Appendix D to Part 80 - Sampling Procedures for Fuel Volatility

1. Scope.

1.1This method covers procedures for obtaining representative samples of gasoline for the purpose of testing for compliance with the Reid vapor pressure (RVP) standards set forth in § 80.27.

2. Summary of method.

2.1It is necessary that the samples be truly representative of the gasoline 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 procedure that is 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 gasoline.

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 70-85% full 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returning it to the top of the gasoline at a uniform rate of speed such that the beaker or bottle is 70-85% full when withdrawn from the gasoline.

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).

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

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

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

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

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

3.11Drain sample is one 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.

3.13Mixed sample is one obtained after mixing or vigorously stirring the contents of the original container, and then pouring out or drawing off the quantity desired.

3.14Nozzle sample is one obtained from a gasoline pump nozzle which dispenses gasoline 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 gasoline, 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 gasoline being sampled are acceptable.

4.2Container closure. Closure devices may be used as long as they meet the following test: The quality of closures and containers must be determined by the particular laboratory or company doing the testing through the analysis of at least six sample pairs of gasoline and gasoline-oxygenate blends. The six sample pairs must include at least one pair of ethanol at 10 percent and one pair of MTBE at 15 percent. The second half of the pair must be analyzed in a period of no less than 90 days after the first. The data obtained must meet the following criteria and should be made available to the EPA upon request;

n = number of pairs d = duplicate bottle's-initial bottle's vapor pressure t = student t statistic; the double sided 95% confidence interval for n−1 degrees of freedom Σ d/n±(2)1/2 * t * ((Σ d2−(Σ d)2/n)/(n−1))1/2≤0.38 psi

4.2.1Screw caps must be protected by material that will not affect petroleum or petroleum products. A phenolic screw cap with a teflon coated liner may be used, since it has met the requirements of the above performance test upon EPA analysis.

4.3 Cleaning 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, and acids, corrosion, rust, and oil. New sample containers should be inspected and cleaned if necessary. Dry either the container by 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 gasoline, 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. No object or material should be lowered into or suspended in a compartment of a tank which is being filled. A recommended waiting period of no less than five minutes after cessation of pumping will generally permit a substantial relaxation of the electrostatic charge for small volume vessels such as tank cars and tank trucks; under certain conditions a longer period may be deemed advisable. A recommended waiting period of no less than 30 minutes will generally permit a substantial relaxation of the electrostatic charge for large volume vessels such as storage tanks or ship tanks; 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.

7.3When sampling relatively volatile products (more than 2 pounds (0.14 kgf/cm2) RVP), the sampling apparatus shall be filled and allowed to drain before drawing the sample. If the sample is to be transferred to another container, this container shall also be rinsed with some of the volatile product and then drained. When the actual sample is emptied into this container, the sampling apparatus should be upended into the opening of the sample container and remain in this position until the contents have been transferred so that no unsaturated air will be entrained in the transfer of the sample.

8. Handling samples.

8.1Volatile samples. It is necessary to protect all volatile samples of gasoline from evaporation. Transfer the product from the sampling apparatus to the sample container immediately. Keep the container closed except when the material is being transferred. After delivery to the laboratory, volatile samples should be cooled before the container is opened.

8.2Container 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 and vapors during shipment, and to protect against moisture and dust, cover the stoppers of glass bottles with plastic caps that have been swelled in water, wiped dry, placed over the tops of the stoppered bottles, and allowed to shrink tightly in place. The caps of metal 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.

10.1 Label 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;

10.1.4—Brand and grade of material; and

10.1.5—Reference 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.

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 is required. Recommended diameter of opening in the bottle or beaker is 3/4 inch (19 mm).

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 70-85% full as it emerges from the liquid.

11.2.2.2Running sample. Lower the unstoppered bottle 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 70-85% full when withdrawn from the gasoline.

11.2.2.3Upper, middle, and lower samples. Lower the weighted, stoppered bottle to the proper depths (Figure 1) 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) 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. This procedure is recommended for volatile stocks in tanks of the breather and balloon roof type, spheroids, etc. (Samples may be taken from the drain cocks of gage glasses, if the tank is not equipped with sampling taps.) The assembly for tap sampling is shown in figure 3.

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. Before 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. 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)).

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)).

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)).

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 should 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 gasoline. 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.

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.

11.4.1.5.4To 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 ± five 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 containers 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 gasoline from a retail outlet or wholesale purchaser-consumer facility storage tank.

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

11.5.2Retail sampling procedure

11.5.2.1If a nozzle extension as found in figure 7 or 7a is used, 3 gallons of gasoline should first be dispensed from the pump nozzle to purge the pump hose and nozzle. Then a small amount of product should be dispensed through the nozzle extension into the sample container to rinse the sample container. A pump nozzle spacer (figure 6) may be used if the pump is a vapor recovery type. Rinse the sample container and discard the waste product into an appropriate container. Insert the nozzle extension (figure 7 or 7a) into the sample container and insert the pump nozzle into the extension with slot over the air bleed hole (when using figure 7). Fill the sample container slowly through the nozzle extension to 70-85 percent full (figure 8). Remove the nozzle extension. Cap the sample container at once. Check for leaks. Discard the sample container and re-sample if leak occurs. If the sample container is leak tight, label the container and deliver it to the laboratory.

11.5.2.2If a nozzle extension as found in figure 7b is used, 3 gallons of gasoline should first be dispensed from the pump nozzle to purge the pump hose and nozzle. Then screw a dry and dirt free 4 oz sample bottle container onto the bottle filling fixture. Insert the nozzle into the nozzle extension. Insert the discharge end of the modified nozzle extension into a gasoline safety can or into the filler neck of a vehicle. Obtain the sample by pumping at least 0.2 gallon through the sampler. Remove the sample bottle from the fixture. The sample must be 70-85 percent full. Cap the sample container at once. Check for leaks. Discard the sample container and re-sample if a leak occurs. If the sample container is leak tight, label the container and deliver it to the laboratory.

12. Special Precautions and Instructions.

12.1Precautions. Vapor pressures are extremely sensitive to evaporation losses and to slight changes in composition. When obtaining, storing, or handling samples, observe the necessary precautions to ensure samples representative of the product and satisfactory for RVP tests. 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. For nozzle sampling, use containers of not less than 4 ounces (118 ml) nor more than two gallons (7.6 liters) capacity, of sufficient strength to withstand the pressure to which they may be subjected, and of a type that will permit replacement of the cap or stopper with suitable connections for the transfer of the sample to the gasoline chamber of the vapor pressure testing apparatus. For running or all-level sampling procedures, use containers of not less than one quart (0.9 liter) nor more than two gallons (7.6 liters) capacity. 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 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 flush with the inside face of the cap or stopper and the tube is long enough to reach the bottom of the gasoline 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 gasoline 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-levels or a running sample obtained by the bottle procedure described in 11.2 is recommended. When the question exists of stratification of the contents of the tank, it is recommended that either a running or all-levels sample be taken along with upper, middle, and lower spot sampling. Before taking the sample, flush the container by immersing it in the product to be sampled. Then obtain the sample immediately. The sample must be 70-85 percent full. Close the container promptly and confirm it is not leaking. Label the container and deliver it to the laboratory.

12.5.Sampling closed tanks. Containers of the closed type may be used to obtain samples from closed or pressure tanks. Obtain the sample using the purging procedure described in 12.6.

12.6Purging 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.

Table 1—Summary of Gasoline Sampling Procedures and ApplicabilityType of containerProcedureParagraphStorage tanks, ship and barge tanks, tank cars, tank trucksBottle sampling11.2Storage tanks with tapsTap sampling.11.3Pipes and linesContinuous line sampling11.4Retail outlet and whole-sale purchaser-consumer facility storage tanksNozzle sampling11.5 EC01SE92.140 EC01SE92.141 EC01SE92.142 EC01SE92.143 EC01SE92.144 EC01SE92.145 EC01SE92.146 EC01SE92.147