(1) Floating ball valves
The ball of a ball valve is floating. Under the action of medium pressure, the sphere 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 floating ball valve has a simple structure and good sealing performance. However, the load of the sphere bearing the working medium is all transferred to the outlet sealing ring, so it is necessary to consider whether the material of the sealing ring can withstand the working load of the sphere medium. This structure is widely used in medium and low pressure ball valves.
(2) Fixed ball valves
The ball of a ball valve is fixed and does not move under pressure. 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, that is, special lubricating oil is injected between the sealing surfaces to form an oil film, which enhances the sealing performance and reduces the operating torque, which makes it more suitable for high-pressure and large-diameter ball valves.
(3) Elastic ball valves
The ball of a ball valve is elastic. Both the ball and the valve seat sealing ring are made of metal materials, and the sealing specific pressure is very large. According to the pressure of the medium itself, the sealing requirements cannot be met, so external force must be applied. This valve is suitable for high temperature and high pressure medium. The elastic sphere is to open 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 press 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 there is a small gap between the ball and the valve seat, which can reduce the friction and operating torque of the sealing surface.
1. According to the pressure of the ball valve: high pressure ball valve, medium pressure ball valve, low pressure ball valve.
2. According to the type of ball valve flow path: full-bore ball valve, reduced-bore ball valve.
3. According to the position of the ball valve channel: straight-through type, three-way type, right-angle type.
4. According to the temperature of the ball valve: high temperature ball valve, normal temperature ball valve, low temperature ball valve, ultra-low temperature ball valve.
5. According to the ball valve sealing form: soft sealing ball valve, hard sealing ball valve.
6. According to assembling of ball valve stem: top entry ball valve, side entry ball valve.
7. According to the ball valve connection form: flange ball valve, welded ball valve, threaded ball valve, clamp ball valve.
8. According to the ball valve driving method: manual ball valve, automatic control ball valve (pneumatic ball valve, electric ball valve, hydraulic ball valve).
9. According to the diameter of the ball valve: super large diameter ball valve, large diameter ball valve, medium diameter ball valve, small diameter ball valve.
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