ASTM D7415-21

1.Scope*
1.1 This test method covers monitoring sulfate by-products in in-service petroleum and hydrocarbon based diesel crank-case engine and motor oils that have a sulfur content of greater than 500 ppm. This test method should not be employed whenlow-sulfur fuels are used for combustion.

1.2 This test method uses Fourier Transform Infrared (FT-IR) spectrometry for monitoring build-up of sulfate by-products in in-service petroleum and hydrocarbon based lubri-cants as a result of normal machinery operation. Sulfateby-products can result from the introduction of sulfur from
combustion or from the oxidation of sulfur-containing base oiladditives. This test method is designed as afast, simplespectroscopic check for monitoring of sulfate by-products inin-service petroleum and hydrocarbon based lubricants with the objective of helping diagnose the operational condition of the machine based on measuring the level of sulfate by-products in the oil.

1.3 Acquisition of FT-IR spectral data for measuring sulfate by-products in in-service oil and lubricant samples is described in Practice D7418. In this test method, measurement and data interpretation parameters for sulfate by-products using both direct trend analysis and differential (spectral subtraction) trend
analysis are presented.

1.4 This test method is based on trending of spectral changes associated with sulfate by-products of in-service petroleum and hydrocarbon based lubricants. Warnings or alarm limits can be set on the basis of a fixed minimum value