Different Reasons Why the Centrifugal Pump May Have Low Flow


When you experience certain low flow problems in the centrifugal pumps, it may surely impact the performance of the process. This kind of problem can be very frustrating but you should not blame the pump, unnecessarily.

Quite many of you may even consider replacing the some parts or the whole pump. Sanitary replacements parts can be purchased from the black market. However, first check some of the following functions.

  • Reversed impeller rotation

Though it may look like a no-brainer, it can really be the common problem. While wiring the motor of the pump to power, it is important to check which way your motor is turning first.

One very common practice is to do “Bump Starting” the motor. The motor can be started without hooking the pump for ensuring proper rotation of your shaft.

In case the motor turns in wrong way then impeller may potentially back off your shaft, which may cause serious damage.

  • Clogged suction

Ensure that the suction pipe remains free and without any debris. Lesser flow into the pump will naturally yield lesser flow out of the pump.

  • Worn impeller/ring/plate

In case vanes on your impeller are worn out, then hydraulic capacity of the pump is reduced.

With wear ring as well as wear plate it will be same. As the clearances open up because of wear, more recirculation will occur inside the pump, and reduce the flow.

  • Excessive clearances

In case the clearances are much wide for type of fluid that is pumped, then there may be occurrence of excessive slip. Fluid may continue to recirculate within the pump, yielding much lower flow-out from the pumps.

  • Debris in your impeller

In case the impeller eye is totally plugged with debris, then it removes hydraulic capacity of your impeller for creating a low-pressure area.

  • Closed discharge/suction valve

Though this one may really appear simple, but something which is easy to overlook.

  • Open bypass valve

Make sure and check the flow is not being diverted anywhere else through bypass valve.

  • Vortexing

Such thing is more common when pumps are in suction lift positions, like self-priming pump, or vertical turbine. Ensure that minimum requirements of submergence are fulfilled, so as to avoid vortexing.

Any centrifugal pumps producing insufficient flow may cause problems not just for pump itself but for other equipment also in the process.

In case you checked all these points listed above, then it could be a much bigger system issue.

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