Classification structure and principle of butterfly valve

&1) butterfly valve is a kind of valve which uses the disc type opening and closing piece to rotate about 90 degrees to open, close and adjust the fluid channel. Butterfly valve is not only simple in structure, small in volume, light in weight, low in material consumption, small in installation size, small in driving torque, simple and rapid in operation, but also has good flow throttling function and closing sealing characteristics. It is one of the fastest-growing valve varieties in recent ten years. Especially in the United States, Japan, Germany, France, Italy and other industrial developed countries, the use of butterfly valve is very extensive. Its variety and quantity are still expanding, and to high temperature, high pressure, large diameter, high sealing, long life, excellent regulation characteristics and one valve multi-functional direction, its reliability and other performance indicators are up to a high level, and has partially replaced the stop valve and gate Valves and ball valves. With the development of butterfly valve technology. In the foreseeable short time, especially in the field of large and medium caliber, medium and low pressure, butterfly valve will become the leading valve form. &The original butterfly valve is a kind of simple and loosely closed flapper valve, which is usually used as flow regulating valve and damping valve in water pipeline system With the application of chemical resistant synthetic rubber in butterfly valve, the performance of butterfly valve is improved. Synthetic rubber is widely used to make lining and elastic seat of butterfly valve because of its corrosion resistance, erosion resistance, stable size, good resilience, easy forming, low cost, etc. and it can choose different performance synthetic rubber according to different use requirements to meet the operating conditions of butterfly valve
& nbsp; & nbsp; & nbsp; & nbsp; because PTFE has strong corrosion resistance, stable performance, not easy to aging, low friction coefficient, easy to form, and stable size, and it can also be filled and added with appropriate materials to improve its comprehensive performance to obtain butterfly valve sealing materials with better strength and lower friction coefficient, which overcomes some limitations of synthetic rubber, so it can be polymerized Polytetrafluoroethylene (TFE) as the representative polymer material and its filling and modifying materials have been widely used in butterfly valves, which further improves the performance of butterfly valves. There are butterfly valves with wider temperature and pressure range, sealing performance and longer service life In order to meet the requirements of high and low temperature, strong erosion, long life and other industrial applications, the metal sealed butterfly valve has been greatly developed in recent years. With the application of high temperature resistance, low temperature resistance, strong corrosion resistance, strong erosion resistance and high-strength alloy materials in butterfly valves, metal sealed butterfly valves have been widely used in high and low temperature, strong erosion resistance, long life and other industrial fields. Large diameter (9750mm), high pressure (2.2kn / cm2), wide temperature range (- 102-606 ℃) butterfly valves have emerged, which makes the technology of butterfly valves reach a new water Ping. Because of the application of CAD, cam and FMS in valve industry, the design and manufacture of butterfly valve have reached a new level. It not only completely innovates the design calculation method of the valve, reduces the heavy repetitive conventional design work of the professional and technical personnel, makes the technical personnel have more energy to improve the technical performance of the product and the research and development of the new product, shortens the cycle and improves the labor productivity. Especially in the field of metal sealed butterfly valve, due to the application of CAD / CAM, there are three-dimensional sealing pairs designed by CAD and manufactured by cam numerical control, which make the sealing surface of the valve free from any extrusion, scratch and wear during the opening and closing process, thus improving the tightness and service life of the butterfly valve by an order of magnitude When the valve is fully opened, it has small flow resistance. When the valve is opened between 15 ° and 70 °, it can carry out sensitive flow control. Therefore, in the field of large-diameter regulation, the application of butterfly valve is very common and will gradually become the main pilot valve
& nbsp; & nbsp; & nbsp; & nbsp; most butterfly valves can be used for medium with suspended solid particles due to the movement of the valve plate of the butterfly valve with wiping property. According to the strength of the seal, they can also be used for powder and granular medium
& nbsp; & nbsp; & nbsp; & nbsp; II. Classification of butterfly valves A & nbsp; 1. A & nbsp; S & nbsp; S & nbsp; S & nbsp; S & nbsp; (1) a & nbsp; S & nbsp; S & nbsp; S & nbsp; (2) a & nbsp; S & nbsp; S & nbsp; S & nbsp; S & nbsp; (3) a & nbsp; S & nbsp; S & nbsp; S & nbsp; S & nbsp; S & nbsp; (4) a & nbsp; S & nbsp; S & nbsp; a & nbsp; S & nbsp; a & nbsp; S & nbsp; a & nbsp; S & nbsp; S & nbsp; a & nbsp; S & nbsp; a & nbsp; S & nbsp; a & nbsp; S & nbsp; s; a & nbsp; S & nbsp; a & nbsp; a & nbsp; S & nbsp; a & nbsp; S & nbsp; a & nbsp; a & nbsp; a & nbsp; s 2. By cover material Classification a 6031 & nbsp; & nbsp; & nbsp; & nbsp; (1) & nbsp; soft seal butterfly valve a 6031 & nbsp; & nbsp; & nbsp; & nbsp; 1) the sealing pair is composed of non-metallic soft material and non-metallic soft material
& nbsp; & nbsp; & nbsp; 2) the sealing pair is composed of metal hard material and non-metal soft material
& nbsp; metal hard seal butterfly valve. The sealing pair is composed of metal hard material and metal hard material A 6031 & nbsp; & nbsp; & nbsp; 3. Classification by sealing form a 6031 & nbsp; & nbsp; & nbsp; & nbsp; (1) forced sealing butterfly valve
& nbsp; elastic seal butterfly valve. The sealing specific pressure is generated by the elasticity of the valve seat or valve plate when the valve plate presses the valve seat when the valve is closed
& nbsp; & nbsp; & nbsp; 2) externally torque sealed butterfly valve. The specific pressure of the seal is generated by the torque applied to the valve shaft.
& nbsp; pressure sealed butterfly valve. The specific pressure of the seal is produced by charging the elastic sealing element on the valve seat or valve plate
& nbsp; automatic sealing butterfly valve. The specific pressure of the seal is automatically generated by the medium pressure A 6031 & nbsp; & nbsp; & nbsp; 4. Classification by working pressure a 6031 & nbsp; & nbsp; & nbsp; & nbsp; (1) vacuum butterfly valve. Butterfly valve with working pressure lower than standard atmospheric pressure
& nbsp; low pressure butterfly valve. Butterfly valve with nominal pressure PN ≤ 1.6Mpa
& nbsp; medium pressure butterfly valve. Butterfly valve with nominal pressure of 2.5-6.4mpa
& nbsp; high pressure butterfly valve. Butterfly valve with nominal pressure of 10.0-80.ompa
& nbsp; ultra high pressure butterfly valve. Butterfly valve with nominal pressure of PN & lt; 100MPa A 6031 & nbsp; & nbsp; & nbsp; 5. Classification by operating temperature a 6031 & nbsp; & nbsp; & nbsp; & nbsp; (1) high temperature butterfly valve. T & lt; 450 ℃
& nbsp; medium temperature butterfly valve. 120 C