How to Find and Fix Recirculation
Identification of recirculation cavitation in the field.
By Sound
- Popping sounds coming from volute are intermittent and inconsistent in both sound level and frequency
- Sounds begins immediately upon pump startup but may drop to a lower level once the pump is running and stabilized
- Noise seems to be loudest at the suction fitting (dry pit installation)
By Testing
- Injecting a small amount of air into the suction of the pump reduces or eliminates the noise
- Raising the wet well level has very little or no effect on the noise
- Throttling the discharge valve has no effect or may worsen the noise
- Throttling the suction valve on a dry pit pump has no effect or worsens the noise
- (Sometimes extreme throttling will suddenly reduce the noise and will be accompanied by a significant loss in performance)
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