百姓快3

 30 years, the United States invented the butterfly valve, the 50's into Japan, to the 60's in Japan in general, and in our country is the promotion of the 70 years after the. At present, the world is generally in the DN300 mm or more butterfly valve has been gradually replaced. Butterfly valve compared with the valve opening and closing time is short, the operation is small, small installation space and light weight. In DN1000, for example, about 2T, while the valve is about 3.5T, and the valve is easy to combine with a variety of driving device, has good durability and reliability. The
Rubber seal butterfly valve is used for throttling, due to improper use will produce cavitation, so that the rubber block, damage, etc.. Therefore, it has developed 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 has also developed resistance to cavitation erosion, low vibration, low noise, comb shaped butterfly. The
General sealing seat under normal circumstances, the rubber 15 years -20 years, 80 years of metal -90. But how to choose according to the requirements of the working conditions. The
The relationship between the opening degree of the butterfly valve and the flow rate of the valve is changed linearly. If used to control the flow, the flow characteristics of pipe flow resistance are closely related, such as two pipelines installation valve diameter, form, etc. all the same, but different pipe loss coefficient, difference in the flow rate of the valve will be very. The
If the valve is in a large margin, the back of the valve plate prone to cavitation, damage to the valve, the general use of 15 degrees outside. The
Butterfly valve is in the middle of the valve body and the front end of the butterfly valve to form a valve axis as the center of the formation of different states on both sides of the formation of different state, the side of the butterfly plate in the direction of the flow, and the other side of the reverse flow direction, so the side valve body and valve plate form a nozzle shaped opening, the other side of the throttle orifice, and the throttle valve will produce a negative pressure, often appear rubber seal off. The
 Butterfly valve operating torque, due to opening and closing the valve opening and closing direction of different its value, horizontal butterfly valve, especially large diameter valve, due to water depth, the valve shaft, the water head difference generated by the torque can not be ignored. In addition, the formation of drift valve inlet side of the elbow device, torque will be increased. When the valve is in the middle of the opening, the operating mechanism needs to be self - locked due to the flow of water.