ASTM D 7621:2016

1.1 This test method covers procedures (A and B) for the determination of the hydrogen sulfide (H 2 S) content of fuel oils such as marine residual fuels and blend stocks, with viscosity up to 3000mm²s^-1 at 50°C, and marine distillate fuels, as measured in the liquid phase. 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 ). Note 2: A procedure for measuring the amount of hydrogen sulfide in crude oil can be found in Appendix X1 . Full precision for Appendix X1 has not yet been determined. 1.3 Valid ranges for the precision are given in Table2 and Table3. Measurements can be made outside these ranges however precision has not been determined. 1.4 Samples containing FAME do not affect the measurement of hydrogen sulfide by this test method. 1.5 The values stated in SI units are to be regarded as standard. Non-SI units given in parentheses are for information only. 1.6 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.

75.160.20