How To Read A Pump Curve Before You Buy

The pump curve is the single most honest page in a quotation. Before comparing prices, compare these five things on the curve.

1. Where Your Duty Point Sits

Mark your flow and head on the curve. If the point sits far right of best efficiency, the pump will cavitate or overload; far left, it will run hot and vibrate. Aim for the 70 to 120 percent flow band around BEP.

2. The NPSH Line

Compare the required NPSH at your flow with what your suction side can supply. If the margin is under half a metre, ask for a larger suction or a slower pump, not a bigger motor.

3. Power At The End Of The Curve

Non-overloading power means the motor is sized for runout, not just the duty point. Ask whether the quoted motor covers end-of-curve, or you will trip the first time the system runs clean.

4. Efficiency, Honestly

Peak efficiency sells pumps; efficiency at your point runs them. Read the efficiency at your duty, not the brochure peak.

5. Curve Or Family Envelope

A dotted family envelope is not a tested curve. At Aquaflow every quotation curve is generated from the same bench data as the pump’s shipping test sheet, so the two documents agree by construction.

Send us your duty point and we will mark a curve for you, with the NPSH check included.