Overview of single acting pneumatic actuator
Pneumatic actuator is an actuator that uses compressed air to drive the valve switch or regulate the medium flow, also known as pneumatic actuator or pneumatic device, which is generally used with the valve.
The difference between pneumatic actuators is that the single action pneumatic actuator has the reset function, and the internal spring of the actuator can be reset automatically after the air source breaks.
Single acting pneumatic actuator: the single acting pneumatic actuator opens the valve and automatically closes without air source. The single acting pneumatic actuator automatically resets by relying on the spring. It is generally used in dangerous conditions to transport combustible gas or liquid. In the case of air source and emergency, the single acting pneumatic actuator can automatically reset to reduce risks. Double acting pneumatic actuators are generally not easy to reset. Single acting pneumatic actuators are generally divided into normally open type and normally closed type. Normally open type: air off, air off open; Normally closed type: ventilation on/off.
Principle of single acting pneumatic actuator:
The working principle of single acting pneumatic actuator is that when compressed air enters from port A, the left and right pistons in the cylinder move in the opposite direction, and the output shaft rotates counterclockwise. Discharge the compressed air at the sides of both pistons through port B. When the air supply of the pneumatic actuator is lost, the piston moves toward the center due to the effect of the internal spring. At this time, the output shaft rotates clockwise, and the air between the two pistons is discharged through Port A. Under the action of spring tension, the actuator will drive the valve back to the initial set position.
Selection of single acting and double acting pneumatic actuators:
In the selection of valve pneumatic actuator, it is necessary to first confirm the single acting spring return, double acting switch type and other functional forms, namely the common normally open type (vent switch, air shutoff switch) and normally closed type (vent switch, air shutoff switch). Second, functional requirements such as air supply triplet. If single action pneumatic actuator is selected, manual reset device is not required, because single action has its own spring reset. When selecting a double acting pneumatic actuator, consider whether to attach a handwheel operating mechanism to the pneumatic actuator for emergency.
