Pneumatic actuators are devices that convert compressed air energy into mechanical motion to perform work, typically by linear or rotary movement. There are two main types of pneumatic actuators: direct acting and spring return.
Direct Acting Pneumatic Actuators:
These actuators use compressed air to drive the piston or diaphragm in one direction, producing linear or rotary motion. When air pressure is applied to one side of the piston or diaphragm, it moves in the corresponding direction, and when air pressure is removed, it remains in that position due to the air pressure acting against the opposite side. Direct acting actuators are typically used in applications where a steady state position is maintained after the actuator is actuated.
Spring Return Pneumatic Actuators:
These actuators are similar to direct acting actuators, but they have a spring mechanism that returns the actuator to its original position when the air supply is stopped or the pressure is reduced. The spring is typically compressed when air pressure is applied to one side of the piston or diaphragm, driving it in the corresponding direction. When the air pressure is removed, the spring expands, returning the actuator to its original position. Spring return actuators are commonly used in safety-critical applications, such as emergency shutdown systems or safety valves, where it is important to ensure that the actuator returns to a safe position in the absence of air pressure.
In summary, the main difference between direct acting and spring return pneumatic actuators is that the former uses compressed air to maintain its position, while the latter has a spring mechanism that returns it to its original position when the air supply is stopped or the pressure is reduced.
UniTorq Actuators and Controls
2150 Boggs Road, Suite 410
Duluth, GA 30096
Phone: (770) 446-7074
Fax: (770) 447-1825