1.Valves for urban and rural construction and urban construction departments generally use low-pressure valves. Currently, they are developing toward environmental protection and energy conservation. Environmental-friendly rubber sheet valves, balance valves, and midline butterfly valves and metal sealing butterfly valves are gradually replacing low-pressure cast iron gate valves. The most commonly used valves in urban construction in China are balance valves, soft-sealed gate valves, and butterfly valves.