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What are the types and classifications of ball valves
Ball valve is a valve with ball as the closing component, mainly composed of valve body, valve seat, ball, valve rod, handle (or other driving devices, such as electric actuator, pneumatic actuator or hydraulic actuator). The valve stem rotates around the axis of the ball valve. It is mainly used to cut off, distribute and change the flow direction of the medium in the pipeline. It has provided several sets of flange ball valve Q41F, which are widely used in chemical plants in major cities in China and exported to the international market.
It can be divided into:
1. Floating ball valve
The ball of ball valve is floating. Under the action of medium pressure, the ball can produce a certain displacement and press on the sealing surface at the outlet end to ensure the sealing at the outlet end The floating ball valve has simple structure and good sealing performance, but the load of the working medium of the ball bearing is transferred to the outlet sealing ring, so it is necessary to consider whether the sealing ring material can withstand the working load of the ball. This structure is widely used for medium and low pressure ball valves.
2、 Fixed ball valve
The ball of ball valve is fixed and will not move after being pressed. The fixed ball valve has a floating seat. After being pressurized by the medium, the valve seat moves to make the sealing ring tightly press on the ball to ensure sealing. The bearing is usually installed on the upper and lower shafts with the ball, and the operating torque is small, which is suitable for high-pressure large-diameter valves. In order to reduce the operating torque of ball valves and increase the availability of seals, oil-sealed ball valves have emerged in recent years. Special lubricating oil is injected between the sealing surfaces to form an oil film, which not only enhances the sealing performance, but also reduces the operating torque, It is more suitable for high-pressure large-diameter ball valves.
3、 Elastic ball valve
The ball of ball valve is elastic. The sealing rings of the ball and valve seat are made of metal materials, and the sealing pressure is very high. According to the pressure of the medium itself, the pressure cannot meet the sealing requirements, and external force must be applied. The valve is applicable to high temperature and high pressure medium. Elastic sphere is achieved by opening an elastic groove at the lower end of the inner wall of the sphere. When closing the channel, use the wedge head of the valve rod to expand the ball and press the valve seat to achieve sealing. Before rotating the ball, loosen the wedge head first, and the ball will return to its original state, so that there is a small gap between the ball and the valve seat, which can reduce the friction force and operating torque of the sealing surface.
