Designation:D5481−21StandardTestMethodforMeasuringApparentViscosityatHigh-TemperatureandHigh-ShearRatebyMulticellCapillaryViscometer1ThisstandardisissuedunderthefixeddesignationD5481;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.INTRODUCTIONSeveraldifferentconfigurationsofcapillaryviscometershavebeensuccessfullyusedformeasuringtheviscosityofengineoilsatthehighshearratesandhightemperaturesthatoccurinengines.Thistestmethodcoverstheuseofasingleapparatus2atasingletemperatureandsingleshearratetoachievegreateruniformityandimprovedprecision.1.Scope*1.1Thistestmethodcoversthelaboratorydeterminationofhigh-temperaturehigh-shear(HTHS)viscosityofengineoilsatatemperatureof150°Cusingamulticellcapillaryviscometercontainingpressure,temperature,andtiminginstrumentation.Theshearrateforthistestmethodcorrespondstoanapparentshearrateatthewallof1.4millionreciprocalseconds(1.4×106s−1).3Thisshearratehasbeenfoundtodecreasethediscrepancybetweenthistestmethodandotherhigh-temperaturehigh-sheartestmethods3(TestMethodsD4683andD4741)usedforengineoilspecifications.Viscositiesaredetermineddirectlyfromcalibrationsthathavebeenestab-lishedwithNewtonianoilswithnominalviscositiesfrom1.4mPa·sto5.0mPa·sat150°C.Theprecisionhasonlybeendeterminedfortheviscosityrange1.45mPa·sand5.05mPa·sat150°Cforthematerialslistedintheprecisionsection.1.2ThevaluesstatedinSIunitsaretoberegardedasstandard.Nootherunitsofmeasurementareincludedinthisstandard.1.2.1ThecentiPoise(cP)isanon-SImetricunitofviscositythatisnumericallyequaltothemilliPascal-second(mPa·s).1.2.2Poundspersquareinch(psi)isanon-SIunitofpressurethatisapproximatelyequalto6.895kPa.Theseunitsareprovidedforinformationonlyin6.1.1,7.3,9.1.2.1,andthetables.1.3Thisstandarddoesnotpurporttoaddressallofthesafetyconcerns,ifany,associatedwithitsuse.Itist...
