Butterfly valve classification structure and principle

1) The butterfly valve is a type of valve that opens and closes and regulates the fluid passage by reciprocating about 90 degrees with a circular opening and closing member. The butterfly valve not only has the advantages of simple structure, small size, light weight, material consumption, small installation size, small driving torque, simple and quick operation, but also good flow witnessing function and close-seal feature, One of the fastest growing valve varieties in years. Especially in the United States, Japan, Germany, France, Italy and other industrialized countries, the use of butterfly valves is very wide. Its varieties and quantities are still expanding, and to the high temperature, high pressure, large diameter, high sealing, long life, excellent regulation characteristics and a valve multi-function direction, its reliability and other performance indicators are higher Level, and has partially replaced the globe valve, gate valve and ball valve. With the progress of butterfly technology. In the foreseeable short period of time, especially in large and medium caliber, low pressure use, butterfly valve will become the leading form of the valve. The original butterfly valve is a simple, closed flap valve. It is usually used as a flow control valve and a damping valve in water piping systems. With the use of chemically resistant synthetic rubber on butterfly valves, butterfly valve performance is improved. As the synthetic rubber has the characteristics of corrosion resistance, erosion resistance, dimensional stability, good resilience, easy forming, low cost and the like, and can be selected according to different requirements of different performance synthetic rubber to meet the conditions of the use of butterfly valves, which Widely used in the manufacture of butterfly valve lining and flexible seat. Due to its high corrosion resistance, stable performance, easy aging, low coefficient of friction, ease of forming and dimensional stability, PTFE can also be improved in strength by filling and adding appropriate materials to improve its overall performance. Lower friction coefficient of the butterfly valve sealing material to overcome some of the limitations of synthetic rubber, and thus to PTFE as the representative of polymer materials and their filling modified materials in the butterfly valve has been widely used, so that the butterfly valve Performance has been further improved, there has been a wider range of temperature, pressure, sealing performance, longer life butterfly valve. To meet the high and low temperature, high erosion, long life and other industrial applications, the requirements of the past decade, the metal seal butterfly valve has been a great development. With the application of high temperature resistant, low temperature resistant, strong corrosion resistant, strong erosion resistant and high strength alloy material in butterfly valves, the metal sealed butterfly valves have been widely used in industrial fields such as high and low temperature, strong erosion and long life, The emergence of a large diameter (9750mm), high pressure (2.2kN / cm2), a wide temperature range (-102 ~ 606 ℃) of the butterfly valve so that the butterfly valve technology to a whole new level. The design and manufacture of butterfly valves have taken a whole new level due to the application of CAD and CAM and FMS in the valve industry. Not only to fully reform the valve design and calculation methods to reduce the professional and technical personnel heavy repetitive routine design work, so that technicians have more energy used to improve product performance and new product research and development, shorten the cycle and improve Labor productivity. Especially in the field of metal sealing butterfly valve, due to the application of CAD / CAM, a three-dimensional sealing pair developed by CAD and manufactured by cAM numerical control appeared so that the sealing surface of the valve does not have any squeezing, scratching and abrasion during opening and closing , So that the sealing of the butterfly valve and the life of an order of magnitude increase. Butterfly valves, when fully open, have a lower flow resistance and are capable of sensitive flow control when opened at between about 15 ° and 70 °, so the use of butterfly valves is very common in large caliper applications and will Gradually become the dominant valve type. Due to the wiping properties of the butterfly valve disc, most butterfly valves are available for media with suspended solids and can also be used in powdered and granular media depending on the strength of the seal. Second, the classification of butterfly There are many types of butterfly valves, and there are a variety of classification methods. 1. Classified by structure (1) Central sealing butterfly valve (2) Single eccentric sealing butterfly valve (3) Double eccentric sealing butterfly valve (4) Three eccentric sealing butterfly valve According to the sealing surface material classification (1) soft sealing butterfly valve 1) The sealing pair is made of non-metallic soft materials on non-metallic soft materials. 2) The sealing pair is made of metal hard material to non-metal soft material. (2) metal seal butterfly valve. The sealing pair is made of metal hard material to metal hard material. 3. Classified by the seal (1) mandatory seal butterfly valve. 1) Flexible sealing butterfly valve. Sealing pressure than by the valve is closed when the valve plate squeeze valve seat, seat or valve flexibility. 2) plus torque sealing butterfly valve. The seal pressure is generated by the torque applied to the valve shaft. (2) pressure sealing butterfly valve. Sealing pressure than the valve seat or valve plate by the elastic sealing element pressure generated. (3) automatic sealing butterfly valve. Sealing pressure is automatically generated by the media pressure. 4. Classified by working pressure (1) Vacuum butterfly valve. The working pressure is lower than the standard atmospheric pressure butterfly valve. (2) low pressure butterfly valve. Nominal pressure PN ≤ 1.6MPa butterfly valve. (3) medium pressure butterfly valve. Nominal pressure PN is 2.5 ∽ 6.4MPa butterfly valve. (4) high pressure butterfly valve. Nominal pressure PN is 10.0 ∽ 80. OMPa butterfly valve. (5) Ultra-high pressure butterfly valve. Nominal pressure PN <100MPa butterfly valve. 5. Classified by working temperature (1) High temperature butterfly valve. Butterfly valve t <450 ℃. (2) temperature butterfly valve. 120 ℃ (3) Normal temperature butterfly valve. -40 ℃ (4) low temperature butterfly valve. -100 ℃ (5) ultra-low temperature butterfly valve. t ≤-100 ℃ butterfly valve. 6. According to the connection classification (1) Butterflies butterfly valve (2) Flanged butterfly valve (3) Bellow butterfly valve (4) Welded butterfly valve (2) Butterfly valve sealing principle Butterfly valve sealing principle The sealing principle is that the valve plate processing To ensure that the sealing surface has a suitable surface roughness value, the formation of the sealing surface of synthetic rubber valve seat in the formation of a suitable surface roughness value. When the valve is closed, through the rotation of the valve plate, the outer circular sealing surface of the valve plate squeezes the synthetic rubber valve seat to make the synthetic rubber valve seat elastically deform and form the elastic force as the seal pressure to ensure the valve seal.

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