System Operating Point

The point at which a pump functions in a given piping system based on the flow rate and head loss of that system. For a specified system, the volumetric flow rate is compared to system head loss on the system characteristic curve. Through graphing a system characteristic curve and the pump characteristic curve on similar coordinate system, the point at which the pump should operate is specified. For illustration, in figure below, the operating point for the centrifugal pump in the original system is designated by the intersection of the pump curve and the system curve (h_Lo).

Figure: Operating point for a Centrifugal Pump

The system has a flow rate equivalent to V_o and a total system head loss equivalent to ΔP_o. In order to sustain the flow rate, the pump head should be equal to ΔP_o. In the system explained by (V_o) the system curve (h_L1), a valve has been released in the system to decrease the system's resistance to flow. For this system, the pump sustains a large flow rate (V₁) at a smaller pump head (ΔP₁).