated power.
    (c) Rated speed.
    (d) High idle.
    (e) Maximum altitude before deration.
    (f) Engine model number.


Sec. 7.91   Post-approval product audit.

    Upon request by MSHA, but no more than once a year except for 
cause, the approval holder shall make a diesel engine available for 
audit at no cost to MSHA.


Sec. 7.92   New technology.

    MSHA may approve a diesel engine that incorporates technology for 
which the requirements of this subpart are not applicable if MSHA 
determines that the diesel engine is as safe as those which meet the 
requirements of this subpart.
Subpart F--Diesel Power Packages Intended for Use in Areas of 
Underground Coal Mines Where Permissible Electric Equipment Is Required
Sec.
7.95  Purpose and effective date.
7.96  Definitions.
7.97  Application requirements.
7.98  Technical requirements.
7.99  Critical characteristics.
7.100  Explosion tests.
7.101  Surface temperature tests.
7.102  Exhaust gas cooling efficiency test.
7.103  Safety system control test.
7.104  Internal static pressure test.
7.105  Approval marking.
7.106  Post-approval product audit.
7.107  New technology.
7.108  Power package checklist.

Subpart F-Diesel Power Packages Intended for Use in Areas of 
Underground Coal Mines Where Permissible Electric Equipment is 
Required


Sec. 7.95   Purpose and effective date.

    Part 7, subpart A general provisions apply to subpart F. Subpart F 
establishes the specific requirements for MSHA approval of diesel power 
packages intended for use in approved equipment in areas of underground 
coal mines where electric equipment is required to be permissible. It 
is effective November 25, 1996.


Sec. 7.96   Definitions.

    In addition to the definitions in subparts A and E of this part, 
the following definitions apply in this subpart.
    Cylindrical joint. A joint comprised of two contiguous, concentric, 
cylindrical surfaces.
    Diesel power package. A diesel engine with an intake system, 
exhaust system, and a safety shutdown system installed.
    Dry exhaust conditioner. An exhaust conditioner that cools the 
exhaust gas without direct contact with water.
    Exhaust conditioner. An enclosure, containing a cooling system, 
through which the exhaust gases pass.
    Exhaust system. A system connected to the outlet of the diesel 
engine which includes, but is not limited to, the exhaust manifold, the 
exhaust pipe, the exhaust conditioner, the exhaust flame arrester, and 
any adapters between the exhaust manifold and exhaust flame arrester.
    Fastening. A bolt, screw, or stud used to secure adjoining parts to 
prevent the escape of flame from the diesel power package.
    Flame arrester. A device so constructed that flame or sparks from 
the diesel engine cannot propagate an explosion of a flammable mixture 
through it.
    Flame arresting path (explosion-proof joint). Two or more adjoining 
or adjacent surfaces between which the escape of flame is prevented.
    Flammable mixture. A mixture of methane or natural gas with normal 
air, that will propagate flame or explode when ignited.
    Grade. The slope of an incline expressed as a percent.
    High idle speed. The maximum no load speed specified by the engine 
manufacturer.
    Intake system. A system connected to the inlet of the diesel engine 
which includes, but is not limited to, the intake manifold, the intake 
flame arrester, the emergency intake air shutoff device, the air 
cleaner, and all piping and adapters between the intake manifold and 
air cleaner.
    Plane joint. A joint comprised of two adjoining surfaces in 
parallel planes.
    Safety shutdown system. A system which, in response to signals from 
various safety sensors, recognizes the existence of a potential 
hazardous condition and automatically shuts off the fuel supply to the 
engine.
    Step (rabbet) joint. A joint comprised of two adjoining surfaces 
with a change or changes in direction between its inner and outer 
edges. A step joint may be composed of a cylindrical portion and a 
plane portion or of two or more plane portions.
    Threaded joint. A joint consisting of a male- and female-threaded 
member, both of which are the same type and gauge.
    Wet exhaust conditioner. An exhaust conditioner that cools the 
exhaust gas through direct contact with water, commonly called a water 
scrubber.


Sec. 7.97   Application requirements.

    (a) An application for approval of a diesel power package shall 
contain sufficient information to document compliance with the 
technical requirements of this subpart and include: drawings, 
specifications, and descriptions with dimensions (including tolerances) 
demonstrating compliance with the technical requirements of Sec. 7.98. 
The specifications and descriptions shall include the materials of 
construction and quantity. These shall include the following--
    (1) A general arrangement drawing showing the diesel power package 
and the location and identification of the intake system, exhaust 
system, safety shutdown system sensors, flame arresters, exhaust 
conditioner, emergency intake air shutoff device, automatic fuel 
shutoff device and the engine.
    (2) Diesel engine specifications including the MSHA approval 
number, the engine manufacturer, the engine model number, and the rated 
speed, rated horsepower, and fuel rate.
    (3) A drawing(s) which includes the fan blade material 
specifications, the location and identification of all water-cooled 
components, coolant lines, radiator, surge tank, temperature sensors, 
and orifices; arrows indicating proper flow direction; the height 
relationship of water-cooled components to the surge tank; and the 
proper procedure for filling the cooling system.
    (4) A drawing(s) showing the relative location, identification of 
components,

[[Page 55519]]

and design of the safety shutdown system.
    (5) Specific component identification, or specific information 
including detail drawings that identify the characteristics of the 
cooling system and safety shutdown system that ensures compliance with 
the technical requirements.
    (6) Detail drawings of gaskets used to form flame-arresting paths.
    (7) An assembly drawing showing the location and identification of 
all intake system components from the air cleaner to the engine head.
    (8) An assembly drawing showing the location and identification of 
all exhaust system components from the engine head to the exhaust 
outlet.
    (9) Detail drawings of those intake and exhaust system components 
identified in paragraphs (a)(7) and (a)(8) of this section that ensure 
compliance with the technical requirements. An exhaust conditioner 
assembly drawing shall be provided showing the location, dimensions, 
and identification of all internal parts, exhaust inlet and outlet, 
sensors, and the exhaust gas path through the exhaust conditioner. If a 
wet exhaust conditioner is used, the exhaust conditioner assembly 
drawing must also show the location, dimensions, and identification of 
the fill port, drain port, low water check port; high or normal 
operating water level; minimum allowable low water level; and the 
maximum allowable grade that maintains explosion-proof operations.
    (10) A power package checklist which shall consist of a list of 
specific features that must be checked and tests that must be performed 
to determine if a previously approved diesel power package is in 
approved condition. Test procedures shall be specified in sufficient 
detail to allow the evaluation to be made without reference to other 
documents. Illustrations shall be used to fully identify the approved 
configuration of the diesel power package.
    (11) Information showing that the electrical systems and components 
meet the requirements of Sec. 7.98.
    (12) A drawing list consisting of a complete list of those drawings 
and specifications which show the details of the construction and 
design of the diesel power package.
    (b) Composite drawings specifying the required construction details 
may be submitted instead of the individual drawings in paragraph (a) of 
this section.
    (c) All documents shall be titled, dated, numbered, and include the 
latest revision.
    (d) When all testing has been completed, the following information 
shall be submitted and become part of the approval documentation:
    (1) The settings of any adjustable devices used to meet the 
performance requirements of this subpart.
    (2) The coolant temperature sensor setting and exhaust gas 
temperature sensor setting used to meet the performance requirements of 
this subpart.
    (3) The minimum allowable low water level and the low water sensor 
setting used to meet the performance requirements of this subpart for 
systems using a wet exhaust conditioner as the exhaust flame arrester.
    (4) The maximum grade on which the wet exhaust conditioner can be 
operated retaining the flame arresting characteristics.
    (5) A finalized version of the power package checklist.


Sec. 7.98  Technical requirements.

    (a) The diesel power package shall use a category A diesel engine 
approved under subpart E of this part with the following additional 
requirements:
    (1) A hydraulic, pneumatic, or other mechanically actuated starting 
mechanism. Other means of starting shall be evaluated in accordance 
with the provisions of Sec. 7.107.
    (2) If an air compressor is provided, the intake air line shall be 
connected to the engine intake system between the air cleaner and the 
flame arrester. If the air compressor's inlet air line is not connected 
to the engine's intake system, it shall have an integral air filter.
    (b) The temperature of any external surface of the diesel power 
package shall not exceed 302  deg.F (150  deg.C).
    (1) Diesel power package designs using water jacketing to meet this 
requirement shall be tested in accordance with Sec. 7.101.
    (2) Diesel power packages using other techniques will be evaluated 
under the provisions of Sec. 7.107.
    (3) When using water-jacketed components, provisions shall be made 
for positive circulation of coolant, venting of the system to prevent 
the accumulation of air pockets, and effective activation of the safety 
shutdown system before the temperature of the coolant in the jackets 
exceeds the manufacturer's specifications or 212 deg. F (100 deg. C), 
whichever is lower.
    (c) External rotating parts shall not be constructed of aluminum 
alloys containing more than 0.6 percent magnesium.
    (d) If nonmetallic rotating parts are used, they shall be provided 
with a means to prevent an accumulation of static electricity. Static 
conducting materials shall have a total resistance of 1 megohm or less, 
measured with an applied potential of 500 volts or more. Static 
conducting materials having a total resistance greater than 1 megohm 
will be evaluated under the provisions of Sec. 7.107.
    (e) All V-belts shall be static conducting and have a resistance 
not exceeding 6 megohms, when measured with a direct current potential 
of 500 volts or more.
    (f) The engine crankcase breather shall not be connected to the air 
intake system of the engine. The discharge from the breather shall be 
directed away from hot surfaces of the engine and exhaust system.
    (g) Electrical components on diesel power packages shall be 
certified or approved by MSHA under parts 7, 18, 20, and 27 of this 
chapter.
    (h) Electrical systems on diesel power packages consisting of 
electrical components, interconnecting wiring, and mechanical and 
electrical protection shall meet the requirements of parts 7, 18, and 
27 of this chapter, as applicable.
    (i) The diesel power package shall be equipped with a safety 
shutdown system which will automatically shut off the fuel supply and 
stop the engine in response to signals from sensors indicating--
    (1) The coolant temperature limit specified in paragraph (b) of 
this section;
    (2) The exhaust gas temperature limit specified in paragraph (s)(4) 
of this section;
    (3) The minimum allowable low water level, for a wet exhaust 
conditioner, as established by tests in Sec. 7.100. Restarting of the 
engine shall be prevented until the water level in the wet exhaust 
conditioner has been replenished above the minimum allowable low water 
level; and
    (4) The presence of other safety hazards such as high methane 
concentration, actuation of the fire suppression system, etc., if such 
sensors are included in the safety shutdown system.
    (j) The safety shutdown system shall have the following features:
    (1) A means to automatically disable the starting circuit and 
prevent engagement of the starting mechanism while the engine is 
running, or a starting mechanism constructed of nonsparking materials.
    (2) If the design of the safety shutdown system requires that the 
lack of engine oil pressure must be overridden to start the engine, the

[[Page 55520]]

override shall not be capable of overriding any of the safety shutdown 
sensors specified in paragraph (i) of this section.
    (k) The diesel power package shall be explosion-proof as determined 
by the tests set out in Sec. 7.100.
    (l) Engine joints that directly or indirectly connect the 
combustion chamber to the surrounding atmosphere shall be explosion-
proof in accordance with paragraphs (m) through (q) of this section and 
Sec. 7.100. This paragraph does not apply to the following:
    (1) Pistons to piston rings;
    (2) Pistons to cylinder walls;
    (3) Piston rings to cylinder walls;
    (4) Cylinder head to cylinder block;
    (5) Valve stem to valve guide; or
    (6) Injector body to cylinder head.
    (m) Each segment of the intake system and exhaust system required 
to provide explosion-proof features shall be constructed of metal and 
designed to withstand a minimum internal pressure equal to four times 
the maximum pressure observed in that segment in tests under Sec. 7.100 
or a pressure of 150 psig, whichever is less. Castings shall be free 
from blowholes.
    (n) Welded joints forming the explosion-proof intake and exhaust 
systems shall be continuous and gas-tight. At a minimum, they shall be 
made in accordance with American Welding Society Standard D14.4-77 or 
meet the test requirements of Sec. 7.104 with the internal pressure 
equal to four times the maximum pressure observed in tests under 
Sec. 7.100 or a pressure of 150 psig, whichever is less.
    (o) Flexible connections shall be permitted in segments of the 
intake and exhaust systems required to provide explosion-proof 
features, provided that failure of the connection activates the safety 
shutdown system before the explosion-proof characteristics are lost.
    (p) Flame-arresting paths in the intake and exhaust systems shall 
be formed either by--
    (1) Flanged metal to metal joints meeting the requirements of 
paragraph (q) of this section; or
    (2) Metal flanges fitted with metal gaskets and meeting the 
following requirements:
    (i) Flat surfaces between bolt holes that form any part of a flame-
arresting path shall be planed to within a maximum deviation of one-
half the maximum clearance specified in paragraph (q)(7) of this 
section. All metal surfaces forming a flame-arresting path shall be 
finished during the manufacturing process to not more than 250 
microinches.
    (ii) A means shall be provided to ensure that fastenings maintain 
the tightness of joints. The means provided shall not lose its 
effectiveness through repeated assembly and disassembly.
    (iii) Fastenings shall be as uniform in size as practicable to 
preclude improper assembly.
    (iv) Holes for fastenings shall not penetrate to the interior of an 
intake or exhaust system and shall be threaded to ensure that all 
specified bolts or screws will not bottom even if the washers are 
omitted.
    (v) Fastenings used for joints of flame-arresting paths on intake 
or exhaust systems shall be used only for attaching parts that are 
essential in maintaining the explosion-proof integrity. They shall not 
be used for attaching brackets or other parts.
    (vi) The minimum thickness of material for flanges shall be \1/2\-
inch, except that a final thickness of \7/16\-inch is allowed after 
machining rolled plate.
    (vii) The maximum fastening spacing shall be 6 inches.
    (viii) The minimum diameter of fastenings shall be \3/8\-inch, 
except smaller diameter fastenings may be used if the joint first meets 
the requirements of the static pressure test in Sec. 7.104, and the 
explosion test in Sec. 7.100.
    (ix) The minimum thread engagement of fastenings shall be equal to 
or greater than the nominal diameter of the fastenings specified, or 
the intake or exhaust system must meet the test requirements of the 
explosion tests in Sec. 7.100 and the static pressure test in 
Sec. 7.104.
    (x) The minimum contact surface of gaskets forming flame-arresting 
paths shall be \3/8\-inch, and the thickness of the gaskets shall be no 
greater than \1/16\-inch. The minimum distance from the interior edge 
of a gasket to the edge of a fastening hole shall be \3/8\-inch. The 
gaskets shall be positively positioned, and a means shall be provided 
to preclude improper installation. When the joint is completely 
assembled, it shall be impossible to insert a 0.0015-inch thickness 
gauge to a depth exceeding \1/8\-inch between the gasket and mating 
flanges. Other gasket designs shall be evaluated in accordance with 
Sec. 7.107.
    (q) The following construction requirements shall apply to flame-
arresting paths formed without gaskets:
    (1) Flat surfaces between fastening holes that form any part of a 
flame-arresting path shall be planed to within a maximum deviation of 
one-half the maximum clearance specified in paragraph (q)(7) of this 
section. All metal surfaces forming a flame-arresting path shall be 
finished during the manufacturing process to not more than 250 
microinches. A thin film of nonhardening preparation to inhibit rusting 
may be applied to these finished metal surfaces, as long as the final 
surface can be readily wiped free of any foreign materials.
    (2) A means shall be provided to ensure that fastenings maintain 
the tightness of joints. The means provided shall not lose its 
effectiveness through repeated assembly and disassembly.
    (3) Fastenings shall be as uniform in size as practicable to 
preclude improper assembly.
    (4) Holes for fastenings shall not penetrate to the interior of an 
intake or exhaust system and shall be threaded to ensure that all 
specified bolts or screws will not bottom even if the washers are 
omitted.
    (5) Fastenings used for joints of flame-arresting paths on intake 
or exhaust systems shall be used only for attaching parts that are 
essential in maintaining the explosion-proof integrity. They shall not 
be used for attaching brackets or other parts.
    (6) The flame-arresting path of threaded joints shall conform to 
the requirements of paragraph (q)(7) of this section.
    (7) Intake and exhaust systems joints shall meet the specifications 
set out in Table F-1.

   Table F-1.--Dimensional Requirements for Explosion-Proof Intake and  
                          Exhaust System Joints                         
------------------------------------------------------------------------
                                                                        
------------------------------------------------------------------------
Minimum thickness of material for flanges........  \1/2\'' 1            
Minimum width of joint; all in one plane.........  1''                  
Maximum clearance; joint all in one plane........  0.004''              
Minimum width of joint, portions of which are      \3/4\'' 2            
 different planes; cylinders or equivalent.                             
Maximum clearances; joint in two or more planes,                        
 cylinders or equivalent:                                               
    Portion perpendicular to plane...............  0.008'' 3            
    Plane portion................................  0.006''              
Maximum fastening 4 spacing; joints all in one     6''                  
 plane \5\.                                                             
Maximum fastening spacing; joints, portions of     8''                  
 which are in different planes.                                         

[[Page 55521]]

                                                                        
Minimum diameter of fastening (without regard to   \3/8\''              
 type of joint) \6\.                                                    
Minimum thread engagement of fastening \7\.......  \1/16\''             
Maximum diametrical clearance between fastening                         
 body and unthreaded holes through which it                             
 passes \8\ \9\ \10\.                                                   
Minimum distance from interior of the intake or                         
 exhaust system to the edge of a fastening hole:                        
 \11\                                                                   
    Joint-minimum width 1''......................  \7/16\''\8\ \12\     
Shafts centered by ball or roller bearings:                             
    Minimum length of flame-arresting path.......  1''                  
    Maximum diametrical clearance................  0.030''              
Other cylindrical joints:                                               
    Minimum length of flame-arresting path.......  1''                  
    Maximum diametrical clearance................  0.010''              
------------------------------------------------------------------------
\1\ \1/16\-inch less is allowable for machining rolled plate.           
\2\ If only two planes are involved, neither portion of a joint shall be
  less than \1/8\-inch wide, unless the wider portion conforms to the   
  same requirements as those for a joint that is all in one plane. If   
  more than two planes are involved (as in labyrinths or tongue-in-     
  groove joints), the combined lengths of those portions having         
  prescribed clearances are considered.                                 
\3\ The allowable diametrical clearance is 0.008-inch when the portion  
  perpendicular to the plane portion is \1/4\-inch or greater in length.
  If the perpendicular portion is more than \1/8\-inch but less than \1/
  4\-inch wide, the diametrical clearance shall not exceed 0.006-inch.  
\4\ Studs, when provided, shall bottom in blind holes, be completely    
  welded in place, or have the bottom of the hole closed with a plug    
  secured by weld or braze. Fastenings shall be provided at all corners.
                                                                        
\5\ The requirements as to diametrical clearance around the fastening   
  and minimum distance from the fastening hole to the inside of the     
  intake or exhaust system apply to steel dowel pins. In addition, when 
  such pins are used, the spacing between centers of the fastenings on  
  either side of the pin shall not exceed 5 inches.                     
\6\ Fastening diameters smaller than specified may be used if the joint 
  or assembly meets the test requirements of Sec.  7.104.               
\7\ Minimum thread engagement shall be equal to or greater than the     
  nominal diameter of the fastening specified, or the intake or exhaust 
  system must meet the test requirements of Sec.  7.104.                
\8\ The requirements as to diametrical clearance around the fastening   
  and minimum distance from the fastening hole to the inside of the     
  intake or exhaust system apply to steel dowel pins. In addition, when 
  such pins are used, the spacing between centers of the fastenings on  
  either side of the pin shall not exceed 5 inches.                     
\9\ This maximum clearance only applies when the fastening is located   
  within the flame-arresting path.                                      
\10\ Threaded holes for fastenings shall be machined to remove burrs or 
  projections that affect planarity of a surface forming a flame-       
  arresting path.                                                       
\11\ Edge of the fastening hole shall include any edge of any machining 
  done to the fastening hole, such as chamfering.                       
\12\ f the diametrical clearance for fastenings does not exceed \1/32\- 
  inch, then the minimum distance shall be \1/4\-inch.                  

    (r) Intake system. (1) The intake system shall include a device 
between the air cleaner and intake flame arrester, operable from the 
equipment operator's compartment, to shut off the air supply to the 
engine for emergency purposes. Upon activation, the device must operate 
immediately and the engine shall stop within 15 seconds.
    (2) The intake system shall include a flame arrester that will 
prevent an explosion within the system from propagating to a 
surrounding flammable mixture when tested in accordance with the 
explosion tests in Sec. 7.100. The flame arrester shall be located 
between the air cleaner and the intake manifold and shall be attached 
so that it can be removed for inspection or cleaning. The flame 
arrester shall be constructed of corrosion-resistant metal and meet the 
following requirements:
    (i) Two intake flame arrester designs, the spaced-plate type and 
the crimped ribbon type, will be tested in accordance with the 
requirements of Sec. 7.100. Variations to these designs or other intake 
flame arrester designs will be evaluated under the provisions of 
Sec. 7.107.
    (ii) In flame arresters of the spaced-plate type, the thickness of 
the plates shall be at least 0.125-inch; spacing between the plates 
shall not exceed 0.018-inch; and the flame-arresting path formed by the 
plates shall be at least 1 inch wide. The unsupported length of the 
plates shall be short enough that permanent deformation resulting from 
explosion tests shall not exceed 0.002-inch. The plates and flame 
arrester housing shall be an integral unit which cannot be 
disassembled.
    (iii) In flame arresters of the crimped ribbon type, the dimensions 
of the core openings shall be such that a plug gauge 0.018-inch in 
diameter shall not pass through, and the flame-arresting path core 
thickness shall be at least 1 inch. The core and flame arrester housing 
shall be an integral unit which cannot be disassembled.
    (3) The intake system shall be designed so that improper 
installation of the flame arrester is impossible.
    (4) The intake system shall include an air cleaner service 
indicator. The air cleaner shall be installed so that only filtered air 
will enter the flame arrester. The air cleaner shall be sized and the 
service indicator set in accordance with the engine manufacturer's 
recommendations. Unless the service indicator is explosion-proof, it 
shall be located between the air cleaner and flame arrester, and the 
service indicator setting shall be reduced to account for the 
additional restriction imposed by the flame arrester.
    (5) The intake system shall include a connection between the intake 
flame arrester and the engine head for temporary attachment of a device 
to indicate the total vacuum in the system. This opening shall be 
closed by a plug or other suitable device that is sealed or locked in 
place except when in use.
    (s) Exhaust system. (1) The exhaust system shall include a flame 
arrester that will prevent propagation of flame or discharge of glowing 
particles to a surrounding flammable mixture. The flame arrester shall 
be constructed of corrosion-resistant metal.
    (i) If a mechanical flame arrester is used, it shall be positioned 
so that only cooled exhaust gas at a maximum temperature of 302 deg. F 
(150 deg. C) will be discharged through it.
    (ii) If a mechanical flame arrester of the spaced-plate type is 
used, it must meet the requirements of paragraph (r)(2)(ii) of this 
section and the test requirements of Sec. 7.100. Variations to the 
spaced-plate flame arrester design and other mechanical flame arrester 
designs shall be evaluated under the provisions of Sec. 7.107. The 
flame arrester shall be designed and attached so that it can be removed 
for inspection and cleaning.
    (2) The exhaust system shall allow a wet exhaust conditioner to be 
used as the exhaust flame arrester provided that

[[Page 55522]]

the explosion tests of Sec. 7.100 demonstrate that the wet exhaust 
conditioner will arrest flame. When used as a flame arrester, the wet 
exhaust conditioner shall be equipped with a sensor to automatically 
activate the safety shutdown system at or above the minimum allowable 
low water level established by Sec. 7.100. Restarting of the engine 
shall be prevented until the water supply in the wet exhaust 
conditioner has been replenished above the minimum allowable low water 
level. All parts of the wet exhaust conditioner and associated 
components that come in contact with contaminated exhaust conditioner 
water shall be constructed of corrosion-resistant material. The wet 
exhaust conditioner shall include a means for verifying that the safety 
shutdown system operates at the proper water level. A means shall be 
provided for draining and cleaning the wet exhaust conditioner. The 
final exhaust gas temperature at discharge from the wet exhaust 
conditioner shall not exceed 170 deg. F (76 deg. C) under test 
conditions specified in Sec. 7.102. A sensor shall be provided that 
activates the safety shutdown system before the exhaust gas temperature 
at discharge from the wet exhaust conditioner exceeds 185 deg. F 
(85 deg. C) under test conditions specified in Sec. 7.103(a)(4).
    (3) The exhaust system shall be designed so that improper 
installation of the flame arrester is impossible.
    (4) The exhaust system shall provide a means to cool the exhaust 
gas and prevent discharge of glowing particles.
    (i) When a wet exhaust conditioner is used to cool the exhaust gas 
and prevent the discharge of glowing particles, the temperature of the 
exhaust gas at the discharge from the exhaust conditioner shall not 
exceed 170 deg. F (76 deg. C) when tested in accordance with the 
exhaust gas cooling efficiency test in Sec. 7.102. A sensor shall be 
provided that activates the safety shutdown system before the exhaust 
gas temperature at discharge from the wet exhaust conditioner exceeds 
185 deg. F (85 deg. C) when tested in accordance with the safety system 
controls test in Sec. 7.103. All parts of the wet exhaust conditioner 
and associated components that come in contact with contaminated 
exhaust conditioner water shall be constructed of corrosion-resistant 
material.
    (ii) When a dry exhaust conditioner is used to cool the exhaust 
gas, the temperature of the exhaust gas at discharge from the diesel 
power package shall not exceed 302 deg. F (150 deg. C) when tested in 
accordance with the exhaust gas cooling efficiency test of Sec. 7.102. 
A sensor shall be provided that activates the safety shutdown system 
before the exhaust gas exceeds 302 deg. F (150 deg. C) when tested in 
accordance with the safety system control test in Sec. 7.103. A means 
shall be provided to prevent the discharge of glowing particles, and it 
shall be evaluated under the provisions of Sec. 7.107.
    (5) Other means for cooling the exhaust gas and preventing the 
propagation of flame or discharge of glowing particles shall be 
evaluated under the provisions of Sec. 7.107.
    (6) There shall be a connection in the exhaust system for temporary 
attachment of a device to indicate the total backpressure in the system 
and collection of exhaust gas samples. This opening shall be closed by 
a plug or other suitable device that is sealed or locked in place 
except when in use.


Sec. 7.99  Critical characteristics.

    The following critical characteristics shall be inspected or tested 
on each diesel power package to which an approval marking is affixed:
    (a) Finish, width, planarity, and clearances of surfaces that form 
any part of a flame-arresting path.
    (b) Thickness of walls and flanges that are essential in 
maintaining the explosion-proof integrity of the diesel power package.
    (c) Size, spacing, and tightness of fastenings.
    (d) The means provided to maintain tightness of fastenings.
    (e) Length of thread engagement on fastenings and threaded parts 
that ensure the explosion-proof integrity of the diesel power package.
    (f) Diesel engine approval marking.
    (g) Fuel rate setting to ensure that it is appropriate for the 
intended application, or a warning tag shall be affixed to the fuel 
system notifying the purchaser of the need to make proper adjustments.
    (h) Material and dimensions of gaskets that are essential in 
maintaining the explosion-proof integrity of the diesel power package.
    (i) Dimensions and assembly of flame arresters.
    (j) Materials of construction to ensure that the intake system, 
exhaust system, cooling fans, and belts have been fabricated from the 
required material.
    (k) Proper interconnection of the coolant system components and use 
of specified components.
    (l) Proper interconnection of the safety shutdown system components 
and use of specified components.
    (m) All plugs and covers to ensure that they are tightly installed.
    (n) The inspections and tests described in the diesel power package 
checklist shall be performed and all requirements shall be met.


Sec. 7.100  Explosion tests.

    (a) Test procedures. (1) Prepare to test the diesel power package 
as follows:
    (i) Perform a detailed check of parts against the drawings and 
specifications submitted under Sec. 7.97 to determine that the parts 
and drawings agree.
    (ii) Remove all parts that do not contribute to the operation or 
ensure the explosion-proof integrity of the diesel power package such 
as the air cleaner and exhaust gas dilution system.
    (iii) Fill coolant system fluid and engine oil to the engine 
manufacturer's recommended levels.
    (iv) Interrupt fuel supply to the injector pump.
    (v) Establish a preliminary low water level for systems using the 
wet exhaust conditioner as a flame arrester.
    (2) Perform static and dynamic tests of the intake system as 
follows:
    (i) Install the diesel power package in an explosion test chamber 
which is large enough to contain the complete diesel power package. The 
chamber must be sufficiently darkened and provide viewing capabilities 
of the flame-arresting paths to allow observation during testing of any 
discharge of flame or ignition of the flammable mixture surrounding the 
diesel power package. Couple the diesel power package to an auxiliary 
drive mechanism. Attach a pressure measuring device, a temperature 
measuring device, and an ignition source to the intake system. The 
pressure measuring device shall be capable of indicating the peak 
pressure accurate to 1 pound-per-square inch gauge (psig) 
at 100 psig static pressure and shall have a frequency response of 40 
Hertz or greater. The ignition source shall be an electric spark with a 
minimum energy of 100 millijoules. The ignition source shall be located 
immediately adjacent to the intake manifold and the pressure and 
temperature devices shall be located immediately adjacent to the flame 
arrester.
    (ii) For systems using the wet exhaust conditioner as an exhaust 
flame arrester, fill the exhaust conditioner to the specified high or 
normal operating water level.
    (iii) Fill the test chamber with a mixture of natural gas and air 
or methane and air. If natural gas is used, the content of combustible 
hydrocarbons shall total at least 98.0 percent, by volume, with the 
remainder being inert. At least 80.0 percent, by volume, of the gas 
shall be methane. For all tests, the methane or natural gas 
concentration shall be 8.51.8 percent, by volume, and the 
oxygen

[[Page 55523]]

concentration shall be no less than 18 percent, by volume.
    (iv) Using the auxiliary drive mechanism, motor the engine to fill 
the intake and exhaust systems with the flammable mixture. The intake 
system, exhaust system, and test chamber gas concentration shall not 
differ by more than 0.3 percent, by volume, at the time of 
ignition.
    (v) For static tests, stop the engine, actuate the ignition source, 
and observe the peak pressure. The peak pressure shall not exceed 110 
psig. If the peak pressure exceeds 110 psig, construction changes shall 
be made that result in a reduction of pressure to 110 psig or less, or 
the system shall be tested in accordance with the static pressure test 
of Sec. 7.104 with the pressure parameter replaced with a static 
pressure of twice the highest value recorded.
    (vi) If the peak pressure does not exceed 110 psig or if the system 
meets the static pressure test requirements of this section and there 
is no discharge of visible flames or glowing particles or ignition of 
the flammable mixture in the chamber, a total of 20 tests shall be 
conducted in accordance with the explosion test specified above.
    (vii) For dynamic tests, follow the same procedures for static 
tests, except actuate the ignition source while motoring the engine. 
Forty dynamic tests shall be conducted at two speeds, twenty at 
1800200 RPM and twenty at 1000200 RPM. Under 
some circumstances, during dynamic testing the flammable mixture may 
continue to burn within the diesel power package after ignition. This 
condition can be recognized by the presence of a rumbling noise and a 
rapid increase in temperature. This can cause the flame-arrester to 
reach temperatures which can ignite the surrounding flammable mixture. 
Ignition of the flammable mixture in the test chamber under these 
circumstances does not constitute failure of the flame arrester. 
However; if this condition is observed, the test operator should 
immediately stop the engine and allow components to cool to prevent 
damage to the components.
    (3) Perform static and dynamic tests of the exhaust system as 
follows:
    (i) Prepare the diesel power package for explosion tests according 
to Sec. 7.100(a)(2)(i) as follows:
    (A) Install the ignition source immediately adjacent to the exhaust 
manifold.
    (B) Install pressure measuring devices in each segment as follows: 
immediately adjacent to the exhaust conditioner inlet; in the exhaust 
conditioner; and immediately adjacent to the flame arrester, if 
applicable.
    (C) Install a temperature device immediately adjacent to the 
exhaust conditioner inlet.
    (ii) If the exhaust system is provided with a spaced-plate flame 
arrester in addition to an exhaust conditioner, explosion tests of the 
exhaust system shall be performed as described for the intake system in 
accordance with this section. Water shall not be present in a wet 
exhaust conditioner for the tests.
    (iii) If the wet exhaust conditioner is used as the exhaust flame 
arrester, explosion testing of this type of system shall be performed 
as described for the intake system in accordance with this section with 
the following modifications:
    (A) Twenty static tests, twenty dynamic tests at 1800  
200 RPM, and twenty dynamic tests at 1000200 RPM shall be 
conducted at 2 inches below the minimum allowable low water level. All 
entrances in the wet exhaust conditioner which do not form explosion-
proof joints shall be opened. These openings may include lines which 
connect the reserve water supply to the wet exhaust conditioner, insert 
flanges, float flanges, and cover plates. These entrances are opened 
during this test to verify that they are not flame paths.
    (B) Twenty static tests, twenty dynamic tests at 1800 
200 RPM rated speed, and twenty dynamic tests at 1000200 
RPM shall be conducted at 2 inches below the minimum allowable low 
water level. All entrances in the wet exhaust conditioner (except the 
exhaust conditioner outlet) which do not form explosion-proof joints 
shall be closed. These openings are closed to simulate normal 
operation.
    (C) Twenty static tests, twenty dynamic tests at 
1800200 RPM rated speed, and twenty dynamic tests at 
1000200 RPM shall be conducted at the specified high or 
normal operating water level. All entrances in the wet exhaust 
conditioner which do not form explosion-proof joints shall be opened.
    (D) Twenty static tests, twenty dynamic tests at 
1800200 RPM, and twenty dynamic tests at 
1000200 RPM shall be conducted at the specified high or 
normal operating water level. All entrances in the wet exhaust 
conditioner (except the exhaust conditioner outlet) which do not form 
explosion-proof joints shall be closed.
    (iv) After successful completion of the explosion tests of the 
exhaust system, the minimum allowable low water level, for a wet 
exhaust conditioner used as the exhaust flame arrester, shall be 
determined by adding two inches to the lowest water level that passed 
the explosion tests.
    (v) A determination shall be made of the maximum grade on which the 
wet exhaust conditioner can be operated retaining the flame-arresting 
characteristics.
    (b) Acceptable performance. The explosion tests shall not result in 
any of the following--
    (1) Discharge of flame or glowing particles.
    (2) Visible discharge of gas through gasketed joints.
    (3) Ignition of the flammable mixture in the test chamber.
    (4) Rupture of any part that affects the explosion-proof integrity.
    (5) Clearances, in excess of those specified in this subpart, along 
accessible flame-arresting paths, following any necessary retightening 
of fastenings.
    (6) Pressure exceeding 110 psig, unless the intake system or 
exhaust system has withstood a static pressure of twice the highest 
value recorded in the explosion tests of this section following the 
static pressure test procedures of Sec. 7.104.
    (7) Permanent distortion of any planar surface of the diesel power 
package exceeding 0.04-inches/linear foot.
    (8) Permanent deformation exceeding 0.002-inch between the plates 
of spaced-plate flame arrester designs.


Sec. 7.101  Surface temperature tests.

    The test for determination of exhaust gas cooling efficiency 
described in Sec. 7.102 may be done simultaneously with this test.
    (a) Test procedures. (1) Prepare to test the diesel power package 
as follows:
    (i) Perform a detailed check of parts against the drawings and 
specifications submitted to MSHA under compliance with Sec. 7.97 to 
determine that the parts and drawings agree.
    (ii) Fill the coolant system with a mixture of equal parts of 
antifreeze and water, following the procedures specified in the 
application, Sec. 7.97(a)(3).
    (iii) If a wet exhaust conditioner is used to cool the exhaust gas, 
fill the exhaust conditioner to the high or normal operating water 
level and have a reserve water supply available, if applicable.
    (2) Tests shall be conducted as follows:
    (i) The engine shall be set to the rated horsepower specified in 
Sec. 7.97(a)(2).
    (ii) Install sufficient temperature measuring devices to determine 
the location of the highest coolant temperature. The temperature 
measuring devices shall be accurate to 4  deg.F 
(2  deg.C).
    (iii) Operate the engine at rated horsepower and with 
0.50.1 percent,

[[Page 55524]]

by volume, of methane in the intake air mixture until all parts of the 
engine, exhaust coolant system, and other components reach their 
respective equilibrium temperatures. The liquid fuel temperature into 
the engine shall be maintained at 100  deg.F (38  deg.C) 10 
 deg.F (6  deg.C) and the intake air temperature shall be maintained at 
70  deg.F (21  deg.C) 5  deg.F (3  deg.C).
    (iv) Increase the coolant system temperatures until the highest 
coolant temperature is 205  deg.F to 212  deg.F (96  deg.C to 100 
deg.C), or to the maximum temperature specified by the applicant, if 
lower.
    (v) After all coolant system temperatures stabilize, operate the 
engine for 1 hour.
    (vi) The ambient temperature shall be between 50  deg.F (10  deg.C) 
and 104  deg.F (40  deg.C) throughout the tests.
    (b) Acceptable performance. The surface temperature of any external 
surface of the diesel power package shall not exceed 302  deg.F (150 
deg.C) during the test.


Sec. 7.102  Exhaust gas cooling efficiency test.

    (a) Test procedures. (1) Follow the procedures specified in 
Sec. 7.101(a).
    (2) Install a temperature measuring device to measure the exhaust 
gas temperature at discharge from the exhaust conditioner. The 
temperature measuring device shall be accurate to 4  deg.F 
(2  deg.C).
    (3) Determine the exhaust gas temperature at discharge from the 
exhaust conditioner before the exhaust gas is diluted with air.
    (b) Acceptable performance.
    (1) The exhaust gas temperature at discharge from a wet exhaust 
conditioner before the exhaust gas is diluted with air shall not exceed 
170  deg.F (76  deg.C).
    (2) The exhaust gas temperature at discharge from a dry exhaust 
conditioner before the gas is diluted with air shall not exceed 302 
deg.F (150  deg.C).


Sec. 7.103  Safety system control test.

    (a) Test procedures. (1) Prior to testing, perform the tasks 
specified in Sec. 7.101(a)(1) and install sufficient temperature 
measuring devices to measure the highest coolant temperature and 
exhaust gas temperature at discharge from the exhaust conditioner. The 
temperature measuring devices shall be accurate to 4  deg.F 
(2  deg.C).
    (2) Determine the effectiveness of the coolant system temperature 
shutdown sensors which will automatically activate the safety shutdown 
system and stop the engine before the coolant temperature in the 
cooling jackets exceeds manufacturer's specifications or 212  deg.F 
(100  deg.C), whichever is lower, by operating the engine and causing 
the coolant in the cooling jackets to exceed the specified temperature.
    (3) For systems using a dry exhaust gas conditioner, determine the 
effectiveness of the temperature sensor in the exhaust gas stream which 
will automatically activate the safety shutdown system and stop the 
engine before the cooled exhaust gas temperature exceeds 302  deg.F 
(150  deg.C), by operating the engine and causing the cooled exhaust 
gas to exceed the specified temperature.
    (4) For systems using a wet exhaust conditioner, determine the 
effectiveness of the temperature sensor in the exhaust gas stream which 
will automatically activate the safety shutdown system and stop the 
engine before the cooled exhaust gas temperature exceeds 185  deg.F (85 
 deg.C), with the engine operating at a high idle speed condition. 
Temporarily disable the reserve water supply, if applicable, and any 
safety shutdown system control that might interfere with the evaluation 
of the operation of the exhaust gas temperature sensor. Prior to 
testing, set the water level in the wet exhaust conditioner to a level 
just above the minimum allowable low water level. Run the engine until 
the exhaust gas temperature sensor activates the safety shutdown system 
and stops the engine.
    (5) For systems using a wet exhaust conditioner as an exhaust flame 
arrester, determine the effectiveness of the low water sensor which 
will automatically activate the safety shutdown system and stop the 
engine at or above the minimum allowable low water level established 
from results of the explosion tests in Sec. 7.100 with the engine 
operating at a high idle speed condition. Temporarily disable the 
reserve water supply, if applicable, and any safety shutdown system 
control that might interfere with the evaluation of the operation of 
the low water sensor. Prior to testing, set the water level in the wet 
exhaust conditioner to a level just above the minimum allowable low 
water level. Run the engine until the low water sensor activates the 
safety shutdown system and stops the engine. Measure the low water 
level. Attempt to restart the engine.
    (6) Determine the effectiveness of the device in the intake system 
which is designed to shut off the air supply and stop the engine for 
emergency purposes with the engine operating at both a high idle speed 
condition and a low idle speed condition. Run the engine and activate 
the emergency intake air shutoff device.
    (7) Determine the total air inlet restriction of the complete 
intake system, including the air cleaner, as measured between the 
intake flame arrester and the engine head with the engine operating at 
maximum air flow.
    (8) Determine the total exhaust backpressure with the engine 
operating at rated horsepower as specified in Sec. 7.103(a)(7). If a 
wet exhaust conditioner is used, it must be filled to the high or 
normal operating water level during this test.
    (9) The starting mechanism shall be tested to ensure that 
engagement is not possible while the engine is running. Operate the 
engine and attempt to engage the starting mechanism.
    (10) Where the lack of engine oil pressure must be overridden in 
order to start the engine, test the override to ensure that it does not 
override any of the safety shutdown sensors specified in Sec. 7.98(i). 
After each safety shutdown sensor test specified in paragraphs (a)(2) 
through (a)(5) of this section, immediately override the engine oil 
pressure and attempt to restart the engine.
    (b) Acceptable performance. Tests of the safety system controls 
shall result in the following:
    (1) The coolant system temperature shutdown sensor shall 
automatically activate the safety shutdown system and stop the engine 
before the water temperature in the cooling jackets exceeds 
manufacturer's specifications or 212  deg.F (100  deg.C), whichever is 
lower.
    (2) The temperature sensor in the exhaust gas stream of a system 
using a dry exhaust conditioner shall automatically activate the safety 
shutdown system and stop the engine before the cooled exhaust gas 
exceeds 302  deg.F (150  deg.C).
    (3) The temperature sensor in the exhaust gas stream of a system 
using a wet exhaust conditioner shall automatically activate the safety 
shutdown system and stop the engine before the cooled exhaust gas 
exceeds 185  deg.F (85  deg.C).
    (4) The low water sensor for systems using a wet exhaust 
conditioner shall automatically activate the safety shutdown system and 
stop the engine at or above the minimum allowable low water level and 
prevent restarting of the engine.
    (5) The emergency intake air shutoff device shall operate 
immediately when activated and stop the engine within 15 seconds.
    (6) The total intake air inlet restriction and the total exhaust 
backpressure shall not exceed the engine manufacturer's specifications.

[[Page 55525]]

    (7) It shall not be possible to engage the starting mechanism while 
the engine is running, unless the starting mechanism is constructed of 
nonsparking material.
    (8) The engine oil pressure override shall not override any of the 
shutdown sensors.


Sec. 7.104  Internal static pressure test.

    (a) Test procedures. (1) Isolate and seal each segment of the 
intake system or exhaust system to allow pressurization.
    (2) Internally pressurize each segment of the intake system or 
exhaust system to four times the maximum pressure observed in each 
segment during the tests of Sec. 7.100, or 150 psig  5 
psig, whichever is less. Maintain the pressure for a minimum of 10 
seconds.
    (3) Following the pressure hold, the pressure shall be removed and 
the pressurizing agent removed from the intake system or exhaust 
system.
    (b) Acceptable performance. (1) The intake system or exhaust 
system, during pressurization, shall not exhibit--
    (i) Leakage through welds and gasketed joints; or
    (ii) Leakage other than along joints meeting the explosion-proof 
requirements of Sec. 7.98(q).
    (2) Following removal of the pressurizing agent, the intake system 
or exhaust system shall not exhibit any--
    (i) Changes in fastening torque;
    (ii) Visible cracks in welds;
    (iii) Permanent deformation affecting the length or gap of any 
flame-arresting paths;
    (iv) Stretched or bent fastenings;
    (v) Damaged threads of parts affecting the explosion-proof 
integrity of the intake system or exhaust system; or
    (vi) Permanent distortion of any planar surface of the diesel power 
package exceeding 0.04-inches/linear foot.


Sec. 7.105  Approval marking.

    Each approved diesel power package shall be identified by a legible 
and permanent approval plate inscribed with the assigned MSHA approval 
number and securely attached to the diesel power package in a manner 
that does not impair any explosion-proof characteristics. The grade 
limitation of a wet exhaust conditioner used as an exhaust flame 
arrester shall be included on the approval marking.


Sec. 7.106  Post-approval product audit.

    Upon request by MSHA, but not more than once a year except for 
cause, the approval-holder shall make an approved diesel power package 
available for audit at no cost to MSHA.


Sec. 7.107  New technology.

    MSHA may approve a diesel power package that incorporates 
technology for which the requirements of this subpart are not 
applicable if MSHA determines that the diesel power package is as safe 
as those which meet the requirements of this subpart.


Sec. 7.108  Power package checklist.

    Each diesel power package bearing an MSHA approval plate shall be 
accompanied by a power package checklist. The power package checklist 
shall consist of a list of specific features that must be checked and 
tests that must be performed to determine if a previously approved 
diesel power package is in approved condition. Test procedures shall be 
specified in sufficient detail to allow evaluation to be made without 
reference to other documents. Illustrations shall be used to fully 
identify the approved configuration of the diesel power package.

PARTS 31--DIESEL MINE LOCOMOTIVES [REMOVED]

    3. Part 31 is removed.

PART 32--MOBILE DIESEL-POWERED EQUIPMENT FOR NONCOAL MINES 
[REMOVED]

    4. Part 32 is removed.

PART 36--[AMENDED]

    5. The authority for part 36 continues as follows:

    Authority: 30 U.S.C. 957, 961.

    6. The heading of part 36 is revised to read as follows:

PART 36--APPROVAL REQUIREMENTS FOR PERMISSIBLE MOBILE DIESEL-
POWERED TRANSPORTATION EQUIPMENT.

    7. Section 36.1 is revised to read as follows:


Sec. 36.1  Purpose.

    The regulations in this part set forth the requirements for mobile 
diesel-powered transportation equipment to procure their approval and 
certification as permissible; procedures for applying for such 
certification; and fees.
    8. Section 36.2 is revised to read as follows:


Sec. 36.2  Definitions.

    The following definitions apply in this part.
    Applicant An individual, partnership, company, corporation, 
association, or other organization, that designs, manufactures, 
assembles, or controls the assembly and that seeks a certificate of 
approval or preliminary testing of mobile diesel-powered transportation 
equipment as permissible.
    Certificate of approval. A formal document issued by MSHA stating 
that the complete assembly has met the requirements of this part for 
mobile diesel-powered transportation equipment and authorizing the use 
and attachment of an official approval plate so indicating.
    Component. A piece, part, or fixture of mobile diesel-powered 
transportation equipment that is essential to its operation as a 
permissible assembly.
    Diesel engine. A compression-ignition, internal-combustion engine 
that utilizes diesel fuel.
    Explosion proof. A component or subassembly that is so constructed 
and protected by an enclosure and/or flame arrester (s) that if a 
flammable mixture of gas is ignited within the enclosure it will 
withstand the resultant pressure without damage to the enclosure and/or 
flame arrester(s). Also the enclosure and/or flame arrester(s) shall 
prevent the discharge of flame or ignition of any flammable mixture 
that surrounds the enclosure.
    Flame arrester. A device so constructed that flame or sparks from 
the diesel engine cannot propagate an explosion of a flammable mixture 
through it.
    Flammable mixture. A mixture of gas, such as methane, natural gas, 
or similar hydrocarbon gas with normal air, that will propagate flame 
or explode violently when initiated by an incendive source.
    Fuel-air ratio. The composition of the mixture of fuel and air in 
the combustion chamber of the diesel engine expressed as weight-pound 
of fuel per pound of air.
    MSHA. The United States Department of Labor, Mine Safety and Health 
Administration.
    Mobile diesel-powered transportation equipment. Equipment that is:
    (1) Used for transporting the product being mined or excavated, or 
for transporting materials and supplies used in mining or excavating 
operations;
    (2) Mounted on wheels or crawler treads (tracks); and
    (3) Powered by a diesel engine as the prime mover.
    Normal operation. When each component and the entire assembly of 
the mobile diesel-powered transportation equipment performs the 
functions for which they were designed.
    Permissible. As applied to mobile diesel-powered transportation 
equipment, this means that the

[[Page 55526]]

complete assembly conforms to the requirements of this part, and that a 
certificate of approval to that effect has been issued.
    Subassembly. A group or combination of components.
    9. Section 36.6, paragraphs (b)(2), (b)(3), and (b)(4) are amended 
by inserting the phrase ``Except for equipment utilizing part 7, 
subpart F power packages,'' at the beginning of the first sentence of 
each paragraph.
    10. Section 36.9 is amended by revising the third sentence of 
paragraph (a) to read as follows:


Sec. 36.9  Conduct of investigations, tests, and demonstrations.

    (a) * * * After the issuance of a certificate of approval, MSHA may 
conduct such public demonstrations and tests of the approved mobile 
diesel-powered transportation equipment as it deems appropriate. * * *
* * * * *
    11. Section 36.20, paragraphs (b) is revised and paragraph (c) is 
added to read as follows:


Sec. 36.20  Quality of material, workmanship, and design.

* * * * *
    (b) The quality of material, workmanship, and design shall conform 
to the requirements of Sec. 7.98(q) of this chapter.
    (c) Power packages approved under part 7, subpart F of this chapter 
are considered to be acceptable for use in equipment submitted for 
approval under this part. Sections 36.21 through 36.26 (except 
Sec. 36.25(f)) and Secs. 36.43 through 36.48 are not applicable to 
equipment utilizing part 7, subpart F power packages, since these 
requirements have already been satisfied.
    12. Section 36.21 is amended by revising the first sentence to read 
as follows:


Sec. 36.21  Engine for equipment considered for certification.

    Only equipment powered by a compression-ignition (diesel) engine 
and burning diesel fuel will be considered for approval and 
certification. ***
    13. Section 36.43 is amended by removing the phrase ``in 
underground gassy noncoal mines and tunnels'' from the last sentence of 
paragraph (a).
    14. The note of Sec. 36.48 is revised to read as follows:


Sec. 36.48  Tests of surface temperature of engine and components of 
the cooling system.

* * * * *
    Note to Sec. 36.48: The engine may be operated under test 
conditions prescribed by MSHA while completely surrounded by a 
flammable mixture. MSHA reserves the right to apply combustible 
materials to any surface for test. Operation under such conditions 
shall not ignite the flammable mixture.

PART 70--[AMENDED]

    15. The authority citation for part 70 continues to read as 
follows:

    Authority: 30 U.S.C. 811, 813(h), 957, and 961.

    16. Subparts G-S are reserved and a new subpart T is added to part 
70 to read as follows:
* * * * *

Subpart T--Diesel Exhaust Gas Monitoring

Sec.
70.1900  Exhaust Gas Monitoring

SUBPART T--DIESEL EXHAUST GAS MONITORING


Sec. 70.1900  Exhaust Gas Monitoring.

    (a) During on-shift examinations required by Sec. 75.362, a 
certified person as defined by Sec. 75.100 of this chapter and 
designated by the operator as trained or experienced in the appropriate 
sampling procedures, shall determine the concentration of carbon 
monoxide (CO) and nitrogen dioxide (NO2):
    (1) In the return of each working section where diesel equipment is 
used, at a location which represents the contribution of all diesel 
equipment on such section;
    (2) In the area of the section loading point if diesel haulage 
equipment is operated on the working section;
    (3) At a point inby the last piece of diesel equipment on the 
longwall or shortwall face when mining equipment is being installed or 
removed; and
    (4) In any other area designated by the district manager as 
specified in the mine operator's approved ventilation plan where diesel 
equipment is operated in a manner which can result in significant 
concentrations of diesel exhaust.
    (b) Samples of CO and NO2 shall be--
    (1) Collected in a manner that makes the results available 
immediately to the person collecting the samples;
    (2) Collected and analyzed by appropriate instrumentation which has 
been maintained and calibrated in accordance with the manufacturer's 
recommendations; and
    (3) Collected during periods that are representative of conditions 
during normal operations.
    (c) Except as provided in Sec. 75.325(j) of this chapter, when 
sampling results indicate a concentration of CO and/or NO2 
exceeding an action level of 50 percent of the threshold limit values 
(TLV) adopted by the American Conference of Governmental 
Industrial Hygienists, the mine operator shall immediately take 
appropriate corrective action to reduce the concentrations of CO and/or 
NO2 to below the applicable action level. The publication, 
``Threshold Limit Values for Substance in Workroom Air'' (1972) is 
incorporated by reference and may be inspected at MSHA's Office of 
Standards, Regulations, and Variances, 4015 Wilson Boulevard, 
Arlington, VA 22203; at any Coal Mine Health and Safety District and 
Subdistrict Office; and at the Office of the Federal Register, 800 
North Capitol Street, NW Suite 700, Washington, DC. This incorporation 
by reference was approved by the Director of the Federal Register in 
accordance with 5 U.S.C. 552(a) and 1 CFR part 51. In addition, copies 
of the document may be purchased from the Secretary-Treasurer, American 
Conference of Governmental Industrial Hygienists, Post Office Box 1937, 
Cincinnati, OH 45202.
    (d) A record shall be made when sampling results exceed the action 
level for the applicable TLV for CO and/or NO2. The 
record shall be made as part of and in the same manner as the records 
for hazards required by Sec. 75.363 of this chapter and include the 
following:
    (1) Location where each sample was collected;
    (2) Substance sampled and the measured concentration; and
    (3) Corrective action taken to reduce the concentration of CO and/
or NO2 to or below the applicable action level.
    (e) As of November 25, 1997 exhaust gas monitoring shall be 
conducted in accordance with the requirements of this section.

PART 75--[AMENDED]

    17. The authority citation for part 75 continues to read as 
follows:

    Authority: 30 U.S.C. 811.

    18. New paragraphs (f) through (k) are added to Sec. 75.325 to read 
as follows:


Sec. 75.325  Air quantity.

* * * * *
    (f) The minimum ventilating air quantity for an individual unit of 
diesel-powered equipment being operated shall be at least that 
specified on the approval plate for that equipment. Such air quantity 
shall be maintained--
    (1) In any working place where the equipment is being operated;
    (2) At the section loading point during any shift the equipment is 
being operated on the working section;

[[Page 55527]]

    (3) In any entry where the equipment is being operated outby the 
section loading point in areas of the mine developed on or after April 
25, 1997;
    (4) In any air course with single or multiple entries where the 
equipment is being operated outby the section loading point in areas of 
the mine developed prior to April 25, 1997; and
    (5) At any other location required by the district manager and 
specified in the approved ventilation plan.
    (g) The minimum ventilating air quantity where multiple units of 
diesel-powered equipment are operated on working sections and in areas 
where mechanized mining equipment is being installed or removed must be 
at least the sum of that specified on the approval plates of all the 
diesel-powered equipment on the working section or in the area where 
mechanized mining equipment is being installed or removed. The minimum 
ventilating air quantity shall be specified in the approved ventilation 
plan. For working sections such air quantity must be maintained--
    (1) In the last open crosscut of each set of entries or rooms in 
each working section;
    (2) In the intake, reaching the working face of each longwall; and
    (3) At the intake end of any pillar line.
    (h) The following equipment may be excluded from the calculations 
of ventilating air quantity under paragraph (g) if such equipment 
exclusion is approved by the district manager and specified in the 
ventilation plan:
    (1) Self-propelled equipment meeting the requirements of 
Sec. 75.1908(b);
    (2) Equipment that discharges its exhaust into intake air that is 
coursed directly to a return air course;
    (3) Equipment that discharges its exhaust directly into a return 
air course; and
    (4) Other equipment having duty cycles such that the emissions 
would not significantly affect the exposure of miners.
    (i) A ventilating air quantity that is less than what is required 
by paragraph (g) of this section may be approved by the district 
manager in the ventilation plan based upon the results of sampling that 
demonstrate that the lesser air quantity will maintain continuous 
compliance with applicable TLV's.
    (j) If during sampling required by Sec. 70.1900(c) of this 
subchapter the ventilating air is found to contain concentrations of CO 
or NO2 in excess of the action level specified by Sec. 70.1900(c), 
higher action levels may be approved by the district manager based on 
the results of sampling that demonstrate that a higher action level 
will maintain continuous compliance with applicable TLV's. 
Action levels other than those specified in Sec. 70.1900(c) shall be 
specified in the approved ventilation plan.
    (k) As of November 25, 1977 the ventilating air quantity required 
where diesel-powered equipment is operated shall meet the requirements 
of paragraphs (f) through (j) of this section. Mine operators utilizing 
diesel-powered equipment in underground coal mines shall submit to the 
appropriate MSHA district manager a revised ventilation plan or 
appropriate amendments to the existing plan, in accordance with 
Sec. 75.371, which implement the requirements of paragraphs (f) through 
(j) of this section.
    19. Section 75.342 is amended by revising paragraph (b)(2) and the 
introductory text of paragraph (c) to read as follows:


Sec. 75.342   Methane monitors.

* * * * *
    (b)(1) * * *
    (2) The warning signal device of the methane monitor shall be 
visible to a person who can deenergize electric equipment or shut down 
diesel-powered equipment on which the monitor is mounted.
    (c) The methane monitor shall automatically deenergize electric 
equipment or shut down diesel-powered equipment on which it is mounted 
when--
* * * * *
    20. Section 75.344 is amended by removing paragraph (d) and 
redesignating paragraph (e) as new paragraph (d).
    21. Section 75.360 is amended by revising paragraph (b)(7) as 
follows:


Sec. 75.360  Preshift Examination.

* * * * *
    (b) * * *
    (7) Areas where trolley wires or trolley feeder wires are to be or 
will remain energized during the oncoming shift.
* * * * *
    22. Section 75.371 is amended by revising paragraph (r) and adding 
new paragraphs (kk), (ll), (mm), (nn), (oo), and (pp) to read as 
follows:


Sec. 75.371  Mine ventilation plan; contents.

* * * * *
    (r) The minimum quantity of air that will be provided during the 
installation and removal of mechanized mining equipment, the location 
where this quantity will be provided, and the ventilation controls that 
will be used (see Sec. 75.325(d), (g), and (i)).
* * * * *
    (kk) Areas designated by the district manager where measurements of 
CO and NO2 concentrations will be made (see Sec. 70.1900(a)(4)).
    (ll) Location where the air quantity will be maintained at the 
section loading point (see Sec. 75.325(f)(2)).
    (mm) Any additional location(s) required by the district manager 
where a minimum air quantity must be maintained for an individual unit 
of diesel-powered equipment. (see Sec. 75.325(f)(5)).
    (nn) The minimum air quantities that will be provided where 
multiple units of diesel-powered equipment are operated (see 
Sec. 75.325(g) (1)-(3) and (i)).
    (oo) The diesel-powered mining equipment excluded from the 
calculation under Sec. 75.325(g). (see Sec. 75.325(h)).
    (pp) Action levels higher than the 50 percent level specified by 
Sec. 70.1900(c). (see Sec. 75.325(j)).
    23. Section 75.380 is amended by removing paragraph (f)(3)(i) and 
by redesignating paragraphs (f)(3)(ii) through (f)(3)(v) as paragraphs 
(f)(3)(i) through (f)(3)(iv).
    24. Section 75.400 is revised to read as follows:


Sec. 75.400  Accumulation of combustible materials.

    Coal dust, including float coal dust deposited on rock-dusted 
surfaces, loose coal, and other combustible materials, shall be cleaned 
up and not be permitted to accumulate in active workings, or on diesel-
powered and electric equipment therein.
    25. Section 75.1710 is revised to read as follows:


Sec. 75.1710  Canopies or cabs; diesel-powered and electric face 
equipment.

    In any coal mine where the height of the coalbed permits, an 
authorized representative of the Secretary may require that diesel-
powered and electric face equipment, including shuttle cars, be 
provided with substantially constructed canopies or cabs to protect the 
miners operating such equipment from roof falls and from rib and face 
rolls.
    26. Section 75.1710-1 is amended by replacing the phrase ``electric 
face equipment'' with ``diesel-powered and electric face equipment'' in 
the title and in paragraphs (a) and (f).
    27. A new subpart T is added to part 75 to read as follows:

Subpart T--Diesel-Powered Equipment

Sec.
75.1900  Definitions.
75.1901  Diesel fuel requirements.
75.1902  Underground diesel fuel storage--general requirements.

[[Page 55528]]

75.1903  Underground diesel fuel storage facilities and areas; 
construction and safety precautions.
75.1904  Underground diesel fuel tanks and safety cans.
75.1905  Dispensing of diesel fuel.
75.1905-1  Diesel fuel piping systems.
75.1906  Transport of diesel fuel.
75.1907  Diesel-powered equipment intended for use in underground 
coal mines.
75.1908  Nonpermissible diesel-powered equipment-categories.
75.1909  Nonpermissible diesel-powered equipment; design and 
performance requirements.
75.1910  Nonpermissible diesel-powered equipment; electrical system 
design and performance requirements.
75.1911  Fire suppression systems for diesel-powered equipment and 
diesel fuel transportation units.
75.1912  Fire suppression systems for permanent underground diesel 
fuel storage facilities.
75.1913  Starting aids.
75.1914  Maintenance of diesel-powered equipment.
75.1915  Training and qualification of persons working on diesel-
powered equipment.
75.1916  Operation of diesel-powered equipment.

Subpart T--Diesel-Powered Equipment


Sec. 75.1900  Definitions.

    The following definitions apply in this subpart.
    Diesel fuel tank. A closed metal vessel specifically designed for 
the storage or transport of diesel fuel.
    Diesel fuel transportation unit. A self-propelled or portable 
wheeled vehicle used to transport a diesel fuel tank.
    Noncombustible material. A material that will continue to serve its 
intended function for 1 hour when subjected to a fire test 
incorporating an ASTM E119-88 time/temperature heat input, or 
equivalent. The publication ASTM E119-88 ``Standard Test Methods for 
Fire Tests of Building Construction and Materials'' is incorporated by 
reference and may be inspected at any Coal Mine Health and Safety 
District and Subdistrict Office; at MSHA's Office of Standards, 
Regulations, and Variances, 4105 Wilson Boulevard, Arlington, VA 22203; 
or at the Office of the Federal Register, 800 North Capitol Street, 
NW., Washington, DC. This incorporation by reference was approved by 
the Director of the Federal Register in accordance with 5 U.S.C. 552(a) 
and 1 CFR part 51. In addition, copies of the document may be purchased 
from the American Society for Testing Materials (ASTM), 1916 Race 
Street, Philadelphia, PA 19103.
    Permanent underground diesel fuel storage facility. A facility 
designed and constructed to remain at one location for the storage or 
dispensing of diesel fuel, which does not move as mining progresses.
    Safety can. A metal container intended for storage, transport or 
dispensing of diesel fuel, with a nominal capacity of 5 gallons, listed 
or approved by a nationally recognized independent testing laboratory.
    Temporary underground diesel fuel storage area. An area of the mine 
provided for the short-term storage of diesel fuel in a fuel 
transportation unit, which moves as mining progresses.


Sec. 75.1901  Diesel fuel requirements.

    (a) Diesel-powered equipment shall be used underground only with a 
diesel fuel having a sulfur content no greater than 0.05 percent and a 
flash point of 100 deg. F (38 deg. C) or greater. Upon request, the 
mine operator shall provide to an authorized representative of the 
Secretary evidence that the diesel fuel purchased for use in diesel-
powered equipment underground meets these requirements.
    (b) Flammable liquids shall not be added to diesel fuel used in 
diesel-powered equipment underground.
    (c) Only diesel fuel additives that have been registered by the 
Environmental Protection Agency may be used in diesel-powered equipment 
underground.


Sec. 75.1902  Underground diesel fuel storage--general requirements.

    (a) All diesel fuel must be stored in:
    (1) Diesel fuel tanks in permanent underground diesel fuel storage 
facilities;
    (2) Diesel fuel tanks on diesel fuel transportation units in 
permanent underground diesel fuel storage facilities or in temporary 
underground fuel storage areas; or
    (3) Safety cans.
    (b) The total capacity of stationary diesel fuel tanks in permanent 
underground diesel fuel storage facilities must not exceed 1000 
gallons.
    (c)(1) Only one temporary underground diesel fuel storage area is 
permitted for each working section or in each area of the mine where 
equipment is being installed or removed.
    (2) The temporary underground diesel fuel storage area must be 
located--
    (i) Within 500 feet of the loading point;
    (ii) Within 500 feet of the projected loading point where equipment 
is being installed; or
    (iii) Within 500 feet of the last loading point where equipment is 
being removed.
    (3) No more than one diesel fuel transportation unit at a time 
shall be parked in the temporary underground diesel fuel storage area.
    (d) Permanent underground diesel fuel storage facilities and 
temporary underground diesel fuel storage areas must be--
    (1) At least 100 feet from shafts, slopes, shops, or explosives 
magazines;
    (2) At least 25 feet from trolley wires or power cables, or 
electric equipment not necessary for the operation of the storage 
facilities or areas; and
    (3) In a location that is protected from damage by other mobile 
equipment.
    (e) Permanent underground diesel fuel storage facilities must not 
be located within the primary escapeway.


Sec. 75.1903  Underground diesel fuel storage facilities and areas; 
construction and safety precautions.

    (a) Permanent underground diesel fuel storage facilities must be--
    (1) Constructed of noncombustible materials, including floors, 
roofs, roof supports, doors, and door frames. Exposed coal within fuel 
storage areas must be covered with noncombustible materials. If 
bulkheads are used they must be tightly sealed and must be built of or 
covered with noncombustible materials;
    (2) Provided with either self-closing doors or a means for 
automatic enclosure;
    (3) Provided with a means for personnel to enter and exit the 
facility after closure;
    (4) Ventilated with intake air that is coursed into a return air 
course or to the surface and that is not used to ventilate working 
places, using ventilation controls meeting the requirements of 
Sec. 75.333(e);
    (5) Equipped with an automatic fire suppression system that meets 
the requirements of Sec. 75.1912. Actuation of the automatic fire 
suppression system shall initiate the means for automatic enclosure;
    (6) Provided with a means of containment capable of holding 150 
percent of the maximum capacity of the fuel storage system; and
    (7) Provided with a competent concrete floor or equivalent to 
prevent fuel spills from saturating the mine floor.
    (b) Permanent underground diesel fuel storage facilities and 
temporary underground diesel fuel storage areas must be--
    (1) Equipped with at least 240 pounds of rock dust and provided 
with two portable multipurpose dry chemical type (ABC) fire 
extinguishers that are listed or approved by a nationally recognized 
independent testing laboratory and have a 10A:60B:C or

[[Page 55529]]

higher rating. Both fire extinguishers must be easily accessible to 
personnel, and at least one fire extinguisher must be located outside 
of the storage facility or area upwind of the facility, in intake air; 
or
    (2) Provided with three portable multipurpose dry chemical type 
(ABC) fire extinguishers that are listed or approved by a nationally 
recognized independent testing laboratory and have a 10A:60B:C or 
higher rating. All fire extinguishers must be easily accessible to 
personnel, and at least one fire extinguisher must be located outside 
of the storage facility or area upwind of the facility, in intake air.
    (3) Identified with conspicuous markings designating diesel fuel 
storage; and
    (4) Maintained to prevent the accumulation of water.
    (c) Welding or cutting other than that performed in accordance with 
paragraph (d) of this section shall not be performed within 50 feet of 
a permanent underground diesel fuel storage facility or a temporary 
underground diesel fuel storage area.
    (d) When it is necessary to weld, cut, or solder pipelines, tanks, 
or other containers that may have contained diesel fuel, these 
practices shall be followed:
    (1) Cutting or welding shall not be performed on or within 
pipelines, tanks, or other containers that have contained diesel fuel 
until they have been thoroughly purged and cleaned or inerted and a 
vent or opening is provided to allow for sufficient release of any 
buildup pressure before heat is applied.
    (2) Diesel fuel shall not be allowed to enter pipelines, tanks, or 
containers that have been welded, soldered, brazed, or cut until the 
metal has cooled to ambient temperature.


Sec. 75.1904  Underground diesel fuel tanks and safety cans.

    (a) Diesel fuel tanks used underground shall--
    (1) Have steel walls of a minimum \3/16\-inch thickness, or walls 
made of other metal of a thickness that provides equivalent strength;
    (2) Be protected from corrosion;
    (3) Be of seamless construction or have liquid tight welded seams;
    (4) Not leak; and
    (5) For stationary tanks in permanent underground diesel fuel 
storage facilities, be placed on supports constructed of noncombustible 
material so that the tanks are at least 12 inches above the floor.
    (b) Underground diesel fuel tanks must be provided with--
    (1) Devices for emergency venting designed to open at a pressure 
not to exceed 2.5 psi according to the following--
    (i) Tanks with a capacity greater than 500 gallons must have an 
emergency venting device whose area is equivalent to a pipe with a 
nominal inside diameter of 5 inches or greater; and
    (ii) Tanks with a capacity of 500 gallons or less must have an 
emergency venting device whose area is equivalent to a pipe with a 
nominal inside diameter of 4 inches or greater.
    (2) Tethered or self-closing caps for stationary tanks in permanent 
underground diesel fuel storage facilities and self-closing caps for 
diesel fuel tanks on diesel fuel transportation units;
    (3) Vents to permit the free discharge of liquid, at least as large 
as the fill or withdrawal connection, whichever is larger, but not less 
than 1\1/4\ inch nominal inside diameter;
    (4) Liquid tight connections for all tank openings that are--
    (i) Identified by conspicuous markings that specify the function; 
and
    (ii) Closed when not in use.
    (5) Vent pipes that drain toward the tank without sagging and are 
higher than the fill pipe opening;
    (6) Shutoff valves located as close as practicable to the tank 
shell on each connection through which liquid can normally flow; and
    (7) An automatic closing, heat-actuated valve on each withdrawal 
connection below the liquid level.
    (c) When tanks are provided with openings for manual gauging, 
liquid tight, tethered or self-closing caps or covers must be provided 
and must be kept closed when not open for gauging.
    (d) Surfaces of the tank and its associated components must be 
protected against damage by collision.
    (e) Before being placed in service, tanks and their associated 
components must be tested for leakage at a pressure equal to the 
working pressure, except tanks and components connected directly to 
piping systems, which must be properly designed for the application.
    (f) Safety cans must be:
    (1) Limited to a nominal capacity of 5 gallons or less;
    (2) Equipped with a flexible or rigid tubular nozzle attached to a 
valved spout;
    (3) Provided with a vent valve designed to open and close 
simultaneously and automatically with the opening and closing of the 
pouring valve; and
    (4) Designed so that they will safely relieve internal pressure 
when exposed to fire.


Sec. 75.1905  Dispensing of diesel fuel.

    (a) Diesel-powered equipment in underground coal mines may be 
refueled only from safety cans, from tanks on diesel fuel 
transportation units, or from stationary tanks.
    (b) Fuel that is dispensed from other than safety cans must be 
dispensed by means of--
    (1) Gravity feed with a hose equipped with a nozzle with a self-
closing valve and no latch-open device;
    (2) A manual pump with a hose equipped with a nozzle containing a 
self-closing valve; or
    (3) A powered pump with:
    (i) An accessible emergency shutoff switch for each nozzle;
    (ii) A hose equipped with a self-closing valve and no latch-open 
device; and
    (iii) An anti-siphoning device.
    (c) Diesel fuel must not be dispensed using compressed gas.
    (d) Diesel fuel must not be dispensed to the fuel tank of diesel-
powered equipment while the equipment engine is running.
    (e) Powered pumps shall be shut off when fuel is not being 
dispensed.


Sec. 75.1905-1   Diesel fuel piping systems.

    (a) Diesel fuel piping systems from the surface must be designed 
and operated as dry systems, unless an automatic shutdown is 
incorporated that prevents accidental loss or spillage of fuel and that 
activates an alarm system.
    (b) All piping, valves and fittings must be--
    (1) Capable of withstanding working pressures and stresses;
    (2) Capable of withstanding four times the static pressures;
    (3) Compatible with diesel fuel; and
    (4) Maintained in a manner that prevents leakage.
    (c) Pipelines must have manual shutoff valves installed at the 
surface filling point, and at the underground discharge point.
    (d) If diesel fuel lines are not buried in the ground sufficiently 
to protect them from damage, shutoff valves must be located every 300 
feet.
    (e) Shutoff valves must be installed at each branch line where the 
branch line joins the main line.
    (f) An automatic means must be provided to prevent unintentional 
transfer of diesel fuel from the surface into the permanent underground 
diesel fuel storage facility.
    (g) Diesel fuel piping systems from the surface shall only be used 
to transport diesel fuel directly to stationary tanks or diesel fuel 
transportation units in a permanent underground diesel fuel storage 
facility.

[[Page 55530]]

    (h) The diesel fuel piping system must not be located in a borehole 
with electric power cables.
    (i) Diesel fuel piping systems located in entries must not be 
located on the same side of the entry as electric cables or power 
lines. Where it is necessary for piping systems to cross electric 
cables or power lines, guarding must be provided to prevent severed 
electrical cables or power lines near broken fuel lines.
    (j) Diesel fuel piping systems must be protected and located to 
prevent physical damage.


Sec. 75.1906   Transport of diesel fuel.

    (a) Diesel fuel shall be transported only by diesel fuel 
transportation units or in safety cans.
    (b) No more than one safety can shall be transported on a vehicle 
at any time. The can must be protected from damage during transport. 
All other safety cans must be stored in permanent underground diesel 
fuel storage facilities.
    (c) Safety cans that leak must be promptly removed from the mine.
    (d) Diesel fuel transportation unit tanks and safety cans must be 
conspicuously marked as containing diesel fuel.
    (e) Diesel fuel transportation units must transport no more than 
500 gallons of diesel fuel at a time.
    (f) Tanks on diesel fuel transportation units must be permanently 
fixed to the unit and have a total capacity of no greater than 500 
gallons of diesel fuel.
    (g) Non-self-propelled diesel fuel transportation units with 
electrical components for dispensing fuel that are connected to a 
source of electrical power must be protected by a fire suppression 
device that meets the requirements of Secs. 75.1107-3 through 75.1107-6 
and Secs. 75.1107-8 and 75.1107-16.
    (h) Diesel fuel transportation units and vehicles transporting 
safety cans containing diesel fuel must have at least two multipurpose, 
dry chemical type (ABC) fire extinguishers, listed or approved by a 
nationally recognized independent testing laboratory and having a 
10A:60B:C or higher rating, with one fire extinguisher provided on each 
side of the vehicle.
    (i) Diesel fuel transportation units shall be parked only in 
permanent underground diesel fuel storage facilities or temporary 
underground diesel fuel storage areas when not in use.
    (j) When the distance between a diesel fuel transportation unit and 
an energized trolley wire at any location is less than 12 inches, the 
requirements of Sec. 75.1003-2 must be followed.
    (k) Diesel fuel shall not be transported on or with mantrips or on 
conveyor belts.
    (l) Diesel fuel shall be stored and handled in accordance with the 
requirements of Secs. 75.1902 through 75.1906 of this part as of 
November 25, 1997.


Sec. 75.1907   Diesel-powered equipment intended for use in underground 
coal mines.

    (a) As of November 25, 1996 all diesel-powered equipment used where 
permissible electrical equipment is required must be approved under 
part 36 of this chapter.
    (b) Diesel-powered equipment approved under part 36 of this chapter 
must be provided with additional safety features in accordance with the 
following time schedule:
    (1) As of April 25, 1997 the equipment must have a safety component 
system that limits surface temperatures to those specified in subpart F 
of part 7 of this title;
    (2) As of November 25, 1999 the equipment must have an automatic or 
manual fire suppression system that meets the requirements of 
Sec. 75.1911 of this part, and at least one portable multipurpose dry 
chemical type (ABC) fire extinguisher, listed or approved by a 
nationally recognized independent testing laboratory and having a 
10A:60B:C or higher rating. The fire extinguisher must be located 
within easy reach of the equipment operator and be protected from 
damage by collision.
    (3) As of November 25, 1999 the equipment must have a brake system 
that meets the requirements of Sec. 75.1909 (b)(6), (b)(7), (b)(8), 
(c), (d), and (e);
    (4) As of November 25, 1997 a particulate index and dilution air 
quantity shall be determined for the equipment in accordance with 
subpart E of part 7 of this chapter; and
    (5) Permissible diesel-powered equipment manufactured on or after 
November 25, 1999 and that is used in an underground coal mine shall 
incorporate a power package approved in accordance with part 7, subpart 
F of this chapter.
    (c) As of November 25, 1999 nonpermissible diesel-powered 
equipment, except the special category of equipment under 
Sec. 75.1908(d), shall meet the requirements of Secs. 75.1909 and 
75.1910 of this part.


Sec. 75.1908   Nonpermissible diesel-powered equipment--categories.

    (a) Heavy-duty diesel-powered equipment includes--
    (1) Equipment that cuts or moves rock or coal;
    (2) Equipment that performs drilling or bolting functions;
    (3) Equipment that moves longwall components;
    (4) Self-propelled diesel fuel transportation units and self-
propelled lube units; or
    (5) Machines used to transport portable diesel fuel transportation 
units or portable lube units.
    (b) Light-duty diesel-powered equipment is any diesel-powered 
equipment that does not meet the criteria of paragraph (a).
    (c) For the purposes of this subpart, the following equipment is 
considered attended:
    (1) Any machine or device operated by a miner; or
    (2) Any machine or device that is mounted in the direct line of 
sight of a job site located within 500 feet of such machine or device, 
which job site is occupied by a miner.
    (d) Diesel-powered ambulances and fire fighting equipment are a 
special category of equipment that may be used underground only in 
accordance with the mine fire fighting and evacuation plan under 
Sec. 75.1101-23.


Sec. 75.1909   Nonpermissible diesel-powered equipment; design and 
performance requirements.

    (a) Nonpermissible diesel-powered equipment, except for the special 
category of equipment under Sec. 75.1908(d), must be equipped with the 
following features:
    (1) An engine approved under subpart E of part 7 of this title 
equipped with an air filter sized in accordance with the engine 
manufacturer's recommendations, and an air filter service indicator set 
in accordance with the engine manufacturer's recommendations;
    (2) At least one portable multipurpose dry chemical type (ABC) fire 
extinguisher listed or approved by a nationally recognized independent 
testing laboratory with a 10A:60B:C or higher rating. The fire 
extinguisher must be located within easy reach of the equipment 
operator and protected from damage;
    (3) A fuel system specifically designed for diesel fuel meeting the 
following requirements:
    (i) A fuel tank and fuel lines that do not leak;
    (ii) A fuel tank that is substantially constructed and protected 
against damage by collision;
    (iii) A vent opening that maintains atmospheric pressure in the 
fuel tank, and that is designed to prevent fuel from splashing out of 
the vent opening;
    (iv) A self-closing filler cap on the fuel tank;

[[Page 55531]]

    (v) The fuel tank, filler and vent must be located so that leaks or 
spillage during refueling will not contact hot surfaces;
    (vi) Fuel line piping must be either steel-wire reinforced; 
synthetic elastomer-covered hose suitable for use with diesel fuel that 
has been tested and has been determined to be fire-resistant by the 
manufacturer; or metal;
    (vii) Fuel line piping must be clamped;
    (viii) Primary fuel lines must be located so that fuel line leaks 
do not contact hot surfaces;
    (ix) The fuel lines must be separated from electrical wiring and 
protected from damage in ordinary use;
    (x) A manual shutoff valve must be installed in the fuel system as 
close as practicable to the tank; and
    (xi) A water separator and fuel filter(s) must be provided.
    (4) A sensor to monitor the temperature and provide a visual 
warning of an overheated cylinder head on air-cooled engines;
    (5) Guarding to protect fuel, hydraulic, and electric lines when 
such lines pass near rotating parts or in the event of shaft failure;
    (6) Hydraulic tanks, fillers, vents, and lines located to prevent 
spillage or leaks from contacting hot surfaces;
    (7) Reflectors or warning lights mounted on the equipment which can 
be readily seen in all directions;
    (8) A means to direct exhaust gas away from the equipment operator, 
persons on board the machine, and combustible machine components;
    (9) A means to prevent unintentional free and uncontrolled descent 
of personnel-elevating work platforms; and
    (10) A means to prevent the spray from ruptured hydraulic or 
lubricating oil lines from being ignited by contact with engine exhaust 
system component surfaces.
    (b) Self-propelled nonpermissible diesel-powered equipment must 
have the following features in addition to those in paragraph (a):
    (1) A means to ensure that no stored hydraulic energy that will 
cause machine articulation is available after the engine is shut down;
    (2) A neutral start feature which ensures that engine cranking 
torque will not be transmitted through the powertrain and cause machine 
movement on vehicles utilizing fluid power transmissions;
    (3) For machines with steering wheels, brake pedals, and 
accelerator pedals, controls which are of automobile orientation;
    (4) An audible warning device conveniently located near the 
equipment operator;
    (5) Lights provided and maintained on both ends of the equipment. 
Equipment normally operated in both directions must be equipped with 
headlights for both directions;
    (6) Service brakes that act on each wheel of the vehicle and that 
are designed such that failure of any single component, except the 
brake actuation pedal or other similar actuation device, must not 
result in a complete loss of service braking capability;
    (7) Service brakes that safely bring the fully loaded vehicle to a 
complete stop on the maximum grade on which it is operated; and
    (8) No device that traps a column of fluid to hold the brake in the 
applied position shall be installed in any brake system, unless the 
trapped column of fluid is released when the equipment operator is no 
longer in contact with the brake activation device.
    (c) Self-propelled nonpermissible heavy-duty diesel-powered 
equipment under Sec. 75.1908(a), except rail-mounted equipment, shall 
be provided with a supplemental braking system that:
    (1) Engages automatically within 5 seconds of the shutdown of the 
engine;
    (2) Safely brings the equipment when fully loaded to a complete 
stop on the maximum grade on which it is operated;
    (3) Holds the equipment stationary, despite any contraction of 
brake parts, exhaustion of any nonmechanical source of energy, or 
leakage;
    (4) Releases only by a manual control that does not operate any 
other equipment function;
    (5) Has a means in the equipment operator's compartment to apply 
the brakes manually without the engine operating, and a means to 
release and reengage the brakes without the engine operating; and
    (6) Has a means to ensure that the supplemental braking system is 
released before the equipment can be trammed, and is designed to ensure 
the brake is fully released at all times while the equipment is 
trammed.
    (d) Self-propelled nonpermissible light-duty diesel-powered 
equipment under Sec. 75.1908(b), except rail-mounted equipment, must be 
provided with a parking brake that holds the fully loaded equipment 
stationary on the maximum grade on which it is operated despite any 
contraction of the brake parts, exhaustion of any nonmechanical source 
of energy, or leakage.
    (e) The supplemental and park brake systems required by paragraphs 
(c) and (d) must be applied when the equipment operator is not at the 
controls of the equipment, except during movement of disabled 
equipment.
    (f) Self-propelled personnel-elevating work platforms must be 
provided with a means to ensure that the parking braking system is 
released before the equipment can be trammed, and must be designed to 
ensure the brake is fully released at all times while the equipment is 
trammed.
    (g) Any nonpermissible equipment that discharges its exhaust 
directly into a return air course must be provided with a power package 
approved under subpart F of part 7 of this title.
    (h) Self-propelled nonpermissible heavy-duty diesel-powered 
equipment meeting the requirements of Sec. 75.1908(a) must be provided 
with an automatic fire suppression system meeting the requirements of 
Sec. 75.1911.
    (i) Self-propelled nonpermissible light-duty diesel-powered 
equipment meeting the requirements of Sec. 75.1908(b) must be provided 
with an automatic or manual fire suppression system meeting the 
requirements of Sec. 75.1911.
    (j) Nonpermissible equipment that is not self-propelled must have 
the following features in addition to those listed in paragraph (a):
    (1) A means to prevent inadvertent movement of the equipment when 
parked;
    (2) Safety chains or other suitable secondary connections on 
equipment that is being towed; and
    (3) An automatic fire suppression system meeting the requirements 
of Sec. 75.1911.


Sec. 75.1910   Nonpermissible diesel-powered equipment; electrical 
system design and performance requirements.

    Electrical circuits and components associated with or connected to 
electrical systems on nonpermissible diesel-powered equipment utilizing 
storage batteries and integral charging systems, except for the special 
category of equipment under Sec. 75.1908(d), must conform to the 
following requirements:
    (a) Overload and short circuit protection must be provided for 
electric circuits and components in accordance with Secs. 75.518 and 
75.518-1 of this part;
    (b) Each electric conductor from the battery to the starting motor 
must be protected against short circuit by fuses or other circuit-
interrupting devices placed as near as practicable to the battery 
terminals;
    (c) Each branch circuit conductor connected to the main circuit 
between the battery and charging generator must be protected against 
short circuit by fuses or other automatic circuit-interrupting devices;
    (d) The electrical system shall be equipped with a circuit-
interrupting

[[Page 55532]]

device by means of which all power conductors can be deenergized. The 
device must be located as close as practicable to the battery terminals 
and be designed to operate within its electrical rating without damage. 
The device shall not automatically reset after being actuated. All 
magnetic circuit-interrupting devices must be mounted in a manner to 
preclude their closing by force of gravity;
    (e) Each motor and charging generator must be protected by an 
automatic overcurrent device. One protective device will be acceptable 
when two motors of the same rating operate simultaneously and perform 
virtually the same duty;
    (f) Each ungrounded conductor must have insulation compatible with 
the impressed voltage. Insulation materials must be resistant to 
deterioration from engine heat and oil. Electric conductors must meet 
the applicable requirements of Secs. 75.513 and 75.513-1, except 
electric conductors for starting motors, which must only meet the 
requirements of Sec. 75.513;
    (g) All wiring must have adequate mechanical protection to prevent 
damage to the cable that might result in short circuits;
    (h) Sharp edges and corners must be removed at all points where 
there is a possibility of damaging wires, cables, or conduits by 
cutting or abrasion. The insulation of the cables within a battery box 
must be protected against abrasion;
    (i) When insulated wires other than cables pass through metal 
frames, the holes must be substantially bushed with insulated bushings. 
Cables must enter metal frames of motors, splice boxes, and electric 
components only through proper fittings. All electrical connections and 
splices must be mechanically and electrically efficient, and suitable 
connectors shall be used. All electrical connectors or splices in 
insulated wire must be reinsulated at least to the same degree of 
protection as the remainder of the wire;
    (j) The battery must be secured to prevent movement, and must be 
protected from external damage by position. Batteries that are not 
protected from external damage by position must be enclosed in a 
battery box. Flame-resistant insulation treated to resist chemical 
reaction to electrolyte must be provided on battery connections to 
prevent battery terminals from contacting conducting surfaces;
    (k) A battery box, including the cover, must be constructed of 
steel with a minimum thickness of \1/8\ inch, or of a material other 
than steel that provides equivalent strength;
    (l) Battery-box covers must be lined with a flame-resistant 
insulating material permanently attached to the underside of the cover, 
unless equivalent protection is provided. Battery-box covers must be 
provided with a means for securing them in closed position. At least 
\1/2\ inch of air space must be provided between the underside of the 
cover and the top of the battery, including terminals;
    (m) Battery boxes must be provided with ventilation openings to 
prevent the accumulation of flammable or toxic gases or vapors within 
the battery box. The size and locations of openings for ventilation 
must prevent direct access to battery terminals;
    (n) The battery must be insulated from the battery-box walls and 
supported on insulating materials. Insulating materials that may be 
subject to chemical reaction with electrolyte must be treated to resist 
such action; and
    (o) Drainage holes must be provided in the bottom of each battery 
box.


Sec. 75.1911   Fire suppression systems for diesel-powered equipment 
and fuel transportation units.

    (a) The fire suppression system required by Secs. 75.1907 and 
75.1909 shall be a multipurpose dry chemical type (ABC) fire 
suppression system listed or approved by a nationally recognized 
independent testing laboratory and appropriate for installation on 
diesel-powered equipment and fuel transportation units.
    (1) The system shall be installed in accordance with the 
manufacturer's specifications and the limitations of the listing or 
approval.
    (2) The system shall be installed in a protected location or 
guarded to minimize physical damage from routine vehicle operations.
    (3) Suppressant agent distribution tubing or piping shall be 
secured and protected against damage, including pinching, crimping, 
stretching, abrasion, and corrosion.
    (4) Discharge nozzles shall be positioned and aimed for maximum 
fire suppression effectiveness. Nozzles shall also be protected against 
the entrance of foreign materials such as mud, coal dust, or rock dust.
    (b) The fire suppression system shall provide fire suppression and, 
if automatic, fire detection for the engine including the starter, 
transmission, hydraulic pumps and tanks, fuel tanks, exposed brake 
units, air compressors and battery areas on diesel-powered equipment 
and electric panels or controls used on fuel transportation units and 
other areas as necessary.
    (c) If automatic, the fire suppression system shall include audible 
and visual alarms to warn of fires or system faults.
    (d) The fire suppression system shall provide for automatic engine 
shutdown. If the fire suppression system is automatic, engine shutdown 
and discharge of suppressant agent may be delayed for a maximum of 15 
seconds after the fire is detected by the system.
    (e) The fire suppression system shall be operable by at least two 
manual actuators. One actuator shall be located on each side of the 
equipment. If the equipment is provided with an operator's compartment, 
one of the manual actuators shall be located in the compartment within 
reach of the operator.
    (f) The fire suppression system shall remain operative in the event 
of engine shutdown, equipment electrical system failure, or failure of 
any other equipment system.
    (g) The electrical components of each fire suppression system 
installed on equipment used where permissible electric equipment is 
required shall be permissible or intrinsically safe and such components 
shall be maintained in permissible or intrinsically safe condition.
    (h) Electrically operated detection and actuation circuits shall be 
monitored and provided with status indicators showing power and circuit 
continuity. If the system is not electrically operated, a means shall 
be provided to indicate the functional readiness status of the 
detection system.
    (i) Each fire suppression system shall be tested and maintained in 
accordance with the manufacturer's recommended inspection and 
maintenance program and as required by the nationally recognized 
independent testing laboratory listing or approval, and be visually 
inspected at least once each week by a person trained to make such 
inspections.
    (j) Recordkeeping Persons performing inspections and tests of fire 
suppression systems under paragraph (i) shall record when a fire 
suppression system does not meet the installation or maintenance 
requirements of this section.
    (1) The record shall include the equipment on which the fire 
suppression system did not meet the installation or maintenance 
requirements of this section, the defect found, and the corrective 
action taken.
    (2) Records are to be kept manually in a secure manner not 
susceptible to alteration or recorded electronically in a secured 
computer system that is not susceptible to alteration.
    (3) Records shall be maintained at a surface location at the mine 
for one year

[[Page 55533]]

and made available for inspection by an authorized representative of 
the Secretary and miners' representatives.
    (k) All miners normally assigned to the active workings of the mine 
shall be instructed about the hazards inherent to the operation of the 
fire suppression systems and, where appropriate, the safeguards 
available for each system.
    (l) For purposes of Sec. 75.380(f), a fire suppression system 
installed on diesel-powered equipment and meeting the requirements of 
this section is equivalent to a fire suppression system meeting the 
requirements of Secs. 75.1107-3 through 75.1107-16.


Sec. 75.1912  Fire suppression systems for permanent underground diesel 
fuel storage facilities.

    (a) The fire suppression system required by Sec. 75.1903 shall be 
an automatic multipurpose dry chemical type (ABC) fire suppression 
system listed or approved as an engineered dry chemical extinguishing 
system by a nationally recognized independent testing laboratory and 
appropriate for installation at a permanent underground diesel fuel 
storage facility.
    (1) Alternate types of fire suppression systems shall be approved 
in accordance with Sec. 75.1107-13 of this part.
    (2) The system shall be installed in accordance with the 
manufacturer's specifications and the limitations of the listing or 
approval.
    (3) The system shall be installed in a protected location or 
guarded to prevent physical damage from routine operations.
    (4) Suppressant agent distribution tubing or piping shall be 
secured and protected against damage, including pinching, crimping, 
stretching, abrasion, and corrosion.
    (5) Discharge nozzles shall be positioned and aimed for maximum 
fire suppression effectiveness in the protected areas. Nozzles must 
also be protected against the entrance of foreign materials such as 
mud, coal dust, and rock dust.
    (b) The fire suppression system shall provide automatic fire 
detection and automatic fire suppression for all areas within the 
facility.
    (c) Audible and visual alarms to warn of fire or system faults 
shall be provided at the protected area and at a surface location which 
is continually monitored by a person when personnel are underground. In 
the event of a fire, personnel shall be warned in accordance with the 
provisions set forth in Sec. 75.1101-23.
    (d) The fire suppression system shall deenergize all power to the 
diesel fuel storage facility when actuated except that required for 
automatic enclosure and alarms.
    (e) Fire suppression systems shall include two manual actuators 
located as follows:
    (1) At least one within the fuel storage facility; and
    (2) At least one a safe distance away from the storage facility and 
located in intake air, upwind of the storage facility.
    (f) The fire suppression system shall remain operational in the 
event of electrical system failure.
    (g) Electrically operated detection and actuation circuits shall be 
monitored and provided with status indicators showing power and circuit 
continuity. If the system is not electrically operated, a means shall 
be provided to indicate the functional readiness status of the 
detection system.
    (h) Each fire suppression system shall be tested and maintained in 
accordance with the manufacturer's recommended inspection and 
maintenance program and as required by the nationally recognized 
independent testing laboratory listing or approval, and be visually 
inspected at least once each week by a person trained to make such 
inspections.
    (i) Recordkeeping. Persons performing inspections and tests of fire 
suppression systems under paragraph (h) shall record when a fire 
suppression system does not meet the installation or maintenance 
requirements of this section.
    (1) The record shall include the facility whose fire suppression 
system did not meet the installation or maintenance requirements of 
this section, the defect found, and the corrective action taken.
    (2) Records are to be kept manually in a secure manner not 
susceptible to alteration or recorded electronically in a secured 
computer system that is not susceptible to alteration.
    (3) Records shall be maintained at a surface location at the mine 
for one year and made available for inspection by an authorized 
representative of the Secretary and miners' representatives.
    (j) All miners normally assigned to the active workings of the mine 
shall be instructed about the hazards inherent to the operation of the 
fire suppression systems and, where appropriate, the safeguards 
available for each system.


Sec. 75.1913  Starting aids.

    (a) Volatile fuel starting aids shall be used in accordance with 
recommendations provided by the starting aid manufacturer, the engine 
manufacturer, and the machine manufacturer.
    (b) Containers of volatile fuel starting aids shall be 
conspicuously marked to indicate the contents. When not in use, 
containers of volatile fuel starting aids shall be stored in metal 
enclosures that are used only for storage of starting aids. Such metal 
enclosures must be conspicuously marked, secured, and protected from 
damage.
    (c) Volatile fuel starting aids shall not be:
    (1) Taken into or used in areas where permissible equipment is 
required;
    (2) Used in the presence of open flames or burning flame safety 
lamps, or when welding or cutting is taking place; or
    (3) Used in any area where 1.0 percent or greater concentration of 
methane is present.
    (d) Compressed oxygen or compressed flammable gases shall not be 
connected to diesel air-start systems.


Sec. 75.1914  Maintenance of diesel-powered equipment.

    (a) Diesel-powered equipment shall be maintained in approved and 
safe condition or removed from service.
    (b) Maintenance and repairs of approved features and those features 
required by Secs. 75.1909 and 75.1910 on diesel-powered equipment shall 
be made only by a person qualified under Sec. 75.1915.
    (c) The water scrubber system on diesel-powered equipment shall be 
drained and flushed, by a person who is trained to perform this task, 
at least once on each shift in which the equipment is operated.
    (d) The intake air filter on diesel-powered equipment shall be 
replaced or serviced, by a person who is trained to perform this task, 
when the intake air pressure drop device so indicates or when the 
engine manufacturer's maximum allowable air pressure drop level is 
exceeded.
    (e) Mobile diesel-powered equipment that is to be used during a 
shift shall be visually examined by the equipment operator before being 
placed in operation. Equipment defects affecting safety shall be 
reported promptly to the mine operator.
    (f) All diesel-powered equipment shall be examined and tested 
weekly by a person qualified under Sec. 75.1915.
    (1) Examinations and tests shall be conducted in accordance with 
approved checklists and manufacturers' maintenance manuals.
    (2) Persons performing weekly examinations and tests of diesel-
powered equipment under this paragraph shall make a record when the 
equipment is not in approved or safe condition. The record shall 
include the

[[Page 55534]]

equipment that is not in approved or safe condition, the defect found, 
and the corrective action taken.
    (g) Undiluted exhaust emissions of diesel engines in diesel-powered 
equipment approved under part 36 and heavy-duty nonpermissible diesel-
powered equipment as defined in Sec. 75.1908(a) in use in underground 
coal mines shall be tested and evaluated weekly by a person who is 
trained to perform this task. The mine operator shall develop and 
implement written standard operating procedures for such testing and 
evaluation that specify the following:
    (1) The method of achieving a repeatable loaded engine operating 
condition for each type of equipment;
    (2) Sampling and analytical methods (including calibration of 
instrumentation) that are capable of accurately detecting carbon 
monoxide in the expected concentrations;
    (3) The method of evaluation and interpretation of the results;
    (4) The concentration or changes in concentration of carbon 
monoxide that will indicate a change in engine performance. Carbon 
monoxide concentration shall not exceed 2500 parts per million; and
    (5) The maintenance of records necessary to track engine 
performance.
    (h) Recordkeeping. Records required by paragraphs (f)(2) and (g)(5) 
shall be--
    (1) Recorded in a secure book that is not susceptible to 
alteration, or recorded electronically in a computer system that is 
secure and not susceptible to alteration; and
    (2) Retained at a surface location at the mine for at least 1 year 
and made available for inspection by an authorized representative of 
the Secretary and by miners' representatives.
    (i) Diesel-powered equipment must be maintained in accordance with 
this part as of November 25, 1997.


Sec. 75.1915  Training and qualification of persons working on diesel-
powered equipment.

    (a) To be qualified to perform maintenance, repairs, examinations 
and tests on diesel-powered equipment, as required by Sec. 75.1914, a 
person must successfully complete a training and qualification program 
that meets the requirements of this section. A person qualified to 
perform these tasks shall be retrained as necessary to maintain the 
ability to perform all assigned diesel-powered equipment maintenance, 
repairs, examinations and tests.
    (b) A training and qualification program under this section must:
    (1) Be presented by a competent instructor;
    (2) Be sufficient to prepare or update a person's ability to 
perform all assigned tasks with respect to diesel-powered equipment 
maintenance, repairs, examinations and tests;
    (3) Address, at a minimum, the following:
    (i) The requirements of subpart T of this part;
    (ii) Use of appropriate power package or machine checklists to 
conduct tests to ensure that diesel-powered equipment is in approved 
and safe condition, with acceptable emission levels;
    (iii) Proper maintenance of approved features and the correct use 
of the appropriate maintenance manuals, including machine adjustments, 
service, and assembly;
    (iv) Diesel-powered equipment fire suppression system tests and 
maintenance;
    (v) Fire and ignition sources and their control or elimination, 
including cleaning of the equipment;
    (vi) Safe fueling procedures and maintenance of the fuel system of 
the equipment; and
    (vii) Intake air system maintenance and tests.
    (4) Include an examination that requires demonstration of the 
ability to perform all assigned tasks with respect to diesel-powered 
equipment maintenance, repairs, examinations and tests; and
    (5) Be in writing. The written program shall include a description 
of the course content, materials, and teaching methods for initial 
training and retraining.
    (c) Recordkeeping. The operator shall maintain a copy of the 
training and qualification program required by this section and a 
record of the names of all persons qualified under the program.
    (1) The record of the names of qualified persons shall be made in a 
manner that is not susceptible to alteration, or recorded 
electronically in a computer system that is secure and not susceptible 
to alteration.
    (2) The training and qualification program and record of qualified 
persons are to be kept at surface location of the mine and made 
available for inspection by an authorized representative of the 
Secretary and by miners' representatives.


Sec. 75.1916  Operation of diesel-powered equipment.

    (a) Diesel-powered equipment shall be operated at a speed that is 
consistent with the type of equipment being operated, roadway 
conditions, grades, clearances, visibility, and other traffic.
    (b) Operators of mobile diesel-powered equipment shall maintain 
full control of the equipment while it is in motion.
    (c) Standardized traffic rules, including speed limits, signals and 
warning signs, shall be established at each mine and followed.
    (d) Except as required in normal mining operations, mobile diesel-
powered equipment shall not be idled.
    (e) Diesel-powered equipment shall not be operated unattended.

[FR Doc. 96-26838 Filed 10-24-96; 8:45 am]
BILLING CODE 4510-43-P