1. Core structural components
Valve body and butterfly plate
The valve body is a cylindrical structure with pipes connected at both ends to form a fluid channel inside; the butterfly plate is a disc-shaped component installed inside the valve body and the channel cross-sectional area is adjusted by rotation.
The diameter of the butterfly plate matches the valve body channel, and the rotation angle is usually 0° (fully closed) to 90° (fully open), forming a seal with the valve seat during the opening and closing process.
Pneumatic actuator
Double-acting actuator: The piston is driven by alternating air intake on both sides of the cylinder to drive the valve stem to rotate. It requires continuous air supply to maintain the state, which is suitable for high-frequency operation or precise adjustment.
Single-acting actuator (spring reset): Only one side of the cylinder is driven by air intake. When the air is cut off, it relies on the spring force to reset to the preset safe position (normally open or normally closed), which is suitable for emergency cut-off scenarios.
2. Drive and control process
Power transmission mechanism
After compressed air enters the actuator, it pushes the piston or diaphragm to produce linear motion, which is converted into rotational motion through gear racks, connecting rods and other mechanisms to drive the valve stem and butterfly plate to rotate.
Signal and action response
The control system (such as PLC) sends an electrical signal to the solenoid valve to switch the direction of the air source passage and control the intake/exhaust of the actuator.
When equipped with an electrical positioner, the 4~20mA signal can be converted into air pressure changes to accurately adjust the butterfly plate opening (such as 30°, 60°) to achieve linear flow control.
3. Key action characteristics
Opening and closing range and sealing
The butterfly plate can be fully opened or fully closed by rotating 90°. When closed, the butterfly plate fits the valve seat, the medium pressure enhances the sealing effect, and the leakage is low.
Response speed and applicable scenarios
Typical response time ≤10 seconds, and higher speed can be achieved in emergency cut-off scenarios.
It is suitable for media such as gas, liquid, powder, etc., and has significant advantages especially in large-diameter pipelines that need to be quickly cut off or adjusted.