A valve is a device that regulates, directs or controls the flow of a gas, liquid or slurry by opening, closing, or partially obstructing various passageways.
Most valves either operate as Multi-turn or Quarter-turn. 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.
Actuators may be used 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.
Methods to actuate a valve are Manual, Electric, Pneumatic and Hydraulic
