What is hydraulic head in relation to pump performance?

• A. The mechanical energy in the motor
• B. The pressure contribution the pump provides to overcome system losses and elevation
• C. The total horsepower of the pump
• D. The flow rate at shut-off

Answer: (B)

Hydraulic head is the energy per unit weight of fluid that the pump adds to move water through the system. It represents the pressure rise the pump provides (pressure head) plus the vertical lift the water must overcome (static or elevation head), and, if relevant, the velocity of the moving fluid. In practical terms, the pump must deliver enough head to overcome system losses from friction, fittings, and elevation so water reaches the desired points in the system. The pump curve shows head at a given flow, illustrating how much pressure the pump can impart as flow changes. This concept is distinct from the motor’s mechanical energy (shaft power), the total horsepower of the pump (which includes efficiency losses), and the flow rate at shut-off (a different operating point).