What are the Types of Ball Valves?
A ball valve is a valve with a ball as the closing part, which is mainly composed of a valve body, a valve seat, a ball, a valve stem, a handle or other driving devices, such as electric actuators, pneumatic actuators or hydraulic actuators. The ball valve is driven by the valve stem and rotates around the axis. It is mainly used for cutting, distributing and changing the flow direction of the medium in the pipeline.
There are many types of ball valves, and the principle of action, the medium used and the application site are different. Users should choose different types of ball valves according to the working conditions. The types of ball valves are classified according to the actual working conditions on site.
Divided by structure
Floating Ball Valve
The ball of the ball valve is floating. Under the action of medium pressure, the ball can produce a certain displacement and press tightly on the sealing surface of the outlet end to ensure the sealing of the outlet end. The structure of the floating ball valve is simple and the sealing performance is good, but the load of the ball bearing the working medium is all 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 medium. This structure is widely used in medium and low pressure ball valves.
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 being pressurized by the medium, the valve seat moves, so that the sealing ring is tightly pressed on the ball to ensure the sealing. Bearings are usually installed on the upper and lower shafts with the ball, and the operating torque is small, which is 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, oil-sealed ball valves have appeared in recent years. Special lubricating oil is injected between the sealing surfaces to form an oil film, which enhances the sealing performance and reduces the operation. Torque, more suitable for high-pressure and large-diameter ball valves.
Elastic ball valve
The ball of the ball valve is elastic. The ball and valve seat seals are made of metal materials, and the specific pressure of the seal is very large. According to the pressure of the medium itself, the pressure cannot meet the sealing requirements, and external force must be applied. This valve is suitable for high temperature and high pressure medium.
The elastic sphere is obtained by opening an elastic groove at the lower end of the inner wall of the sphere to obtain elasticity. When closing the channel, use the wedge head of the valve stem to expand the ball and compress the valve seat to achieve sealing. Before turning the ball, loosen the wedge head, and the ball will return to its original shape, so that a small gap appears between the ball and the valve seat, which can reduce the friction and operating torque of the sealing surface.
Commonly used ball valve classifications are as follows:
- According to the pressure: high pressure ball valve, medium pressure ball valve, low pressure ball valve
- According to flow channel type: full-bore ball valve, reduced-bore ball valve
- According to channel position: 2 way, 3 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 sealing form: soft sealing ball valve, hard sealing ball valve
- According to valve stem assembly: top entry ball valve, side entry ball valve
- According to the connection form: flanged ball valve, welded ball valve, threaded ball valve, clamp ball valve
- According to the driving method: manual ball valve, pneumatic ball valve, electric ball valve, hydraulic ball valve
- According to caliber size: super large diameter ball valve, large diameter ball valve, medium diameter ball valve, small diameter ball valve