Using pump flow test data to create a pump curve

 Product(s): WaterGEMS, WaterCAD Version(s): 08.XX.XX.XX, 10.XX.XX.XX Area: Modeling

Problem

How can pump flow test data be used to enter a pump definition? (pump curve)

Solution

If you do not have pump definition information available from the manufacturer, or if you want to check for actual performance (due to age for example), you can measure the flow and pressure at your pump and use that information to create the pump definition (pump characteristic curve) for your hydrualic model.

You can use either the three point, design point or multi-point pump curve types. Design point would only be used for a quick estimate if you only have a single "design" point (near the normal expected operating point).

You will need to convert the measured pressures to head (that the pump will add at the given flow). This will be the difference in hydraulic grade between the suction and discharge side of the pump. If your measurements are pressure, convert them to feet or meters first and add to the elevation (the elevation at which the measurement was taken) to get the hydraulic grade.

If you only have a measurement at the discharge side, you will need to determine or assume an upstream HGL. If you have storage or a well immediately upstream, you could make an estimate based on its water surface elevation minus the expected headloss in the pipe between. For an aquifer/well, it would be the water surface elevation minus the drawdown (see article further below).

Once both the suction and discharge HGL are determined for each flow measurement, find the difference between them to determine the head. This would then be entered in your pump definition for the row with the respective flow.

It is best to have at least three points of measurement - the shutoff (zero flow), design point, and the maximum operating point.

See Also

Accounting for well drawdown

What is the 1 point design pump definition used for?

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