Noise from newly installed centrifugal pump
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A new centrifugal pump has been installed; the frequency is set at 40% and it is operating normally. At 80%, the pump vibrates and makes noise. (Imported version has a siphon tank and flexible connections.) What could be the reason for this?
Based on the description, it is a pump equipped with an inlet suction tank. It is recommended to check two aspects: 1. Listen to determine whether the noise originates from the inlet or the outlet; if it’s from the inlet, keep the frequency at 80% and gradually close the outlet valve to see if there are any changes in the vibration noise. If the noise at the inlet decreases significantly, it indicates that there is insufficient suction at the inlet, and it is necessary to verify whether the suction conditions meet the pump’s net positive suction head requirement； 2. If the noise occurs mainly at the outlet, it indicates that there are issues with the pump’s outlet and the outlet piping; the high flow rate creates significant stress on the pipes, and adjustments need to be made.
It relates to operational issues of variable-frequency self-priming pumps with inlet siphon tanks. Adjusting the frequency from high to low generally does not result in arcing, whereas arcing is likely to occur in the opposite direction (noise is caused by arcing). Frequency regulation must be matched to the outlet flow rate (valve opening). Adjust slowly.