How are valves and dampers commonly controlled?

How are valves and dampers commonly controlled?

• A. By mechanical actuators
• B. By manual handwheels only
• C. By electric switches only
• D. By pneumatic cylinders only

Answer: (A)

Valves and dampers are moved to the desired position by actuators that convert a control signal into physical motion. In modern building automation, the control system sends a signal to an actuator, and the actuator then drives the valve stem or damper blade to open, close, or partially open. This is why the broad term mechanical actuators fits best: it covers the common ways this motion is produced—electric motors, pneumatic cylinders, or hydraulic devices—rather than relying on manual handwheels or just a simple electrical switch. Manual handwheels are impractical for automatic control; electric switches alone cannot position the device precisely; and limiting to pneumatic cylinders only ignores other actuator types that are routinely used. The essence is that the control process relies on an actuator to provide the necessary mechanical movement.

Valves and dampers are moved to the desired position by actuators that convert a control signal into physical motion. In modern building automation, the control system sends a signal to an actuator, and the actuator then drives the valve stem or damper blade to open, close, or partially open. This is why the broad term mechanical actuators fits best: it covers the common ways this motion is produced—electric motors, pneumatic cylinders, or hydraulic devices—rather than relying on manual handwheels or just a simple electrical switch. Manual handwheels are impractical for automatic control; electric switches alone cannot position the device precisely; and limiting to pneumatic cylinders only ignores other actuator types that are routinely used. The essence is that the control process relies on an actuator to provide the necessary mechanical movement.