... new draining valve with functions of forward inflow and reverse back stop.2:Based on analysis and calculation of stress,the ... 3 There is sound seal for back stop,no leakage,back flow prevention,the higher the back pressure is ,the better the effect ... service life5 Wide size,norminal size:DN50~DN3000mm c:Rubber Check Valve Application Scope 1 product performance, complete specifications,wide application2 ...