How the pneumatic ball valve works

How the pneumatic ball valve works
Pneumatic ball valves only need to be closed tightly with a pneumatic actuator that rotates by 90 degrees with a pneumatic source and a small rotational torque. The completely equal valve body cavity provides a small, straight flow path for the medium. It is generally considered that ball valves are most suitable for opening and closing directly, but recent developments have designed the ball valve to be used for throttling and controlling flow. The main characteristics of the ball valve are its compact structure, easy operation and maintenance, suitable for general working medium such as water, solvent, acid and natural gas, and also suitable for working medium with poor working conditions such as oxygen, hydrogen peroxide, methane and ethylene. The ball valve body can be integral or modular.

Pneumatic ball valve according to the structure of a classification, floating pneumatic ball valve

The ball of the pneumatic ball valve is floating. Under the effect of medium pressure, the ball can generate a certain displacement and press on the sealing surface of the outlet end to ensure that the outlet end is sealed.

The structure of the floating pneumatic ball valve is simple and the sealing is good. However, the load of the ball bearing the working medium is all transmitted to the outlet sealing ring. Therefore, 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 low and medium pressure ball valves.

Second, fixed ball pneumatic valve

The ball of the pneumatic ball valve is fixed and does not move after being pressed. The fixed ball ball valve has a floating valve seat. After the medium pressure, the valve seat moves and the seal ring is pressed against the ball to ensure the seal. Bearings are usually mounted on the upper and lower shafts of the ball, and the operating torque is small, suitable for high pressure and large diameter valves.

In order to reduce the operating torque of the pneumatic ball valve and increase the reliability of the seal, oil seal ball valves have appeared in recent years. The special lubricant is injected between the sealing surfaces to form a layer of oil film, which enhances the sealing performance and reduces the operation. Torque, more suitable for high pressure large diameter ball valve.

Three, elastic ball pneumatic valve

The ball of the pneumatic ball valve is elastic. The ball body and the valve seat seal ring are made of metal materials, and the specific pressure of the seal is large. The pressure of the medium itself cannot meet the requirements of the seal, and external force must be applied. This valve is suitable for high temperature and high pressure media.

The elastic ball is to open a flexible groove at the lower end of the inner wall of the ball to obtain elasticity. When closing the channel, use the wedge head of the valve stem to make the ball expand and seal with the valve seat. Loosen the wedge head before turning the ball, 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.

Pneumatic ball valve according to its position can be divided into straight-through, three-style and right-angle. The latter two ball valves are used to distribute media and change the direction of the media.

Pneumatic ball valve features

1. The fluid resistance is small, and the ball valve is the one with the smallest fluid resistance in all valves. Even if it is a reduced diameter ball valve, the fluid resistance is also very small.

2. The thrust bearing reduces the friction torque of the valve stem, which can make the valve stem operate steadily and flexibly for a long time.

3, the valve seat sealing performance is good, using PTFE and other elastic materials made of seals, the structure is easy to seal, and the ball valve sealing ability increases with the increase of medium pressure.

4. The valve stem seal is reliable, because the valve stem is only used for imitating rotation without lifting movement, the filling seal of the valve stem is not easy to damage, and the sealing capacity increases as the pressure of the medium increases.

5, due to PTFE and other materials have good self-lubricating properties, and the ball friction loss is small, so the ball valve has a long service life.

6. The convex stem of the bottom-mounted stem and the stem head prevents the valve stem from being sprayed. If the fire causes the stem seal to fail, a metallic contact can also be formed between the convex step and the valve body to ensure the stem seal.

7, anti-static function: set the ball between the ball, stem, valve body, can export static electricity generated during the switch.