mixing valve failure

Valve failure are: valve can not commutation or commutation slow, gas leaks, solenoid pilot valve is faulty and so on.
(1) valve commutation or commutation can not slow, usually due to poor lubrication, the spring is stuck or damaged, oil or impurities stuck sliding parts and other causes. In this regard, you should first check the lubricator is working properly; lubricant viscosity is appropriate. If necessary, replace the oil, clean the sliding valve parts, or replace the springs and valve.
(2) after prolonged usage valve steel cement silo  prone to wear and tear, stem and seat damage phenomena, leading to gas leakage inside the valve, the valve motion is slow or does not change to the other failures. At this point, you should replace the seals, stem and seat, or valve replaced.
(3) If the solenoid pilot valve inlet, sludge and other vent is clogged, closed lax plunger is stuck, circuit failure, can lead to valve can not be normal commutation. Wheel Loader three cases should be cleaned on the core activities of the pilot valve and the sludge and impurities. The circuit failures are generally divided into the solenoid control circuit faults and fault types. After checking circuit fault, should first manual valve knob a few turns to see the rated pressure valve is working correctly for commutation, if normal commutation, then the circuit is faulty. Inspection, the available instrument measuring the voltage of the solenoid, to see whether the rated voltage, if the voltage is too low, should further examine the power control circuit and the associated limit switch circuit.