Pneumatic butterfly valve is composed of pneumatic actuator and butterfly valve. The pneumatic butterfly valve uses a round butterfly plate that rotates with the valve stem for opening and closing, so as to realize the starting action. The pneumatic valve is mainly used as a block valve. It can also be designed to have the function of regulating or section valve and regulating. At present, butterfly valves are increasingly used in low-pressure large and medium-sized pipelines.

3. Classification according to sealing form
(1) Forced sealing butterfly valve. 1) Resilient sealing butterfly valve. The sealing specific pressure is generated by the elasticity of the valve seat or valve plate when the valve plate squeezes the valve seat when the valve is closed. 2) Applied torque sealed butterfly valve. The sealing pressure is generated by the torque applied to the valve shaft.
(2) Pressurized and sealed butterfly valve. The sealing specific pressure is generated by charging the elastic sealing element on the valve seat or valve plate.
(3) Automatic sealing butterfly valve. The sealing pressure is automatically generated by the medium pressure.