This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards Guides and Remendations issued by the World Trade Organization Technical Barriers to Trade (TBT)Committee. Designation:D7415-21 INTERNATIONAL Standard Test Method for Condition Monitoring of Sulfate By-Products in In-Service Petroleum and Hydrocarbon Based Lubricants by Trend Analysis Using Fourier Transform Infrared (FT-IR) Spectrometry This standard is issued under the fixed designation D7415:the number immediately following the designation indicates the year of original adoption or in the case of revision the year of last revision.A number in parentheses indicates the year of last reapproval.A superseript epsilon (e)indicates an editorial change since the last revision or reapproval. 1.Scope* for a single measurement or alternatively can be based on a 1.I This test method covers monitoring sulfate by-products rate of change of the response measured see Ref (1).2 in in-service petroleum and hydrocarbon based diesel crank- 1.4.1 For direct trend analysis values are recorded directly case engine and motor oils that have a sulfur content of greater from absorption spectra and reported in units of absorbance per than 500 ppm.This test method should not be employed when 0.1 mm pathlength. low-sulfur fuels are used for bustion. 1.4.2 For differential trend analysis value...