The type and advantages of ball valves
Ball valves and plug valves are of the same type of valve, only its closure is a sphere, the sphere around the center of the valve body to rotate to achieve the opening, closing a valve.
Ball valves are mainly used in piping to cut, distribute and change the flow direction of the media. Ball valve is widely used in recent years, a new type of valve, it has the following advantages:
1. The fluid resistance is small and the drag coefficient is equal to the pipe length of the same length.
2. Simple structure, small size, light weight.
3. Close and reliable, the current ball valve sealing material widely used plastic, good sealing, in the vacuum system has also been widely used.
4. Easy to operate, open and close quickly, from full open to full clearance as long as the rotation 90 °, easy to remote control.
5. Easy maintenance, ball valve structure is simple, the seals are generally active, demolition and replacement are more convenient.
6. When fully open or fully closed, the ball and the valve seat sealing surface and the media isolation, the media through, will not cause the valve sealing surface erosion.
7. Applicable to a wide range of diameter from small to a few millimeters, large to a few meters, from high vacuum to high pressure can be applied.
Ball valve has been widely used in petroleum, chemical, power generation, paper, atomic energy, aviation, rockets and other departments, as well as people's daily lives.
Ball valve according to the structure can be divided:
A floating ball valve
Ball of the ball is floating, under the action of the medium pressure, the ball can produce a certain displacement and pressed on the outlet side of the sealing surface to ensure that the export side of the seal.
Floating ball valve structure is simple, good sealing, but the ball to bear the working medium of the load all passed to the export seal, so consider the sealing material can withstand the work of the ball media load. This structure is widely used in medium and low pressure ball valves.
Second, fixed ball valve
Ball of the ball is fixed, after the pressure does not produce movement. Fixed ball valve with a floating seat, by the media pressure, the valve seat movement, so that the seal on the ball to ensure that the seal. Usually with the ball on the lower shaft with bearings, operating torque is small, suitable for high pressure and large diameter valves.
In order to reduce the operating torque of the ball valve and increase the reliability of the seal, in recent years there have been oil seal ball valve, both in the sealing surface between the injection of special lubricants to form a layer of oil film, which enhances the seal, but also reduces the operating torque , More suitable for high pressure large diameter ball valve.
Three, flexible ball valve
The ball of the ball is elastic. Ball and valve seat seals are made of metal materials, sealing pressure is very large, relying on the pressure of the medium itself has been less than the requirements of the seal, you must exert external force. This valve is suitable for high temperature and high pressure medium.
The elastic sphere is an elastic groove at the lower end of the inner wall of the sphere, and is elastic. When closing the channel, use the wedge of the stem to keep the ball open and seal against the seat. In the rotation of the ball before the first release of the wedge-shaped head, the ball with the original prototype to restore the ball and the seat between the small gap, you can reduce the sealing surface friction and operating torque.