Designation:D664−18´2BritishStandard4457Designation177/96StandardTestMethodforAcidNumberofPetroleumProductsbyPotentiometricTitration1ThisstandardisissuedunderthefixeddesignationD664;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.ε1NOTE—Subsection13.3.1andastatementintheSummaryofChangeswerecorrectededitoriallyinDecember2018.ε2NOTE—Subsections16.1.1.1and16.1.2.1werecorrectededitoriallyinJanuary2019.ThisstandardhasbeenapprovedforusebyagenciesoftheU.S.DepartmentofDefense.1.Scope*1.1Thistestmethodcoversproceduresforthedetermina-tionofacidicconstituentsinpetroleumproducts,lubricants,biodiesel,andblendsofbiodiesel.1.1.1TestMethodA—Forpetroleumproductsandlubricantssolubleornearlysolubleinmixturesoftolueneandpropan-2-ol.Itisapplicableforthedeterminationofacidswhosedissociationconstantsinwaterarelargerthan10–9;extremelyweakacidswhosedissociationconstantsaresmallerthan10–9donotinterfere.Saltsreactiftheirhydrolysisconstantsarelargerthan10–9.Therangeofacidnumbersincludedintheprecisionstatementis0.1mg⁄gKOHto150mg⁄gKOH.1.1.2TestMethodB—Developedspecificallyforbiodieselandbiodieselblendswithlowacidityandslightlydifferentsolubility.Thistestmethodrequirestheuseofanautomatictitratorwithautomaticendpoint-seekingcapability.NOTE1—Innewandusedoils,theconstituentsthatmaybeconsideredtohaveacidiccharacteristicsincludeorganicandinorganicacids,esters,phenoliccompounds,lactones,resins,saltsofheavymetals,saltsofammoniaandotherweakbases,acidsaltsofpolybasicacids,andadditionagentssuchasinhibitorsanddetergents.1.2Thetestmethodmaybeusedtoindicaterelativechangesthatoccurinoilduringuseunderoxidizingconditionsregardlessofthecolororotherpropertiesoftheresultingoil.Althoughthetitrationismadeunderdefiniteequilibriumconditions,thetestmethodisnotintendedtomeasureanabsoluteacidicproper...
