Pump Performance Curves

  • Identify the appropriate pump performance curves for a system.

  • Use pump scaling laws to predict the performance of a system.

  • Head-Flow Curves

  • Power-Flow Curves

A centrifugal pump performance curve is a tool that shows how a pump will perform in terms of head and flow. Pumps can generate high volume flow rates when pumping against low-pressure head or low volume flow rates when pumping against high-pressure head. The possible combinations of total pressure and volume flow rate for a specific pump can be plotted to create a pump curve. The curve defines the range of possible operating conditions for the pump. Pump curves plot data on a graph with x and y axes. The x axis (vertical) shows total head while the y axis (horizontal) shows flow capacity, typically gpm.
The operating point is where the system curve and the actual pump curve intersect.

Typical pump performance curves are:
  • Head vs. Flow Curve (H-Q Curve)
  • Efficiency Curve
  • Power/ Energy Curve
  • NPSH Curve

Solved Example:

67-1-01

The system head curve shows:

Correct Answer: C

Solved Example:

67-1-02

A performance curve for a given centrifugal pump shows that:

Correct Answer: B

Solved Example:

67-1-03

The ______________ of a centrifugal pump identifies the point at which the system head curve intersects the pump H-Q curve.

Correct Answer: D