The application of supersonic spraying on metal sealed pneumatic ball valve is introduced today. The supersonic spraying is to burn the fuel gas in oxygen to produce a high-pressure high-speed airflow, and then send the alloy powder into this airflow to spray the workpiece surface (Figure 1). The characteristic of spraying is that the velocity of alloy powder particles exceeds the speed of sound,

Basic protection method for overload of mine explosion-proof pneumatic butterfly valve:
1. Thermostat is used for overload protection of continuous operation or inching operation of motor;
2. Thermal relay is used for the protection of motor locked rotor;
3. Fuse or overcurrent relay shall be used for short circuit accident.