Appendix G to Part 80 - Sampling Procedures for Diesel Fuel

1. Scope

1.1This method covers procedures for obtaining representative samples of diesel fuel for the purpose of testing for compliance with the cetane index and sulfur percentage standards set forth in § 80.29.

2. Summary of Method

2.1It is necessary that the samples be truly representative of the diesel fuel in question. The precautions required to ensure the representative character of the samples are numerous and depend upon the tank, carrier, container or line from which the sample is being obtained, the type and cleanliness of the sample container, and the sampling procedures that are to be used. A summary of the sampling procedures and their application is presented in Table 1. Each procedure is suitable for sampling a material under definite storage, transportation, or container conditions. The basic principle of each procedure is to obtain a sample in such manner and from such locations in the tank or other container that the sample will be truly representative of the diesel fuel.

3. Description of Terms

3.1Average sample is one that consists of proportionate parts from all sections of the container.

3.2All-levels sample is one obtained by submerging a stoppered beaker or bottle to a point as near as possible to the draw-off level, then opening the sampler and raising it at a rate such that it is about 3/4 full (maximum 85 percent) as it emerges from the liquid. An all-levels sample is not necessarily an average sample because the tank volume may not be proportional to the depth and because the operator may not be able to raise the sampler at the variable rate required for proportionate filling. The rate of filling is proportional to the square root of the depth of immersion.

3.3Running sample is one obtained by lowering an unstoppered beaker or bottle from the top of the gasoline to the level of the bottom of the outlet connection or swing line, and returning it to the top of the top of the diesel fuel at a uniform rate of speed such that the beaker or bottle is about 3/4 full when withdrawn from the diesel fuel.

3.4Spot sample is one obtained at some specific location in the tank by means of a thief bottle, or beaker.

3.5Top sample is a spot sample obtained 6 inches (150 mm) below the top surface of the liquid (Figure 1 of appendix D).

3.6Upper sample is a spot sample taken at the mid-point of the upper third of the tank contents (Figure 1 of appendix D).

3.7Middle sample is a spot sample obtained from the middle of the tank contents (Figure 1 of appendix D).

3.8Lower sample is a spot sample obtained at the level of the fixed tank outlet or the swing line outlet (Figure 1 of appendix D).

3.9Clearance sample is a spot sample taken 4 inches (100 mm) below the level of the tank outlet (Figure 1 of appendix D).

3.10Bottom sample is a spot sample obtained from the material on the bottom surface of the tank, container, or line at its lowest point.

3.11Drain sample is a tap sample obtained from the draw-off or discharge valve. Occasionally, a drain sample may be the same as a bottom sample, as in the case of a tank car.

3.12Continuous sample is one obtained from a pipeline in such manner as to give a representative average of a moving stream.

3.13Nozzle sample is one obtained from a diesel pump nozzle which dispenses diesel fuel from a storage tank at a retail outlet or a wholesale purchaser-consumer facility.

4. Sample Containers

4.1Sample containers may be clear or brown glass bottles, or cans. The clear glass bottle is advantageous because it may be examined visually for cleanliness, and also allows visual inspection of the sample for free water or solid impurities. The brown glass bottle affords some protection from light. Cans with the seams soldered on the exterior surface with a flux of rosin in a suitable solvent are preferred because such a flux is easily removed with diesel fuel, whereas many others are very difficult to remove. If such cans are not available, other cans made with a welded construction that are not affected by, and that do not affect, the diesel fuel being sampled are acceptable.

4.2Container closure. Cork or glass stoppers, or screw caps of plastic or metal may be used for glass bottles; screw caps only shall be used for cans to provide a vapor-tight closure seal. Corks must be of good quality, clean and free from holes and loose bits of cork. Never use rubber stoppers. Contact of the sample with the cork may be prevented by wrapping tin or aluminum foil around the cork before forcing it into the bottle.

Glass stoppers must be a perfect fit. Screw caps must be protected by a cork disk faced with tin or aluminum foil, or other material that will not affect petroleum or petroleum products. In addition, a phenolic cap with a teflon coated liner may be used.

4.3Cleaning procedure. The method of cleaning all sample containers must be consistent with the residual materials in the container and must produce sample containers that are clean and free of water, dirt, lint, washing compounds, naphtha, or other solvents, soldering fluxes or acids, corrosion, rust, and oil.

New sample containers should be inspected and cleaned if necessary. Dry the container by either passing a current of clean, warm air through the container or by allowing it to air dry in a clean area at room temperature. When dry, stopper or cap the container immediately.

5. Sampling Apparatus

5.1Sampling apparatus is described in detail under each of the specific sampling procedures. Clean, dry, and free all sampling apparatus from any substance that might contaminate the material, using the procedure described in 4.3.

6. Time and Place of Sampling

6.1When loading or discharging diesel fuel, take samples from both shipping and receiving tanks, and from the pipeline if required.

6.2Ship or barge tanks. Sample each product after the vessel is loaded or just before unloading.

6.3Tank cars. Sample the product after the car is loaded or just before unloading.

Note:

When taking samples from tanks suspected of containing flammable at-mos-pheres, precautions should be taken to guard against ignitions due to static electricity. Metal or conductive objects, such as gage tapes, sample containers, and thermometers, should not be lowered into or suspended in a compartment or tank which is being filled or immediately after cessation of pumping. A waiting period of approximately one minute will generally permit a substantial relaxation of the electrostatic charge; under certain conditions a longer period may be deemed advisable.

7. Obtaining Samples

7.1Directions for sampling cannot be made explicit enough to cover all cases. Extreme care and good judgment are necessary to ensure samples that represent the general character and average condition of the material. Clean hands are important. Clean gloves may be worn but only when absolutely necessary, such as in cold weather, or when handling materials at high temperature, or for reasons of safety. Select wiping cloths so that lint is not introduced, contaminating samples.

7.2As many petroleum vapors are toxic and flammable, avoid breathing them or igniting them from an open flame or a spark produced by static. Follow all safety precautions specific to the material being sampled.

8. Handling Samples

8.1Container outage. Never completely fill a sample container, but allow adequate room for expansion, taking into consideration the temperature of the liquid at the time of filling and the probable maximum temperature to which the filled container may be subjected.

9. Shipping Samples

9.1To prevent loss of liquid during shipment, and to protect against moisture and dust, cover with suitable vapor tight caps. The caps of all containers must be screwed down tightly and checked for leakage. Postal and express office regulations applying to the shipment of flammable liquids must be observed.

10. Labeling Sample Containers

10.1Label the container immediately after a sample is obtained. Use waterproof and oilproof ink or a pencil hard enough to dent the tag, since soft pencil and ordinary ink markings are subject to obliteration from moisture, oil smearing and handling. An indelible identification symbol, such as a bar code, may be used in lieu of a manually addressed label. The label shall reference the following information:

10.1.1Date and time (the period elapsed during continuous sampling);

10.1.2Name of the sample;

10.1.3Name or number and owner of the vessel, car, or container;

10.1.4Brand and grade of material; and

10.1.5Reference symbol or identification number.

11. Sampling procedures

11.1The standard sampling procedures described in this method are summarized in Table 1. Alternative sampling procedures may be used if a mutually satisfactory agreement has been reached by the party(ies) involved and EPA and such agreement has been put in writing and signed by authorized officials.

Table 1—Summary of Diesel Fuel Sampling Procedures and ApplicabilityType of containerProcedureParagraphStorage tanks, ship and barge tanks, tank cars, tank trucksBottle sampling11.2Storage tanks with tapsTap sampling11.3Pipe and linesContinuous line sampling11.4Retail outlet and whole-sale purchaser-consumer facility storage tanksNozzle sampling11.5

11.2Bottle or beaker sampling. The bottle or beaker sampling procedure is applicable for sampling liquids of 16 pounds (1.12 kgf/cm2) RVP or less in tank cars, tank trucks, shore tanks, ship tanks, and barge tanks.

11.2.1Apparatus. A suitable sampling bottle or beaker as shown in figure 2 of appendix D is required.

11.2.2Procedure.

11.2.2.1All-levels sample. Lower the weighted, stoppered bottle or beaker as near as possible to the draw-off level, pull out the stopper with a sharp jerk of the cord or chain and raise the bottle at a uniform rate so that it is about 3/4 full as it emerges from the liquid.

11.2.2.2Running sample. Lower the un-stoppered bottles or beaker as near as possible to the level of the bottom of the outlet connection or swing line and then raise the bottle or beaker to the top of the gasoline at a uniform rate of speed such that it is about 3/4 full when withdrawn from the diesel fuel.

11.2.2.3Upper, middle, and lower samples. Lower the weighted, stoppered bottle to the proper depths (Figure 1 of appendix D) as follows:

Upper samplemiddle of upper third of the tank contentsMiddle samplemiddle of the tank contentsLower samplelevel of the fixed tank outlet or the swing-line outlet

At the selected level pull out the stopper with a sharp jerk of the cord or chain and allow the bottle or beaker to fill completely, as evidenced by the cessation of air bubbles. When full, raise the bottle or beaker, pour off a small amount, and stopper immediately.

11.2.2.4Top sample. Obtain this sample (Figure 1 of appendix D) in the same manner as specified in 11.2.2.3 but at six inches (150 mm) below the top surface of the tank contents.

11.2.2.5Handling. Stopper and label bottle samples immediately after taking them, and deliver to the laboratory in the original sampling bottles.

11.3Tap sampling. The tap sampling procedure is applicable for sampling liquids of twenty-six pounds (1.83 kgf/cm2) RVP or less in tanks which are equipped with suitable sampling taps or lines. The assembly for tap sampling is shown in figure 3 of appendix D.

11.3.1Apparatus

11.3.1.1Tank taps. The tank should be equipped with at least three sampling taps placed equidistant throughout the tank height and extending at least three feet (0.9 meter) inside the tank shell. A standard 1/4 inch pipe with suitable valve is satisfactory.

11.3.1.2Tube. A delivery tube that will not contaminate the product being sampled and long enough to reach to the bottom of the sample container is required to allow submerged filling.

11.3.1.3Sample containers. Use clean, dry glass bottles of convenient size and strength or metal containers to receive the samples.

11.3.2Procedure

11.3.2.1Before a sample is drawn, flush the tap (or gage glass drain cock) and line until they are purged completely. Connect the clean delivery tube to the tap. Draw upper, middle, or lower samples directly from the respective taps after the flushing operation. Stopper and label the sample container immediately after filling, and deliver it to the laboratory.

11.4Continuous sampling. The continuous sampling procedure is applicable for sampling liquids of 16 pounds (1.12 kgf/cm2) RVP or less and semiliquids in pipelines, filling lines, and transfer lines. The continuous sampling may be done manually or by using automatic devices.

11.4.1Apparatus

11.4.1.1Sampling probe. The function of the sampling probe is to withdraw from the flow stream a portion that will be representative of the entire stream. The apparatus assembly for continuous sampling is shown in figure 4 of appendix D. Probe designs that are commonly used are as follows:

11.4.1.1.1A tube extending to the center of the line and beveled at a 45 degree angle facing upstream (Figure 4(a) of appendix D).

11.4.1.1.2A long-radius forged elbow or pipe bend extending to the center line of the pipe and facing upstream. The end of the probe should be reamed to give a sharp entrance edge (Figure 4(b) of appendix D).

11.4.1.1.3A closed-end tube with a round orifice spaced near the closed end which should be positioned in such a way that the orifice is in the center of the pipeline and is facing the stream as shown in figure 4(c) of appendix D.

11.4.1.2Probe location. Since the fluid to be sampled may not in all cases be homogeneous, the location, the position and the size of the sampling probe shoud be such as to minimize stratification or dropping out of heavier particles within the tube or the displacement of the product within the tube as a result of variation in gravity of the flowing stream. The sampling probe should be located preferably in a vertical run of pipe and as near as practicable to the point where the product passes to the receiver. The probe should always be in a horizontal position.

11.4.1.2.1The sampling lines should be as short as practicable and should be cleared before any samples are taken.

11.4.1.2.2Where adequate flowing velocity is not available, a suitable device for mixing the fluid flow to ensure a homogeneous mixture at all rates of flow and to eliminate stratification should be installed upstream of the sampling tap. Some effective devices for obtaining a homogeneous mixture are as follows: Reduction in pipe size; a series of baffles; orifice or perforated plate; and a combination of any of these methods.

11.4.1.2.3The design or sizing of these devices is optional with the user, as long as the flow past the sampling point is homogeneous and stratification is eliminated.

11.4.1.3To control the rate at which the sample is withdrawn, the probe or probes should be fitted with valves or plug cocks.

11.4.1.4Automatic sampling devices that meet the standards set out in 11.4.1.5 may be used in obtaining samples of diesel fuel. The quality of sample collected must be of sufficient size for analysis, and its composition should be identical with the composition of the batch flowing in the line while the sample is being taken. An automatic sampler installation necessarily includes not only the automatic sampling device that extracts the samples from the line, but also a suitable probe, connecting lines, auxiliary equipment, and a container in which the sample is collected. Automatic samplers may be classified as follows:

11.4.1.4.1Continuous sampler, time cycle (nonproportional) type. A sampler designed and operated in such a manner that it transfers equal increments of liquid from the pipeline to the sample container at a uniform rate of one or more increments per minute is a continuous sampler.

11.4.1.4.2Continuous sampler, flow-responsive (proportional) type. A sampler that is designed and operated in such a manner that it will automatically adjust the quantity of sample in proportion to the rate of flow is a flow-responsive (proportional) sampler. Adjustment of the quantity of sample may be made either by varying the frequency of transferring equal increments of sample to the sample container, or by varying the volume of the increments while maintaining a constant frequency of transferring the increments to the sample container. The apparatus assembly for continuous sampling is shown in figure 4 of appendix D.

11.4.1.4.3Intermittent sampler. A sampler that is designed and operated in such a manner that it transfers equal increments of liquid from a pipeline to the sample container at a uniform rate of less than one increment per minute is an intermittent sampler.

11.4.1.5Standards of installation. Automatic sampler installations should meet all safety requirements in the plant or area where used, and should comply with American National Standard Code for Pressure Piping, and other applicable codes (ANSI B31.1). The sampler should be so installed as to provide ample access space for inspection and maintenance.

11.4.1.5.1Small lines connecting various elements of the installation should be so arranged that complete purging of the automatic sampler and of all lines can be accomplished effectively. All fluid remaining in the sampler and the lines from the preceding sampling cycle should be purged immediately before the start of any given sampling operation.

11.4.1.5.2In those cases where the sampler design is such that complete purging of the sampling lines and the sampler is not possible, a small pump should be installed in order to circulate a continuous stream from the sampling tube past or through the sampler and back into the line. The automatic sampler should then withdraw the sample from the sidestream through the shortest possible connection.

11.4.1.5.3Under certain conditions, there may be a tendency for water and heavy particles to drop out in the discharge line from the sampling device and appear in the sample container during some subsequent sampling period. To circumvent this possibility, the discharge pipe from the sampling device should be free of pockets or enlarged pipe areas, and preferably should be pitched downward to the sample container.

11.4.1.5To ensure clean, free-flowing lines, piping should be designed for periodic cleaning.

11.4.1.6Field calibration. Composite samples obtained from the automatic sampler installation should be verified for quantity performance in a manner that meets with the approval of all parties concerned (including EPA), at least once a month and more often if conditions warrant. In the case of time-cycle samplers, deviations in quantity of the sample taken should not exceed ± five percent for any given setting. In the case of flow-responsive samplers, the deviation in quantity of sample taken per 1,000 barrels of flowing stream should not exceed ± 5 percent. For the purpose of field-calibrating an installation, the composite sample obtained from the automatic sampler under test should be verified for quality by comparing on the basis of physical and chemical properties, with either a properly secured continuous nonautomatic sample or tank sample. The tank sample should be taken under the following conditions:

11.4.1.6.1The batch pumped during the test interval should be diverted into a clean tank and a sample taken within one hour after cessation of pumping.

11.4.1.6.2If the sampling of the delivery tank is to be delayed beyond one hour, then the tank selected must be equipped with an adequate mixing means. For valid comparison, the sampling of the delivery tank must be completed within eight hours after cessation of pumping, even though the tank is equipped with a motor-driven mixer.

11.4.1.6.3When making a normal full-tank delivery from a tank, a properly secured sample may be used to check the results of the sampler if the parties (including EPA) mutually agree to this procedure.

11.4.1.7Receiver. The receiver must be a clean, dry container of convenient size to receive the sample. All connections from the sample probe to the sample container must be free of leaks. Two types of container may be used, depending upon service requirements.

11.4.1.7.1Atmospheric container. The atmospheric container shall be constructed in such a way that it retards evaporation loss and protects the sample from extraneous material such as rain, snow, dust, and trash. The construction should allow cleaning, interior inspection, and complete mixing of the sample prior to removal. The container should be provided with a suitable vent.

11.4.1.7.2Closed container. The closed container shall be constructed in such a manner that it prevents evaporation loss. The construction must allow cleaning, interior inspection and complete mixing of the sample prior to removal. The container should be equipped with a pressure-relief valve.

11.4.2Procedure.

11.4.2.1Nonautomatic sample. Adjust the valve or plug cock from the sampling probe so that a steady stream is drawn from the probe. Whenever possible, the rate of sample withdrawal should be such that the velocity of liquid flowing through the probe is approximately equal to the average linear velocity of the stream flowing through the pipeline. Measure and record the rate of sample withdrawal as gallons per hour. Divert the sample stream to the sampling container continuously or intermittently to provide a quantity of sample that will be of sufficient size for analysis.

11.4.2.2Automatic sampling. Purge the sampler and the sampling lines immediately before the start of a sampling operation. If the sample design is such that complete purging is not possible, circulate a continuous stream from the probe past or through the sampler and back into the line. Withdraw the sample from the side stream through the automatic sampler using the shortest possible connections. Adjust the sampler to deliver not less than one and not more than 40 gallons (151 liters) of sample during the desired sampling period. For time-cycle samplers, record the rate at which sample increments were taken per minute. For flow-responsive samplers, record the proportion of sample to total stream. Label the samples and deliver them to the laboratory in the containers in which they were collected.

11.5Nozzle sampling. The nozzle sampling procedure is applicable for sampling diesel fuel from a retail outlet or wholesale purchaser-consumer facility storage tank.

11.5.1Apparatus. Sample containers conforming with 4.1 should be used. A spacer, if appropriate (Figure 6 of appendix D), and a nozzle extension device similar to that shown in figures 7 or 7a of appendix D shall be used when nozzle sampling. The nozzle extension device does not need to be identical to that shown in figure 7 or 7a of appendix D but it should be a device that will bottom fill the container.

11.5.2Procedure. Immediately after diesel fuel has been delivered from the pump and the pump has been reset, deliver a small amount of product into the sample container. Rinse sample container and dump product into waste container. Insert nozzle extension (Figure 7 or 7a of appendix D) into sample container and insert pump nozzle into extension with slot over air bleed hole. Fill slowly through nozzle extension to 70-80 percent full (Figure 8 of appendix D). Remove nozzle extension. Cap sample container at once. Check for leaks.

12. Special Precautions and Instructions.

12.1Precautions. Official samples should be taken by, or under the immediate supervision of, a person of judgment, skill, and sampling experience. Never prepare composite samples for this test. Make certain that containers which are to be shipped by common carrier conform to applicable Interstate Commerce Commission, State, and local regulations. When flushing or purging lines or containers, observe the pertinent regulations and precautions against fire, explosion, and other hazards.

12.2Sample containers. Use containers of not less than one quart (0.9 liter) nor more than two gallons (7.6 liters) capacity, of sufficient strength to withstand the pressure to which they may be subjected. Open-type containers have a single opening which permits sampling by immersion. Closed-type containers have two openings, one in each end (or the equivalent thereof), fitted with valves suitable for sampling by water displacement or by purging.

12.3Transfer connections. The transfer connection for the open-type container consists of an air tube and a liquid delivery tube assembled in a cap or stopper. The air tube extends to the bottom of the container. One end of the liquid delivery tube is long enough to reach the bottom of the diesel fuel chamber while the sample is being transferred to the chamber. The transfer connection for the closed-type container consists of a single tube with a connection suitable for attaching it to one of the openings of the sample container. The tube is long enough to reach the bottom of the diesel chamber while the sample is being transferred.

12.4Sampling open tanks. Use clean containers of the open type when sampling open tanks and tank cars. An all-level sample obtained by the bottle procedure described in 11.2 is recommended. Before taking the sample, flush the container by immersing it in the product to be sampled. Then obtain the sample immediately. Pour off enough so that the container will be 70-80 percent full and close it promptly. Label the container and deliver it to the laboratory.

12.5Sampling closed tanks. Containers of either the open or closed type may be used to obtain samples from closed or pressure tanks. If the closed type is used, obtain the sample using the water displacement procedure described in 12.8 or the purging procedure described in 12.9. The water displacement procedure is preferable because the flow of product involved in the purging procedure may be hazardous.

12.6Water displacement procedure. Completely fill the closed-type container with water and close the valves. While permitting a small amount of product to flow through the fittings, connect the top or inlet valve of the container to the tank sampling tap or valve. Then open all valves on the inlet side of the container. Open the bottom or outlet valve slightly to allow the water to be displaced slowly by the sample entering the container. Regulate the flow so that there is no appreciable change in pressure within the container. Close the outlet valve as soon as diesel fuel discharges from the outlet; then in succession close the inlet valve and the sampling valve on the tank. Disconnect the container and withdraw enough of the contents so that it will be 70-80 percent full. If the vapor pressure of the product is not high enough to force liquid from the container, open both the upper and lower valves slightly to remove the excess. Promptly seal and label the container, and deliver it to the laboratory.

12.7Purging procedure. Connect the inlet valve of the closed-type container to the tank sampling tap or valve. Throttle the outlet valve of the container so that the pressure in it will be approximately equal to that in the container being sampled. Allow a volume of product equal to at least twice that of the container to flow through the sampling system. Then close all valves, the outlet valve first, the inlet valve of the container second, and the tank sampling valve last, and disconnect the container immediately. Withdraw enough of the contents so that the sample container will be 70-80 percent full. If the vapor pressure of the product is not high enough to force liquid from the container, open both the upper and lower valves slightly to remove the excess. Promptly seal and label the container, and deliver it to the laboratory.

EC01SE92.154