... the basis of Gongyi Changmao Supplying and Draining of Water Materials Comapny and Sino-SouthKorea Joint Venture Henan Changmao ... , pipe damper, seal, gate valve,check valve, foot valve, filters, valves, pressure balance valve, valve, butterfly valve, pipe expansion ... with character of "Forward flow, reverse Check" new type water drainage product.Depend on pressure analysis and stress calculatioin,for ...