# Result Charts - Centrifugal Pump

A typical centrifugal pump chart is shown in Figure 1. Figure 1: Centrifugal Pump Chart. The upper chart shows the pump performance curve (blue), the system curve (black) and the duty point (where the 2 lines intersect) is shown by the larger yellow triangle. The upper chart also shows the operating limits of the pump as specified in the database (the crosses X on the performance curve) and the efficiency curve (red). The duty point on the efficiency curve is also shown (smaller yellow triangle in the upper chart). The lower chart shows the power (purple) and NPSH required (lilac) curves, together with the duty point on each curve. Pump charts provide invaluable information that should be utilized when considering your system designs. For example, we need to consider if the pump is being operated near to the best efficiency point (BEP). The BEP occurs at the maximum height of the efficiency curve. Efficient designs should have duty points as near as possible to the BEP. Composite Pump Charts Users can develop composite pump charts (series and parallel) by selecting the "Tools | Composite Chart Setup..." menu item, then select the tab titled "Parallel & Series Pumping" (see Figure 2 below). Note: Composite pump charts are not available for centrifugal pumps when the "Automatically Size" option is set to "On". Figure 2: Composite Pump Chart Setup From this dialog, select the pumps you wish to be included in the composite chart. We have based this example on the model file "[FluidFlow3 folder]\QA Incompressible Flow\Boosters\4 Pumps in Parallel 3 Operating.ff3". All pumps in this model are operating in parallel and we are going to plot a chart for pumps 10 & 11 only. Ensure pump User Numbers 10 & 11 are checked ON and select "Make Plot". FluidFlow will now develop a composite chart which will appear as per Figure 3. Figure 3: Sample Composite Pump Chart The chart configuration can be edited by selecting the "Configure Chart" icon at the bottom left corner of the graph plot. The X & Y axis can also be adjusted as desired by increasing or decreasing the limits of the chart coordinates. Note, when developing the composite chart for multiple pumps in a system, the composite curve can potentially turn upwards unexpectedly as shown below. This is an example of three pumps in parallel. This can occur if the pump capacity curve(s) as defined in the database have not been fully defined across the full quadrant and/or if the Equation Order for the defined pump curve(s) is set to Quintic etc. To resolve this, you can complete the definition of the pump capacity curve(s) in the database across the full quadrant and set the Equation Order to an alternative type such as Cubic etc. If any of the above is unclear or you require any further information, please contact us at: support@fluidflowinfo.com.