Designation:D1533−20StandardTestMethodforWaterinInsulatingLiquidsbyCoulometricKarlFischerTitration1ThisstandardisissuedunderthefixeddesignationD1533;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope1.1ThistestmethodcoversthemeasurementofwaterpresentininsulatingliquidsbycoulometricKarlFischertitration.Thistestmethodisusedcommonlyfortestspecimensbelow100%relativesaturationofwaterinoil.Thecoulomet-rictestmethodisknownforitshighdegreeofsensitivity(typically10µgH2O).Thistestmethodrequirestheuseofequipmentspecificallydesignedforcoulometrictitration.1.2ThistestmethodrecommendstheuseofcommerciallyavailablecoulometricKarlFischertitratorsandreagents.1.3ThevaluesstatedinSIunitsaretoberegardedasstandard.Nootherunitsofmeasurementareincludedinthisstandard.1.4Thisstandarddoesnotpurporttoaddressallofthesafetyconcerns,ifany,associatedwithitsuse.Itistheresponsibilityoftheuserofthisstandardtoestablishappro-priatesafety,health,andenvironmentalpracticesanddeter-minetheapplicabilityofregulatorylimitationspriortouse.Forspecificprecautionarystatementssee8.1andA2.1.1.5Thisinternationalstandardwasdevelopedinaccor-dancewithinternationallyrecognizedprinciplesonstandard-izationestablishedintheDecisiononPrinciplesfortheDevelopmentofInternationalStandards,GuidesandRecom-mendationsissuedbytheWorldTradeOrganizationTechnicalBarrierstoTrade(TBT)Committee.2.ReferencedDocuments2.1ASTMStandards:2D923PracticesforSamplingElectricalInsulatingLiquids3.SummaryofTestMethod3.1ThistestmethodisbasedonthereductionofiodinecontainingreagentaccordingtothetraditionalKarlFischerreaction.Theproposedreactionmechanismisasfollows:3SO21CH3OH1RN5@RNH#SO3CH3(1)H2O1I21@RNH#SO3CH312RN5@RNH#SO4CH312@RNH#I~RN5Base!Theendpointisdeterminedamperometricallywithaplati-numelectrodethatsensesasharpchangeincellresistance...
