ThisInternationalStandardspecifiesagravimetricmethodforthepreparationofcalibrationgasmixturesincylindersofwhichthetargetaccuracyofthecompositionhasbeenpre-defined.Itisapplicableonlytomixturesofgaseousortotallyvaporizedcomponentswhichdonotreactwitheachotherorwiththecylinderwalls.Aprocedureisgivenforamethodofpreparationbasedonrequirementsforthefinalgasmixturecompositiontobewithinpre-setlevelsofuncertainty.Multi-componentgasmixtures(includingnaturalgas)andmultipledilutionmixturesareincludedinthisInternationalStandardandareconsideredtobespecialcasesofthesinglecomponentgravimetricpreparationmethod.ThisInternationalStandardalsodescribestheprocedureforverifyingthecompositionofgravimetricallypreparedcalibrationgases.Providedrigorousandcomprehensivequalityassuranceandqualitycontrolproceduresareadoptedduringthepreparationandvalidationofthesegravimetricgasmixtures,calibrationgasesofthehighestaccuracycanbeobtainedforawiderangeofgasmixtures,incomparisonwithothermethodsofpreparingsuchgases.