Both the desktop and web-based PUMP-FLO software have an easy-to-use Multiple Pump Calculator to assist you in searching for pumps in parallel or series. To use it, start your search on the Design Point Search screen and simply click on the "Multiple Pump Calculator" button (see figure 1).

     
 Figure 1                                                                      Figure 2 

In the calculator dialogue window that opens (see figure 2), enter the number of pumps you intend to run and click the parallel or series radio button. Then enter the Total System Head and Flow and click "OK." PUMP-FLO will divide the total head or flow by the number of pumps and search for a single pump that will meet your total system head and flow when operated in parallel or series.

Make sure  the "Generate SRC" checkbox is checked, then click "Search."  When you choose a pump from the list of results you will see two blue curves displayed: one which intersects the load for each single pump, and one which represents the total system resistance curve when operating multiple pumps. The default curve view shows a single curve.  To view the head curve of multiple pumps, enter the number of pumps in the "Multiple Pumps" tab, and choose Parallel or Series and click "Update."

**Note** on the web, the Multiple Pumps area is on the Pump Curve screen to the right of the curve; after entering your multiple pump data, click "Redraw."