1, floating ball valve

Ball valve ball is floating, under medium pressure, the ball can produce a certain displacement and squeeze the sealing surface at the outlet end, to ensure that the outlet end of the seal.

Floating ball valve structure is simple, good sealing, but the ball to withstand the load of the working medium are all passed to the export seal, so to consider whether the seal material can withstand the working load of the ball medium, when subjected to high pressure shock , The sphere may be offset. This structure, generally used in low pressure ball valve.

2, fixed ball valve

Ball valve ball is fixed, no pressure to move. Fixed ball valve with a floating valve seat, subject to media pressure, the valve seat to move so that the ring is pressed on the ball in order to ensure the seal. Usually with the ball on the lower shaft equipped with bearings, operating torque is small, suitable for high pressure and large diameter of the valve.

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 valves, both in the sealing surface injection of special lubricants to form a layer of oil film, which enhances the tightness and reduces operating torque , More suitable for high pressure large diameter ball valve.

3, flexible ball valve (orbital ball valve)

Ball valve ball is flexible. Sphere and seat ring are made of metal materials, sealing a large pressure, relying on the pressure of the media itself has reached the seal requirements, must impose external forces. This valve is suitable for high temperature and pressure medium.

Elastic ball is in the lower end of the ball wall to open a flexible groove, and to obtain flexibility. When closing the channel, the wedge-shaped head of the valve stem causes the ball to expand and press against the valve seat to seal. Before turning the sphere, the wedged head is released and the sphere then restores its original shape. This results in a small gap between the sphere and the seat, which can reduce the friction and operating torque of the sealing surface.