Mainly used in supply, drainage pipes of clean water、source water、sewage、seawater and other media, installed in the exit of pump, for cutting off the return media, and protecting the safe operation of pipe and pump. Main features: 1.small size、light weight、short structure 2. good performance of slow-close, not affected by the media of pipe, the disc first close quickly and then close slowly, protect the water hammer. 3. soft sealing with rubber, good performance of sealing, anti-abrasion, long using life. 4.stable opening and closing, no vibration, no noise 5. smaller flow resistance than old, good throttling performance