A valve actuator is a device that produces force to open or close the valve utilizing a power source.
This source of power can be manual (hand, gear, chain-wheel, lever, etc.) or can be electric, hydraulic or pneumatic.
Basic actuators turn valves to either fully opened or fully closed positions. But modern actuators have much more advanced capabilities. They not only act as devices for opening and closing valves, but also provide intermediate position with high degree of accuracy.
The valve actuator can be packaged together with logic control and digital communication ability to allow remote operation as well as allowing predictive maintenance data.