Failure of pneumatic diaphragm control valve
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Our company has pneumatic diaphragm control valves (air-actuated valves) that need to be set at 80% in order to close, and at 30% in order to open. What could be the reason for this?
““The pneumatic diaphragm control valve (air-actuated valve) needs to be set at 80% in order to close, and it must be set at 30% in order to open.” I’m not sure if this is expressed correctly The possible reason is that the mechanism of action is reversed and not properly adjusted.
Possible reasons: 1. Zero point, the stroke is not properly adjusted. 2. The positioner is faulty or the feedback cam in the positioner is used incorrectly. 3. Low air supply pressure.
Re-calibrate zero point and travel distance； Try replacing it with a valve positioner from a regulator of the same type.
The original poster didn’t explain it clearly; does it mean that the system should be turned off when the input signal reaches 80% (i.e., 16.8 MA), and turned on when it reaches 20% (7.2 MA)? If that’s the case, then as mentioned above, the way it works must be reversed.
It seems like your itinerary isn’t set up properly; recalibrating it should fix the issue
Agree with the person above; is there something wrong with the description given by the OP? It’s so confusing!
This situation cannot occur once it has been properly debugged. I’ll ask about it – what’s the stroke and linearity of the valve?
It seems the original poster didn’t express themselves clearly! It seems that the mode of operation was selected incorrectly; recalibrating it should resolve the issue