The ball of the fixed ball pneumatic ball valve is fixed and does not move after being pressed. The fixed ball pneumatic ball valves are equipped with floating valve seats. After the pressure of the medium, the valve seats will move, making the seal ring tightly press on the ball to ensure sealing. Generally, bearings are installed on the upper and lower shafts of the ball, and the operating torque is small. It is suitable for valves with high pressure and large diameter. In order to reduce the operating torque of pneumatic ball valve and increase the reliability of sealing, oil sealed pneumatic ball valve has appeared in recent years. It not only injects special lubricating oil between 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 and large caliber pneumatic ball valves.

It must be noted that when Δ When P<2.5MPa, even if cavitation occurs, the damage to the material is not serious, so no special measures need to be taken. If the pressure difference is high, try to avoid and solve the cavitation problem. For example, if the diagonal valve uses side inlet fluid, the service life of the valve element is longer than that of the bottom inlet fluid, because direct damage to the sealing surface is avoided. In addition, a flow limiting orifice installed in front of and behind the valve can also absorb some pressure drop.