Pneumatic ventilation butterfly valve

Pneumatic butterfly valve is a valve composed of pneumatic actuator and butterfly valve, which controls the fluid medium inside the pipeline by driving the butterfly plate to rotate through compressed air. Here is a detailed introduction about it:

structural composition

Valve body: usually cylindrical, connected to pipes at both ends, forming fluid channels inside, made of materials such as cast iron, stainless steel, etc., it needs to withstand fluid pressure and protect structural stability.

Butterfly plate: It is a key control component that is disc-shaped with a diameter that matches the inner diameter of the valve body. It changes the channel opening by rotating and is made of materials such as carbon steel and stainless steel.

Valve stem: One end is connected to the butterfly plate, and the other end is connected to the pneumatic actuator for torque transmission. It needs to have high height and corrosion resistance (based on actual reports), and the surface is often treated with anti-corrosion (based on actual reports).

Sealing device: including soft seal and hard seal. The soft seal is made of elastic materials such as rubber and is suitable for low-pressure and room temperature environments; Hard seals are made of metal or alloy materials, which are resistant to high temperatures (based on actual reports) and high pressures, but require high processing accuracy. Shaft seals have packing seals or mechanical seals to prevent medium leakage from the valve stem.

Pneumatic actuator: There are two types: double acting and single acting. The double acting actuator is designed with dual chambers, which can achieve bidirectional torque output; The single acting actuator is a structure consisting of a single chamber and a spring, which has the characteristic of fault safety. When the gas is cut off, the spring resets and closes the butterfly plate.

working principle

The double acting pneumatic actuator uses compressed air to alternately enter two chambers, pushing the piston to drive the valve stem and butterfly plate to rotate, achieving the opening and closing of the valve. A single acting pneumatic actuator opens the butterfly plate by compressing air against the spring force during ventilation, and closes the butterfly plate by resetting the spring when the air is cut off.