The system resistance curve is a plot of a piping system's total resistance over a range of flow rates.  The system resistance curve can be a very useful tool to have when selecting a pump.  In the construction of the system resistance curve, losses due to pipe friction, valves and fittings, and various process equipment such as strainers and filters must be considered.  In addition to overcoming the flow resistance of these components, the pump head required (TDH) in an open loop system may have to be increased to account for differences in the system suction and discharge levels.  Also, if the discharge pressure is different than the suction pressure, this must be taken into account as well.  Using PIPE-FLO, you can quickly generate a system resistance curve and plot it, as well as export it to a file for later use in the pump selection and control valve selection modules.

When creating a system resistance curve, note the following limitations:

There can only be one active pump in the system (all other pumps are shut off).

The program sets all controls (FCVs, PRVs, and BPVs) in the system to fully open.

The program sets all flow demands in the system to zero.