Page 93 - Know and Understand Centrifugal Pumps

Understanding

Pump Curves

Pump performance curves

Pump performance curves are the least used, least consulted, least
appreciated, and least understood aspect of the world of industrial
pumps. The plant personnel who most need their pump curves,
mechanics and operators, generally don’t have the curves and
accompanying information at their disposal. The people who control
the performance curves store them in a file, in a drawer, in a cabinet
that’s almost never opened. They don’t share the information
contained in the curves with the people who need it. Maybe it’s because
they themselves don’t understand the information to share it. In the
next few paragraphs and pages, we’re going to explain the pump
performance curves. This might be the most important chapter of the
book.
In reality, the performance curve is easy to understand. It isn’t rocket
science. The performance curve indicates that the pump will discharge a
certain volume or flow (gpm) of a liquid, at a certain pressure or head
(H), at an indicated velocity or speed, while consuming a specific
quantity of horsepower (BHP). The performance curve is actually four
curves relating with each other on a common graph. These four curves
are:
1. The Head-Flow Curve. It is called the H-Q Curve.
2. The Efficiency Curve.

3. The Energy Curve. It records Brake Horsepower, BHP.
4. The Pump’s Minimum Requirement Curve. Its called Net Positive
Suction Head required, NPSHr.

Think of the pump curve like the dashboard or control panel of a car.
No one would operate a car without the dash instrumentation panel.