How to read a pump performance curve

How to read a pump performance curve

In order to help people understand how to read a pump performance curve, Xylem has created a short white paper that explains the basics. Impeller recently spoke with Larry Konopacz, manager of training and education for the Bell & Gossett Little Red Schoolhouse in Morton Grove, Illinois, to learn more about the white paper and why this knowledge is important.

“Understanding how to read a pump curve is critical in selecting the right pump,” Konopacz says. “With the right pump, you can maximize pump and system efficiency, and contribute to overall longer operational life.”

Konopacz says this white paper is ideal for end users, service technicians or new consultants who want to understand more about their pumping system.

Learning about pump curves is a regular part of the Bell & Gossett Little Red Schoolhouse training program. The Little Red Schoolhouse learning center has trained more than 60,000 engineers, contractors and installers in the proper design, installation and maintenance of hydronic and steam systems.

Avoiding mistakes in reading pump curves

“Our seminars often include a section on how to read a pump performance curve, since this is a key part of the successful operation of the system,” Konopacz says. “One mistake people can make when reading a pump curve is determining the actual pump head, which we go over in the white paper. Also the horsepower can be a little misleading or confusing, since the horsepower on the curve is based on water, with a specific gravity of one. But if the fluid has a different specific gravity, this will affect the horsepower requirements.”

There are different performance curves for every pump design, speed (RPM) and impeller diameter. By understanding all of the information provided by a performance curve, users can make intelligent decisions about the pump type, size, RPM, horsepower and efficiencies that will be required for the system. The new white paper will be part of a longer series, which will include a section in the future on pump selection.

“Pump curves are created based on an actual performance tests according to international standards,” Konopacz says. “It is important that everyone follows the same standards, even with different manufacturers, so that people can compare apples to apples.”

The Bell & Gossett Little Red Schoolhouse has also produced several training manuals on a number of subjects. These can be found here:

Free online courses are also available at The Bell & Gossett Little Red Schoolhouse. Four new modules on waterside economization will be launched at the American HVAC trade show at the end of this month. Read more about the online courses here.

by Simon