What this tool does
Build a transparent head balance before reading a pump curve. The calculation separates elevation, required delivery pressure, pipe loss, fittings or equipment loss, and available inlet pressure.
When to use it
Use it after required flow is known and after pipe friction has been measured or calculated. A flooded suction can contribute positive inlet pressure; a suction lift should be represented through the elevation and inlet conditions without mixing gauge and absolute pressure.
Inputs and supported units
Each labelled field explains the quantity it expects. Unit-system changes convert existing numeric entries once and keep calculations on a single SI internal basis. Supported shared units include L/min and GPM, metres and feet, kPa and psi, millimetres and inches, kW and hp, and °C and °F as relevant.
Calculation or decision method
Pressure is converted to head using H = p/(ρg) with water near 20 °C. This page treats delivery and inlet entries as gauge pressure; absolute pressure belongs in the NPSH calculation.
How to interpret the result
Read the primary result with the supporting breakdown and warning. A plausible number is not evidence that every input, operating case or design constraint has been included.
Worked example
A system lifting water 18 m, delivering at 250 kPa, losing 6.5 m in pipework and 2 m through fittings/equipment, with 35 kPa available at the inlet, produces roughly 48.4 m TDH.
Assumptions
Steady incompressible water flow; pressure readings refer to comparable gauge locations; listed losses represent the duty flow.
Limitations
No transient, control-valve, acceleration, open-channel, non-water or system-curve calculation is included.
Sources
- Hydraulic Institute — Combined Pump & System Curves
- U.S. Department of Energy — Pump Systems
- U.S. Geological Survey — Pressure transducers and pressure-head conversions