The pump performance or characteristic curve is often referred to as a water performance curve (see Figure 1). Water is naturally the fluid of choice for testing pumps because of its availability. The question is: can the water performance curve be used for other fluids? The answer is YES with care.

The pump manufacturers will sometimes identify the unit of the total head axis as feet of water, or sometimes there will be a notice somewhere on the chart saying: tested with water at 70ºF. This is the manufacturer’s way of telling the user that the pump was tested with water and that the power curves are ONLY valid for water, but careful there are other pitfalls.

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