Designation:D7668−17StandardTestMethodforDeterminationofDerivedCetaneNumber(DCN)ofDieselFuelOils—IgnitionDelayandCombustionDelayUsingaConstantVolumeCombustionChamberMethod1ThisstandardisissuedunderthefixeddesignationD7668;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope*1.1Thistestmethodcoversthequantitativedeterminationofthederivedcetanenumberofconventionaldieselfueloils,dieselfueloilscontainingcetanenumberimproveradditives,andisapplicabletoproductstypicalofSpecificationD975,GradesNo.1-Dand2-Dregular,lowandultra-low-sulfurdieselfueloils,EuropeanstandardEN590,andCanadianstandardsCAN/CGSB-3.517andCAN/CGSB3.6.Thetestmethodmaybeappliedtothequantitativedeterminationofthederivedcetanenumberofbiodiesel,blendsofdieselfueloilscontainingbiodieselmaterial(forexample,SpecificationsD975,D6751,andD7467),anddieselfueloilblendingcomponents.1.2Thistestmethodutilizesaconstantvolumecombustionchamberwithdirectfuelinjectionintoheated,compressedsyntheticair.Adynamicpressurewaveisproducedfromthecombustionofthesample.Anequationconvertstheignitiondelayandthecombustiondelaydeterminedfromthedynamicpressurecurvetoaderivedcetanenumber(DCN).1.3Thistestmethodcoverstheignitiondelayrangingfrom1.9msto25msandcombustiondelayrangingfrom2.5msto160ms(30DCNto70DCN).However,theprecisionstatedonlycoverstherangeofDCNfrom39to67.1.4ThevaluesstatedinSIunitsaretoberegardedasstandard.Nootherunitsofmeasurementareincludedinthisstandard.1.5Thisstandarddoesnotpurporttoaddressallofthesafetyconcerns,ifany,associatedwithitsuse.Itistheresponsibilityoftheuserofthisstandardtoestablishappro-priatesafety,health,andenvironmentalpracticesanddeter-minetheapplicabilityofregulatorylimitationspriortouse.1.6Thisinternationalstandardwasdevelopedinaccor-dancewithinternationallyrecognizedprinciplesonstandard-izatione...
