pnBAS ASTM D 6304:2025

1.1 This test method covers the direct determination of entrained water in petroleum products and hydrocarbons using automated instrumentation. This test method also covers the indirect analysis of water thermally removed from samples and swept with dry inert gas into the Karl Fischer titration cell. Mercaptan, sulfide (S– or H2S), sulfur, and other compounds are known to interfere with this test method (see Section 6). The precision statement of this method covers the nominal range of 20 mg/kg to 25 000 mg/kg for Procedure A, 30 mg/kg to 2100 mg/kg for Procedure B, and 20 mg/kg to 360 mg/kg for Procedure C. 1.2 This test method is intended for use with commercially available coulometric Karl Fischer reagents and for the determination of water in additives, lube oils, base oils, automatic transmission fluids, hydrocarbon solvents, and other petroleum products. By proper choice of the sample size, this test method may be used for the determination of water from mg/kg to percent level concentrations.