Pump Curves

Question 1

What is a Duty Point on a pump curve?

Answer 1

Design Duty Point Of The Pump. Defined as that Duty Point on the H-Q curve where a centrifugal pump operates at maximum efficiency. It is determined by the Flow Rate and the Total Head at the respective pump speed.

Question 2

Explain the “axis” relationship of a pump curve

Answer 2

As with any standard line graph, a pump curve has two axes, a horizontal (“x”) and a vertical (“y”). On a pump curve, the horizontal (“x”) axis shows the flow rate through the pump and the vertical (“y”) axis shows the head, which is sometimes referred to as ‘pressure’.

Question 3

Duty Point

Determines pump size

Answer 3

The curve then gives an indication of the pump’s maximum flow rate for any given head value, or vice versa. Once you have worked out the maximum flow rate and head required in your application, you will be able to determine whether the pump you are looking at will be capable of satisfying your requirements.

Question 4

Duty Point

Pump sizing continues

Answer 4

All you need to do is plot two lines, a horizontal line across from your required head value, and a vertical line up from your required flow rate value. The point at which these lines intersect is called the duty point. Provided this point is below the curve, as in the example above, you can be sure that the pump is capable of satisfying your requirements.