Dual phaj kos valve kuj hu ua wafer hom npauj npaim kos valve, viav vias kos valve.Tnws hom kev kuaj vavle muaj qhov ua tau zoo tsis rov qab los, kev nyab xeeb thiab kev ntseeg tau, me me ntws tsis kam coefficient.It yog tsuas yog siv rau hauv roj av, tshuaj, khoom noj khoom haus, dej thiab tso dej, thiab lub zog hluav taws xob.Muaj ntau yam khoom siv, xws li cam khwb cia hlau, ductile hlau, stainless hlau thiab lwm yam.