... butterfly Valve manufacture directly suppling:hand lever operated cast iron wafer butterfly valve dn50Flange Drilling:Universal flange drilling ... JIS 10K,BS10 TABLE "E"Optional Materials:Body: Cast Iron GG25, Ductile Iron GGG40, GGG50Disc: DI+Nickel painted,SS304/316, ... flow rate and low flow resistance.6. Suitable medium: water, sewage, sea water, air, steam, food, medicament, oils, acids, alkalis ...