Valve actuator

_and_with_Linear_Pneumatic_Actuator_(R)4143.jpg)
![Electric multi-turn actuator with controls [2]](/uploads/202501/10/Schnittbild_drehnatrieb_014143.jpg)
![The positioner [1] is supplied with a setpoint [2] and an actual value [3]. The motor is controlled until the actual value is identical to the setpoint. The DCS generally needs a feedback signal [4]](/uploads/202501/10/Actuator_positioner4143.jpg)
A valve actuator is the mechanism for opening and closing a valve. Manually operated valves require someone in attendance to adjust them using a direct or geared mechanism attached to the valve stem. Power-operated actuators, using gas pressure, hydraulic pressure or electricity, allow a valve to be adjusted remotely, or allow rapid operation of large valves. Power-operated valve actuators may be the final elements of an automatic control loop which automatically regulates some flow, level or other process. Actuators may be only to open and close the valve, or may allow intermediate positioning; some valve actuators include switches or other ways to remotely indicate the position of the valve.