... water,oil,gas. 3.Certification:CE. Durable Forged Brass Check Valve.1.Model No. : LDM-CV042.Material ... 3,CW614n,CW617n, CuZn39pb3,,CuZn40pb2,CW3770,DZR. Stem Brass Stem, Brass as above. Sealing PTFE/TEFLON,VITON,O-RINGS ... etc.6.Size: 1/2''----4''.7.Surface: Brass yellow.8.Standard: GB,DIN,ANSI,EN,BS, ... and Quality!We smelt the brass bars,make the hot forging,machining and CNC processing,assembly,pressure test ...