Control valve does not act the reason and treatment method
At the use site, when the regulating valve does not operate, the following measures can be taken.
a. No air source pressure, no input signal. The causes are as follows: The air compressor power supply is faulty; Mechanical and electrical faults of the air compressor itself; Air main leak. Solution: overhaul the air compressor; Check the air main.
b. There is air source pressure, no input signal. Caused by the following reasons: the regulator failure; Signal pipeline leakage; Regulating valve diaphragm or piston ring leakage; The locator is faulty. Solution: Check the controller; Check the signal pipeline; Check the regulating valve diaphragm; Check the O-ring of the cylinder; Check whether the locator is faulty.
C. The locator is faulty.
i. Positioner has no air source pressure. Air filter reducing valve failure; Leakage or blockage of pipes and joints. Solution: Check the air filter pressure reducing valve; Check pipes and joints.
ii. The locator has air source pressure, but no output signal. The throttle hole of the amplifier in the positioner is blocked; There is water vapor in the compressed air, which accumulates at the ball valve of the amplifier. Solution: Check the throttle hole of the amplifier in the positioner to eliminate blockage; Remove moisture that has accumulated at the amplifier ball valve.
ii. The positioner has an output signal, but the valve does not operate. The throttle part of the regulating valve is stuck; Spool and stem fall off; Valve stem bent or broken; The pneumatic actuator is faulty. Solution: Remove the control valve body components and check the valve internals; Reconnect the spool and stem; Replace the valve stem; Check the pneumatic actuator and remove the fault.
