Danny Dotson
The mining, petrochemical and oil & gas industry has gone through a lot of technical and development transformations that allows more controlled functions and precision valve automation. If you are anyway associated with these industries, then the word pneumatics, hydraulics, rotary actuators, linear actuators, and control valve actuators might not be new to you. However, for general understanding, I’ll provide a little introduction to the basics.
A pneumatic system is the use of pressurized air or gas to control automation in the industries. The pneumatic system comprised of various parts and tools; however, the most significant part, which is essential for pressure control, is the control valve. The control valve regulates the flow of pressure through the chamber and thus provides more control and precision.
Control Valve Actuator
A control valve actuator is a part attached to the control valve that offers the required power to move the moveable parts of the control valve. The main feature of the control valve is to control the flow of pressurized air through the chamber. The control valve actuator performs two types of functions in a control valve:
- Follow the signal from the control valve and move the moveable parts to the required position
- Offer default positioning system in the absence of any driving force.
- The actuator receives the signals from the control system and thus moves the valves accordingly into the open or closed position.
Types Of Control Valve Actuator
The control valve actuator offers the required drive power to holds the valve in the required position. It also ensures that the valve remains shut when there is no driving force in action. There are three basic types of drive forces that are associated with the control valve actuators.
- Pneumatic
- Electrical
- Hydraulics
Pneumatic Valve Actuator
These are the most commonly available and used form of valve actuators. Due to the precision and freedom, they offer you can find them almost in every machinery application. Due to the use of springs in their design, they stay responding even after the loss of drive power. The pneumatic control valve actuators come in the diaphragm, rotatory vane, and piston form.
Electrical Actuators
Widely used in the pharmaceutical industry or power generation plants, the electrical actuators use the electrical motor along with gear reduction for moving the valve. They offer various positioning control features by delivering position feedback to the controller and thus are in great demand.
Hydraulic Actuators
As the name mentioned, the hydraulic actuators use the power of liquids to offer the control feature. The hydraulic actuators use piston chambers to convert the liquid pressure into the mechanical force for the required functioning. However, due to the enormous mechanical force, these actuators offer they can only be used in isolation valves of gas pipelines.
Differences between a pneumatic and hydraulic control valve actuator
Both pneumatic and hydraulic actuators work similarly, but differ in the way the cylinder moves. Hydraulic actuator moves a cylinder with incompressible fluid, while pneumatic actuators move cylinders with compressed air. Together they are described as a combination of two different mechanical systems, one mechanical and one hydraulic.
Pnematic actuators are not so convenient for large devices that require large bore cylinders for compressed air consumption.
Hydraulic linear actuators work much like pneumatic actuators, but there is incompressible fluid in the pump, and air is pressurized and drilled to move the cylinder. Hydraulic actuators have higher unit costs than pnematic and electric actuators. It can generate force that operates at pressures up to 4,000 psi, and can be produced at pressures of 1,500 psi with a maximum power of 2,200 psi.
You can choose the type of form of an actuator according to the function you intend them to perform. These actuators offer the desired drive function and the control feature to allow control valves to perform perfectly.
