Troubleshooting Tips For A Non-Functioning Valve

When attempting to service a non-functioning valve installed in a system; please note that it is rarely the spool or body at fault. So it is highly unlikely that the body will have to be taken out of the system.

  1. Loosen Clamps: If there are any clamps around the valve body, loosen them. If there are clamps on the tubing within six tube diameters of the body, loosen them also. If there is anything stopping the tubing from expanding or contracting, such as a bulkhead or wall, make sure that the tubing has the freedom to move.
  2. Check If Coil Is Being Energized: With the coil energized, place a piece of steel or a screwdriver on the screw holding the coil. A faint buzzing or magnetic pull should be felt. After ascertaining that the coil is functioning properly, the pilot is most likely to be the problem and should be replaced if in the past the valve had been operating successfully.
  3. If The Problem Still Persists:
    Check the valve and spool assembly for operation by installing a gage set with one hose connected to one end of the valve and the other hose to the opposite end with the third hose connected to the suction. The valve can then be operated with the gage hand valves.
  4. If The Valve Is Still Inoperable:
    It is possible that the spool may be too tight within the body. Remove the gas from the system and remove the end caps by loosening the bolts on both ends of the valve simultaneously so that there is no gas pressure on either end. (DO NOT REMOVE ONE END CAP WITHOUT CHECKING THAT THERE IS NO TRAPPED PRESSURE AT THE OTHER END). After removing the end caps, try moving the spool. If the spool is too tight, use a block of wood or a piece of plastic to try and hammer it out. If the spool was exceedingly tight, carefully inspect the O.D. of the spool for small shiny spots. The presence of these spots would indicate that the spool has been damaged by something passing through the valve or being hit with a hard object. Any burrs or shiny spots may be taken off with a hand stone (DO NOT UNDER ANY CIRCUMSTANCES SAND PAPER THE SPOOL, IT IS FITTED TO VERY CLOSE TOLERANCES AND WILL NOT ENTER THE BODY UNLESS VERY ACCURATELY ALIGNED). Carefully clean the spool and body. Then re-oil the spool and carefully place it back into the body.
  5. If The Spool Is Still Too Tight:
    The tubing to the valve can have the body under stress: at this point we would recommend cutting the shortest, largest line closest to the valve and checking whether the spool will move. If the spool still fails to move, cut the next line and check the spool for movement again, as this should now have relieved the body sufficiently to allow the spool to move.

On rare occasions, you may see what appear to be orange or brown stains in the body. It is possible for this to be copper plating caused by moisture in the system, the spool will be too tight to move and may score the body when being taken out, this valve needs to be replaced.

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