3.2 The sealing mechanism of the floating pneumatic ball valve is shown in Figure 1 (a). Since there is no fixed support at the lower end of the ball, when the floating pneumatic ball valve is closed, the ball will produce a certain amount of floating (displacement) under the effect of the medium pressure, leave the sealing seat at the inlet end and press it against the sealing seat at the outlet end, so that the medium will be blocked at the sealing seat at the outlet end. That is to say, the floating pneumatic ball valve actually only has the sealing seat at the outlet end to play a sealing role, while a small floating gap is kept between the sealing seat at the inlet end and the ball.

Main features of pneumatic floating ball valve:
1. The fluid resistance of pneumatic ball valve is small, and the fluid resistance of pneumatic ball valve is small in all valve categories. Even for reduced diameter pneumatic ball valve, the fluid resistance is relatively small.
2. The thrust bearing reduces the friction torque of the valve stem, which can make the valve stem operate stably and flexibly for a long time.
3. The sealing performance of the valve seat is good. The sealing ring made of elastic materials such as polytetrafluoroethylene is easy to seal, and the sealing capacity of the pneumatic ball valve increases with the increase of the medium pressure.
4. The valve stem seal is reliable. Because the valve stem only operates as if it is rotating rather than lifting, the packing seal of the valve stem is not easy to be damaged, and the sealing capacity increases with the increase of the pressure of the medium.
5. Since materials such as polytetrafluoroethylene have good self-lubricating property and small friction loss with the ball, the service life of pneumatic ball valve is long.
6. The lower mounted valve stem and the convex step at the head of the valve stem prevent the valve stem from ejecting. If the valve stem seal is damaged due to fire, metal contact can also be formed between the convex step and the valve body to ensure the valve stem sealing.
7. Anti static function: set a spring between the ball, valve stem and valve body, which can lead out the static electricity generated during the switching process.