Pneumatic actuator is a valve device for automatic control, usually used in regulating valves, ball valves, butterfly valves or gate valves. Pneumatic actuators provide fast, efficient and reliable operation for applications requiring remote control or operating in hazardous environments. The following is mainly to introduce the working principle and basic structure of the pneumatic actuator.

The working principle of the pneumatic actuator is based on the conversion of gas pressure into mechanical motion. When compressed air (or other gas) enters the actuator, it pushes a piston or diaphragm, which in turn is connected to a robotic arm, which in turn is connected to the valve stem. The movement of the piston or diaphragm turns or pushes the stem through a mechanical arm to open or close the valve.

The basic structure of the pneumatic actuator usually includes the following parts: 

1, the shell: usually made of high-strength, corrosion-resistant materials, used to protect the internal components from the influence of the external environment. 

2, piston: In the linear (or reciprocating) pneumatic actuator, the piston moves inside the housing and is driven by the compressed air entering. 

3, diaphragm: In diaphragm type pneumatic actuators, the diaphragm is moved by the force of compressed air, usually used for smaller force requirements. 

4, Spring: In spring-returned pneumatic actuators, the spring is used to close the valve or return to the initial position when compressed air is lost. 

5, valve stem: connected to the piston or diaphragm, the aerodynamic force into the valve switching action. 

6, control end: used to introduce compressed air into the actuator and discharge the actuator. 

7, Positioner: an optional control device that receives the control signal and ensures that the valve is opened or closed in the correct position. 

8, accessories: such as limit switch, relief valve, manual operation mechanism, etc., to provide additional functions and control capabilities.