mixing valve failure

Valve failure are: valve can not commutation or commutation slow, gas leaks, solenoid pilot valve is faulty and so on.
(A) Concrete batching plant 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 spool seals prone to wear and tear, stem and seat damage phenomena, ready mix concrete plant 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.