1 Classification of pneumatic ball valves Pneumatic ball valves are divided into two categories: floating type and fixed type?
1.1 Floating ball pneumatic ball valve The ball of the pneumatic ball valve is floating. Under the action of medium pressure, the ball can produce a certain displacement and press on the sealing surface at the outlet end to ensure the sealing of the pneumatic ball valve. The floating ball pneumatic ball valve has simple structure and good sealing performance, but the load of the working medium borne by the ball is all transferred to the outlet seal ring. Therefore, it is necessary to consider whether the seal ring material can withstand the working load of the ball medium. This structure is widely used for middle and low pressure pneumatic ball valves.
1.2 Fixed Ball Pneumatic Ball Valve The ball of the 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 valves and increase the reliability of sealing, oil sealed pneumatic ball valves have appeared in recent years, which not only inject special lubricating oil between the sealing surfaces to form an oil film, frequently enhance the sealing performance, but also reduce the operating torque, and are more suitable for high-pressure and large diameter pneumatic ball valves. This paper mainly discusses the sealing opening and closing torque of the floating pneumatic ball valve, hoping to help the application of the pneumatic ball valve.

What is the reason why the pneumatic butterfly valve is corroded?
The oxygen in the atmosphere will react to form an oxide film on the surface. The iron oxide formed on ordinary carbon steel continues to stop oxidation, so that the corrosion will expand from time to time and eventually form holes. It is possible to apply paint or oxidation resistant metals (such as zinc, nickel and chromium) to stop electroplating to ensure the appearance of carbon steel, but, as people know, this maintenance is just a film. If the maintenance layer is destroyed, the steel below will begin to rust.
The corrosion resistance of stainless steel pneumatic butterfly valve depends on the chromium content. When the chromium content reaches 10.5%, the atmospheric corrosion resistance of steel increases significantly, but when the chromium content is higher, although the corrosion resistance can still be improved, it is not obvious. The reason is that when the steel is alloyed with chromium, the type of external oxide is changed to be similar to the external oxide formed on pure chromium metal. This tightly adhered chromium rich oxide maintains the appearance and avoids further oxidation. This kind of oxide layer is extremely thin, through which you can see the natural luster of the stainless steel surface, so that stainless steel has a common appearance. Moreover, if the surface layer is damaged, the exposed steel surface will stop self repairing with the atmospheric reaction, and form this "passivation film" again to continue to play a maintenance role.