Designation:D2144−07(Reapproved2021)StandardPracticesforExaminationofElectricalInsulatingOilsbyInfraredAbsorption1ThisstandardisissuedunderthefixeddesignationD2144;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope1.1Thesepracticesaretobeusedfortherecordingandinterpretationofinfraredabsorptionspectraofelectricalinsu-latingoilsfrom4000cm−1to400cm−1(2.5µmto25µm).NOTE1—Whilethesepracticesarespecifictoratiorecordingoropticalnulldouble-beamdispersivespectrophotometers,single-beamandHATR(horizontalattenuatedtotalreflectance),Fourier-transformrapidscaninfraredspectrophotometersmayalsobeused.Bycomputerizedsubtrac-tiontechniques,ratiomethodscanbeused.AnyofthesetypesofequipmentmaybesuitableiftheycomplywiththespecificationsdescribedinPracticeE932.1.2Twopracticesarecovered,aReferenceStandardPrac-ticeandaDifferentialPractice.1.3Thesepracticesaredesignedprimarilyforuseasrapidcontinuitytestsforidentifyingashipmentofoilfromasupplierbycomparingitsspectrumwiththatobtainedfrompreviousshipments,orwiththesampleonwhichapprovaltestsweremade.Theyalsomaybeusedforthedetectionofcertaintypesofcontaminationinoils,andfortheidentificationofoilsinstorageorservice,bycomparisonofthespectraoftheunknownandknownoils.Thepracticesarenotintendedforthedeterminationofthevariousconstituentsofanoil.1.4Warning—Infraredabsorptionisatoolofhighresolv-ingpower.Conclusionsastocontinuityofoilqualityshouldnotbedrawnuntilsufficientdatahavebeenaccumulatedsothattheshipment-to-shipmentvariationisclearlyestablished,forexample.1.5ThevaluesstatedinSIunitsaretoberegardedasstandard.Nootherunitsofmeasurementareincludedinthisstandard.1.6Thisstandarddoesnotpurporttoaddressallofthesafetyconcerns,ifany,associatedwithitsuse.Itistheresponsibilityoftheuserofthisstandardtoestablishappro-priatesafety,health,andenvir...
