Selection of pneumatic actuator torque

Pneumatic actuator  is an actuator that uses air pressure to drive the opening and closing or adjust the valve, also known as Pneumatic Actuator or pneumatic device, or cylinder, pneumatic head; However, it is generally called Pneumatic Actuator. The actuator and adjusting mechanism of the pneumatic actuator are a unified whole, and the product series of the imported pneumatic actuator brand THEOBORN commonly used in the installation valve factory are classified, and the actuator has a membrane actuator, a piston actuator, a fork actuator and a rack and pinion actuator.
The piston type has a long stroke, which is suitable for occasions that require large thrust; The diaphragm type has a smaller stroke and can only drive the valve stem directly. The fork 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, and is commonly used in the valve with large torque. The Rack And Pinion Pneumatic Actuator has the advantages of simple structure, stable and reliable action, and safety and explosion-proof, and has a wide range of applications in power plants, chemical industry, oil refining and other production processes with high safety requirements.
The selection of pneumatic actuators is mainly the selection of torque
Before selecting a pneumatic actuator, check the valve torque. And increase the safety value on the torque, and increase the safety value by 25% for water vapor or non-lubricating liquid medium; The safety value of non-lubricating slurry liquid media is increased by 30%.

The torque of the selected valve is 210NM, the air source pressure is only 5bar, the medium is non-lubricated water vapor, taking into account the safety factor, increase the safety value by 25%, that is, 262NM, according to the double-acting output torque table to find the corresponding torque value when the air source pressure is 5bar. 277NM should be selected.
After selecting the model for torque, you can learn about the performance characteristics of THEOBORN pneumatic actuators and see if it is suitable for selection.
1. The rated output force or torque of the pneumatic device shall comply with the provisions of GB/T12222 and GB/T12223, and the above is a membrane actuator;
2. In the case of no load, the air pressure should be input into the cylinder according to the regulations, and its action should be stable, without jamming and crawling;
3. Under the air pressure of 0.6MPa, the output torque or thrust of the pneumatic device in the opening and closing directions shall not be less than the value indicated on the pneumatic device signage, and the action shall be flexible, and permanent deformation and other abnormal phenomena shall not be allowed in each part;
4. When the sealing test is carried out with the maximum working pressure, the amount of air leaked from the respective back pressure side is not allowed to exceed (3+0.15D) cm3/min (standard state); The amount of air leaking from the end cap and output shaft is not allowed to exceed (3+0.15d)cm3/min;
5. The strength test is carried out with 1.5 times the maximum working pressure, and after maintaining the test pressure for 3min, the end cover and static sealing part of the cylinder block are not allowed to leak and structural deformation;
6. The number of action life, the pneumatic device simulates the action of the pneumatic valve, and the opening and closing times of the opening and closing operation should not be less than 50,000 times (the opening and closing cycle is one) under the condition of maintaining the output torque or thrust capacity in both directions;
7. Pneumatic device with buffer mechanism, when the piston moves to the end position of the stroke, the impact phenomenon is not allowed.