What are the differences between gate valves and butterfly valves, and what are their respective characteristics?

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Gate valves and butterfly valves are both used in pipelines to open and close as well as to regulate flow rate. Of course, there are methods for selecting between butterfly valves and gate valves. Valve manufacturers in Shanghai will show you how to make such selections: in water supply networks, in order to reduce the depth of soil covering the pipes, butterfly valves are generally used for pipes with larger diameters. For pipes where the depth of soil coverage is not a significant concern, gate valves are preferred; however, gate valves of the same specification are more expensive than butterfly valves. As for the boundary for caliber, it should be determined locally based on specific circumstances. Based on usage over the past decade, butterfly valves experience more failures than gate valves; therefore, it is worth considering expanding the use of gate valves where conditions permit. 　　Regarding gate valves, in recent years many valve manufacturers in China have developed and replicated soft-sealed gate valves. These types of gate valves have the following advantages over traditional wedge-type or parallel double-plate gate valves: a. The valve body and valve cover of soft-sealed gate valves are manufactured using precision casting, resulting in a one-piece structure that requires little to no mechanical processing; moreover, seal copper rings are not used, thereby saving non-ferrous metals. 　　b. The bottom of the soft-sealed gate valve has no pits, so no debris accumulates, resulting in a low failure rate when opening and closing the valve. 　　c. The soft-sealed rubber-lined valve plates have uniform dimensions, offering high interchangeability. 　　Therefore, soft-sealed gate valves will be a type favored by the water supply industry. Currently, the diameter of soft-sealed gate valves manufactured in China can reach 1500 mm, but most manufacturers produce valves with diameters ranging from 80 to 300 mm. There are still many issues related to the manufacturing processes in China. In domestically produced soft-sealed gate valves, the copper nut blocks are mounted above the rubber-lined valve plate, following a structure similar to that of gate valves; however, the friction caused by the movement of these nut blocks can easily lead to the peeling off of the rubber lining on the valve plate. In the soft-seal gate valves produced by a foreign company, the copper nut is embedded within the rubber-lined gate plate, forming a single unit that overcomes the aforementioned disadvantages; however, a high degree of concentricity is required between the valve cover and the valve body. 　　However, when opening and closing soft-sealed gate valves, they must not be closed too tightly; it is sufficient to achieve water sealing, otherwise it will be difficult to open them or the rubber lining may peel off. A valve manufacturer uses torque wrenches to control the degree of closure during valve pressure testing, and valve operators for water supply companies should also adopt this method of opening and closing valves.