Valve actuators, used for operating valves for opening, closing or modulating service, come in a variety of configurations and power sources. Two of the most recognizable types based on this criteria are pneumatic, and hydraulic. Each has positives and negatives depending in part on the specific application, space requirements, operating pressures and speeds needed for safe valve operation.
Even on a single application, a pipeline perhaps, there can be a combination of both pneumatic and hydraulic valve actuators. In remote locations where compressed air is not normally available, hydraulic is often the choice. In refineries, manufacturing plants and pipeline compressor stations, where compressed air sources are available, the features and capabilities of a pneumatic actuator are usually more favorable.
Pneumatic actuators are designed to operate a piston within a closed cylinder. Pressure from an external air or gas source powers the actuator, moving the cylinder to fully open or close the valve, or partially modulate its open/close movement. Depending on the valve type, the actuator can either operate in a 90 degree horizontal direction or in a linear up and down motion. Hydraulic actuators operate similarly to pneumatics except the power medium is a non-compressible fluid which, if leaked, can have potentially effects. Both can be configured either with a compressible spring that extends or retracts the piston, or a design with an air or liquid inlet on either side of the piston that allows double-acting operation.
What are the advantages in choosing pneumatic actuators for an application where compressed air, hydraulic sources, or even electrical capability are available? They are many:
ATI has extensive expertise in pneumatic and hydraulic valve operation, in both linear and quarter-turn configurations and for virtually any application. For more information, we can be reached at firstname.lastname@example.org or +1 713/934-0171.