A butterfly valve is a type of valve that opens and closes and regulates a fluid passage by using a circular disc as an opening and closing member and rotating with a valve stem. Butterfly butterfly valve installed in the pipe diameter direction. In the butterfly valve body cylindrical channel, the disc-shaped disc rotates about the axis, the rotation angle is between 0 ° ~ 90 °, when rotated to 90 °, the valve is fully open state card. Butterfly valve development history In the 1930s, the United States invented the butterfly valve, introduced to Japan in the 1950s, it was not widely used in Japan until the 1960s, and promotion in our country was after the 1970s. At present, butterfly valves of DN300 mm or above have gradually replaced gate valves in the world. Compared with the gate valve butterfly valve has a short opening and closing time for the moment of small, small installation space and light weight. Take 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 may occur due to improper use, causing the rubber seat to peel and damage. To this end, the international development of metal seal butterfly valve, cavitation area decreases in recent years, China has also developed a metal seal butterfly valve in Japan in recent years also developed cavitation-resistant, low vibration, low noise comb-shaped butterfly valve. General seal seat life under normal circumstances, rubber 15 years - 20 years, metal 80 years - 90 years. But how to choose correctly according to working conditions. Butterfly valve opening and the relationship between flow, basically a linear change in proportion. If it is used to control the flow, its flow characteristics are closely related to the flow resistance of the pipe. For example, the diameters and forms of the valves installed in the two pipes are all the same, while the pipe loss coefficient is different, and the flow difference of the valve will also be very large. ? If the valve is in a state of large throttling, the back of the valve plate is prone to cavitation, the possibility of damage to the valve, are generally used outside the 15 °. When the butterfly valve is at the opening, the shape of the opening formed by the valve body and the front end of the butterfly plate is centered on the valve shaft, and the two sides form a different state. The front end of the butterfly plate on one side moves in the direction of flowing water while the direction of the counter flow Therefore, one side of the valve body and the valve plate is formed like a nozzle-shaped opening, the other side is similar to the orifice-shaped opening, the nozzle side is faster than the throttling side of the flow rate, and the throttling side valve generates a negative pressure below, Rubber seals tend to come off. Butterfly valve and the butterfly itself does not have self-locking ability, in order to disc positioning, to install a worm reducer on the stem. The use of worm reducer, not only can make the disc self-locking ability to stop the butterfly plate in any position, but also to improve valve performance. Butterfly valve operating torque, due to the opening and opening and closing the valve of different values, the horizontal butterfly valve, especially the large-diameter valve, due to the depth of the valve shaft, the head of the difference between the torque can not be ignored. In addition, the valve inlet side of the device elbow, the formation of bias current, the torque will increase. Valve in the middle of the opening, due to the role of water flow torque, the operating mechanism needs self-locking. Butterfly valve structure is simple, only a few parts, material consumption province; small size, light weight, small installation size, small driving torque, easy to operate, quickly, simply swivel 90 ° to quickly open and close; and at the same time With good flow regulation and closing seal features, the butterfly valve is the dominant valve form for large, medium and low pressure applications. When the butterfly valve is fully open, the thickness of the disc is the only resistance to the flow of the medium through the valve body, so the pressure drop across the valve is small and therefore has good flow control characteristics. Butterfly valve seal and metal seal two types of seal. Flexible sealing valves, seals can be embedded in the body or attached to the butterfly plate around. Valves with metal seals generally have a longer life than elastomeric valves, but are harder to seal completely. Metal seals can adapt to higher operating temperatures, while flexible seals have temperature-limited defects. If the butterfly valve is required to be used as a flow control, the main choice is the correct size and type of valve. The structural principle of the butterfly valve is especially suitable for making large diameter valves. Butterfly valve not only in the oil, gas, chemicals, water treatment and other general industry has been widely used, but also used in thermal power station cooling water system. Commonly used butterfly valve clamp butterfly valve and flange two. The butterfly valve on the folder is to use double-headed bolts to connect the valve between the two pipe flanges, flanged butterfly valve is equipped with a flange on the valve, with bolts on both sides of the valve flange connected to the pipe flange. Valve strength performance refers to the ability of the valve to withstand medium pressure. Valves are mechanical products subject to internal pressure and must therefore have sufficient strength and rigidity to ensure long term use without rupture or deformation. With the application of anti-corrosion synthetic rubber and PTFE, the performance of butterfly valve can be improved and satisfied with different working conditions. Over the past decade, the rapid development of metal seal butterfly valve, with the high temperature, low temperature, corrosion resistance, resistance to erosion, high strength alloy material in the butterfly valve application, the metal seal butterfly valve in the high temperature, low temperature, strong erosion Under conditions such as operating conditions have been widely used, and partially replaced the globe valve, gate valve and ball valve. Structural characteristics of the butterfly valve Butterfly valve has the advantages of simple structure, small size, light weight, material consumption, small installation size, rapid switching, 90 ° reciprocating rotation, small driving torque, etc., used to cut off, connect, adjust the pipeline Medium, with good fluid control features and close the sealing performance. Butterfly valve can carry mud, the liquid accumulated in the pipeline port at least. Under low pressure, a good seal can be achieved. Good regulation. Butterfly-shaped streamlined design, the fluid resistance loss is small, can be described as an energy-saving products. Stem for the rod structure, quenched and tempered, have a good comprehensive mechanical properties and corrosion resistance, abrasion resistance. When the butterfly valve is opened and closed, the stem only rotates for the movement without lifting. The packing of the stem is not easily damaged and the seal is reliable. Cone pin with the butterfly plate fixed, the outstretched end of the anti-flush design, so as to avoid accidental fracture stem and disc junction stem collapse. Connection flange connection, on the folder connection, butt welding connection and lugs folder connection. Drive in the form of manual, worm gear, electric, pneumatic, hydraulic, electro-hydraulic linkage and other implementing agencies, enabling long-distance control and automation.

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Stainless steel is a corrosion resistant steel alloy with a minimum of 10% chromium. There are different grades and surface finishes of stainless steel produced to accommodate the environment in which the material will be implemented. Unlike carbon steel, stainless steel does not rust when exposed to air and moisture due to the sufficient amount of chromium present. The chromium creates an invisible passive film of chromium oxide that will not let oxygen attack the surface and prevents rusting of the iron base.

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Stainless Steel Bright Annealed Tube,Bright Annealing Seamless Tube ,Bright Annealing Tube

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