Pump Operating Point
Intersection of bundled pump curve with H_sys = H_static + k Q^2; SVG plot + numeric table at sample flows.
Example
You enter
- Pump curve small_centrifugal_60Hz
- Static head (ft) 30
- Friction k (ft per gpm²) 0.003
You get
- Operating gpm 113.2
- Head at operating point 68.5 ft
- Efficiency at point 67.9 %
No published worked example is on file for this calculation. It is checked against a hand-worked derivation of its method and an independent reference test.
Details, formula, and sources
Formula or tableOperating point at the intersection of the bundled pump curve H_p(Q) (linearly interpolated polyline) and the system curve H_sys = H_static + k × Q². Solved by binary search on Q in [0, Q_max].
Source and editionHydraulic Institute by name. Both bundled curves are engineering-practice composites, attributed as such per entry in data/plumbing/pump-curves.json; neither is a manufacturer's published curve.
Free accessHI standards licensed; manufacturer technical bulletins free at each manufacturer site.
What governsEstimate. AHJ and licensed plumber / gas fitter govern. Verify against the IPC / IFGC edition adopted in your jurisdiction.
API field namespump, static_head_ft, k_friction, operating_gpm, head_ft, efficiency
- System curve form H_sys = H_static + k × Q² (turbulent / fully-rough flow)Hazen-Williams and Darcy-Weisbach Q² scaling
- Curve interpolation linear between published points (no quadratic / cubic fit)engineering practice
- Curve provenance both bundled curves are engineering-practice composites; replace with the manufacturer curve before selecting a pumpdata/plumbing/pump-curves.json attribution field