Working principle of valve pneumatic actuator

Column：Valve knowledge Time：2018-03-24
The pneumatic actuator (namely pneumatic head) and pneumatic actuator or pneumatic device to drive the executing device open and close valves by using compressed air or air pressure, mainly consists of ...

Valve pneumatic actuator overview

The pneumatic actuator (namely pneumatic head) and pneumatic actuator or pneumatic device to drive the executing device open and close valves by using compressed air or air pressure, mainly consists of cylinder, piston, gear shaft, end cover, seal, screw etc.. Pneumatic actuators are generally used with all kinds of valves, including opening indication, travel limit, solenoid valve, positioner, pneumatic element, manual mechanism, signal feedback and other components. The opening, closing, opening, and closing of the valve are controlled by compressed air.


Valve pneumatic actuator working principle

Pneumatic actuators can be divided into single action and double action according to the form of action. The double acting actuator is characterized by gas opening and closing, that is, ventilation opens, ventilation closes, and no action is lost when gas is lost. The single acting actuator has the function of spring reset, usually with normally closed and normally open type, that is, when ventilation is opened, when the gas source is lost, it is automatically reset to the initial state. Use more in dangerous conditions, can quickly turn off or open the valve when there is a sudden failure of the gas source.


working principle of double acting pneumatic actuator

圖片.png

When the pressure of gas enters from the intake port (2) to the middle chamber of the two piston, the two piston is moved to the two ends of the cylinder. The air at the two ends of the air chamber is discharged through the gas port (4), while the two piston rack synchronously drives the output shaft (gear) to rotate counterclockwise. On the contrary, when the gas pressure enters the air chamber at the two ends of the cylinder from the gas inlet (4), the two piston moves to the middle of the cylinder. The air in the middle air chamber is discharged through the gas port (2), and the two piston rack synchronously drives the output shaft (gear) to rotate in a clockwise direction. If the piston is installed in opposite direction, the output axis turns to reverse rotation.


Working principle of single acting pneumatic actuator (with a spring complex)

圖片.png

When the air pressure from the air intake (2) between the two piston into the cylinder cavity, the two ends of the cylinder piston moves to the separation direction, forcing the ends of the compression spring, both ends of the air chamber air through the air intake (4) discharged, while making two piston rack synchronous drive output shaft (gear) counterclockwise. When the air pressure is changed back through the solenoid valve, the two piston of the cylinder moves in the middle direction under the elastic force of the spring, and the air in the middle air chamber is discharged from the gas port (2). At the same time, the two piston rack synchronously drives the output shaft (gear) to rotate in a clockwise direction. If the piston is installed in opposite direction, the output axis of the spring is turned back to reverse rotation when the spring is reset.