How does a single‑acting pneumatic butterfly valve work?
A single‑acting pneumatic butterfly valve uses a pneumatic actuator powered by compressed air. The actuator opens the valve by moving a membrane or piston with compressed air, rotating the disc into the open position and allowing flow. When the air supply stops, an integrated spring returns the butterfly valve to its original “fail‑safe” position (typically closed).
How does a double‑acting pneumatic butterfly valve work?
A double‑acting pneumatic butterfly valve uses a pneumatic actuator that employs compressed air for both opening and closing the valve. Unlike single‑acting drives, the double‑acting actuator does not use a return spring, but controls both directions exclusively with air pressure.
By feeding compressed air into the appropriate chamber of the actuator, the disc is rotated precisely into the required position to regulate or completely stop the flow. This design offers greater control flexibility and is typically used in applications requiring rapid and accurate switching.
Important accessories for pneumatic butterfly valves: Optimising functionality & automation
For butterfly valves with single‑ or double‑acting pneumatic actuators there are numerous accessories available that enhance performance and automation. Key items include end‑switch boxes, which transmit valve position feedback to control systems like PLCs, and solenoid valves, which convert electrical signals into pneumatic action and control air supply.
A mounting bracket (air‑distribution plate) ensures efficient air routing, while a positioner enables proportional control of the valve, ideal for control‑system applications. A filter‑regulator cleans and stabilises the air supply, extending actuator life. Manual override allows operation in emergency mode, and feedback sensors enable accurate monitoring of the valve’s performance.


















