In general, the selection of pneumatic actuators needs to consider multiple factors, such as the operating conditions of the valve, operating temperature, operating frequency, management and pressure difference, conveying medium (lubrication, drying, mud), etc., in the selection of pneumatic actuators In the process, the main points are as follows.
1. Operating thrust: There are two main structures of the valve electric device: one is not equipped with a thrust plate, and the torque is directly output; the other is equipped with a thrust plate, and the output torque is converted into the output thrust through the valve stem nut in the thrust plate.
2. Operating torque: Select the main parameters of the valve electric device, and the output torque of the pneumatic actuator should be 1.2 to 1.5 times the maximum operating torque of the valve.
3. Stem diameter for multi-turn rising stem valves: If the large stem diameter allowed by the electric device cannot pass through the valve stem of the equipped valve, it cannot be assembled into an electric valve. Therefore, the inner diameter of the hollow output shaft of the electric device must be larger than the outer diameter of the valve stem of the rising stem valve. For part-turn valves and dark-stem valves in multi-turn valves, although there is no need to consider the passage of the diameter of the valve stem, the diameter of the valve stem and the size of the keyway should also be fully considered when selecting, so that the valve can work normally after assembly.
