ASTM D4928

ASTM D4928 – Standard Test Method for Water in Crude Oils by Coulometric Karl Fischer Titration

Description:

Significance and Use

5.1 The accurate analysis of a crude oil sample to determine the water content is important in the refining, purchase, sale, or transfer of crude oils.

Scope

1.1 This test method covers the determination of water with true concentration range from 0.02 % to 5.00 % by mass or volume in crude oils using Procedures A and B and from 0.04 % to 3.75 % by mass or volume for Procedure C. Mercaptan (RSH) and sulfide (S⁻ or H₂S) as sulfur are known to interfere with this test method, but at levels of less than 500 μg/g [ppm(m)], the interference from these compounds is insignificant (see Section 6).

Note 1: To accommodate testing variations for Procedure C, refer to Section 16 for valid reporting range of test results.

1.2 This test method can be used to determine water in the 0.005 % to 0.02 % by mass range, but the effects of the mercaptan and sulfide interference at these levels has not been determined. For the range 0.005 % to 0.02 % by mass, there is no precision or bias statement.

1.3 This test method is intended for use with standard commercially available coulometric Karl Fischer reagent.

1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.