The valves on the water supply network are not operated frequently and are on standby for a long time. Once needed, the valves should be able to close and intercept the flow; Normally, it is required that the valve be opened in place to reduce the head loss of the pipeline section, so the valve is a control device that can sustain troops for thousands of days and use them for a while; The integrity rate of valves is related to valve selection, valve manufacturing, pipeline design, valve assembly, valve opening and closing, and valve management. Of course, the main reason is still the quality of valves. Valves are numerous, widely distributed, and have a significant role in the water supply network. Therefore, there are many issues worth discussing in valve selection, inspection, performance, and management.

Valves include butterfly valves, gate valves, ball valves, and plug valves, which are used in different ranges in water supply networks. In order to reduce soil cover on pipelines, butterfly valves are generally selected for larger diameter pipelines; For those that have little impact on soil cover, strive to select gate valves; Ball valves and plug valves are difficult to cast and process, and are relatively expensive. They are generally suitable for small and medium-sized pipelines. In recent years, due to the improvement of casting technology, resin sand casting has been adopted, which can avoid or reduce mechanical processing, thereby reducing costs. Therefore, the feasibility of using ball valves on large-diameter pipelines is worth exploring. As for the boundary line of caliber size, it should be divided according to specific circumstances in each region. The main disadvantage of butterfly valves is the water passage section occupied by the butterfly plate, which increases the head loss; Although gate valves do not have this problem, the height of large-diameter vertical gate valves affects the soil covering of pipelines, and the length of large-diameter horizontal gate valves increases the lateral area occupied by pipelines, affecting the arrangement of other pipelines; Ball valves and plug valves maintain the advantages of single gate valves, low water flow resistance, sealing, flexible action, and easy operation and maintenance. Plug valves also have similar advantages, but the water passage section is not perfectly circular.
In recent years, many domestic valve manufacturers have developed soft seal gate valves. Compared with traditional wedge or parallel double gate plate gate valves, this type of gate valve has the following characteristics: 1. The valve body and cover of the soft seal gate valve are cast by casting method, one-time molding, no longer requiring mechanical processing, no use of sealing copper rings, and saving non-ferrous metals; 2. The bottom of the soft sealed gate valve has no pits, no accumulation of slag, and the failure rate of gate valve opening and closing is low; 3. The size of the soft sealed rubber lined valve plate is uniform and has strong interchangeability. Therefore, soft sealed gate valves will be the development direction of gate valves and a type of valve that the water supply industry is willing to adopt. When opening and closing soft sealed gate valves, do not close them too tightly. As long as the water stop effect is achieved, it is not easy to open or peel off the lining. The butterfly valves used in the water supply industry are mostly soft sealed butterfly valves. In response to the damage of the rubber ring during installation, which affects the sealing performance of butterfly valves, many manufacturers have introduced metal sealed butterfly valves instead of rubber ring sealed butterfly valves. Metal sealed butterfly valves generally adopt eccentric structures, especially three-dimensional eccentric structures, due to the low elasticity of the sealing components.