Pneumatic ball valve refers to the valve with the ball as the opening and closing part. In western industrial developed countries, the use of pneumatic ball valves is increasing year by year. In China, pneumatic ball valves are widely used in petroleum refining, long-distance pipeline, chemical industry, paper making, pharmacy, water conservancy, power, municipal administration, steel and other industries, and play an important role in the national economy.
1、 Analysis of the causes affecting the sealing performance and service life of pneumatic ball valves Pneumatic ball valves can be divided into floating pneumatic ball valves and fixed pneumatic ball valves according to the ball structure. However, regardless of the type of pneumatic ball valves with ball structures, especially pneumatic ball valves with large diameters, the dead weight of the ball will have an adverse impact on the sealing performance and service life of the valves. For example, the ball of a floating pneumatic ball valve has no lower stem support shaft, so the fitting surface of the seal seat bears the dead weight of the ball. Therefore, under the same working condition, the greater the dead weight of the ball, the greater the wear on the sealing fitting surface of its gravity direction, which greatly reduces the service life of the pneumatic ball valve. At the same time, once the preload between the ball and the seal seat disappears, the greater the mass of the ball, the greater the differential pressure necessary for low-pressure sealing, which greatly reduces the low-pressure sealing performance. Similarly, if the pneumatic ball valve is equipped with a pneumatic drive device for quick opening and closing, its inertia torque will increase several times, dozens of times. Therefore, how to find ways to reduce the dead weight of the ball will have considerable social and economic benefits for the performance, life, inertia torque and manufacturing cost of the product.

The valve is a control part in the fluid conveying system, which has the functions of cut-off, regulation, diversion, prevention of countercurrent, pressure stabilization, diversion or overflow pressure relief. The valves used in the fluid control system range from the simple shut-off valve of Zui to various valves used in the extremely complex automatic control system, with a wide variety of varieties and specifications. The valve can be used to control the flow of various fluids such as air, water, steam, various corrosive media, mud, oil, liquid metal and radioactive media.