[Federal Register Volume 59, Number 226 (Friday, November 25, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-28973]
[[Page Unknown]]
[Federal Register: November 25, 1994]
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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Part 60
[AD-FRL-4507-6]
Amendments to Standards of Performance for New Stationary
Sources; Monitoring Requirements
AGENCY: Environmental Protection Agency (EPA).
ACTION: Proposed rule and notice of public hearing.
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SUMMARY: Revisions are proposed to the monitoring requirements of
subpart A and to performance specification 1 (PS-1) of appendix B.
Today's action proposes revisions to clarify and update requirements
for source owners and operators who must install and use continuous
stack or duct opacity monitoring equipment. Today's action also
proposes amendments regarding design and performance validation
requirements for continuous opacity monitoring system (COMS) equipment
in appendix B, PS-1. These amendments to subpart A and PS-1 will not
change the affected facilities' applicable emission standards or
requirement to monitor. The amendments will: (1) clarify owner and
operator and monitor vendor obligations, (2) reaffirm and update COMS
design and performance requirements, and (3) provide EPA and affected
facilities with equipment assurances for carrying out effective
monitoring.
A public hearing will be held, if requested, to provide interested
persons an opportunity for oral presentation of data, views, or
arguments concerning the proposed rule.
DATES: Comments. Comments must be received on or before January 24,
1995.
Public Hearing. If anyone contacts EPA requesting to speak at a
public hearing by December 16, 1994, a public hearing will be held on
December 27, 1994 beginning at 10 a.m. Persons interested in attending
the hearing should call the contact person mentioned under ADDRESSES to
verify that a hearing will be held.
Request to Speak at Hearing. Persons wishing to present oral
testimony at the public hearing must contact EPA by December 5, 1994.
ADDRESSES: Comments. Comments should be submitted (in duplicate if
possible) to: Air Docket Section (LE-131), Attention: Docket No. A-91-
07, U.S. Environmental Protection Agency, 401 M Street, SW.,
Washington, DC 20460.
Public Hearing. If anyone contacts EPA requesting a public hearing,
it will be held at EPA's Office of Emission Measurement Laboratory
Building, Research Triangle Park, North Carolina. Persons interested in
attending the hearing or wishing to present oral testimony should
contact Mr. Solomon O. Ricks, Emission Measurement Branch (MD-19),
Technical Support Division, U.S. Environmental Protection Agency,
Research Triangle Park, North Carolina 27711, telephone number (919)
541-3576.
Docket. A docket, No. A-91-07, containing information relevant to
this rulemaking, is available for public inspection between 8:30 a.m.
and noon and 1:30 p.m. and 3:30 p.m., Monday through Friday, at EPA's
Air Docket Section, room M-1500, First Floor, Waterside Mall, 401 M
Street, SW., Washington, DC 20460. A reasonable fee may be charged for
copying.
FOR FURTHER INFORMATION CONTACT: For information concerning the
standard, contact Mr. Solomon Ricks at (919) 541-5242, Emission
Measurement Branch, Technical Support Division (MD-19), U.S.
Environmental Protection Agency, Research Triangle Park, North Carolina
27711.
SUPPLEMENTARY INFORMATION: The following outline is provided to aid in
reading the preamble to the proposed method.
I. Introduction
II. Summary of Proposed Revision
A. Design
B. Demonstration of Design
C. Performance Specifications
III. Administrative Requirements
A. Public Hearing
B. Docket
C. Office of Management and Budget Reviews
D. Regulatory Flexibility Act Compliance
I. Introduction
These revisions to subpart A and PS-1 will apply to all continuous
opacity monitors installed for purposes of monitoring opacity, as
required in the Code of Federal Regulations (CFR). These requirements
may also apply to stationary sources located in a State, District,
Reservation, or Territory that has adopted these requirements into its
implementation plan.
The PS-1, Specifications and Test Procedures for Opacity Continuous
Emission Monitoring Systems in Stationary Sources, was first
promulgated in the Federal Register (40 FR 64250) on October 6, 1975. A
subsequent revision to this specification was promulgated in the
Federal Register March 30, 1983 (48 FR 13322). These specification
revisions for COMS's are based on information obtained by EPA from
additional experience with the procedures since that promulgated
revision. Prior to today's action, the proposal was distributed for
comment to a review group of EPA Regional Offices and a State agency.
In addition, EPA solicited input from opacity monitor manufacturers and
concerned industries. The EPA considered comments from these sources
and incorporated additional changes.
The specifications, in total, shall apply to all COMS's installed
or replaced after the date of promulgation. All COMS that have been
installed prior to the date of promulgation of these revisions would
not be subject to these revisions unless replaced or specifically
required to comply. Following promulgation, a source owner, operator,
or manufacturer will be subject to these PS's if installing a new COMS,
relocating a COMS, replacing a COMS, recertifying a COMS that has
undergone substantial refurbishing (in the opinion of the enforcing
agency), or has been specifically required to recertify the COMS with
these revisions.
The COMS, which met PS-1 prior to these revisions, may not meet
today's proposed specifications. Alternative designs or procedural
modifications to PS-1, approved by the Administrator prior to the
proposal of these revisions, are not applicable to monitors subject to
these revisions. However, source owners and operators, as well as
manufacturers, may apply or reapply per Sec. 60.11(i) to the
Administrator for alternatives to these PS's.
II. Summary of Proposed Revisions
Today's action proposes to restructure and clarify PS-1. The
proposal restructures organization of the specification and delineation
of responsibilities to demonstrate conformance with design, location,
and performance requirements.
Opacity monitoring system technology works in the following way:
light with specific spectral characteristics is projected from a lamp
through the effluent in the stack or duct, and the intensity of the
projected light is then measured by a sensor. The projected light is
attenuated because of absorption and scatter by the particulate matter
in the effluent; the percentage of light attenuated is defined as the
opacity of the emission. Transparent stack emissions that do not
attenuate light have a transmittance of 100 percent or an opacity of
zero percent. Opaque stack emissions that attenuate all of the light
have a transmittance of zero percent or an opacity of 100 percent. The
opacity measured at the location of the COMS is corrected for
differences in measurement pathlength from stack or vent exit
conditions and reported as the facility's opacity emission.
A. Design
The design requirements, as promulgated March 30, 1983, continue to
be required. The following additional and upgraded requirements are
being proposed:
1. The optical alignment device, used to assure that the system is
optically aligned, must clearly indicate misalignment before the
2 percent opacity shift allowed by the design performance limit
occurs. Therefore, systems with subjective observation indicators,
e.g., ``top-dead-center,'' may not comply. Manufacturer evaluations,
conducted in 1989 and 1990, found that several manufacturers were
revising their alignment devices to clearly indicate misalignment.
However, 1992 evaluations have identified a continuing problem of
clearly depicting misalignment. Specifically, a COMS was placed in zero
alignment, yet, the alignment sight directions would have indicated
that it was misaligned. Realignment in this instance could have caused
a negative bias in future recordings.
2. In addition, in 1992, EPA observed COMS responses over different
distances for the COMS alignment test and concluded that the alignment
check should be done at the installation pathlength and not at 8
meters, as currently required by PS-1. This is also a practice of the
manufacturers due to specific aperture, objective lens, and
installation pathlength requirements. Because the alignment check and
performance test are considered installation pathlength specific and
because of the Agency's need to assure clarity in the misalignment, the
optical alignment test is now required at the site of the installation.
This will provide an opportunity for the enforcing agency and source
owner or operator to evaluate and establish clarity in the depiction of
misalignment.
3. The angle of view (AOV) and angle of projection (AOP)
specifications have been revised. Defined as the angle that contains
all of the photopic radiation either detected or projected by the COMS,
the calumniation of the light beam has been reduced to a maximum total
of 4 degrees. From 1989 to 1992 time period, EPA observed the AOV and
AOP testing, conducted by 10 major manufacturers of COMS sold in the
United States, and concluded that the AOV and AOP should be reduced
from the current 5 degrees to 4 degrees. This change also reflects
manufacturers' improvement in the instruments.
4. The COMS must provide a means to simulate a zero and upscale
calibration value in order to check the COMS transmitter/receiver
calibration. The calibration checking system shall include, at the same
time, all the optical and electromechanical equipment used in the
normal measurement mode. The checking system will measure and provide a
permanent record of the COMS calibration status. The COMS's, which
conduct zero and upscale calibration drift (CD) assessments without
simultaneously checking all the components actively used in normal day-
to-day opacity measurement, are deemed to deviate from the proposed
specifications. The Agency recognizes that some existing dual-path
COMS's do not include the reflector in the daily zero and span check.
However, these COMS's have been, and will continue to be, an accepted
exception to the simultaneous check requirement.
5. The COMS shall provide operators visual or audible alarms for
exceeding PS-1, operation specification, equipment failures, and
effluent opacity standards.
6. The COMS shall provide an automated means to assess and record
accumulated automatic zero compensations on a 1-hour and 24-hour basis.
The 1-hour is specifically required only during a specific 24-hour
period of the operational test period. The 24-hour assessment and
recording of the 24-hour accumulated CD is a continual requirement of
the system.
7. The automatic compensation for dirt accumulation on the window
surfaces of the COMS requires including the compensation allowance in
the 4 percent opacity tolerance for zero CD adjustment. The measurement
for determining compensation shall be conducted on those surfaces that
are directly in line with the light beam used to measure the effluent
opacity. In addition, only those optical surfaces, directly in the
light beam path under normal operation to measure opacity, may be
compensated for dust accumulation. The EPA has determined that systems
that attempt to measure dust accumulation in locations, other than the
measurement path of the normally transmitted measurement light beam or
assume equal and uniform dust accumulations on unmeasured surfaces
(e.g., reflectors), could result in unacceptable negative biases in
opacity measurements. Those automatic dust compensation systems that
meet the optical path assessment criteria may demonstrate and petition
the Administrator for an increase in compensation to 20 percent opacity
adjustment.
8. Providing a means to independently audit the COMS will be
required of all new and replacement COMS's. Manufacturers of COMS's,
meeting the March 30, 1983 specifications, have routinely incorporated
this performance check allowance into their designs. In addition, the
proposed specifications recognize and allow for the use of a ``zero-
jig.'' This apparatus, which must have a unique serial number specific
to the installed COMS, may be used to conduct performance check audits
as well as for zero calibrations of the COMS transmitter/receiver
(dual-path systems) during installation.
9. The COMS must automatically correct opacity emissions measured
at the COMS installation location to the emission outlet pathlength.
The capability to automatically display and record the pathlength
correction factor (PLCF) changes must be incorporated into the COMS
design.
B. Demonstration of Design
The proposed demonstration of design conformance requirements of
PS-1 have evolved from historical observation of the current required
demonstrations. Such demonstrations have customarily been done by COMS
manufacturers due to their unique capabilities at the manufacturing
locations. The EPA believed this to be appropriate in 1983 when it
allowed the source owner or operator to obtain a Manufacturer's
Certificate of Conformance (MCOC) rather than conducting design
performance testing at the source. The EPA, then and now, continues to
hold the source owner and operator responsible for the overall
demonstration that the COMS meets all of PS-1 requirements. Today's
proposed specification requires COMS manufacturers to conduct the
design specification testing required in section 6.0, Design
Specification Verification Procedure. However, this does not relieve
the source owners or operators from demonstrating compliance with
applicable COMS requirements. Manufacturers of COMS's are encouraged,
although not required, to seek an EPA evaluation of their design
specification demonstration procedures for each model of COMS marketed
as conforming with these specifications. The evaluation will provide
competitive advantages to successful demonstrations as well as
providing purchaser assurances of initial conformance to regulatory
requirements. The activity is expected to reduce retrofit and
corrective costs potentially encountered with nonconforming systems.
The evaluation will also ensure that COMS's manufactured outside the
United States (U.S.), for subsequent sale in the U.S., perform testing
in the U.S. prior to sale.
The design specification testing requirements assume that apparatus
used to conduct demonstrations is proper. Adequately rugged apparatus
will assure the accuracy and rigor required at the specification
frequency. The testing requirements for demonstrating conformance with
the design specifications assume that the testing apparatus, used to
conduct such tests, were properly chosen, adequately rugged, and
sufficiently accurate. The 1989-1990 evaluation of procedures,
conducted by the COMS manufacturers, found a broad spectrum of
sophistication in demonstration apparatus. The detection limits of some
equipment, used in the manufacturers' procedures, were found to be a
limiting factor in the conduct of some tests. If manufacturers'
operations are not sufficiently precise, accurate, or permanent,
evaluations may indicate problems in repeatability.
The 1983 monitor selection process for design demonstration testing
did not clearly specify how to select a monitor if the manufacturing
operation was not continuous or did not include large inventories. Most
COMS manufacturing operations are likely to use off-the-shelf or
imported components, and the COMS's are constructed and shipped as
orders are received. Large inventories generally do not exist, and
production is demand-based. Today's proposed monitor selection process
revises the 1983 process to recognize some of these typical
manufacturing operations. The proposal requires that each COMS
installed, pursuant to the requirements of an applicable standard, have
a serial number assigned by the manufacturer. (Note: If a zero-jig is
manufactured and provided for the COMS model type, a unique serial
number for the zero-jig, corresponding to the installed COMS serial
number, is required.) The proposed model selection process of section
6, Design Specification Verification Procedure, specifies that the COMS
(per model) selection will be based on a randomly-selected COMS
produced during the month or a randomly-selected COMS per 20 such
monitors produced, whichever is more frequent.
If 20 or more COMS's of a particular model are produced in a month,
the manufacturer shall randomly select a COMS of that model from that
month's production for conducting the design conformance tests in
sections 6.2 through 6.6. Otherwise, the manufacturer shall select a
COMS with a serial number in a distinct lot of 20 monitors of that
model produced, or to be produced, and shall test that COMS for
demonstrating conformance with the design specifications.
The proposed specification does not require additional sampling and
testing upon the finding of nonconformance with the design
requirements. Upon such finding, however, the specification requires
the manufacturer to notify all sources who have purchased that model of
COMS if the COMS was manufactured since the model's last successful
demonstration of conformance. The manufacturer must send a copy of all
such notifications to EPA.
The design specification demonstration incorporates other
requirements.
1. An outline of an example of a MCOC is provided to give direction
on the presentation of supporting documentation for performance
demonstration tests.
2. The current specifications do not require verification of
supporting COMS component conformance documentation, such as lamp
emissivity, which is used for the construction of a spectral response
curve. Also, the 1983 specifications did not put any limit on the valid
time period for certain supporting demonstrations such as development
of the spectral response curve. As a result, some MCOC's now reflect 5-
year old data. The 1989-1990 evaluations of the COMS manufacturers
identified incorrect calculation procedures as well as inclusion of a
component that caused an unacceptable COMS response. The manufacturer
in the latter case, who calculated the response curve, was unaware that
the component's characteristics had changed.
The proposed PS's require the manufacturer to measure the spectral
response curve of the COMS. The specifications will no longer allow the
manufacturer, or source owner or operator, to calculate the spectral
response curve from lamp emissivity, detector response, and filter
characteristics. The EPA has identified two acceptable systems and
procedures for measuring the COMS spectral response curve at 10 nm
intervals from 300 to 800 nm. Information, provided by the
manufacturers, indicates that this requirement is not overly
burdensome. This information is necessary because, from this
information, both the peak and mean spectral response can be accurately
determined.
3. The AOV and AOP tests have been clarified and reaffirmed in the
specification. Note that no alternative procedures have been approved
for the AOV and AOP, even though manufacturers may be using
alternatives. The specification clearly states that alternative
procedures require approval by the Administrator. Therefore, source
owners and operators must obtain approvals of an alternative procedure
prior to seeking a site-specific COMS approval.
C. Performance Specifications
The major change to the PS-1 demonstrations from the 1983
specification occurs in section 7, Performance Specification
Verification Procedures. The proposal requires that testing be
conducted at the affected facility. Current practices have allowed
verification tests to be conducted at the COMS manufacturers' facility.
However, the 1983 specifications intended verification testing to be
performed at the affected facility to ensure that the entire COMS
system was evaluated for the specific installation. The current
practices have resulted in excluding the data recording portion of the
system used at the installation under normal measurement conditions
and, thereby, limiting assessment of the COMS for the specific
installation. For this reason, the proposed specification clarifies
where the required PS-1 testing of section 7 is to be conducted.
The proposal also simplifies procedures for calibration attenuator
selection. The COMS's have been typically required to demonstrate a
certain degree of calibration error over a range of emissions specified
as the span value. This span value may or may not correspond to the
actual instrument range (0 to 100 percent opacity). The primary concern
of COMS data users is the capability of the instrument to measure
accurately opacities at, or near the applicable standard. Once the
opacity level exceeds the standard, the magnitude of the emissions
tends to be of lesser concern than the duration of the operation.
Therefore, the proposal includes selection of appropriate attenuators
and calibration error test for the applicable opacity emission
standard.
The specifications recognize the need to set a surrogate emission
limit for purposes of conducting the calibration error test. This is
due to the fact that some authorities set opacity limitations of zero
percent, and the specification must assess calibration accuracy and
linearity around the standard. Attenuator opacity values are specified
in terms of optical density (or transmittance) which exhibits a
logarithmic relationship to opacity. Because of the nonlinear nature of
this relationship, COMS calibration at high opacity values becomes more
difficult. At the low opacity emission limitations of current
regulations, e.g., 20 percent, the nonlinear relationship of opacity
and optical density is not severe and is within the error specification
in this proposal. Therefore, a surrogate limit for purposes of the
calibration error test would continue to assure acceptable COMS
accuracy, even though the actual emission limitation was below the
surrogate value. Consequently, where emission standards have been set
at 10 percent opacity or less, the proposal specifies a surrogate 10
percent opacity limit for purposes of conducting the calibration error
test. The EPA contacted attenuator manufacturers who indicated that
certifiable low opacity, i.e., 2 percent opacity (98 percent
transmittance) attenuators, necessary to comply with the required
testing, are available.
Where dual standards are specified, e.g., a 10-percent opacity
limitation with an allowance for one 6-minute period in an hour not to
exceed 40 percent opacity, the calibration error test must be conducted
over the full range of standards. The test may be conducted as a three-
point calibration error test over the range, i.e., 10 to 40 percent
opacity, or separate three-point calibration error tests around each
requirement.
The proposal describes procedures for setting the instrument zero
and upscale calibration values and zero alignment. The proposal
specifies that a check of the adequacy of the zero setting with the
alignment must be made. If discrepancies between measured values exist,
they should be resolved prior to stack installation. At this time (if
part of the system), the zero-jig zero setting also should be adjusted
to coincide with the instrument zero for the monitor pathlength,
recorded and permanently set.
The 1983 specifications did not specify the use of secondary
instruments to establish secondary attenuators for calibration error
tests. Today's specification provides a procedure for qualifying a
secondary instrument. The conditioning period has been incorporated
into the operational test period. The operational test period is now a
336-hour test period during which the maintenance and operational
restrictions, that were required of both conditioning and operational
periods in the 1983 specifications, still apply. An additional test has
been included to address short-term diurnal fluctuations in COMS's
opacity output readings. This 1-hour drift test and specification are
designed to assess and limit the amount of zero and upscale calibration
value drifts due to operational conditions occurring during a 24-hour
period.
III. Administrative Requirements
A. Public Hearing
In accordance with section 307(d)(5) of the Clean Air Act as
amended by Public Law 101-549, the Clean Air Act Amendments of 1990, a
public hearing will be held, if requested, to discuss the proposed
revisions to subpart A and appendix B. Persons wishing to make oral
presentations should contact EPA at the address given in the ADDRESSES
section of this preamble. Oral presentations will be limited to 15
minutes each. Any member of the public may file a written statement
with the EPA before, during, or within 30 days after the hearing.
Written statements should be addressed to the Air Docket Section
address given in the ADDRESSES section of this preamble.
A verbatim transcript of the hearing and written statements will be
available for public inspection and copying during normal working hours
at EPA's Air Docket Section in Washington, D.C. (see ADDRESSES section
of this preamble).
B. Docket
The docket is an organized and complete file for all information
submitted or otherwise considered by EPA in the development of this
proposed rulemaking. The principal purposes of the docket are: (1) to
allow interested parties to identify and locate documents so that they
can effectively participate in the rulemaking process, and (2) to serve
as the record in case of judicial review (except for interagency review
materials) [Clean Air Act Section 307(d)(7)(A)].
C. Office of Management and Budget Review
Due to the timing of review which was pre-Executive Order 12866 (58
FR 51735; October 4, 1993), this NPRM underwent Executive Order 12291
Review. Under Executive Order 12291, EPA must judge whether a
regulation is ``major'' and, therefore, subject to the requirement of a
regulatory impact analysis. This rulemaking is not major because it
will not have an annual effect on the economy of $100 million or more;
it will not result in a major increase in costs or prices; and there
will be no significant adverse effects on competition, employment,
investment, productivity, innovation, or on the ability of U.S.-based
enterprises to compete with foreign-based enterprises in domestic or
export markets.
D. Regulatory Flexibility Act Compliance
Pursuant to section 605(b) of the Regulatory Flexibility Act, 5
U.S.C. 605(b), the Administrator certifies that this rule will not have
a significant impact on a substantial number of small entities because
no additional cost will be incurred by such entities. The requirements
of the proposal reaffirm the existing requirements for demonstrating
conformance with the COMS PS's. Small entities will be affected to the
same degree that they are affected under existing requirements.
This rule does not contain any information collection requirements
subject to the Office of Management and Budget review under the
Paperwork Reduction Act of 1980, 44 U.S.C. 3501 et seq.
List of Subjects in 40 CFR Part 60
Environmental protection, Air pollution control, Particulate
matter.
Dated: November 8, 1994.
Carol M. Browner,
Administrator.
The EPA proposes that 40 CFR part 60 be amended as follows:
1. The authority citation for part 60 continues to read as follows:
Authority: 42 U.S.C. 7401, 7411, 7414, 7416, and 7601.
Subpart A--[Amended]
2. Section 60.13 is amended by revising paragraph (d)(1) to read as
follows:
Sec. 60.13 Monitoring requirements.
* * * * *
(d)(1) Owners and operators of continuous emission monitoring
systems (CEMS's) installed in accordance with the provisions of this
part, shall automatically check the zero (or low level value between 0
and 20 percent of span value) and span (50 to 100 percent of span
value) calibration drifts (CD's) at least once daily. For CEMS's used
to measure opacity in accordance with the provisions of this part,
owners and operators shall automatically, intrinsic to the continuous
opacity monitoring system (COMS), check the zero and upscale
calibration drifts at least once daily. For a particular COMS, the
acceptable range of zero and upscale calibration materials shall be as
defined in the applicable version of PS-1 in appendix B of this part.
Where an opacity standard of 10 percent or less, corrected to stack
exit conditions, has been specified, a surrogate 10 percent opacity
standard shall be used for determining the daily calibration values for
the drift assessments required above. The zero and upscale value shall,
as a minimum, be adjusted whenever either the 24-hour zero drift or the
24-hour span drift exceeds two times the limit of the applicable PS in
appendix B. The system must allow the amount of the excess zero and
span drift to be recorded and quantified whenever specified. For
COMS's, the optical surfaces, exposed to the effluent gases, shall be
cleaned prior to performing the zero and span drift adjustments, except
for systems using automatic zero adjustments. The optical surfaces
shall be cleaned when the cumulative automatic zero compensation
exceeds 4 percent opacity.
* * * * *
Appendix B--[Amended]
3. Appendix B to part 60 is amended by revising Performance
Specification 1 to read as follows:
Appendix B to Part 60--Performance Specifications
* * * * *
Performance Specification 1--Specifications and Test Procedures for
Continuous Opacity Monitoring Systems in Stationary Sources
1. Applicability and Principle
1.1 Applicability.
1.1.1 This specification contains requirements for the design,
performance, and installation of instruments for continuous opacity
monitoring systems (COMS's) and data computation procedures for
evaluating the acceptability of a COMS. Certain design requirements
and test procedures, established in this specification, may not
apply to all instrument designs proposed for installation after the
effective date of these specifications. In such instances, approval
for the use of alternative design requirements and test procedures
shall be obtained from the Administrator prior to a demonstration of
conformance with these specifications.
1.1.2 Performance Specification 1 (PS-1) applies to COMS's
installed on or after the effective date which is the date of
promulgation of these specifications. The COMS's installed prior to
the effective date are required to comply with the provisions and
requirements of PS-1 as promulgated on March 30, 1983 (48 FR 13322).
1.1.3 A COMS installed before the effective date of these
specifications need not be re-tested to demonstrate compliance with
these PS's unless specifically required by regulatory action other
than the promulgation of PS-1. If a COMS installed prior to the
effective date is replaced or relocated, this PS-1 shall apply to
the COMS replacement or as relocated.
1.2 Principle.
1.2.1 The opacity of particulate matter in stack emissions is
continuously monitored and corrected to a stack exit pathlength by a
measurement system, based upon the principle of transmissometry.
Light, having specific spectral characteristics, is projected from a
lamp through the effluent in the stack or duct, and the intensity of
the projected light is measured by a sensor. The projected light is
attenuated because of absorption and scatter by the particulate
matter in the effluent; the percentage of visible light energy
attenuated is defined as the opacity of the emission.
1.2.2 This specification establishes specific design,
performance, and installation criteria for the COMS. Prior to
installation, source owners and operators must provide verification
that the COMS has met the design specifications. Prior to
installation, it is recommended that the COMS installation location
be reviewed and approved by the appropriate regulatory authority.
Then, the owner and operator calibrates, installs, and operates the
COMS for a specified test period. During this specified test period,
the COMS is further evaluated to determine conformance with PS-1.
2. Definitions
2.1 Angle of Projection (AOP). The angle that contains all of
the radiation projected from the lamp assembly of the analyzer at a
level of greater than 2.5 percent of the peak illuminance.
2.2 Angle of View (AOV). The angle that contains all of the
radiation detected by the photodetector assembly of the analyzer at
a level greater than 2.5 percent of the peak detector response.
2.3 Calibration Drift (CD). The difference in the COMS output
readings from the upscale calibration value after a stated period of
normal continuous operation during which no unscheduled maintenance,
repair, or adjustment took place.
2.4 Calibration Error. The difference between the opacity
values indicated by the COMS and the known values of a series of
calibration attenuators (filters or screens).
2.5 Centroid Area. A concentric area that is geometrically
similar to the stack or duct cross-section and is no greater than 1
percent of the stack or duct cross-sectional area.
2.6 Continuous Opacity Monitoring System. The total equipment
required for the determination of opacity. The system consists of
the following major subsystems:
2.6.1 Analyzer. That portion of the installed COMS that senses
the pollutant and generates an output that is a function of the
opacity.
2.6.2 Data Recorder. That portion of the installed COMS that
provides a permanent record of the analyzer output in terms of
opacity. The data recorder may include automatic data reduction
capabilities.
2.6.3 Sample Interface. That portion of the installed COMS that
protects the analyzer from the effects of the stack effluent and
aids in keeping the optical surfaces clean.
2.7 External Audit Device. The inherent design, equipment, or
accommodation of the COMS allowing the independent assessment of
system calibration and operation. An adequate design shall permit
the use of external (i.e., not intrinsic to the instrument) neutral
density filters to assess monitor operation.
2.8 External Zeroing Device (Zero-Jig). An external, removable
device for simulating or checking the cross-stack zero alignment of
the COMS.
2.9 Full Scale. The maximum data display output of the COMS.
For purposes of recordkeeping and reporting, full scale shall be
greater than 80 percent opacity.
2.10 Mean Spectral Response. The mean response wavelength of
the wavelength distribution for the effective spectral response
curve of the transmissometer.
2.11 Opacity. The fraction of incident light that is attenuated
by an optical medium. Opacity (Op) and transmittance (Tr) are
related by: Op=1-Tr.
2.12 Operational Test Period. A period of time (336 hours)
during which the COMS is expected to operate within the established
PS's without any unscheduled maintenance, repair, or adjustment.
2.13 Optical Density. A logarithmic measure of the amount of
incident light attenuated. Optical Density (OD) is related to the
transmittance and opacity as follows: OD = -log10 (1-Op).
2.14 Pathlength. The depth of effluent in the light beam
between the receiver and the transmitter of a single-pass trans-
missometer, or the depth of effluent between the transceiver and
reflector of a double-pass transmissometer. Three pathlengths are
referenced by this specification as follows:
2.14.1 Emission Outlet Pathlength. The pathlength (depth of
effluent) at the location where emissions are released to the
atmosphere. For noncircular outlets, D = (2LW)/(L + W), where L is
the length of the outlet and W is the width of the outlet. Note that
this definition does not apply to positive pressure baghouse outlets
with multiple stacks, side discharge vents, ridge roof monitors,
etc.
2.14.2 Installation Pathlength. The installation flange-to-
flange distance.
2.14.3 Monitoring Pathlength. The effective depth of effluent
(the distance over which the light beam is actually evaluating the
stack effluent) measured by the COMS at the installation location.
Monitoring pathlength is to be used for the optical alignment,
response, and calibration error tests of section 7 and calculation
of the pathlength correction factor (PLCF). The effective depth of
effluent measured by the COMS must be equal to or greater than 90
percent of the distance between duct or stack walls.
2.15 Peak Spectral Response. The wavelength of maximum
sensitivity of the transmissometer.
2.16 Primary Attenuators. Primary attenuators are those
calibrated by the National Institute of Standards and Technology
(NIST).
2.17 Response Time. The amount of time it takes the COMS to
display on the data recorder 95 percent of a step change in opacity.
2.18 Secondary Attenuators. Secondary attenuators are those
calibrated against primary attenuators according to procedures in
section 7.1.3.
2.19 Transmissometer. That portion of the installed COMS that
includes the sample interface and the analyzer.
2.20 Transmittance. The fraction of incident light that is
transmitted through an optical medium.
2.21 Upscale Calibration Value. The opacity value at which a
calibration check of the COMS is performed by simulating an upscale
opacity condition as viewed by the receiver. An opacity value
(corrected for pathlength) that is 150 to 190 percent of the
applicable opacity standard.
2.22 Zero Calibration Value. A value at which a calibration
check of the COMS is performed by simulating a zero opacity
condition as viewed by the receiver. An opacity value (corrected for
pathlength) that is 0 to 10 percent of the applicable opacity
standard.
2.23 Zero Drift. The difference in the COMS output readings
from the zero calibration value after a stated period of normal
continuous operation during which no unscheduled maintenance,
repair, or adjustment took place.
2.24 Zero and Upscale Calibration Value Attenuator System. An
inherent system of the COMS which can be an automatic electro-
mechanical and filter system for simulating both a zero and upscale
calibration value, providing an assessment and record on the
calibration of the instrument. Optical filters or screens with
neutral spectral characteristics, or other device that produces a
zero or an upscale calibration value shall be used.
3. Apparatus
3.1 Continuous Opacity Monitoring System. A COMS that meets the
design and PS's of PS-1, including a suitable data recorder, such as
an analog strip chart recorder or other suitable device (e.g.,
digital computer) with an input signal range compatible with the
analyzer output.
3.2 Calibration Attenuators. Minimum of three. These
attenuators must be optical filters with neutral spectral
characteristics selected and calibrated according to the procedures
in sections 7.1.2 and 7.1.3 and of sufficient size to attenuate the
entire light beam received by the detector of the COMS.
3.3 Calibration Spectrophotometer. A laboratory
spectrophotometer meeting the following minimum design
specifications:
------------------------------------------------------------------------
Parameter Specification
------------------------------------------------------------------------
Wavelength range................... 300-800 nm.
Detector angle of view............. <10 deg..="" accuracy...........................=""><0.5% transmittance,="" nist="" traceable="" calibration.="" ------------------------------------------------------------------------="" 3.4="" spectral="" response="" measurement="" system.="" equipment="" and="" procedures="" capable="" of="" providing="" an="" accurate="" evaluation="" and="" recording="" of="" the="" spectral="" response="" curve="" of="" the="" coms.="" the="" equipment="" will="" include,="" but="" is="" not="" limited="" to,="" a="" helium-neon="" laser="" for="" calibration,="" a="" monochrometer="" capable="" of="" 10="" nm="" incremental="" changes="" over="" a="" range="" of="" 300="" to="" 800="" nm,="" and="" other="" appropriate="" optical="" bench="" requirements.="" 3.5="" coms="" test="" stands="" and="" related="" equipment.="" equipment="" capable="" of="" allowing="" the="" accurate="" conduct="" of="" the="" performance="" tests="" to="" the="" necessary="" tolerances="" called="" for="" by="" these="" specifications.="" 4.="" installation="" specifications="" install="" the="" coms="" at="" a="" location="" where="" the="" opacity="" measurements="" are="" representative="" of="" the="" total="" emissions="" from="" the="" affected="" facility.="" this="" requirement="" can="" be="" met="" as="" follows:="" 4.1="" measurement="" location.="" select="" a="" measurement="" location="" that="" is="" (a)="" at="" least="" 4="" duct="" diameters="" downstream="" from="" all="" partic-="" ulate="" control="" equipment="" or="" flow="" disturbance,="" (b)="" at="" least="" 2="" duct="" diameters="" upstream="" of="" a="" flow="" disturbance,="" (c)="" where="" condensed="" water="" vapor="" is="" not="" present,="" (d)="" free="" of="" interference="" from="" ambient="" light,="" and="" (e)="" accessible="" in="" order="" to="" permit="" maintenance.="" 4.2="" measurement="" location.="" the="" primary="" concern="" in="" locating="" a="" coms="" is="" determining="" a="" location="" of="" well-mixed="" stack="" gas.="" two="" factors="" contribute="" to="" complete="" mixing="" of="" emission="" gases:="" turbulence="" and="" sufficient="" mixing="" time.="" the="" criteria="" listed="" below="" define="" conditions="" under="" which="" well-mixed="" emissions="" can="" be="" expected.="" select="" a="" light="" beam="" path="" that="" passes="" through="" the="" centroidal="" area="" of="" the="" stack="" or="" duct.="" additional="" requirements="" or="" modifications="" must="" be="" met="" for="" the="" following="" locations:="" 4.2.1="" if="" the="" location="" is="" in="" a="" straight="" vertical="" section="" of="" stack="" or="" duct="" and="" is="" less="" than="" 4="" equivalent="" diameters="" downstream="" from="" a="" bend,="" use="" a="" light="" beam="" path="" that="" is="" in="" the="" plane="" defined="" by="" the="" upstream="" bend="" (see="" figure="" 1-1).="" 4.2.2="" if="" the="" location="" is="" in="" a="" straight="" vertical="" section="" of="" stack="" or="" duct="" and="" is="" less="" than="" 4="" equivalent="" stack="" or="" duct="" diameters="" upstream="" from="" a="" bend,="" use="" a="" light="" beam="" path="" that="" is="" in="" the="" plane="" defined="" by="" the="" bend="" (see="" figure="" 1-2).="" 4.2.3="" if="" the="" location="" is="" in="" a="" straight="" vertical="" section="" of="" stack="" or="" duct="" and="" is="" less="" than="" 4="" equivalent="" stack="" or="" duct="" diameters="" downstream="" and="" is="" also="" less="" than="" 1="" diameter="" upstream="" from="" a="" bend,="" use="" a="" light="" beam="" path="" in="" the="" plane="" defined="" by="" the="" upstream="" bend="" (see="" figure="" 1-3).="" 4.2.4="" if="" the="" location="" is="" in="" a="" horizontal="" section="" of="" stack="" or="" duct="" and="" is="" at="" least="" 4="" equivalent="" stack="" or="" duct="" diameters="" downstream="" from="" a="" vertical="" bend,="" use="" a="" light="" beam="" path="" in="" the="" horizontal="" plane="" that="" is="" between="" \1/3\="" and="" \1/2\="" the="" distance="" up="" the="" vertical="" axis="" from="" the="" bottom="" of="" the="" duct="" (see="" figure="" 1-4).="" 4.2.5="" if="" the="" location="" is="" in="" a="" horizontal="" section="" of="" duct="" and="" is="" less="" than="" 4="" diameters="" downstream="" from="" a="" vertical="" bend,="" use="" a="" light="" beam="" path="" in="" the="" horizontal="" plane="" that="" is="" between="" \1/2\="" and="" \2/3\="" the="" distance="" up="" the="" vertical="" axis="" from="" the="" bottom="" of="" the="" duct="" for="" upward="" flow="" in="" the="" vertical="" section,="" and="" is="" between="" \1/3\="" and="" \1/2\="" the="" distance="" up="" the="" vertical="" axis="" from="" the="" bottom="" of="" the="" duct="" for="" downward="" flow="" (figure="" 1-5).="" 4.3="" alternative="" locations="" and="" light="" beam="" paths.="" locations="" and="" light="" beam="" paths,="" other="" than="" those="" cited="" above,="" may="" be="" selected="" by="" demonstrating,="" to="" the="" administrator="" or="" delegated="" agent,="" that="" the="" average="" opacity="" measured="" at="" the="" alternative="" location="" or="" path="" is="" equivalent="" to="" the="" opacity="" as="" measured="" at="" a="" location="" meeting="" the="" criteria="" of="" section="" 4.1="" or="" 4.2.="" the="" opacity="" at="" the="" alternative="" location="" is="" considered="" equivalent="" if="" the="" average="" opacity="" value="" measured="" at="" the="" alternative="" location="" is="" within="">10
percent of the average opacity value measured at the location
meeting the installation criteria in section 4.2, and the difference
between any two average opacity values is less than 2 percent
opacity (absolute). To conduct this demonstration, simultaneously
measure the opacities at the two locations or paths for a minimum
period of time (e.g., 180-minutes) covering the range of normal
operating conditions and compare the results. The opacities of the
two locations or paths may be measured at different times, but must
represent the same process operating conditions. Alternative
procedures for determining acceptable locations may be used if
approved by the Administrator.
4.4 Slotted Tube. For COMS that uses a slotted tube, the
slotted tube must be of sufficient size and orientation so as not to
interfere with the free flow of effluent through the entire optical
volume of the COMS photodetector. The manufacturer must also present
information in the certificate of conformance that the slotted tube
minimizes light reflections. As a minimum, this demonstration shall
consist of laboratory operation of the COMS both with, and without
the slotted tube in position. The slotted portion must meet the
monitoring pathlength requirements of 2.14.3.
5. Design Specifications
5.1 Design Specifications. The COMS shall comply with the
following design specifications:
5.1.1 Peak and Mean Spectral Responses. The peak and mean
spectral responses must occur between 500 nm and 600 nm. The
response at any wavelength below 400 nm or above 700 nm shall be
less than 10 percent of the peak spectral response.
5.1.2 Angle of View. The total AOV shall be no greater than 4
degrees.
5.1.3 Angle of Projection. The total AOP shall be no greater
than 4 degrees.
5.1.4 Optical Alignment Sight. Each analyzer must provide some
method for visually determining that the instrument is optically
aligned. The method provided must be capable of clearly indicating
that the unit is misaligned when an error of no greater than
2 percent opacity occurs due to misalignment at the
installation monitoring pathlength. Instruments that are capable of
providing a clear path zero check while in operation on a stack or
duct with effluent present, and while maintaining the same optical
alignment during measurement and calibration, need not meet this
requirement (e.g., some ``zero pipe'' units). The owner and operator
shall insure that the COMS manufacturer's written procedures and the
certificate of conformance depict the correct alignment and the
misalignment corresponding to a 2 percent opacity shift
as viewed using the alignment sight.
5.1.5 Simulated Zero and Upscale Calibration System. Each
analyzer must include a calibration system for simulating a zero and
upscale calibration value. This calibration system must provide, as
a minimum, a simultaneous system check of all of the active analyzer
internal optics, all active electronic circuitry including the
primary light source (lamp) and photodetector assembly, and electro-
mechanical systems used during normal measurement operation.
5.1.6 Automatic Zero and Upscale Value Compensation Indicator
and Alarm. The COMS shall provide an automated means for determining
and recording the actual amount of 24-hour zero compensation on a
daily basis. The COMS also shall provide an alarm (visual or
audible) when a 4 percent opacity zero compensation has
been exceeded. This indicator shall be at a location which can be
seen or heard by the operator (e.g., process control room) and
accessible to the operator (e.g., the data output terminal).
5.1.6.1 During the operational test period, the COMS also must
provide a means for determining and automatically recording the
actual amount of upscale calibration value compensation at specified
1-hour intervals so that the actual 1-hour upscale calibration value
shift can be determined (see section 7.2.3).
5.1.6.2 If the COMS has a feature that provides automatic zero
compensation for dirt accumulation on exposed optical and mechanical
surfaces, the compensation allowance for dust may be included up to
20 percent opacity. For all other systems, the dirt accumulation on
exposed optical and mechanical surfaces are limited to 4 percent
opacity zero compensation allowance of section 5.1.6. The
determination of dirt accumulation on all surfaces exposed to the
effluent being measured shall include only those surfaces in the
direct path of the measuring light beam under normal opacity
measurement. The dust accumulation must actually be measured.
5.1.7 External Calibration Filter Access. The COMS must be
designed to accommodate an independent assessment of the total
systems response to audit filters. An adequate design shall permit
the use of external (i.e., not intrinsic to the instrument) neutral
density filters to assess monitor operation. This system may include
an external audit zero-jig as identified in section 3.0.
5.1.8 Pathlength Correction Factor. The COMS shall display and
record all opacity values corrected to the emission outlet
pathlength. Equations 1-7 or 1-8 may be used. The system must be
capable of independent display of the PLCF and automatically record
any changes made to the PLCF.
5.1.9 External Fault Indicator. The installed COMS must provide
a means to automatically alert the owner or operator when a
component or performance parameter has failed or been exceeded
(e.g., projector lamp failure, zero or CD operation, purge air
blower failure, data recorder failure). Indicator lights or alarms
must be visible or audible to the operator(s).
5.1.10 Data recorder resolution. The data recorder and data
acquisition system shall record and display opacity values to 0.5
percent opacity.
Table 1-1.--COMS Design Specifications
1. Peak spectral response.
2. Mean spectral response.
3. Angle of view.
4. Angle of projection.
5. Optical alignment sight.
6. Simulated zero and upscale calibration system.
7. Automated zero compensation recording and indicating system.
8. Automated upscale calibration compensation recording and indicating
system.
9. External calibration filter access.
10. Pathlength correction factor recording and indicating system.
6. Design Specifications Verification Procedures
These procedures apply to all instruments installed for purposes
of complying with opacity monitoring requirements (see section 1.1,
Applicability). The source owner or operator is responsible for the
overall COMS performance demonstration required by the applicable
standards. As an alternative, the COMS manufacturer may conduct the
COMS design verification procedures called for in this section and
provide to the source owner or operator a Manufacturer's Certificate
of Conformance (MCOC). These procedures shall be conducted,
detailed, and the results submitted in the MCOC (section 9.5) as an
integral part of each COMS demonstration required by the applicable
standards. In order to assure that the design and procedures to
demonstrate conformance with this section coincide with the design
procedures as stated in the MCOC, the manufacturer is encouraged to
seek an evaluation by the Administrator of the manufacturer's
conformance demonstration practices. The procedures to demonstrate
conformance with this section may require modification to
accommodate instrument designs. All procedural modifications
required to demonstrate conformance with the specifications of this
section must be approved, in writing, by the Administrator. The
owner and operator or the manufacturer, as appropriate, shall obtain
any approvals of modifications to the specifications of this section
before regulatory agency review and acceptance of the overall COMS
performance evaluations.
Each analyzer design shall be selected as follows, in order to
demonstrate conformance with the design specifications of sections
5.1.1 to 5.1.10. The MCOC, section 9.5, for all instruments subject
to this specification shall detail the demonstration procedures as
follows:
6.1 Selection of Analyzer. For conducting the performance test
in sections 6.2 through 6.6, the manufacturer shall randomly select
(1) a COMS model from each month's production, or (2) a COMS model
with a serial number in a distinct lot of 20 such monitors produced,
whichever is more frequent.
6.2 Spectral Response. The owner and operator, or manufacturer,
shall conduct a laboratory measurement of the instrument's spectral
response curve. The procedures of this laboratory evaluation are
subject to approval of the Administrator and shall be provided to
the Administrator upon request. The owner and operator or
manufacturer, shall measure, develop, and report the effective
spectral response curve of the COMS at 10 nm intervals. Determine
and report in the MCOC the peak spectral response wavelength, the
mean spectral response wavelength using equation 1-9, and the
maximum response at any wavelength below 400 nm and above 700 nm
expressed as a percentage of the peak response.
6.3 Angle of View. In the laboratory, set up the COMS detector
as specified by the manufacturer's written instructions. Draw a
circular arc with the center of the circle located at the centroid
of a plane described by the COMS photodetector housing which the
radiation from the nondirectional light source first encounters. The
arc shall have a radius of 3 meters in the horizontal plane of the
COMS photodetector housing. Using a small (less than 3 cm)
nondirectional light source, measure and record the COMS receiver
response as the light is moved at each 5-cm interval on the arc for
30 cm on either side of the COMS detector centerline. Identify the
point on the arc furthest from the centerline which corresponds to
the point where 2.5 percent of the peak COMS detector response is
recorded. Repeat the test in the vertical direction. Then, for both
the horizontal and vertical directions, calculate the response of
the COMS detector as a function of viewing angle (26 cm of arc with
a radius of 3 cm equals 5 degrees), report relative angle of view
curves, and determine and report the angle of view.
6.4 Angle of Projection. In the laboratory, set up the COMS
light source as specified by the manufacturer's written
instructions. Draw a circular arc with the center of the circle
located at the centroid of a plane described by the last part of the
COMS lamp assembly housing encountered by the light radiation
projected from the light assembly. The arc shall have a radius of 3
meters in the horizontal plane of the COMS lamp assembly housing.
Using a small (less than 3 cm) photoelectric light detector, measure
and record the COMS light intensity as the photoelectric light
detector is moved at each 5-cm interval on the arc for 30 cm on
either side of the centerline of the light source projection. Repeat
the test in the vertical direction.
Then, for both the horizontal and vertical directions, calculate
the response of the photoelectric detector as a function of the
projection angle (26 cm of arc with a radius of 3 m equals 5
degrees). Identify the point on the arc furthest from the centerline
at which a light intensity of 2.5 percent of the peak light
intensity of the COMS light source is recorded, report the relative
angle of projection curves, and determine and report the angle of
projection.
6.5 Unacceptable Findings. Whenever a manufacturer finds that a
COMS model does not conform to any of the requirements of this
section, the manufacturer shall notify and provide the findings to
all source owners or operators that have received or installed such
nonconforming COMS models manufactured after the date of the
previous successful conformance demonstration. The manufacturer
shall also submit copies of such notifications to the U.S.
Environmental Protection Agency, Director, Stationary Source
Compliance Division (EN-341W), 401 M Street, S.W., Washington, D.C.
20460.
7. Performance Specifications Verification Procedure
The owner and operator shall perform following procedures and
tests on each COMS that conforms to the design specifications (Table
1-1) to determine conformance with the specifications of Table 1-2.
The tests described in sections 7.1.1, 7.1.4, and 7.1.5, shall be
conducted at the affected facility, in a dust-free environment,
before installing the measurement portion of the COMS system on the
stack or duct. These tests are to be performed using the entire COMS
system, including the data recording component normally used during
monitoring.
Table 1-2.--Performance Specifications
------------------------------------------------------------------------
Parameter Specifications
------------------------------------------------------------------------
Calibration errora................. 3 percent opacity.
Response time...................... 10 seconds.
Operational test periodb........... 336 hours.
Zero drift (24-hour)a.............. 2 percent opacity.
Calibration drift (24-hour)........ 2 percent opacity.
Zero drift (1-hour)................ 2 percent opacity.
Calibration drift (1-hour)......... 2 percent opacity.
------------------------------------------------------------------------
aExpressed as the sum of the absolute value of the mean and the absolute
value of the confidence coefficient.
bDuring the operational test period, the COMS must not require any
corrective maintenance, repair, replacement, or adjustment other than
that clearly specified as routine and required in the operation and
maintenance manuals.
7.1 Preliminary Adjustments and Tests.
7.1.1 Equipment Preparation.
7.1.1.1 Set up and calibrate the COMS for the monitoring
pathlength to be used in the installation as specified by the
manufacturer's written instructions. For this specification, the
monitoring pathlength distance (depth of effluent at the
installation location) specified in engineering drawings must be
verified. The owner and operator shall, following the manufacturer's
instructions, adjust the PLCF signal to yield opacity results based
on the emission outlet pathlength.
7.1.1.2 Under a clear path condition and at the required
monitoring pathlength, align the instrument using the optical sight
and set the instrument actual zero response. As part of this
alignment, include tilting the reflector unit (detector unit for
single pass instruments) on its axis until the point of maximum
instrument response is obtained. Check and record the instrument
alignment with the alignment sight. Deviations in alignment must be
rectified prior to proceeding with the following performance tests.
7.1.1.3 Optical Alignment Sight. At the monitoring pathlength,
align, zero, and span the instrument. Insert an attenuator of 8 to
15 percent actual opacity into the monitoring pathlength.
7.1.1.3.1 Single Path Monitors. Using the optical alignment
site, record and report the visual depiction of alignment prior to
misalignment. Slowly misalign the COMS light assembly unit by
tilting it in the vertical plane until a 2 percent
opacity shift is obtained by the data recorder. Then, following the
manufacturer's written instructions, check the alignment.
Misalignment should be clearly discernable. Record and report the
visual depiction of misalignment as viewed using the optical
alignment sight. Realign the instrument and record the visual
depiction of alignment. Repeat this test for lateral misalignment of
the light source unit. Realign the instrument and follow the same
procedure for checking misalignment of the COMS detector unit.
7.1.1.3.2 Dual Path Monitors. Using the optical alignment site,
record and report the visual depiction of alignment prior to
misalignment. Slowly misalign the COMS transceiver unit (combined
light source and detector unit) by tilting it in the vertical plane
until a 2 percent opacity shift is obtained by the data
recorder. Then, following the manufacturer's written instructions,
check the alignment. Misalignment should be clearly discernable.
Record and report the visual depiction of misalignment as viewed
using the optical alignment sight. Realign the COMS and record and
report the visual depiction of alignment. Repeat this test for
lateral misalignment of the transceiver unit. As an alternative to
the lateral misalignment of the transceiver unit, a lateral
misalignment of the reflector unit may be performed.
7.1.1.4 Simulated Zero and Calibration Value Check. Adjust,
record, and report the COMS zero alignment response so that the
simulated zero output equals the COMS actual clear path zero output
established for the monitoring pathlength. Measure and record the
indicated upscale calibration value. The upscale calibration value
reading must be within the required opacity range (see Definition
2.21).
7.1.2 Calibration Attenuator Selection.
7.1.2.1 Based on the required opacity standard, select a
minimum of three calibration attenuators (low-, mid-, and high-
level) based on the following formulas in Table 1-3:
Table 1-3.--Required Calibration Attenuator Values
Low level--20 to 60 percent of the opacity standard.
Mid level--80 to 120 percent of the opacity standard.
High level--150 to 200 percent of the opacity standard.
7.1.2.2 Calculate the attenuator values required to obtain a
system response equivalent to the applicable values in the ranges
specified in table 1-2 using equation 1-1. Select attenuators having
the values closest to those calculated by equation 1-1. A series of
filters with actual opacity values relative to the values calculated
are commercially available.
TP25NO94.000
Where:
OP1=Nominal opacity value of required
low-, mid-, or high-range calibration attenuators.
OP2=Desired attenuator opacity value from Table 1-2 at the span
required by the applicable subpart.
L1=Monitoring pathlength.
L2=Emission outlet pathlength.
7.1.3 Attenuator Calibration.
7.1.3.1 Primary Attenuators. Attenuators are designated as
primary in one of two ways:
7.1.3.1.1 They are calibrated by NIST; or
7.1.3.1.2 They are calibrated on a 6-month frequency through
the assignment of a luminous transmittance value in the following
manner:
7.1.3.1.2.1 Use a spectrophotometer meeting the specifications
of section 3.6 to calibrate the required filters. The
spectrophotometer calibration must be verified through use of a NIST
930D Standard Reference Material (SRM). The SRM 930D consists of
three (3) neutral density glass filters and a blank, each mounted in
a cuvette. The wavelengths and temperature to be used in the
calibration are listed on the NIST certificate that accompanies the
reported values. Determine and record a transmittance of the SRM
values at the NIST wavelengths (three filters at five wavelengths
each for a total of 15 determinations). A percent difference shall
be calculated between the NIST certified values and the
spectrophotometer response. At least 12 of the 15 differences (in
percent) shall be within 0.5 percent of the NIST SRM
values. No one value shall have a difference of 1.0
percent. Failure to achieve these criteria identifies a need to
recalibrate the SRM or service the spectrophotometer.
7.1.3.1.2.2 Scan the filter to be tested and the NIST blank
from wavelength 380 to 780 nm, and record the spectrophotometer
percent transmittance responses at 10 nm intervals. The sequence of
testing is: blank filter, tested filter, tested filter rotated 90
degrees in the plane of the filter, blank filter. Calculate the
average transmittance at each 10 nm interval. If any pair of the
tested filter transmittance values (for the same filter and
wavelength) differ by more than 0.25 percent, rescan the
tested filter. Failure to achieve this tolerance shall prevent the
use of the filter in the calibration tests of the COMS.
7.1.3.1.2.3 Correct the tested filter transmittance values by
dividing the average tested filter transmittance by the average
blank filter transmittance at each 10 nm interval.
7.1.3.1.2.4 Calculate the weighted tested filter transmittance
by multiplying the transmittance value by the corresponding response
factor shown in table 1-4, to obtain the Source C Human Eye
Response.
Table 1-4--Source C, Human Eye Response Factor
------------------------------------------------------------------------
Wavelength Weighting Wavelength Weighting
nanometers factora nanometers factora
------------------------------------------------------------------------
380.............. 0 590 6627
390.............. 0 600 5316
400.............. 2 610 4176
410.............. 9 620 3153
420.............. 37 630 2190
430.............. 122 640 1443
440.............. 262 650 886
450.............. 443 660 504
460.............. 694 670 259
470.............. 1058 680 134
480.............. 1618 690 62
490.............. 2358 700 29
500.............. 3401 720 14
510.............. 4833 720 6
520.............. 6462 730 3
530.............. 7934 740 2
540.............. 9194 750 1
550.............. 9832 760 1
560.............. 9841 770 0
570.............. 9147 780 0
580.............. 7992 ................. ................
------------------------------------------------------------------------
aTotal of weighting factors=100,000.
7.1.3.1.2.5 Calculate, record and report the luminous
transmittance value of the filter as follows:
TP25NO94.001
Where:
LT=Luminous transmittance
T=Weighted tested filter transmittance.
7.1.3.1.3 Recalibrate the Primary Attenuators Used for the
Required Calibration Error Test Quarterly. Recalibrates semi-
annually if the primary attenuators are used only for quarterly
calibration of secondary attenuators.
7.1.3.2 Secondary Attenuators. Calibrate the secondary
attenuators, if used to conduct COMS calibration error tests,
monthly. The filter calibration may be conducted using a laboratory-
based transmissometer calibrated as follows:
7.1.3.2.1 Use at least three primary filters of nominal
luminous transmittance 50, 70 and 90 percent, calibrated as
specified in section 7.1.3.1, to calibrate the laboratory-based
transmissometer. Using linear regression through zero opacity,
determine and record the slope of the calibration line. The slope of
the calibration line shall be between 0.99 and 1.01, and the
laboratory-based transmissometer reading for each primary filter
shall not deviate by more than 2 percent from the exact
linear regression line. If the calibration of the laboratory-based
transmissometer yields a slope or individual readings outside the
specified ranges, secondary filter calibrations shall not be
performed. Determine the source of the variations (either
transmissometer performance or changes in the primary filters) and
repeat the transmissometer calibration before proceeding with the
attenuator calibration.
7.1.3.2.2 Immediately following the laboratory-based
transmissometer calibration, insert the secondary attenuators and
determine and record the percent effective opacity value per
secondary attenuator from the calibration curve (linear regression
line).
7.1.4 Calibration Error Test. Insert the calibration
attenuators (low-, mid-, and high-level) into the light path between
the transceiver and reflector (or transmitter and receiver) at a
point where the effluent will be measured; i.e., do not place the
calibration attenuator in the instrument housing. While inserting
the attenuator, assure that the entire beam received by the detector
will pass through the attenuator and that the attenuator is inserted
in a manner which minimizes interference from the reflected light.
The placement and removal of the attenuator shall be such that an
integrated measurement of opacity is conducted over the averaging
time of the standard found in the applicable subpart. Make a total
of five nonconsecutive readings for each filter using the data
recording system to be used at the installation. Record the
monitoring system output readings in percent opacity on the data
sheet (see example figure 1-6). Subtract the ``path adjusted''
calibration attenuator values from the measurement system recorder
responses (the ``path adjusted'' calibration attenuator values are
calculated using equation 1-7 or 1-8). Calculate the arithmetic mean
difference, standard deviation, and confidence coefficient of the
five tests at each attenuator value using equations 1-3, 1-4, and 1-
5 (sections 8.1 to 8.3). Calculate the sum of the absolute value of
the mean difference and the absolute value of the confidence
coefficient for each of the three test attenuators. Report these
three values as the calibration error.
7.1.5 System Response Test. Using the high-range calibration
attenuator, alternately insert the filter five times and remove it
from the transmissometer light path. For each filter insertion and
removal, record the amount of time required for the COMS to display
on the primary data recorder 95 percent of the final step change in
opacity. Specifically, for a filter insertion, the owner or operator
shall record the time it takes to reach 95 percent of the final,
steady upscale reading; for filter removal, the time it takes for
the display reading to fall to 5 percent of the initial upscale
opacity reading (see example figure 1-7). Calculate the mean time of
the five upscale and five downscale tests. Report the greater value
as the COMS response time.
7.1.6 Data Recorder Resolution. Review the output from the
calibration error test; the COMS data recorder shall provide output
capable of being resolved into 0.5 percent opacity increments.
7.2 Preliminary Field Adjustments. Install the COMS on the
affected facility according to the manufacturer's written
instructions and the specifications in section 4, and perform the
following preliminary adjustments:
7.2.1 Optical and Zero Alignment. When the facility is not in
operation, optically align the light beam of the transmissometer
upon the optical surface located across the duct or stack (i.e., the
reflector or photodetector, as applicable) in accordance with the
manufacturer's instructions; verify the alignment with the optical
alignment sight. Under clear stack conditions, verify the zero
alignment (performed in section 7.1.1) by assuring that the
monitoring system zero response for the installation zero check
coincides with the instrument actual zero measured by the COMS as
set for the monitor pathlength prior to installation. Record these
values. Adjust the instrument actual zero response, if necessary,
and only if a clear stack condition exists. Then, after the affected
facility has been started up and the effluent stream reaches normal
operating temperature, recheck the optical alignment. If the optical
alignment has shifted, realign the optics. Note: Careful
consideration should be given to whether a ``clear stack'' condition
exists. The stack shall be monitored and the data output
(instantaneous real-time basis) examined to determine whether
fluctuations from zero opacity are occurring before a clear stack
condition is assumed to exist. Check and record the upscale
calibration value.
7.2.2 Optical and Zero Alignment (Alternative Procedure). The
procedure given in section 7.2.1 is the preferred procedure and
should be used whenever possible. However, if the facility is
operating and a zero stack condition cannot practicably be obtained,
use the zero alignment obtained during the preliminary adjustments
(section 7.1.1.2) before installing the COMS on the stack. After
completing all the preliminary adjustments and tests required in
section 7.1, install the system at the source and align the optics,
i.e., align the light beam from the transmissometer upon the optical
surface located across the duct or stack in accordance with the
manufacturer's instruction. Verify the alignment with the optical
alignment sight. The zero alignment conducted in this manner must be
verified and adjusted, if necessary, the first time a clear stack
condition is obtained after the operation test period has been
completed.
7.3 Operational Test Period. Prior to conducting the
operational testing, the owner and operator, or the manufacturer as
appropriate, should have successfully completed all prior testing of
the COMS. After completing all preliminary field adjustments
(section 7.2), operate the COMS for an initial 336-hour test period
while the source is operating. Except during times of instrument
zero and upscale calibration checks, the owner and operator must
ensure that they analyze the effluent gas for opacity and produce a
permanent record of the COMS output. During this period, the owner
and operator may not perform unscheduled maintenance, repair, or
adjustment. The owner or operator may perform zero and calibration
adjustments, exposed optical and other CEMS surface cleaning, and
optical realignment only at 24-hour intervals. Automatic zero and
calibration adjustments, made by the COMS without operator
intervention or initiation, are allowable at any time. During the
operational test period, record all adjustments, realignments, and
exposed surface cleaning. At the end of the operational test period,
verify and record that the COMS optical alignment is correct. If the
operational test period is interrupted because of source breakdown,
continue the 336-hour period following resumption of source
operation. If the test period is interrupted because of COMS
failure, record the time when the failure occurred, after the
failure is corrected, the 336-hour period and tests are restarted.
During the operational test period, perform the following test
procedures:
7.3.1 Zero Calibration Drift Test. At the outset of the 336-
hour operational test period and at each 24-hour period, record the
initial (Reference A) zero calibration value and upscale calibration
value (UC Value), see example format figure 1-8. These values are
the initial 336-hour value established during the optical and zero
alignment procedure (see section 7.2.1). After each 24-hour
interval, check and record the COMS zero response reading before any
cleaning and adjustment. Perform the zero and upscale calibration
adjustments, exposed optical and other instrument surface cleaning,
and optical realignment only at 24-hour intervals (or at such
shorter intervals as the manufacturer's written instructions
specify). If shorter intervals of zero and span adjustment are
conducted, record the drift adjustment. However, adjustments and
cleaning must be performed when the accumulated zero calibration or
upscale CD exceeds the 24-hour drift specification (2
percent opacity). From the initial and final zero readings,
calculate the zero drift for each 24-hour period. Then, calculate
the arithmetic mean, standard deviation, and confidence coefficient
of the 24-hour zero drift and the 95 percent confidence interval
using equations 1-3, 1-4, and 1-5. Calculate the sum of the absolute
value of the mean and the absolute value of the confidence
coefficient, and report this value as the 24-hour zero drift. At the
conclusion of the 336-hour operational test period, record and
report the 336-hour accumulated drift.
7.3.2 Upscale Calibration Drift Test. At each 24-hour interval,
after the zero calibration value has been checked and any optional
or required adjustments have been made, check and record the COMS
response to the upscale calibration value established under the
optical and zero alignment procedure of section 7.2.1. The upscale
calibration value established in section 7.2.1 shall be used each
24-hour period. From the initial and final upscale readings,
calculate the upscale calibration value drift for each 24-hour
period. Then, calculate the arithmetic mean, standard deviation, and
confidence coefficient of the 24-hour CD and the 95 percent
confidence interval using equations 1-3, 1-4, and 1-5. Calculate the
sum of the absolute value of the mean and the absolute value of the
confidence coefficient, and report this value as the 24-hour
calibration value drift. At the conclusion of the 336-hour
operational test period, record and report the 336-hour accumulated
drift.
7.3.3 Calibration Stability Test. Immediately following or
during, the operational test period, conduct a calibration stability
test over a 24-hour period. During this period, there will be no
unscheduled maintenance, repair, adjustment, zero and calibration
adjustments, exposed optical and other instrument surface cleaning,
or optical realignment performed. Record the initial zero and
upscale calibration opacity values and operate the monitor in a
normal manner. After each 1-hour period, record the monitor adjusted
zero and upscale opacity values. Subtract the initial zero and
upscale calibration values from each 1-hour adjusted value and
record the difference. None of these differences shall exceed +2
percent opacity. Figure 1-8 may be used for the recording of the
results of this test.
7.3.4 Retesting. If the COMS fails to meet the specifications
for the tests conducted under the operational test period, make the
necessary corrections and restart the opera- tional test period.
Depending on the correction made, it may be necessary to repeat some
or all design and other preliminary tests.
8. Equations
8.1 Arithmetic Mean. Calculate the mean of a set of data as
follows:
where:
TP25NO94.002
n = Number of data points.
n
xi = Algebraic sum of the individual measurements,
xi. i=1
8.2 Standard Deviation. Calculate the standard deviation
Sd as follows:
TP25NO94.003
8.3 Confidence Coefficient. Calculate the 2.5 percent error
confidence coefficient (one-tailed), CC, as follows:
TP25NO94.004
Where:
t0.975 = t-value (see table 1-5).
8.4 Error. Calculate the error (i.e., calibration error, zero
drift, and CD), Er, as follows:
TP25NO94.005
Table 1-5.--T-Values
------------------------------------------------------------------------
na t0.975
------------------------------------------------------------------------
2............................................................ 12.706
3............................................................ 4.303
4............................................................ 3.182
5............................................................ 2.776
6............................................................ 2.571
7............................................................ 2.447
8............................................................ 2.365
9............................................................ 2.306
10........................................................... 2.262
11........................................................... 2.228
12........................................................... 2.201
13........................................................... 2.179
14........................................................... 2.160
15........................................................... 2.145
16........................................................... 2.131
------------------------------------------------------------------------
aThe values in this table are already corrected for n-1 degrees of
freedom. Use n equal to the number of individual values.
8.5 Conversion of Opacity Values for Monitor Pathlength to
Emission Outlet Pathlength. When the monitor pathlength is different
from the emission outlet pathlength, use either of the following
equations to convert from one basis to the other (this conversion
may be automatically calculated by the monitoring system):
TP25NO94.006
TP25NO94.007
Where:
Op1 = Opacity of the effluent based upon L1.
Op2 = Opacity of the effluent based upon L2.
L1 = Monitor pathlength.
L2 = Emission outlet pathlength.
OD1 = Optical density of the effluent based upon L1.
OD2 = Optical density of the effluent based upon L2.
8.6 Mean Response Wavelength. Calculate the mean of the
effective spectral response curve from the individual responses,
gi, at the wavelength values, Li, as follows:
TP25NO94.008
Where:
Li = The wavelength at which the response gi is calculated
at 20 nm intervals.
gi = The value of the response at Li.
9. Reporting
Report the following (summarize in tabular form where
appropriate):
9.1 General Information.
a. Facility being monitored.
b. Person(s) responsible for operational and conditioning test
periods and affiliation.
c. Instrument manufacturer.
d. Instrument model number.
e. Instrument serial number.
f. Month/year manufactured.
g. Schematic of monitoring system measurement path location.
h. System span value, percent opacity.
i. Emission outlet pathlength, meters.
j. Monitoring pathlength, meters.
k. System span value, percent opacity.
l. Upscale calibration value, percent opacity.
m. Calibrated attenuator values (low-, mid-, and high-range),
percent opacity.
9.2 Design Specification Test Results.
a. Peak spectral response, nm.
b. Mean spectral response, nm.
c. Response above 700 nm, percent of peak.
d. Response below 400 nm, percent of peak.
e. Total angle of view, degrees.
f. Total angle of projection, degrees.
g. Serial number, month/year of manufacturer for unit actually
tested to show design conformance.
9.3 Performance Specification Test Results.
a. Results of optical alignment sight test (if required; see
section 7.1.1.3). The owner and operator shall, in the testing
report, include diagrams indicating the operator's view through the
optical alignment system as depicted during the alignment tests
specified in section 7.1.1.3.
b. Attenuator Calibration. Provide documentation demonstrating
compliance with the requirements for the calibration of primary
attenuators (see section 7.1.3.1). If secondary attenuators (see
section 7.1.3.2) are used, provide documentation listing the
calibration results for the laboratory-based transmissometer, dates
of the latest secondary filter calibrations, and the results of the
secondary filter calibrations. When the primary filter calibration
of section 7.1.3.1. is conducted by the filter manufacturer or by an
independent laboratory, the owner or operator shall include in the
report a statement, from the filter calibration laboratory or
manufacturer, certifying the filter luminous transmittance values
and that the procedures of section 7.1.3.1 have been followed.
c. Calibration Error Test.
(1) Report the required upscale opacity range and indicated
upscale opacity calibration value, as determined in section 7.1.1.4.
(2) Identify the low-, mid-, and high-level calibration
opacities, as determined in section 7.1.2.1.
(3) Present the data and results of the calibration error test
in the format of figure 1-6; all information required by figure 1-6
shall be supplied.
d. System Response Test. Present the data and results of the
system response test in the format of figure 1-7.
e. Zero and Calibration Drift (CD) Tests. In the format of
figure 1-8:
i. Identify the 24-hour zero drift, percent opacity,
ii. Identify the 24-hour CD, percent opacity,
iii. Identify any lens cleaning, clock time,
iv. Identify all optical alignment adjustments, clock time.
9.4 Statements Provide a statement that the operational test
period was completed according to the requirements of section 7.2.
In this statement, include the time periods during which the
operational test period was conducted.
9.5 Manufacturer's Certificate of Conformance (MCOC). The MCOC
must include the results of each test performed for the COMS(s)
sampled under section 6.1. The MCOC also shall specify the date of
testing according to sections 6.2 through 6.4, the COMS monitor
type, serial number, and the intended installation and purchaser of
the tested COMS. Section 9.5.1 identifies the minimally acceptable
information to be submitted by the manufacturer with the
certification of conformance.
9.5.1 Outline of Certificate of Conformance.
a. Instrument Description and Summary of Test Results. The
manufacturer shall supply the results of section 6 tests (spectral
response curve measurement information, angle of view, angle of
projection).
b. Test Procedures. The manufacturer shall supply a complete
description of the test equipment, procedures, and calculations used
in obtaining the results listed in Part I of the certificate. Any
procedures not conforming to those specified in section 6 or 7, must
be clearly noted. Required supporting documentation for each test
(listed below) and any necessary letters demonstrating approval of
the alternate procedure by the Administrator shall appear in the
appropriate section of Part III.
c. Supporting Documentation. Include here any information,
besides the procedural descriptions of Part II, which is necessary
for verification of compliance with sections 5 and 6. In each
section, provide letters demonstrating approval of the alternate
procedures listed in Part II, if necessary.
(1) Spectral Response. Provide the date of testing, measurement
data, and results of the latest calibration performed on the
instrument used in the measurement.
(2) Angle of View. Include the results of testing. Provide
letters demonstrating approval of alternate methods, if necessary.
(3) Angle of Projection. Include the results of testing. Provide
letters demonstrating approval of alternate methods, if necessary.
(4) Verification of Compliance with Additional Design
Specifications. The owner and operator or manufacturer shall provide
diagrams and operational descriptions of the instrument which
demonstrate conformance with the requirements of sections 5.1.5,
5.1.7, 5.1.8, 5.1.9, and 5.1.10.
9.6 Appendix. Provide the data tabulations and calculations for
any of the above demonstrations.
10. Bibliography
1. Experimental Statistics. Department of Commerce. National
Bureau of Standards Handbook 91. Paragraph 3-3.1.4. 1963. 3-31 p.
2. Performance Specifications for Stationary Source Monitoring
Systems for Gases and Visible Emissions, EPA-650/2-74-013, January
1974, U.S. Environmental Protection Agency, Research Triangle Park,
NC.
3. Koontz, E.C., Walton, J. Quality Assurance Programs for
Visible Emission Evaluations. Tennessee Division of Air Pollution
Control. Nashville, TN. 78th Meeting of the Air Pollution Control
Association. Detroit, MI. June 16-21, 1985.
4. Evaluation of Opacity CEMS Reliability and Quality Assurance
Procedures. Volume 1. U.S. Environmental Protection Agency. Research
Triangle Park, NC. EPA-340/1-86-009a.
5. Nimeroff, I. ``Colorimetry Precision Measurement and
Calibration.'' NBS Special Publication 300. Volume 9. June 1972.
6. Technical Assistance Document: Performance Audit Procedures
for Opacity Monitors. U.S. Environmental Protection Agency. Research
Triangle Park, NC. EPA-600/8-87-025. April 1987.
[FR Doc. 94-28973 Filed 11-23-94; 8:45 am]
BILLING CODE 6560-50-P
