Butterfly (English: butterfly valve) is closed parts (valve flap or disc) for the disc, around the valve axis to achieve the opening and closing a valve in the pipe and cut off from the main throttle use. Butterfly valve gate is a disc-shaped pieces of disc, the valve body around its own axis of rotation, or adjustments to achieve the purpose of opening and closing. Valve fully open to fully closed is usually less than 90 °, and the butterfly valve lever itself is not self-locking capability, in order to position disc to install on worm gear on the stem. Using worm reducer, not only can make disc with self-locking capability, so that disc to stop at any position, but also to improve the operational performance of the valve. 
 Industry-specific features to high temperature valve for high pressure range, the valve nominal diameter large, carbon steel valve body, valve plate metal ring seals instead of rubber ring. Large-scale manufacture of welded steel plate heat valve, mainly for high-temperature medium smoke duct and gas pipelines. 
 30 years, the United States invented the butterfly, 50 years into Japan, the 1960s was widely used in Japan, while it is in our promotion 70 years after the thing. The world in general DN300 mm butterfly valve has been replaced gradually. Compared with the butterfly valve opening and closing time is short, torque is small, small installation space and weight. To DN1000, for example, butterfly about 2T, while the gate of about 3.5T, and the butterfly valve is easy with a variety of drive combinations, with good durability and reliability. 
 Rubber seal butterfly valve for throttling drawback is that when used, due to improper use will produce cavitation, peeling off the rubber seat, damage from happening. To this end, we developed is now the international metal sealing butterfly valve, cavitation area decreases, in recent years, China has also developed a metal sealing butterfly valve in Japan in recent years also developed resistance to cavitation, low vibration, low noise, comb-shaped butterfly. 
 General life of the seal seat in normal circumstances, the rubber for 15 years -20 years -90 years, 80 years of metal. But how will have the correct selection based on the conditions required. 
 Butterfly valve opening and the relationship between flow, essentially linearly proportional to the change. If used to control the flow, the flow characteristics and the piping of the flow resistance is also closely related, such as the installation of two pipe valve diameter, forms, etc. all the same, but different loss coefficient pipe, valves, flow will be very different. 
 If the throttle valve in a significant reduction in the state, the valve plate on the back prone to cavitation, a damaged valve may, generally used in the 15 ° outside. 
 Butterfly in the opening, the valve body and disc shape of the front-end to form an opening to the valve shaft as the center, on both sides to complete the formation of different states, the front side of the disc moving along the flow direction, the direction of the other side of the upstream water The move, therefore, the side of the body and the valve plate to form shaped like the nozzle openings, similar to the other side of the orifice-shaped opening, the nozzle side than the expenditure side of the flow much faster, and throttle valve below will produce negative side often there rubber seals off. 
 Valve operating torque, due to open and close the valve opening and its value varies in different directions, horizontal butterfly, especially large-diameter valve, due to water depth, the valve shaft, into the water head difference generated torque can not be ignored. In addition, the valve inlet side of the device when the elbow to form a bias current, torque will increase. Valve opening in the middle, because the water flow torque to work, organizations need to self-locking operation. 
 Shanghai Tang Yang Butterfly products: D943H high electric butterfly valve, single-wafer type butterfly valve, spring-loaded quick closing valve, electric valve, electric air valve, wafer type fluorine butterfly valve, flange with rubber worm butterfly valve, flange butterfly valve, soft seal flange double eccentric butterfly valve, alarm valve, high temperature valve, high vacuum butterfly valve, welded seal butterfly valve, welded seal butterfly valve, butterfly valve plus pole, American Standard Flange butterfly valve, American Standard two-way sealing lug butterfly valve, pneumatic fluorine valve, pneumatic wafer type butterfly valve, pneumatic three eccentric butterfly valve, pneumatic telescopic valve, pneumatic control valve, pneumatic air valve , the center line of soft seal butterfly valve pneumatic, all fluorine valve, three-eccentric hard-seal butterfly valve, expansion valve, soft seal butterfly valve handle, manual ventilation valve, double eccentric butterfly valve PTFE seal, dual water-cooled ultra-high temperature butterfly valve, PTFE seal butterfly valve to regulate the type of PTFE sealing butterfly valve, wafer type butterfly valve worm gear, fire signal valve, accumulator-type hydraulic control slow-return valve closed 
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