Designation:D7194−12StandardSpecificationforAerospacePartsMachinedfromPolychlorotrifluoroethylene(PCTFE)1ThisstandardisissuedunderthefixeddesignationD7194;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope1.1Thisspecificationisintendedtobeameansofcallingoutfinishedmachinedpartsreadyforaerospaceuse.Suchpartsmayalsofinduseinselectedcommercialapplicationswherethereareclearbenefitsderivedfromtheuseofpartswithknownorcontrolledcrystallinity,highmolecularweight,goodmolecularweightretentionduringprocessing,dimensionalstabilityinthefinishedpart,andtightlycontrolledengineeringtolerances.1.2Thisspecificationestablishesrequirementsforpartsmachinedfromvirgin,unplasticized,100%polychlorotrifluo-roethylene(PCTFE)homopolymers.1.3ThisspecificationdoesnotcoverpartsmachinedfromPCTFEcopolymers,PCTFEfilmortapelessthan0.25-mm(0.010-in.)thick,ormodifiedPCTFE(containingpigmentsorplasticizers).1.4Thisspecificationdoesnotallowpartscontainingre-cycledmaterial.1.5ThespecificationdoesnotcoverPCTFEpartsintendedforgeneraluseapplications,inwhichcontrolofdimensionalstability,molecularweight,andcrystallinityarenotasimpor-tant.FormachinedPCTFEpartsintendedforgeneraluse,useSpecificationD7211.1.6Thisspecificationclassifiespartsintothreeclassesbaseduponintendedusesandexposures:oxygen-containingmedia,reactivemedia,andinertmedia.1.7Application—PCTFEcomponentscoveredbythisspeci-ficationarevirgin,100%PCTFEresin,freeofplasticizersandotheradditives.Thecomponentsarecombustionresistantinoxygen,dimensionallystable,andmeetotherspecificphysicalcharacteristicsappropriatefortheirenduse.Theyareusedinvalves,regulators,andotherdevicesinoxygen,air,helium,nitrogen,hydrogen,ammonia,andotheraerospacemediasystems.Thecomponentstypicallyareusedasvalveseats,o-rings,seals,andgaskets.Theyareremovedandreplaceddurin...
