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Diagram of Pump Reliability in dependence of the position of a duty point

Realibility of a pump

The reliability of pumps depends on the position of operating point relatively the BEP.

A pump has the highest reliability when it operates within the preferable operating range or at least not beyond the allowable operating range.


Operators should pay attention on information from the manufacturer regarding recommended operating ranges.

This diagram shows how the reliability of a pump changes depending on where it is operated on its curve. It is seen that this has a major impact on the life of the pump. Similar curves are available for all types of pumps.

Signs of  that the pump operates beyond the recommended operating range

- Excess vibration.

- Hight maintenance cost.

- Excess noise.

- Problems with bearings

- Problems with shaft seals.

- Cavitation. 

- The shaft may break.

What happens when a pump operates beyond the recommended range? 

Radial force acting on the impeller from the liquid in a volute. The value of the force depends on the  operating point and type of volute. 

Radial force in centrifugal pump
Radial force and efficiency

Radial force and vibration increases as pump operation moves away from BEP 

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