Pneumatic control valve does not operate:
1. No signal, no air source.
1) The air source is not open;
2) As the water in the air source freezes in winter, the air duct will be blocked or the filter and pressure reducing valve will be blocked and malfunction;
3) Compressor fault;
4) Leakage of air source main pipe.
2. Air source, no signal.
1) Regulator failure;
2) Signal tube leakage;
3) Leakage from the bellows of the positioner;
4) Adjust the damage of retina tablet.
3. The locator has no air source.
1) Clogged filter;
2) Pressure reducing valve failure;
3) Pipeline leakage or blockage.
4. The positioner has air source and no output. The orifice of the positioner is plugged.
5. Signal, no action.
1) Valve core falls off;
2) Spool or valve seat is jammed;
3) Stem bending or breaking;
4) Frozen valve core of seat or dirt of coke block;
5) The spring of actuator is rusted dead because it is not used for a long time.