A valve actuator is basically a mechanism to open and close the valve. Some valves are actuated manually and some automatically. The valves which are actuated manually require some force to move them in a desired direction by using a geared or direct mechanism. The valve actuator is attached with a valve body and pivot. The categories of valve actuators consist of two main types; Pneumatic valve actuator and Electric valve actuator. The actuator means that the valves require no human interaction to actuate them.
Function of valve actuators
The valve actuators are the controlling domains to perform any mechanism. These mechanisms require energy sources to work. Hence, they can function through gas pressure, hydraulic pressure and electricity. Precise, no human help is required. These valves actuators are moved in the direction to perform the desired task.
The double acting valve actuator is somewhat different from other valves. They require air pressure for opening and closing of the valve. This is the widely used technique for pneumatic valve actuators.
A spring return valve actuator, also called a single actuator, grants energy with the help of spring force. The air and pressure are sent directed in one way to pull or push the piston.
Classification of valve actuators
The valve actuators have distinguished classifications based on the process and requirement; they are actuated through. The valve actuators are categorized into five main types:
- Pneumatic Valve Actuator
- Electric Valve Actuator
- Double acting Actuator
- Hydraulic Actuator
- Spring Return actuators
Pneumatic valve actuator
The pneumatic valves are manufactured to actuate a piston enclosed in a cylinder. The power is given to the actuator through gaseous source or external air. The cylinder allows the actuator to open or close the valve and regulate the function effectively.
These valves are efficient agents for converting compressed gas or air into a mechanical motion that results in the function of pneumatic actuator. These valves are responsible for creating operating energy by effectively using the compressed air. The pressure is applied against a diaphragm or a piston.
Electric valve actuator
The electric valve actuators are the electro-mechanical device which operates the valve to be remotely controlled. The valves that are preferably actuated by electrical actuators are butterfly and ball valves. The function of these electrical actuator control valves is to cause a loaded move or an action which requires force. They are the motors that are used to generate the necessary force to operate valves.
Double Acting actuators
These actuators have a double actuating configuration with air/liquid supplied to both sides of the piston, with one side being higher pressure which achieves the movement required to actuate the valve.
Hydraulic actuators use the liquid as a means of applying pressure to the valve. They generally exert a large amount of force because the liquid is not compressible, but is limited in acceleration and speed.
Spring Return actuators
Actuators with a spring return configuration have air/liquid supplied to only one side of the piston, and the energy to move the valve comes from the spring on the opposite side.