Flange fixed ball valve, flanged gate valve, flanged butterfly valve and oxygen pressure reducing valve is belong to one type of valve, the difference in its closure is a ball, the ball around the center line of the body as a rotation to achieve a kind of open and close the valve. The ball valve is mainly used in the pipeline to cut off, distribute and change the flow direction of the medium. Ball valve is a new type of valve widely adopted in recent years.
A, flange fixed ball valve has the following advantages:
1. Fluid resistance is small, and its drag coefficient is equal to that of the same length.
2. Simple structure, small volume and light weight.
3. Close and reliable, the ball valve sealing material is widely used in plastic and sealing, and has been widely used in vacuum system.
4. Easy to operate, open and close quickly, from open to close just rotate 90 °, is advantageous for the remote control.
5. Easy to maintain, ball valve structure is simple, sealing ring is generally active, remove and replace are convenient.
6. The sealing surface of the ball and seat is separated from the medium during full or closed, without causing the valve sealing surface to be eroded by the medium through.
7. Wide range of applications, ranging from small to several millimeters, large to several meters, from high vacuum to high pressure. When the ball is rotated 90 degrees, the ball should be fully presented at the entrance and exit, thus cutting off the flow.
B, flange fixed ball valve works as follows:
The opening process
1 in the closed position, the ball is pressed by the stem of the stem [wiki] mechanical [/ wiki], pressed against the seat.
When rotating the handwheel counterclockwise, the stem moves in the opposite direction, and its bottom corner plane causes the sphere to unseat.
The stem continues to lift and interacts with the guide pin in the stem spiral groove to cause the ball to spin without friction.
Until full open position, the stem is lifted to the limit position and the ball is rotated to the full open position.
C, fixed ball valve closing process
When closing, turn the handwheel clockwise and the stem begins to drop and cause the ball to turn away from the seat.
2 continue to rotate the handwheel, the valve stem is embedded in the spiral groove on the role of the guide pin, the stem and ball rotate 90 ° at the same time.
3 is close to closing, the sphere has been without contact with the valve seat rotated 90 °.
In the final lap of the handwheel, the Angle plane at the bottom of the stem is mechanically wedged into the oppressing sphere, pressing it tightly against the seat to reach a complete seal.
D, the structural features of flange fixed ball valve:
1. There is no friction between the opening and closing. This feature completely solves the problem that the traditional [wiki] valve [wiki] has been affected by friction between the covers.
2. Coat structure. The valve can be checked and repaired directly on the pipe, which can effectively reduce the parking and reduce the cost.
3. Single seat design. Eliminates the problem that the valve medium cavity is affected by abnormal pressure.
4. Low torque design. Specially designed stem with a small hand wheel valve can easily open and close.
5. Wedge-shaped seal structure. Valve by valve stem provides mechanical force, wedge pressure the ball into the seat and seal, make the valve’s sealing is not affected by changes in the pipeline pressure difference, under various conditions sealed performance has a reliable guarantee.
6. Self-cleaning structure of sealing cover. When the ball tilting away from the seat, fluid in the pipeline along the sphere uniform sealing surface into 360 ° through, not only eliminates the high velocity on the seat of local scour, also washed away by the accumulated on the surface of the sealing material, achieve the goal of the clean.
Source: China Ball Valve Manufacturer – Yaang Pipe Industry Co., Limited (www.yaang.com)