The pneumatic valve can be closed manually to the proper position, but it cannot be closed using pneumatic power
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The pneumatic valve can be closed manually to the proper position, but it cannot be closed using pneumatic power – what could be the reason?
Pneumatic butterfly valve: fails to close fully pneumatically
All of them are adjustable; if the problem arises later on, it’s best to check from the instrument side. If production is to be maintained, it can be adjusted on the valve body. For reference.
It’s possible that the limits of the pneumatic actuator haven’t been set properly (there are mechanical limits as well as limit switches; since it can be rotated manually, the mechanical limits should be fine. It’s possible that the limit switch is sending a signal too early; try setting the solenoid valve to manual mode to see if it can close fully, which will help identify the issue). Another possibility is that there is air leakage somewhere, resulting in insufficient torque and thus an inability to close properly.
It’s most likely that the air supply pressure is insufficient.
What specific type of pneumatic valve is it, and is the cylinder piston-type or slide plate-type?； Is it double-acting or single-acting? Is there a spring for reset? Is the mechanism for switching between manual and pneumatic operation reliable? Or could it be due to faults in other components on the cylinder?