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Butterfly resume development and use of the place must be noted

Author: Published:2013-12-23
1930s, the United States invented the butterfly 1950s introduced into Japan , the 1960s was widely used in Japan , while in China it is a matter of promotion after the 1970s . The world in general DN300 mm butterfly has gradually replaced the valve . Compared with the gate valve opening and closing time is short, the operation of moments , small installation space and light weight. In DN1000 , for example, butterfly about 2T, the gate about 3.5T, and the valve driving apparatus in combination with a variety of easily , has good durability and reliability.
The disadvantage is that when the rubber sealing butterfly valve for throttling due to improper use of cavitation , peeling off the rubber seat , damage from happening . To this end , it has developed internationally metal sealing butterfly valves , cavitation zone is reduced in recent years, China has also developed a metal seal butterfly valve in Japan in recent years has developed resistance to cavitation, low vibration, low noise comb butterfly .
General life of the seal seat under normal circumstances , rubber 15 years -20 years , 80 years -90 years of metal . But how correct choice they should according to the conditions required .
The valve opening degree and the relationship between the flow rate , substantially linearly proportional to the change . If you are used to control the flow , the flow resistance of the flow characteristics and piping is also closely related , such as the installation of two pipelines valve diameter , so the whole form of the same , but different pipe loss coefficient , flow valves will be great differences .
If the valve is throttled by a big margin , the valve plate on the back prone to cavitation, the valve may be damaged , generally used in the 15 ° outside .
When the valve is opening, the opening shape of the front end of the valve disc and the valve shaft is formed in the center on both sides to complete the formation of a different state , the disc along the flow direction of the distal end side of the move, the direction of the other side of the reverse flow water moving , therefore , the side of the valve body and the nozzle plate -like -shaped opening is formed , similar to the other side of the orifice -shaped opening of the nozzle faster than in the side of the throttle flow rate side , and the side of the throttle valve generates a negative pressure below often rubber seals off occurs .
Valve operating torque , due to open and close the valve opening its value varies in different directions , horizontal butterfly valves, especially large diameter valves, due to the depth of the valve shaft, the torque generated by the water head difference can not be ignored . Further , the inlet side of the valve means bend to form a bias current , torque will be increased. When the valve opening in the middle , the moment in the water flow , the operating mechanism requires self-locking.