1. The signal pressure of the pneumatic actuator refers to:
When the compressed air enters the pneumatic actuator from the A nozzle, the gas pushes the double piston to move linearly to both ends (cylinder head end), the rack on the piston drives the gear on the rotating shaft to rotate 90 degrees counterclockwise, and the valve is opened. . At this time, the gas at both ends of the pneumatic actuator valve is discharged with the B nozzle. On the contrary, when the compressed air enters the two ends of the pneumatic actuator from the B nozzle, the gas pushes the double plug to move straight to the middle, the rack on the piston drives the gear on the rotating shaft to rotate 90 degrees clockwise, and the valve is closed. At this time, the gas in the middle of the pneumatic actuator is discharged with the A nozzle.
When the signal pressure increases, the push rod moves downwards, which is called a positive-acting actuator; when the signal pressure increases, the vertebral rod moves upwards is called a reaction-acting actuator.
Second, the definition of pneumatic actuator:
It is an actuator that uses air pressure to drive the opening, closing or regulating valve. It is also called a pneumatic actuator or a pneumatic device, but it is generally called a pneumatic head.
The actuator and adjustment mechanism of the pneumatic actuator are a unified whole, and the actuators include membrane type, piston type, fork type and rack and pinion type. The piston type has a long stroke and is suitable for occasions requiring large thrust; while the diaphragm type has a small stroke and can only directly drive the valve stem. The fork type pneumatic actuator has the characteristics of large torque, small space, and the torque curve is more in line with the torque curve of the valve, but it is not very beautiful; it is often used on valves with high torque. The rack-and-pinion pneumatic actuator has the advantages of simple structure, stable and reliable action, and safety and explosion-proof. It is widely used in power plants, chemical industry, oil refining and other production processes with high safety requirements.
3. Appearance requirements of pneumatic actuators:
1. There shall be no scratches, cuts, pores, burrs, etc. on the end cover, end flange and box of the casting cylinder.
2. The paint layer or chemical treatment layer on the outer surface of the pneumatic device should be flat, smooth, uniform in color, free from oil stains, indentations and other mechanical damages.
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