For open/closed pneumatic actuation a solenoid valve is provided complete with manual over-ride and exhaust port flow restrictors for speed control. For regulating duty a positioner is provided, usually controlled using a 4-20mA control signal. With the addition of a rotary spring return unit, the damper becomes fail-safe on loss of either pneumatic air pressure or electrical control signal, whether controlled by a solenoid valve or positioner.
Flowrite’s preferred pneumatic actuator manufacturer is Kinetrol.
Electric actuation is the next most cost-effective form of powered actuation. Open/closed and regulating control are both available on the electric actuators we use, but a fail-safe facility is more challenging and expensive using electric rather than pneumatic actuation.
Hydraulic actuation is the third type of actuation we fit to our dampers. This usually takes the form of a hydraulic ram which is supplied with pressurised oil from the customer’s hydraulic power pack, but we can also provide a power pack with an individual damper or a batch of dampers.
All the above actuation types are available for use in hazardous areas.
We also manufacture manually-operated dampers, either with a hand lever and locking quadrant or, for large dampers with a higher operating torque requirements, a worm and wheel gearbox with manual hand wheel.
Manually-operated dampers are often used where shut-off is required only fairly infrequently, or where the damper is required for flow balancing (or trimming).
Flowrite also offers gravity-actuated (counter-weight) dampers. These are detailed in the special products section.