When the pneumatic butterfly valve is in the middle opening, the opening shape formed by the valve body and the front end of the butterfly plate takes the valve shaft as the center, and the two sides will form different states. The front end of the butterfly plate on one side rotates along the water, while the other side moves against the water. Therefore, correspondingly, one side of the valve body and valve plate will form a nozzle like opening, and the other side will form a similar orifice like opening. As a result, the flow rate at the nozzle side is much faster than that at the throttling side, and negative pressure will be generated under the valve at the throttling side, which will easily lead to the problem of rubber seals falling off. Pay extra attention to this problem when using the soft seal butterfly valve.

Pneumatic regulating butterfly valve is a valve (valve plate) rotating around a fixed axis perpendicular to the channel. It consists of a piston type double action or single action (spring return type) pneumatic actuator and a butterfly valve. It is a rotary high-performance regulating or shut-off valve, equipped with electric, pneumatic valve positioner or solenoid valve, air filter pressure reducer, limit switch (valve position indicator), It can realize the proportional regulation and two position cut-off control of the fluid medium in the process pipeline, so as to achieve the automatic control of the flow, pressure, temperature, liquid level and other parameters of the fluid medium.