The development history of butterfly valves

In the 1930s, the United States invented the butterfly valve, which was introduced to Japan in the 1950s. It was not widely used in Japan until the 1960s, but it was not until the 1970s that it became popular in my country. The main features of the butterfly valve are its small operating torque, small installation space, and light weight. Taking the DN1000 as an example, the butterfly valve is about 2T, while the gate valve is about 3.5T, and the butterfly valve is easy to combine with various driving devices and has good durability and reliability. The disadvantage of the rubber-sealed butterfly valve is that when it is used for throttling, cavitation will occur due to improper use, which will cause peeling and damage to the rubber seat. So how to choose it correctly depends on the requirements of the working conditions. The relationship between the opening of the butterfly valve and the flow rate basically changes linearly. If it is used to control the flow, its flow characteristics are also closely related to the flow resistance of the piping. For example, if two pipes are installed with the same valve diameter and shape, but the loss coefficient of the pipes is different, the flow rate of the valves will also vary greatly. If the valve is in a state of heavy throttling, cavitation is likely to occur on the back of the valve plate, which may damage the valve. Generally, it is used outside of 15°. When the butterfly valve is in the middle opening, the opening shape formed by the valve body and the front end of the butterfly plate is centered on the valve shaft, and the two sides form different states. The front end of the butterfly plate on one side moves along the direction of flowing water, and the other side moves against the direction of flowing water. Therefore, one side of the valve body and the valve plate form a nozzle-shaped opening, and the other side is similar to a throttle-shaped opening. The flow velocity on the nozzle side is much faster than that on the throttle side, and negative pressure will be generated under the valve on the throttle side, often The rubber seal will come off. The operating torque of the butterfly valve varies with the opening and the opening and closing directions of the valve. For horizontal butterfly valves, especially large-diameter valves, due to the water depth, the torque generated by the difference between the upper and lower heads of the valve shaft cannot be ignored. In addition, when an elbow is installed on the inlet side of the valve, a bias flow is formed, and the torque will increase. When the valve is in the middle of its opening, the operating mechanism needs to be self-locking due to the action of the water flow torque.

There are many valve industry chains in China, but it is not a valve powerhouse. Generally speaking, my country has entered the ranks of the world's valve powers, but in terms of product quality, there is still a long gap between my country and the valve powers. The phenomenon of low production concentration in the industry, low research and development capabilities of high-end products matching valves, and a low level of manufacturing technology in the valve industry still exist, and the import and export trade deficit continues to expand. There are absolutely not so many valve companies that can really survive in the market. However, this high-speed shock in the valve industry will bring huge opportunities, and the result of the shock will make market operations more rational. The road to the localization of high-end valves is extremely bumpy. Basic parts have become a shortboard that restricts the development of my country's manufacturing industry to the high end. During the 12th Five-Year Plan period, the government will continue to increase the localization of high-end equipment parts. Here we select several representative valve industries mentioned in the "Implementation Plan" for a feasibility analysis of import substitution. From the analysis, it can be seen that the feasibility of import substitution of valves in various sub-sectors varies greatly, and high-end valves urgently need more policy guidance and scientific research support.

As an important part of the equipment manufacturing industry, the valve industry plays a very important role in the development of the national economy. Due to the gap between the level of my country's domestic valve manufacturing industry and the international advanced level, many key valves with high parameters (high temperature, high pressure, and high weight) have always relied on imports. For example, the European OMAL brand has always been the main choice for the domestic valve application industry. In order to promote the localization of valves, after the "Several Opinions on Accelerating the Revitalization of the Equipment Manufacturing Industry" issued by the State Council, the relevant state departments have made a series of major deployments according to the requirements of the country for the localization of major equipment, led by the National Development and Reform Commission. The China Machinery Industry Federation and the China General Machinery Industry Association have deployed and formulated a valve localization plan for major equipment in related fields and have coordinated with relevant departments many times. Now the localization of valves has formed a consensus in the domestic valve industry. Actively adopt international standards for product design; absorb excellent foreign design structures (including patented technologies); conduct product testing and performance inspections in strict accordance with international standards; absorb foreign production process experience; and pay attention to the research and promotion of new materials. Parameters The technical parameters and working conditions of valve products are the way to speed up the localization process, promote the continuous updating of valve products, and fully realize the localization of valves. With the acceleration of the reorganization of the valve industry, the future of the industry will be the competition between the quality and safety of valve products and product brands. Products will develop in the direction of high technology, high parameters, strong corrosion resistance, and a long life. New products and technological transformation can gradually improve the technology level of products, meet the needs of domestic equipment, and fully realize the localization of valves. Under the huge demand environment, my country's valve manufacturing industry will surely show a better development prospect.