Ball High pressure needle valve ball is floating in the medium under pressure, can produce some displacement of the sphere, and pressed in the export side of the sealing surface, to ensure that the exit seal. Floating ball valve structure is simple, good sealing, but the ball under the load of all media work to export ring, so to consider the ring material can withstand the work load of the media sphere. This structure, widely used in low-pressure Stainless steel needle valve.
Two, fixed ball valve
The ball valve is fixed, no movement after compression. Fixed with a floating ball valve ball valve seat, by the media pressure, the valve seat have a mobile, so that the sealing ring is pressed on the sphere, in order to ensure the sealing. Usually with the ball in the upper and lower shaft with bearings, operating torque, suitable for high pressure and large diameter of the valve. In order to reduce the valve operating torque and increase the reliability of the seal, valve seal has emerged in recent years, both pressure lubricating oil special note in the sealing surface, to form a layer of oil film, which enhances the sealing, and reduce operating torque, more suitable for large-diameter high-pressure valve.
Three, elastic ball valve
The ball valve is flexible. Ball and valve seat rings are made of metal materials, sealing pressure than the large, rely on the media itself can not seal the pressure has reached the requirements must be imposed by external forces. This valve is suitable for high temperature and high pressure medium. Elastic sphere is a flexible open slot in the sphere of the bottom wall, and get flexible. When the closed channel, with the stem of the wedge-shaped head to open up the ball with the valve seat to seal compression. In the rotating sphere before loose wedge head, ball the subsequent restoration of the original prototype, so that a small gap between the ball and the valve seat sealing surface can reduce friction and operating torque.
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