ASTM D7621-15

5.1 Excessive levels of hydrogen sulfide in the vapor phase above residual fuel oils in storage tanks can result in health hazards, violation of local occupational health and safety regulations, and public complaint. An additional concern is corrosion that can be caused by the presence of H_{5.2 This test method was developed so refiners, fuel terminal operators, and independent testing laboratory personnel can rapidly and precisely measure the amount of H5.3 Test Method D5705 provides a simple and consistent field test method for the rapid determination of H2S in the residual fuel oils vapor phase. However it does not necessarily simulate the vapor phase H5.4 Test Method D6021 does measure the H2S concentration of H5.5 H2S concentrations in the liquid and vapor phase attempt to reach equilibrium in a static system. However, this equilibrium and the related liquid and vapor concentrations can vary greatly depending on temperature and the chemical composition of the liquid phase. The equilibrium of the vapor phase is disrupted the moment a vent or access point is opened to collect a sample.}

1.1 This test method covers procedures (A and B) for the determination of the hydrogen sulfide (H_{Note 1: Specification fuels falling within the scope of this test method are: ASTM Specification D396, MIL-DTL-16884, and ISO 8217.}

1.2 Procedure A has been shown to eliminate interferences such as thiols (mercaptans) and alkyl sulfides. Procedure B can give elevated results if such interferences are present (see Annex A2).

1.3 Valid ranges for the precision are given in Table 2 and Table 3. Measurements can be made outside these ranges however precision has not been determined.

1.4 The values stated in SI units are to be regarded as standard. Non-SI units given in parentheses are for information only.

1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.