COLUMN | Pump System Improvement
How to Tell If Your Pump Operation Is Shortening Equipment Life
Ray Hardee | BEP Logic
For more than 30 years, I have taught pump system fundamentals to engineers and operators around the world. In every class, I say the same thing: “Raise your hand if you know where your pumps are operating on their curve.” Of the thousands of attendees, only two have ever raised a hand.
I ask my students to consider this because where a pump runs on its curve tells you a great deal about a system’s health—yet most facilities do not know the answer.
Why the BEP Matters
Every pump has an ideal operating point—the best efficiency point (BEP)—where it performs most efficiently and reliably because its internal hydraulics are operating as designed by the manufacturer. As a general engineering objective, pumps should operate as close to that point as is practical.
The name suggests BEP is about energy efficiency, and it is. A pump operating away from BEP consumes more energy than necessary. But energy cost is only the immediate expense. The larger cost often comes later—in unplanned downtime, shortened equipment life and maintenance expense.
This is because the hydraulic inefficiencies created by operating away from BEP do not disappear. That wasted energy must go somewhere. Running left of BEP often creates recirculation, turbulence and damaging radial loads. Running right of BEP can introduce cavitation risk, high velocities and overload conditions. In either case, the result is increased vibration, heat, wear and mechanical stress throughout the pump and system.
Paul Barringer quantified this relationship in the 1980s and 1990s through statistical analysis of pump failure data across the process industries. His work showed that component life (bearings, seals and impellers) peaks near BEP and declines rapidly as operating conditions move away from that point. At moderate deviation from BEP, expected reliability can fall nearly in half—even within portions of the operating ranges many manufacturers still permit for routine service.1
The challenge is that most operators do not know when damage from off-BEP operation is occurring. By the time vibration or noise becomes obvious, damage is often already underway. You only know where a pump is operating if someone takes the time to measure it.
Didn’t VFDs Solve This Problem?
The industry has known for decades that many pumps do not operate where they ideally should. The industry’s response was logical: improve the hardware. Variable frequency drives (VFDs) allowed pumps to slow down instead of throttling against valves. Supervisory control and data acquisition (SCADA) systems provided real-time visibility into flow, pressure and power. The assumption was that if operators had the right tools, pumps would be operated efficiently.
Thirty years later, we have the tools, and many assume those tools solved the problem.
| IMAGE 1: Barringer’s reliability analysis shows that pump life declines rapidly as operating conditions move away from BEP. (Images courtesy of the author)
The Data Says Otherwise
A 2025 white paper analyzed 12 months of operating data from 464 pumps. The analysis found the following operating patterns:
- 68% of pumps operated outside the preferred operating region (POR)2 more than half the time.
- 44% operated outside the POR more than 80% of the time.
- 17% operated in limited or restricted operating regions (LOR/ROR) more than half the time.
- 7% operated in LOR/ROR more than 80% of the time.
These were not hypothetical models or laboratory tests. They were real operating pumps monitored in industrial service. Many were operating in zones their manufacturers explicitly warn against.
Thirty years of better hardware has not solved the problem. It has only made the problem easier to identify—provided someone takes the time to look.
| IMAGE 2: Aggregate pump data indicated an operational issue but did not reveal the source.
| IMAGE 3: Single-pump operation frequently exceeded manufacturer-recommended operating ranges.
| IMAGE 4: Two-pump operation remained within optimal and manufacturer-recommended operating ranges.
Case Study: The Missing Piece
We recently analyzed a municipal water treatment plant. It was a relatively new facility with variable-speed pumps, modern SCADA systems, strong instrumentation and an experienced operating team—the type of plant many would assume is operating efficiently.
When a season of operating data was plotted against pump curves adjusted for speed and pump configuration, the results indicated an issue that warranted further investigation.
The root cause became clear after the data was segmented by pump configuration: the problem was concentrated during single-pump operation, which accounted for approximately 55% of plant runtime.
When the plant ran on one pump, that pump consistently operated in an overloaded condition—well right of BEP, with much of its runtime beyond the manufacturer-recommended range. During single-pump operation, the pump remained within the manufacturer-recommended range only 1% of the time. Approximately 62% of runtime occurred in the allowable range—a region where reliability may already be materially degraded—with the remaining 37% outside manufacturer limits entirely.
In that region, high velocities and hydraulic instability increase system stress. Because the facility was relatively new, the damage had not yet become visible in maintenance records. Left uncorrected, however, this operating pattern would quietly shorten equipment life over time.
For comparison, during two-pump operation, both pumps ran comfortably within the manufacturer-recommended range, with approximately 99% of runtime occurring within the optimal or manufacturer-recommended range.
This had gone unnoticed because operators were doing exactly what they believed they should do: running one pump during lower-demand periods to save energy. The logic was intuitive—fewer pumps should mean less energy.
But in this case, the opposite was true. Running a second pump would not only improve efficiency, but also reduce long-term wear by moving both pumps back toward BEP.
The most efficient strategy was the counterintuitive one. The fix required no retrofit or capital expenditure, only a simple control logic adjustment to lower the threshold at which the second pump turned on. The issue was not the VFDs or the SCADA system. The issue was that no one had analyzed the operating data in the context of the pump curve.
Where to Start
Improving pump performance often does not require expensive capital equipment changes. What many facilities lack is the diagnostic step: taking the operating data they already have and determining where their pumps are actually running on the curve over an extended period of time. Once that is understood, operators can make informed adjustments to control settings, sequencing and operating procedures to move pumps closer to BEP and maximize equipment life.
Improvement begins with understanding how the equipment is actually operating. So, do you know where your pumps are operating?
References
- Barringer’s reliability curve is based on statistical analysis of pump failure data across multiple industrial applications and is intended as generalized guidance rather than an exact prediction for any individual pump or service condition. His analysis suggests that expected pump reliability declines materially as operation moves away from BEP, with moderate deviation reducing expected life significantly and larger deviations producing progressively steeper reductions. See: Paul H. Barringer, “A Life Cycle Cost Summary,” International Conference of Maintenance Societies, 1998
- Manufacturer operating regions vary by pump type and OEM, but the POR commonly spans approximately 70%-120% of BEP and represents the range where manufacturers generally intend pumps to operate during normal continuous service. The broader allowable operating region (AOR) extends beyond the POR but is typically intended for temporary or intermittent operation rather than sustained runtime. Beyond the AOR lie limited and restricted operating regions, where manufacturers generally advise minimizing operation due to elevated reliability and performance risks. See: The Multi-Million-Dollar Pump Efficiency Optimization Opportunity, Sulzer, July 2025
Ray Hardee, P.E., is cofounder of BEP Logic. He previously cofounded Engineered Software, Inc., creator of PUMP-FLO and PIPE-FLO. Over his 50-year career, Hardee has helped shape international standards for pump system assessment and has trained thousands of engineers and operators in fluid system optimization. He may be reached at ray@beplogic.com. For more information, visit beplogic.com.
In This Issue
