Designation:D3305–94(Reapproved2005)StandardPracticeforSamplingSmallGasVolumeinaTransformer1ThisstandardisissuedunderthefixeddesignationD3305;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(e)indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope1.1Thispracticecoversthesamplingofgasfromatrans-formergasspaceorfromagas-collectorrelaywherethevolumeofgasavailableissmallandwillnotpermittheuseofPracticeD2759.1.2Thispracticecoverssampling,usingagas-tightsyringeasthesamplingapparatusandcontainer.1.3Iftheapparatustobesampledisfoundtobeunderanegativepressure,theapparatuspressureshouldberaisedbytheadditionofnitrogengasuntilapositivepressureisobtained.1.4Thisstandarddoesnotpurporttoaddressallofthesafetyconcerns,ifany,associatedwithitsuse.Itistheresponsibilityoftheuserofthisstandardtoestablishappro-priatesafetyandhealthpracticesanddeterminetheapplica-bilityofregulatorylimitationspriortouse.2.ReferencedDocuments2.1ASTMStandards:2D2759PracticeforSamplingGasfromaTransformerUnderPositivePressure3.SignificanceandUse3.1Gasesmaybeformedinoil-filledelectricalequipmentasaresultoffaults.Thetypeoffaultanditsseveritymayoftenbeinferredfromthecompositionofthegases.3.2Gassamplesaretakenfromtransformergasspacesorfromgas-collectorrelaysinorderthatthecompositionofthegassamplemaybedetermined.3.3Innitrogen-blanketedtransformers,thegasesgeneratedbyafaultwillpartitionbetweenthegaseousandliquidphases.Ontransformerswithgas-collectorrelays,gasintheformofbubblesmaycollectinagas-collectorrelayandprovideameanstoobtainagassampleforanalysis.3.4Donotdrawsamplesfromanenergizedinstrumenttransformer.4.Apparatus4.1Syringe,gastight,5-mL,withluerloctermination.4.2Stopcock,three-way,plastic.4.3LengthofPTFETubing,1⁄8in.insidediameter.5.Procedure5.1Connecttheplasticstopcocktotheplastictubing.Connecttheotherendoftubingtoasuitablevalvedentrancetothetransforme...
