Selection of pneumatic actuators and selection of accessories

In the selection of pneumatic valves, the selection of valves is relatively simple, but  pneumatic actuators  need to refer to more parameters, this paper combines the common pneumatic actuator brand Theoborn, combined with the characteristics of imported pneumatic ball valves, imported Pneumatic Butterfly Valves, imported pneumatic control valves, and imported pneumatic actuators, and analyzes the selection of pneumatic actuators and accessories.

1. Confirm the torque of the Pneumatic Actuator.

When using pneumatic actuators, the torque of the valve is determined first
(1) Water vapor or non-lubricating medium increases the safety value by 25%;
(2) (2) The safety value of non-lubricated dry gas medium is increased by 60%;
(3) (3) The safety value of granular powder medium conveyed by non-lubricating gas is increased by 100%;
(4) (4) For the clean, frictionless lubricating medium, increase the safety value by 20%, and then according to the air source working pressure, find the torque table of the pneumatic actuator, and the accurate actuator model can be obtained. (Note: This security value is recommended.) 

2, the selection of double-acting pneumatic actuators

For example, Theoborn double-acting pneumatic actuator, choose double-acting: the air source pressure is only 5bar, control a ball valve that requires torque of 200N.m, the medium is non-lubricated water vapor, considering safety factors, increase by 25% is equal to 250N.m, first find the air source pressure of 5bar according to the table, and then find the torque data equal to or similar to the pneumatic actuator torque table in the pneumatic actuator torque table, select 272N.m, and then select the pneumatic actuator model with similar torque in the table.

3. Selection of single-acting pneumatic actuators
For example, the Theoborn single-acting pneumatic actuator uses a single-acting type (spring return): the air pressure is only 4 bar, and the control requires a butterfly valve with a torque of 100N.m, and the medium is a non-lubricated dry gas, which is increased by 60% considering safety factors Equal to 160N.m, first find the end point of spring return according to the table to get a similar torque of 166N.m, and then find the end torque of 4bar along the table 196N.m, the air source pressure torque should be greater than the spring return torque, just the air source pressure torque is greater than the spring return torque, and then select the pneumatic actuator model of similar torque in the table, and the number of spring configurations.

4, the selection of pneumatic actuator accessories
Depending on the conditions available on site and the different requirements of the control system, the following accessories can be selected to meet these requirements:
1. The Solenoid Valve realizes the switching of the air source controlled by the pneumatic actuator, so as to realize the opening or closing function of the pneumatic valve.
2. The feedback device, also known as the limit switch, is used for the display of the valve position switch or the remote feedback of the working position signal when the valve is running.
3. Triple parts, filtering, decompression adjustment, and cylinder lubrication and oil supply for the control air source.
4. Handwheel mechanism, when the controller of the control system fails, the valve can be operated manually.
5. The electrical positioner receives the 4-20mA control signal to turn the on/off valve into a pneumatic Control Valve with adjustment performance. For example, Theoborn pneumatic Control Valve, imported pneumatic control butterfly valve, imported pneumatic  control ball valve, etc.