Designation:D4739−17StandardTestMethodforBaseNumberDeterminationbyPotentiometricHydrochloricAcidTitration1ThisstandardisissuedunderthefixeddesignationD4739;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.INTRODUCTIONCurrently,therearetwoASTMtestmethodsunderthejurisdictionofCommitteeD02usedfordeterminingbasenumberbypotentiometrictitration:TestMethodD2896andTestMethodD4739.Theyarebothusedthroughoutthepetroleumindustry.TestMethodD2896isfornewoilsandisusedinsettingspecificationssinceitismoreaccuratethanTestMethodD4739.TestMethodD4739shallbeusedexclusivelyforthepurposeoftrackingbasenumberlossasanoilproceedsinservice.Inmanycases,thetestmethodswillprovidedifferentresults.SomecomparisonsaregivenintheScopeandtheSignificanceandUsesectionsofthistestmethodtodistinguishbetweenthetwostandardsandtoprovideguidancetousers.1.Scope*1.1Thistestmethodcoversaprocedureforthedetermina-tionofbasicconstituentsinpetroleumproductsandnewandusedlubricants.Thistestmethodresolvestheseconstituentsintogroupshavingweak-baseandstrong-baseionizationproperties,providedthedissociationconstantsofthemorestronglybasiccompoundsareatleast1000timesthanthatofthenextweakergroups.Thistestmethodcoversbasenumbersupto250.1.2Innewandusedlubricants,theconstituentsthatcanbeconsideredtohavebasicpropertiesareprimarilyorganicandinorganicbases,includingaminocompounds.Thistestmethoduseshydrochloricacidasthetitrant,whereasTestMethodD2896usesperchloricacidasthetitrant.Thistestmethodmayormaynottitratetheseweakbasesand,ifso,itwilltitratethemtoalesserdegreeofcompletion;someadditivessuchasinhibitorsordetergentsmayshowbasiccharacteristics.1.3Whentestingusedenginelubricants,itshouldberecognizedthatcertainweakbasesaretheresultoftheserviceratherthanhavingbeenbuiltintotheoil.Thistestmethodcanbeusedtoindicaterelativechangestha...
