AFT Application Topics
Pump vs. System Curves
When a centrifugal pump is being used in a system, the flow that it will deliver is based on the head loss through the system, as well as the static head change in the system (liquid elevation change or tank pressure change from supply to discharge tanks/reservoirs). To better understand how the system and pump will interact, the pump curve is plotted on the same graph as the system curve. This type of curve is termed a Pump vs. System Curve or just a Pump System curve.
AFT Fathom allows users to plot these curves on the same graph to see how they interact. The system curve also allows the user to understand if the system is dominated by friction or by static head to get a more comprehensive understanding of the ideal pump behavior. In Figure 1, for example, the Pump vs. System Curve generated in AFT Fathom shows a system that is static head dominated.
Figure 1: Pump vs. System Curve generated in AFT Fathom with static head-dominated system
Pump vs. System curve calculation can become more complex when there are multiple pumps in parallel or in series, especially when there are different pump curves for each pump. AFT software accounts for these differences and can use a “Traditional” or “Enhanced” method (according to user preference) to develop the desired curve.