... as raw sewage, sludge or slurries. The operating temperature of the valve is limited by the elastomer temperature capacity. 1)Compared with ... 1, It will start and close automatically according to the differential water pressure,safe,reliable,noiseless,no manual operation ... back stop,no leakage,back flow prevention,the higher the back pressure is ,the better the effect is.4, Corrosion protection,aging ...