When we’re scaling out a new control valve, vendors should support with every specification and recommend the right device for the application. Also, what is important to know is which type of control valve actuator is actually needed.
This article will tell you all you need to know about control valve actuators, the part of a control valve that receives commands from the control system to create a force that moves a control valve. Control valve actuators do this either directly or through a control valve positioner, which converts digital or analog signal to pneumatic output.
To know more about control valve positioner, you can read the Visaya Article here
Control valve actuator types
There are five commonly used control valve actuator types. So let’s take a quick look at each.
Pneumatic control valve actuator
This type has a flexible diaphragm with pressure applied against the force of the actuator spring. When the control system sends its signal, the actuator creates a force that overcomes the force of the spring, moving the actuator stem.
We have two types of action in a pneumatic actuator: direct and reverse. Direct action means the actuator pushes the stem down and the spring pushes it up. Reverse action will move the stem up, and the spring moves it down.
Pneumatic control valve piston actuator
This works much like an actuator with a diaphragm and spring. However, this actuator replaces the diaphragm with a piston. We have two types of action here too: linear and rotating. Linear moves the actuator component in a straight line and rotating turns it.
Electric control valve actuator
This actuator has a motor and gearbox to create torque that moves the valve up and down. We can find this type in linear and rotating control valves.
Electric-hydraulic control valve actuator
This type mixes electric signals and hydraulic units to act on the valve. The signal will control the flow of oil to open and close the valve, using a flapper-nozzle system similar to a pneumatic system.
Hydraulic control valve actuator
This works much like a pneumatic actuator, and we can use it in linear and rotating control valves. However, it uses fluid rather than air to create force in its system.
To know more about control valves, you can get in touch with our engineers and we will be happy to help.