Six selection factors for pneumatic actuators
In the actual production process, we often choose what kind of pneumatic actuator to use. The correct choice of pneumatic actuator is very important, because if the actuator is too large, the valve stem may be too large. If the actuator is too small, it cannot produce enough torque to fully operate the valve. In general, the selection of pneumatic actuators needs to consider the use of temperature, frequency of operation, management and pressure difference, transport medium (lubrication, drying, mud) and other factors.
When choosing pneumatic actuators, the main points are as follows:
1. Number of turns of the output shaft: what is the nominal diameter of the valve? The number of thread heads is related, according to M = H/ZS calculation (M electric device should meet the total number of turns, H open the valve height, S for the stem drive thread pitch, Z stem thread heads).
2. Special requirements: can limit torque or axial force. Valve electric devices generally use limited torque coupling. After determining the specification of the electrical device, determine its control torque.
3 output speed valve opening and closing speed: if too fast, easy to produce water blow. Therefore, the appropriate opening and closing speed should be selected according to different conditions of use.
4. Operation thrust: When selecting the pneumatic actuator, we will check its operation thrust. Pneumatic valve device has two main engine structure: one is a direct output torque plate, direct output torque; The other is a thrust plate, through the thrust plate in the valve stem nut conversion output torque
The thrust.
5. Operation torque: select the main parameters of the valve electrical device, the output torque of the pneumatic actuator should be 1.2 ~ 1.5 times the maximum torque of the valve operation.
6. Stem diameter For multi-rotation type open stem valves: If the maximum stem diameter allowed by the electric device does not pass through the valve equipped stem, the valve shall not be assembled as an electric valve. Therefore, the inner diameter of the hollow output shaft of the electrical device must be larger than the outer diameter of the valve stem. For part of the rotary valve and multi-rotary valve in the dark stem valve, although do not need to consider the diameter of the valve stem through, but in the selection should also fully consider the diameter of the valve stem and the size of the keyway, so that after assembly can work normally.
