Designation:D974−21Designation:139/98(2017)StandardTestMethodforAcidandBaseNumberbyColor-IndicatorTitration1ThisstandardisissuedunderthefixeddesignationD974;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.ThisstandardhasbeenapprovedforusebyagenciesoftheU.S.DepartmentofDefense.1.Scope*1.1Thistestmethodcoversthedeterminationofacidicorbasicconstituents(Note1)inpetroleumproducts2andlubri-cantssolubleornearlysolubleinmixturesoftolueneandisopropylalcohol.Itisapplicableforthedeterminationofacidsorbaseswhosedissociationconstantsinwaterarelargerthan10−9;extremelyweakacidsorbaseswhosedissociationconstantsaresmallerthan10−9donotinterfere.Saltsreactiftheirhydrolysisconstantsarelargerthan10−9.NOTE1—Innewandusedoils,theconstituentsconsideredtohaveacidiccharacteristicsincludeorganicandinorganicacids,esters,phenoliccompounds,lactones,resins,saltsofheavymetals,andadditionagentssuchasinhibitorsanddetergents.Similarly,constituentsconsideredtohavebasicpropertiesincludeorganicandinorganicbases,aminocompounds,saltsofweakacids(soaps),basicsaltsofpolyacidicbases,saltsofheavymetals,andadditionagentssuchasinhibitorsanddetergents.NOTE2—Thistestmethodisnotsuitableformeasuringthebasicconstituentsofmanybasicadditive-typelubricatingoils.TestMethodD4739canbeusedforthispurpose.1.2Thistestmethodcanbeusedtoindicaterelativechangesthatoccurinanoilduringuseunderoxidizingconditions.Althoughthetitrationismadeunderdefiniteequilibriumconditions,themethoddoesnotmeasureanabsoluteacidicorbasicpropertythatcanbeusedtopredictperformanceofanoilunderserviceconditions.Nogeneralrelationshipbetweenbearingcorrosionandacidorbasenumbersisknown.NOTE3—Oils,suchasmanycuttingoils,rustproofingoils,andsimilarcompoundedoils,orexcessivelydark-coloredoils,thatcannotbeana-lyzedforacidnumberbythistestmethodduetoobscu...
