... provide wafer or lug butterfly valve, with various rubber seats, EPDM,NBR,VITON,PTFE,e Rubber Seat For concentric butterfly valves. ... Various of rubber for different medium. There are soft seat and rubber seat with glass back.The ... feature is as following: MaterialsApplicable mediumFeatureApplicable temperature°C Natural rubber(X1)Fresh water, Sea water,Salt, Strong base,Weak ...