Designation:D7415−21StandardTestMethodforConditionMonitoringofSulfateBy-ProductsinIn-ServicePetroleumandHydrocarbonBasedLubricantsbyTrendAnalysisUsingFourierTransformInfrared(FT-IR)Spectrometry1ThisstandardisissuedunderthefixeddesignationD7415;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope*1.1Thistestmethodcoversmonitoringsulfateby-productsinin-servicepetroleumandhydrocarbonbaseddieselcrank-caseengineandmotoroilsthathaveasulfurcontentofgreaterthan500ppm.Thistestmethodshouldnotbeemployedwhenlow-sulfurfuelsareusedforcombustion.1.2ThistestmethodusesFourierTransformInfrared(FT-IR)spectrometryformonitoringbuild-upofsulfateby-productsinin-servicepetroleumandhydrocarbonbasedlubri-cantsasaresultofnormalmachineryoperation.Sulfateby-productscanresultfromtheintroductionofsulfurfromcombustionorfromtheoxidationofsulfur-containingbaseoiladditives.Thistestmethodisdesignedasafast,simplespectroscopiccheckformonitoringofsulfateby-productsinin-servicepetroleumandhydrocarbonbasedlubricantswiththeobjectiveofhelpingdiagnosetheoperationalconditionofthemachinebasedonmeasuringthelevelofsulfateby-productsintheoil.1.3AcquisitionofFT-IRspectraldataformeasuringsulfateby-productsinin-serviceoilandlubricantsamplesisdescribedinPracticeD7418.Inthistestmethod,measurementanddatainterpretationparametersforsulfateby-productsusingbothdirecttrendanalysisanddifferential(spectralsubtraction)trendanalysisarepresented.1.4Thistestmethodisbasedontrendingofspectralchangesassociatedwithsulfateby-productsofin-servicepetroleumandhydrocarbonbasedlubricants.Warningsoralarmlimitscanbesetonthebasisofafixedminimumvalueforasinglemeasurementor,alternatively,canbebasedonarateofchangeoftheresponsemeasured,seeRef(1).21.4.1Fordirecttrendanalysis,valuesarerecordeddirectlyfromabsorptionspectraandreportedinuni...
