Malfunctions of check valve
Constructs of check valves are simple and reliable, so they rarely fail if working parameters are observed.
However, for control of their operability, it is recommended to periodically check check valves for flow sealing. To do this, the pipeline section located under pressure to the valve's inlet is disconnected and drained, paying attention to the pressure gauges installed before and after the check valve. If the pressure on the section after the valve's outlet remained the same, and before the inlet it dropped - this means that the valve has tightly closed the flow, and if the pressure has dropped on both gauges - the check valve does not prevent backflow.
If backflow through the valve was detected during the check, it should be dismantled. The most likely cause of failure is clogging of the passageway with sediment, which can be easily cleaned.
Possible malfunctions and methods of their elimination
| Malfunction | Cause | Elimination |
|---|---|---|
| No flow | The pressure difference on the valve disc is less than the opening pressure | Increase the pressure before the check valve or reduce the pressure after it |
| -//- | During installation, the plug of the passage hole or the disc holder was not removed | Disassemble the check valve and remove the plug/holder |
| The valve does not tightly close the flow | The seat or disc is damaged by foreign bodies | Replace the check valve | -//- | A solid particle got under the disc | 1. Try to wash out the particle with the flow, for this, open/close the shut-off valve near the valve several times. 2. Drain the pipeline, disassemble the valve, and remove the particle. |
| The check valve is knocking | A too large diameter of the valve was selected | 1. Install a smaller diameter valve 2. Install a disc damper (this option is only available for some types of check valves) |
| -//- | - high flow turbulence - the check valve is installed too close to the centrifugal pump - vibration of the pipeline |
Change the installation location of the check valve |
| Breakage of the check valve flange | The valve is subject to loads from connected pipelines | Unload the valve body by installing additional supports or compensators for thermal expansion |
| -//- | The bolts are tightened unilaterally or the corresponding flanges are not co-planar | Perform even tightening of the bolts, eliminate the non-coplanarity of the flanges |
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