• ASTM D 6021 - Standard Test Method for Measurement of Total Hydrogen Sulfide in Residual Fuels by Multiple Headspace Extraction and Sulfur Specific Detection. • ASTM D 7621 / IP 570 - Standard Test Method for Determination of Hydrogen Sulfide in Fuel Oils by Rapid Liquid Phase Extraction. It should be noted that H 2 S can be measured in the Vapour phase or the liquid phase. ASTM D 5705 measures the Vapour phase, while ASTM D 6021 and ASTM D 7621 / IP 570 measure the liquid phase.
• Fill at least two 1-L (1 quart) size sample containers with fuel oil.
• Take the samples to the laboratory preferably within one to four hours, but always within twenty- four hours maximum
• Minimize the headspace of the sample container. Cap immediately and deliver to the testing facility.
• Place the samples in refrigerated storage
• Test each sample within one to four hours from the time of sampling.
• Store samples until analysis time but not more than three days
• Samples cannot be stored for later testing as H 2 S loss may occur. Sample integrity is extremely important; therefore, sample containers must be composed of inert materials, filled nearly completely with liquid, and capped tightly until tested. Sample handling should be minimized, and rapid testing for H2S is required. H2S is lost by degassing (elevated temperature and mechanical agitation increases H2S degassing), oxidation, and absorption on water-wet surfaces.
As this procedure requires the sample container to be liquid full, it is mandatory that the person conducting the sampling perform a risk assessment with his or her supervisor to ensure that the container temperature will not exceed the temperature of the sample when it is taken. If this cannot be assured, then we must turn down the job. This risk assessment must also take into consideration highway transportation regulations as these may prohibit the carriage of liquid full sample containers on public highways. In this circumstance, the use of a variable volume, floating piston sampler, if available, may be an alternative. Also, LIQUID FULL SAMPLE CONTAINERS MUST NOT BE TRANSPORTED BY AIR UNDER ANY CIRCUMSTANCES.
ASTM D 5705 Requirements
The sampling of residual fuel oils is done according to normal practice for the sampling of storage tanks, ships, or barges; additionally: • Samples taken for this test method shall be dedicated to a single H 2 S determination and not used for any other testing purpose, as any additional handling can lead to loss of H 2 S and thus erroneous results. • Spot samples should be taken from the midpoint or below midpoint of the fuel oil in a storage tank as liquid samples taken well into the fuel oil have had less H 2 S loss from degassing as compared with those taken from the fuel oil's surface. Samples taken from well within the fuel oil storage provide material that represents the greatest potential for H 2 S exposure during fuel oil movements.
ASTM D 6021 Requirements
Sampling shall be performed using a suitable H2S inert container of 250 to 500 mL size. Suitable containers can be made of borosilicate glass or aluminium. If the sample temperature is below 60 ° C (140 ° F) then a high-density polyethylene bottle can be used. • Fill the container completely to the top so that there is no headspace in the container and cap immediately. (Warning - at no time should the container temperature be allowed to exceed the temperature of the sample at the time).
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