HYDROGEN SULFIDE IN RESIDUAL FUELS: ASTM D6021
EXPLANATION
Excessive levels of hydrogen sulfide in the vapor phase above residual fuel oils in storage tanks may result in health hazard, violation of OSHA limits, and public complaint. Also, it can cause corrosion in refining and other production activities. A concentration of 0.1 ppmw of this gas in the liquid phase of a residual fuel oil can generate about 10 to 100 ppmv in the vapor phase. Hence, an accurate method for low level determination in fuel oils is necessary.
A complementary method, Test Method ASTM D5705, is a simple and consistent field test method for rapid determination of hydrogen sulfide in the vapor phase. However, it does not truly simulate the vapor phase concentration of a fuel storage tank. The current test gives more quantitative indication of potential exposure to hydrogen sulfide.
TEST SUMMARY
A residual fuel oil sample is placed in a headspace vial and heated in an oven at 60° C for more than 5 but less than 15 min. The headspace gas is sampled and injected into an apparatus capable of measuring hydrogen sulfide in the gaseous sample. There are two types of these apparatus, one using lead acetate (Test Methods ASTM D4084 and ASTM D4323), and the other based on chemiluminescence (Test Method ASTM D5504). The procedure of heating and extracting the gas is repeated twice more.
TEST PRECISION
No data are available at present since the round robins have not been completed.
