What does the system head curve represent in pump system design?

• A. The head losses in the piping system as a function of flow
• B. The pump head at zero flow
• C. The flow rate for a given head
• D. The efficiency curve of the pump

Answer: (D)

The system head curve represents the head (pressure) the piping network must provide to move fluid at different flow rates. It accounts for static head—the elevation or pressure difference you must overcome—and the friction losses in pipes and fittings, which grow with increasing flow. As you push more water through the system, friction losses rise, so the required head increases, giving you a curve that climbs with flow. In pump design, this system curve is used with the pump’s head vs. flow curve to find the operating point where the pump can satisfy the system’s demands. The pump’s efficiency curve is a separate characteristic of the pump’s performance, showing how efficiently it converts input power to hydraulic power at different flows, not the system’s requirements.