linear bearings

Ball valve applications and structural features of the door

by:AIRWOLF     2020-06-03
Ball ball valve gate with a circular hole as open-close part, with the valve rod rotation, in order to realize the on-off movement. ball valve gate. Ball valve gate is evolved by the cock valve, also known as ball cock valve. Ball valve door opening and closing as a sphere, using a sphere around the axis of the valve rod rotate 90 degrees to the realization of the aim of opening and closing. Ball valve door in the line is mainly used for cutting, distribution, and change the flow direction of medium, designed to V open ball valve door also has a good flow regulating function. Ball valve door just has to rotate 90 degrees of operating and small rotational torque can be closed tight. Full equality of the valve body cavity for medium resistance is very small, straight flow channel. Ball valve door is not only simple structure, good sealing performance, and within a certain range of nominal pass after small volume, light weight, less material consumption, installation size is small, and the drive torque is small, easy to operate, easy to realize the rapid opening and closing, easy operation and maintenance, applicable to water, solvent, acid and gas, such as general work medium, but also is suitable for the working conditions of media, such as oxygen, hydrogen peroxide, methane and ethylene. Ball valve gate valve door can be a whole body, also can be combined. Ball valve door is appeared in the 50 s of this century a new type of valve gate. In just 30 years, is one of the fastest growing valve door varieties in last decade. Especially in the United States, Germany, Japan, France, Italy, and west, Britain and other developed countries, the ball valve door has a very wide range of use, using the variety and quantity continues to expand, and to high temperature and high pressure, big, high sealing, long life, good regulation performance, and a multifunctional direction valve, its reliability and other performance indicators have reached a higher level, and has set up a part replace gate valve, cut-off valve, throttle valve door. It in aerospace, petrochemical industry, long distance pipeline, light industry, food, architecture, etc are widely used in many ways. This is because, compared with other types of valve ball valve door, has many outstanding advantages. Ball valve door main characteristics are as follows: ( 1) Ball valve fluid resistance small, has the lowest flow resistance ( In fact is zero) Ball valve door reducing and reducing channel is usually two kinds of structure. No matter the structure, the flow resistance coefficient of valve door is small. Especially the so-called full flow type, i. e. , not reducing ball valve door, due to its channel diameter equal to the inner diameter pipeline, local resistance loss only equivalent length of pipe friction resistance, namely in all valve door, this kind of ball valve door minimum flow resistance. In rocket and its experimental system, the requirements of pipeline resistance as small as possible. There are two ways to reduce the resistance of piping system: one is to reduce the fluid velocity, therefore need to increase diameter and valve gate size, for the efficiency of pipeline system tends to produce adverse effect, especially for conveying system at low temperature ( Liquid hydrogen) Is a very bad; One is the local resistance reducing valve door, therefore, the ball valve door naturally become the best choice. ( 2) Ball valve door open/close switch quickly and conveniently. Since only the ball valve door in the general case rotates 90 & deg; Completes the fully open or close the action, it is easy to achieve rapid opening and closing. Can realize the rapid opening and closing, some of the structure of the opening and closing time is only 0. 05 ~ 0. 1 s to ensure that can be used to test the automation system. Quick opening and closing valve door, no impact on the operation. ( 3) Ball valve door sealing performance is good. At present, the vast majority of ball valve gate valve seat is made of elastic material such as ptfe, sealing pair of metallic and non-metallic materials, often referred to as soft seal. In general, soft seal sealing easy to guarantee, and the machining accuracy and surface roughness on the surface of the sealing requirement is not high. ( 4) Ball valve door the service life is long. Because ptfe have good self-lubrication, and sphere of friction and wear is small, and because the ball processing technology improvements, reduce roughness, thus improve the service life of the ball valve gate. W - it is reported that the United States K - M in the test room to life test of ball valve door, switch more than 100000 times. ( 5) Ball valve door high reliability is mainly due to: (1) the spheroid and the valve seat sharp wear a pair of sealing pair will not scratch, such as fault, not stuck at work ( In the absence of lubricant) , so it can be reliably applied with the corrosive medium and low boiling point liquid; (2) built in the valve rod structure, eliminates the valve rod under the effect of fluid pressure may be due to the packing gland to loosen and fly out of accident hidden danger; (3) using anti-static, the structure of the refractory ball valve door, is suitable for conveying petroleum, natural gas, coal gas pipeline. ( 6) Serum, and solid particles. ( 7) Because not stuck at work ( In the absence of lubricant) , so it can be reliably applied with the corrosive medium and low boiling point liquid. ( 8) Spherical closed pieces can automatically locate in position, and can bear the high pressure difference is closed. ( 9) In the earth pressure and temperature range, can realize two-way sealed completely. ( 10) In the full open and full closed, sphere and valve seat sealing surface and the dielectric isolation, so high speed through a medium valve door does not cause the sealing surface erosion. ( 11) Compact structure, light weight, can be used for low temperature medium system think it's the most reasonable structure of the valve door. ( 12) Valve body symmetry, especially when welding valve body structure, well under stress from the pipe. ( 13) All welded ball valve gate valve body, can be directly buried in the ground, make the valve gate is not subject to erosion, the highest service life can be up to 30 years, is the most ideal oil, natural gas pipeline valve gate.
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