Pneumatic ActuatorsPneumatic Actuators Classification

Actuators are divided into three categories: pneumatic, electric and hydraulic according to their energy form, which have their own characteristics and are suitable for different occasions.  Pneumatic actuators  are a category within actuators.Pneumatic Actuators can also be divided into two types: single-acting and double-acting.
Pneumatic actuator: Double-acting actuator
THE SWITCHING ACTION OF THE ACTUATOR IS DRIVEN BY AN AIR SOURCE, WHICH IS CALLED DOUBLE ACTING.
The selection of double-acting actuator takes DA series pneumatic actuator as an example:
The output torque of the rack actuator is obtained by multiplying the piston pressure (supplied by the air source) by the radius of the pitch circle (the arm of the force). And the friction resistance is small and the efficiency is high. Both clockwise and counterclockwise rotation of the output torque are linear. Under normal operating conditions, the recommended safety factor for double-acting actuators is 25-50%
Pneumatic actuator: Single-acting actuator
THE SWITCHING ACTION OF SPRINGRETURN (SINGLE-ACTING) IS ONLY DRIVEN BY AIR WHEN IT IS ON, AND THE SPRING IS RETURNED WHEN IT IS CLOSED.
Taking the SR series pneumatic actuator as an example, in the application of spring return, the output torque is obtained in two different operating processes, and each operation produces two different torque values according to the stroke position.

The output torque of the spring return actuator is obtained by multiplying the force (air pressure or spring force) by the arm The first condition: the output torque is obtained by the air pressure after entering the middle cavity compression spring, which is called the "air stroke output torque" In this case, the air source pressure forces the piston to turn from 0 degrees to the 90 degree position, and the reaction force is generated due to the spring compression.
The torque gradually decreases from the maximum value at the starting point until the second condition: the output torque is obtained by the spring recovery force acting on the piston when the middle cavity is out of gas, which is called the "spring stroke output torque" In this case, due to the elongation of the spring, the output torque gradually decreases from 90 degrees to 0 degrees As mentioned above, the single-acting actuator  is designed on the basis of generating a balanced moment in two conditions. In each case, it is possible to obtain an unbalanced moment by varying the relationship between the number of springs on each side and the pressure of the air supply, and in the case of spring return applications, two conditions can be obtained: degassing on or degassing closing. Under normal operating conditions, the recommended safety factor for the spring return actuator is 25-50%.