Check valve malfunctions
Check valve designs are simple and reliable, so they rarely fail if operating parameters are followed.
However, to ensure proper functioning, it is recommended to periodically test check valves for flow shutoff tightness. To do this, the pipeline section under pressure before the valve inlet is isolated and drained, while monitoring the pressure gauges installed before and after the check valve. If the pressure on the section after the valve outlet remains unchanged, but drops before the inlet, this indicates the valve has tightly shut off the flow. If the pressure drops on both gauges, the valve is allowing reverse flow.
If reverse flow is detected during the test, the valve should be dismantled. The most likely cause of failure is sludge contamination of the passage, which can be resolved by simple cleaning.
Possible malfunctions and troubleshooting methods
| Malfunction | Cause | Solution |
|---|---|---|
| No flow | The pressure difference on the valve disc is less than the opening pressure | Increase the pressure before the valve or decrease the pressure after it |
| -//- | A plug or retainer in the valve passage was not removed during installation | Dismantle the valve and remove the plug/retainer |
| Valve does not seal tightly | The seat or disc is damaged | Replace the check valve | -//- | A solid particle is caught under the disc | 1. Try flushing the particle out by opening/closing the shutoff valve several times near the check valve. 2. Drain the pipeline, dismantle the valve, and remove the particle. |
| Check valve is knocking | The valve diameter is too large | 1. Install a valve with a smaller diameter 2. Install a damper on the disc (this option is available for certain types of check valves) |
| -//- | - high flow turbulence - check valve installed too close to the pump - pipeline vibration |
Change the check valve installation location |
| Flange damage on the check valve | The valve is subject to loads from connected pipelines | Relieve the valve body by installing additional supports or thermal expansion compensators |
| -//- | Bolts are unevenly tightened or the flanges are misaligned | Tighten the bolts evenly, correct flange misalignment |
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