Flow Forum Q&A Series: Understanding pump curves, pump efficiency and cavitation

During his Flow Forum presentation, EASA’s Eugene Vogel will explore the relationship between pump curves and pump efficiency, as well as cavitation.

Large water pumps with electric motors. Parys/iStock.
Large water pumps with electric motors. Parys/iStock.
Large water pumps with electric motors. Parys/iStock.Large water pumps with electric motors. Parys/iStock.

Eugene Vogel
Pump & Vibration Specialist

Flow Control‘s inaugural Flow Forum conference will take place May 7-8 at the Westin O’Hare in Chicago. During the event, Eugene (Gene) Vogel will explore the relationship between pump curves and pump efficiency, as well as the impacts of cavitation-induced vibration. Vogel, who currently serves as the pump and vibration specialist for the Electrical Apparatus Service Association Inc. (EASA), recently sat down with Flow Control to answer a few questions about some of the key points of discussion he’ll cover during his Flow Forum presentation.

In your experience, does the typical pump user have a strong understanding of pump curves and their relationship to pump efficiency?

Knowledge of efficiency related to pump and system curves, and electric motors, varies among different industries. In the petrochem and power generation segments there is good basic awareness and engineers are competent in this area. At the other end of the spectrum, building services, (HVAC applications), has minimal internal technical resources. In between, general industrial manufacturing, municipal water and wastewater segments may or may not have technical staff versed in pump, system and motor efficiency.

Why are pump curves such a crucial consideration when it comes to pump efficiency?

Most folks understand that driving your car with one foot on the gas, one on the brake, is not a good practice for fuel efficiency and wear-n-tear on the vehicle. Unfortunately, many plant operations personnel run their pumps and systems with this type of philosophy. That can only be remedied with at least a basic understanding of pump and system curves.

Why is cavitation such a persistent pain point for so many pump users?

Cavitation is misunderstood. To some pump users any noisy pump is cavitating — and they have no idea what to do about it. The fundamental physics of cavitation — that liquid vaporizes based on both pressure and temperature — is not part of casual knowledge even for industry technicians. The "pain point" results because it is a complex phenomenon that is difficult to diagnose and in some cases even more difficult to correct.

What are the most common pitfalls pump users encounter that lead to unplanned maintenance and downtime?

Mechanical seal leakage and bearing failure are the two most common faults that result in unplanned downtime for pumps. Electric motor winding failure is a third common fault. In some cases, bearing and winding failures are secondary to a seal leakage fault. While erosion, corrosion and cavitation damage are common, since they develop more slowly and tend to be recurrent due to operating conditions, they are often addressed in planned outages.

For those pump users who are struggling with pump maintenance and reliability issues, what are some best practices they can employ to set them on the path to more efficient pumping systems?

Pump systems should be recognized as a unique machine category that requires specific knowledge to ensure proper design, installation and maintenance; all three of which are necessary for an efficient, reliable operation. Like any specialized piece of machinery, once there is a fundamental understanding of the requirements of each of those three critical components, reliability improvement becomes common sense.

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