The main advantages of the pneumatic butterfly valve are simple structure, small size, light weight, and low cost. This characteristic of the pneumatic butterfly valve is particularly remarkable. It is installed in the high-altitude dark passage, and it is easy to operate through the control of the two-position five-way solenoid valve, and the flow medium can also be adjusted. The fluid resistance is small, and the effective flow area of the pneumatic butterfly valve with medium and large diameters is large when fully opened, and the opening and closing are quick and labor-saving. The generated torque is in the opposite direction, so the opening and closing torque is small, and good sealing can be achieved under low pressure. The sealing materials of butterfly valves include nitrile rubber, fluorine rubber, edible rubber, and PTFE lining, so the sealing performance is good. Among them, the hard seal butterfly valve is soft The hard laminated metal sheet has the advantages of metal hard seal and elastic seal, and has excellent sealing performance no matter at low temperature.