Pump head, power and efficiency
Total head, hydraulic and shaft power and pump efficiency from field readings — and what a worn pump costs a year.
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Pumps and Piping Excel kit — coming soon
Pump performance against the maker's curve, NPSH with full suction-line losses, pipe sizing and pressure drop, and control valve sizing — with print-ready reports, any units and visible formulas.
How this calculator works
Total head = (discharge pressure − suction pressure) ÷ (ρ·g) + gauge height difference + (vd² − vs²) ÷ 2g. Hydraulic power = ρ·g·Q·H. Shaft power = motor input power × motor efficiency. Pump efficiency = hydraulic power ÷ shaft power; wire-to-water efficiency = hydraulic power ÷ motor input power.
If you enter the best efficiency from the maker's curve, the calculator shows the power the pump would draw at that efficiency, and the yearly saving from restoring it.
The example is a cooling water pump for the PlantCalcKit example tower: 6,000 m³/h, 0.5 to 2.9 bar g, 560 kW motor input. Total head 25.6 m, hydraulic power 418 kW, shaft power 535 kW, so the pump runs at 78 % against 86 % when new — about 51 kW, or USD 43,000 a year at USD 0.10/kWh.
Limits: for liquids (incompressible); viscous liquids need the maker's correction; motor efficiency taken as constant. References: Perry's Chemical Engineers' Handbook §10; Hydraulic Institute pump standards; Ludwig, Applied Process Design Vol. 1; GPSA Engineering Data Book Sec. 12.