5.1 This test method provides an indication of the presence of surfactants in aviation fuel. Like Test Methods D2550, D3602, D3948, and D7224, this test method can detect carryover traces of refinery treating residues in fuel as produced. In addition, these test methods can detect surface active substances added to or picked up by the fuel during handling from point of production to point of use. Certain additives can affect the WSI. Some of these substances affect the ability of filter separators to separate free water from the fuel.

5.2 The small scale water separation tester has a measurement range from 0.0 WSI to 100.0 WSI.

Note 1: WSI values greater than 100.0 WSI can be caused by a reduction in the light transmittance (see A1.1.5) of the test specimen due to material that was removed during the testing process.

5.3 This test method was developed so refiners, fuel terminal operators, pipelines, and independent testing laboratory personnel can rapidly and precisely measure for the presence of surfactants, with a minimum of training, in a wide range of locations.

1.1 This test method covers a procedure to rate the ability of aviation turbine fuels to release entrained and emulsified water when passed through a water-coalescing filter.

1.2 Results are expressed as a Water Separation Index (WSI).

1.3 The values stated in SI units are to be regarded as standard.

1.3.1 Exception—Units in WSI are included.

1.4 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.