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Ball valve type and classification
Source: | Author:Xinsy WZ | Publish time: 85 days ago | 46 Views | Share:
A ball valve is a valve that uses a ball as a closing member, and is mainly composed of a valve body, a valve seat, a ball, a valve stem, a handle (or other driving device such as an electric actuator, a pneumatic actuator or a hydraulic actuator). The valve stem is driven and rotates around the axis of the ball valve. It is mainly used to cut, distribute and change the flow direction of the medium in the pipeline.
 
For a wide variety of ball valves, including the principle of operation and the use of media and application sites, the user should select different types of ball valves according to the working conditions. The ball valve types are classified according to the actual working conditions on site.

According to the structure, it can be divided into:
 
First, the floating ball valve
 
The ball of the ball valve is floating. Under the action of the medium pressure, the ball can generate a certain displacement and press on the sealing surface at the outlet end to ensure the sealing of the outlet end.
The floating ball valve has a simple structure and good sealing performance, but the load of the ball subjected to the working medium is all transmitted to the outlet sealing ring, so it is necessary to consider whether the sealing ring material can withstand the working load of the spherical medium. This structure is widely used in medium and low pressure ball valves.
 
Second, fixed ball valve
 
The ball of the ball valve is fixed and does not move after being pressed. The fixed ball valve has a floating valve seat. After the medium pressure, the valve seat moves, so that the sealing ring is pressed against the ball to ensure the seal. Usually mounted on the upper and lower shafts of the ball, the 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 availability of the seal, in recent years, an oil seal ball valve has appeared, which injects a special lubricating oil between the sealing faces to form an oil film, which enhances the sealing performance and reduces the operating torque. It is more suitable for high pressure and large diameter ball valves.
 
Third, the elastic ball valve
 
The ball of the ball valve is elastic. The ball and the seat ring are made of metal material, and the sealing specific pressure is very large. According to the pressure of the medium itself, the sealing requirement is not met, and an external force must be applied. This valve is suitable for high temperature and high pressure media.
The elastic sphere is made by opening an elastic groove at the lower end of the inner wall of the sphere to obtain elasticity. When the passage is closed, the wedge of the valve stem is used to open the ball and press against the seat to seal. Before the ball is rotated, the wedge head is loosened, and the ball is restored to its original shape, so that a small gap occurs between the ball and the valve seat, which can reduce the friction and operating torque of the sealing surface.
 
The commonly used ball valve classification methods are as follows:
 
Press pressure: high pressure ball valve, medium pressure ball valve, low pressure ball valve
According to the type of flow channel: full-bore ball valve, reduced-diameter ball valve
By channel position: straight-through, three-way, right-angle
According to the temperature: high temperature ball valve, normal temperature ball valve, low temperature ball valve, ultra low temperature ball valve
According to the seal form: soft seal ball valve, hard seal ball valve
Assembled by stem: top-loading ball valve, side-mounted ball valve
According to the connection form: flange ball valve, welded ball valve, threaded ball valve, clamp ball valve
According to the driving method: manual ball valve, automatic control ball valve (pneumatic ball valve, electric ball valve, hydraulic ball valve)
According to the size of the caliber: super large diameter ball valve, large diameter ball valve, medium diameter ball valve, small diameter ball valve