Valve Actuator, based on the power source, falls into the three categories. Each power source of valve actuator has unique characteristic which provide different advantage to make it suitable for specific application.
Pneumatic actuator is the most commonly used type due to the cheapest price and availability of its power source i.e. compressed air. The use of natural gas is also applicable if it is not feasible to install air compressor system. It is used both for control valve which operates in throttling mode or actuated valve which intermittently operates.
The superiority of hydraulic actuators is its capability of supplying very high torques. Since hydraullic is considered as non-compressible liquid it can provide fast stroking speed. A typical application of hydraullic actuators is for wellhead valves since very high torques and stroking speed become a concern.
Electric actuators has smooth operation, provide very high torque values, and retain thrust. In process platform, motor operated valve is used in sea water intake line where large valve which requires high torque is operating in on-off mode.