Pneumatic actuators are devices that convert the energy of compressed air or gas into a mechanical motion that regulates one or more final control elements. They are used as a form of automation control to reduce mandatory human interaction with a system’s internal mechanisms, which is particularly beneficial for automatic modulation and emergency shutdowns.
The motion of a pneumatic actuator may be linear or rotary depending on the device’s design. Prototypical actuators use an external compressive force, such as compressed air or gas, to move a piston along the inside of a hollow cylinder and build pressure. This generates a linear force relative to the piston’s pressure differential multiplied by its surface area, which is used to move a load along a straight line. So-called linear pressure actuators have been in service for decades but enhancements in diaphragm design and sealing capabilities have vastly improved the technology’s efficiency and scope of functionality.
Rotary pneumatic actuators differ from linear designs in that torque is generated as opposed to a linear motion. This can be accomplished by transferring the linear motion of a piston to a rotating component, or vice versa.
Industrial pneumatic systems typically utilize pressures of 80 – 100 pounds-per-square-inch (psi). Actuators are subsequently used for the movement of comparatively small to large loads such as the manipulation of dampers, inlet vanes, louvers, valves, turbine governors, fluid drives, and other final control elements.
A pneumatically-powered damper is an automatic valve or plate used to regulate the flow of air inside a duct or airflow control system. This is vital for combustion processes as a limited or excess air supply can reduce the heat rate and energy yield from fuel burning while contributing to the generation of harmful emissions such as carbon monoxide (CO). Damper control is one of the primary applications of both linear and rotary pneumatic actuators.