When selecting a pump, one of the key pieces of information provided by the supplier is the pump performance curve.
This curve shows how the pump will perform across different flow rates and pressures—but for many operators and engineers, it’s not always clear what point on that pump curve the pump should actually run at. This is where the Best Efficiency Point (BEP) becomes important.
The Best Efficiency Point (BEP) is the point on a pump curve where the pump operates at its highest efficiency.
At this point, the pump is converting the maximum amount of input power into useful hydraulic energy, with minimal internal losses. It is also the condition where hydraulic forces within the pump are most balanced, supporting stable and efficient operation.
Understanding where this point sits on the pump curve is essential, because it defines how the pump was designed to perform.
In day-to-day operation, pumps rarely run exactly at their Best Efficiency Point. However, how far they operate from this point has a direct impact on performance and reliability.
When a pump is running close to BEP, it will generally operate smoothly, with stable flow and minimal vibration. Equipment tends to run consistently, and components such as bearings and seals last longer with fewer issues.
As the pump moves further away from this point, these conditions begin to change. Operation becomes less stable, vibration increases, and wear on components accelerates. What often shows up on site—such as repeated seal failures, higher maintenance, or constant valve adjustments—is usually linked to operating too far from this optimal point.
In practical terms, BEP becomes a reference for how well your pump is actually running—not just how it was designed to run on the pump curve.
While BEP is a single point, pumps are designed to operate across a range.
This is where operating regions become important:
The Preferred Operating Region (POR) — where the pump runs with maximum reliability
The Allowable Operating Region (AOR) — where the pump can still operate, but with increased stress
Together, these define how your pump behaves across the pump reliability curve, not just at a single point.
When your pumping system is working at maximum reliability, it is in the Preferred Operating Region (POR). As the pump operates within this range, the flow within the pump is relatively uniform, it suits the pump’s hydraulic geometry, and has minimal flow separation within the impeller. As the pump operates in the POR, the service life of the pump will not be affected by the internal hydraulic load or flow induced vibrations - thus increasing your site’s success.
For centrifugal type rotodynamic pumps, the POR is between 70% and 120% of the Best Efficiency Point (BEP). However, this will range is much narrower when we look at Mixed Flow and Axial Flow pumps.
For those pumping systems handling high concentrations of abrasive solids, the POR is primarily determined by wear considerations and may be narrower than for most rotodynamic pumps.
👉 Tip #1: To immediately improve reliability, confirm your pump is operating within this POR (70%–120% of BEP). If your application involves high speeds or abrasive fluids, consider a narrower range.
👉 Tip #2: Consider installing condition monitoring (flow, pressure, vibration). This helps track whether your pump is staying within the POR during operation—not just at commissioning.
If you are unable to maintain the flow within the POR, Global Pumps recommend ensuring your pump is within the Allowable Operating Region (AOR). This AOR refers to the range of flow rates recommended by the pump manufacturer and is verified based on the system’s operating conditions (Net Positive Suction Head).
When you operate your pump outside the POR, the bearing life will be reduced, and noise, vibration and component stresses will be increased.
👉 Tip #3: Due to the reduced bearing life, as well as other consequences, Global Pumps recommends your pump is within the POR. However, in some circumstances this is not possible. Therefore, our team suggest discussing your pump's performance with an expert to optimise it specifically for your application. There may be accessories suitable to ensure optimal performance.
Global Pumps recommend discussing the best efficiency point of a pump, along with the POR and AOR, with your pump supplier or the manufacturer. By understanding these regions and where your pump is operating within them, will ensure your pump’s performance is consistent. It is also important to consider that the POR and AOR will depend on the pump's application and/or pumped product - which is why professional guidance is highly advised.
With over 45 years' experience, Global Pumps can assist you in ensuring your pumping system is reliable, efficient and performing to the best of its capabilities.