When Pressure Relief Valves Leak And What To Do

Recently there have been several claims against ‘leaking’ TPR valves. Upon testing it has been found that the relief valve is neither passing nor failing to reseat, the ‘leak’ appears to be water passing out of the blow-out cage which has opened when the easing lever has been operated too quickly during maintenance.

THE EASING LEVER SHOULD BE OPERATED SLOWLY

The purpose of the blow-out cage is to act as a ‘back-up’ relief valve which may (in certain circumstances) open when a high flow rate is passing through the TPR valve during emergency relief conditions and is normal.

Incorrectly sized or partially blocked relief drains causing back pressure may also cause the blow-out cage to activate again releasing water at the cylinder. The relief pressure of the blow-out cage is roughly 50% of the pressure rating of the TPR valve.

This new plastic device is manually resettable as opposed to the previous model which had a ‘one shot’ non-resettable metallic mechanism.

To reset the blow-out mechanism please follow the instructions belo

  1. (Fig 1) Once the water flow has ceased to turn the blow-out cage anti-clockwise to remove the device from the TPR valve body.
  2. (Fig 2) Push the valve stem back through the cage until both the stem and the washer are completely removed from the cage (a resonable amount of force will be required to push the bevelled end of the shaft through cage, lubricating oil will prevent the rubber washer from being pinched).
  3. (Fig 3) Fit the washer onto the stem and insert fully into the cage until the bevelled end ‘clicks’ back into position.
  4. (Fig 4) Fit the device into the TPR valve body and SLOWLY re-test the valve.

leaking_tpr_valves

One thing to note is that sometimes there may be a case where the valve can be genuinely faulty. Depending on age the valve may or may not be under warranty. In such cases, give us a call to book an inspection in.