... OEM manafacturer experience Rubber Duckbill Valve,flange duckbill valve,rubber check valve 1: Product Introduction 1:Rubber check valve is made of rubber , ... is sound seal for back stop,no leakage,back flow prevention,the higher the back pressure is ,the better the ... 5, Wide size,norminal size:DN50~DN1200mm3:Rubber Check Valve Application Scope Applicable Scope:1:Sewage systems7: Stormwater outfall2: ...