Designation:D3339−12StandardTestMethodforAcidNumberofPetroleumProductsbySemi-MicroColorIndicatorTitration1ThisstandardisissuedunderthefixeddesignationD3339;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope*1.1Thistestmethodcoversthedeterminationofacidicconstituentsinneworusedpetroleumproductsandlubricantssolubleornearlysolubleinmixturesoftoluene,andisopropylalcohol.ThetestmethodisespeciallyintendedforcasesinwhichtheamountofsampleavailabletobeanalyzedistoosmalltoallowaccurateanalysisbyTestMethodsD974orD664.Itisapplicableforthedeterminationofacidshavingdissociationconstantsinwaterlargerthan10−9.Extremelyweakacidshavingdissociationconstantssmallerthan10−9donotinterfere.Saltstitrateiftheirhydrolysisconstantsarelargerthan10−9.1.2Thistestmethodcanbeusedtoindicaterelativechangesinacidnumberthatoccurinanoilduringuseunderoxidizingconditions.Althoughthetitrationismadeunderdefiniteequilibriumconditions,themethoddoesnotmeasureanabsoluteacidicpropertythatcanbeusedtopredictperfor-manceofanoilunderserviceconditions.Nogeneralrelation-shipbetweenbearingcorrosionandacidnumberisknown.1.3SincethistestmethodrequiressubstantiallylesssamplethanTestMethodsD974orD664,itprovidesanadvantageousmeansofmonitoringanoxidationtestbychangesinacidnumberby(1)minimizingtestsampledepletionforacidnumberanalysesandthusminimizingthedisturbanceofthetestor(2)allowingadditionalacidnumberanalysestobemadewhilemaintainingthesametestsampledepletionandthusprovidingadditionaldata.NOTE1—Someoils,suchasmanycuttingoils,rust-proofingoils,andsimilarcompoundedoils,orexcessivelydark-coloredoils,maybemoredifficulttoanalyzebythistestmethodduetoobscurityofthecolor-indicatorendpoint.TheseoilscanbeanalyzedbyTestMethodD664providedsufficientsampleisavailable.However,thissituationismuchlesslikelyusingTestMethod...
