# What is the pump performance curve used for?

What is the pump performance curve used for?

The pump performance curve, also referred to as performance data, helps you choose the correct pump. It shows the relationship between the flow-rate (Q) and the delivery head (H) of a pump.

Explanation of the performance curve below

At the maximum flow rate (Q) of 130 litres per minute, measured directly on the pressure duct of the pump, the delivery head height equals 0 cm. At maximum delivery head Height (H) of 400 cm the flow-rate equals 0 litres.

Determining the operating point

In our example we need the pump to displace water 1 m above the water surface. By looking at the pumps performance curve, we can locate the operating point (see example image) you can see the red mark at 1 m in height, that is our operating point and at that point we can see that approx. 90 l/m are displaced – This is determined theoretically as small hose diameter, the hose length, any fittings and built in curvature can change the value of the flow in the extreme.

The delivery head is specified in mwc (metre water column).
1 mwc ~ 0.1 bar
A Pump Performance Curve is produced by a pump manufacturer from actual tests performed and shows the relationship between Flow and Total Dynamic Head. Higher TDH = lower flow, Lower TDH = higher flow).