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Total head is not the lift height — it is the total energy the pump must overcome.
Head formula
Total Head (m)H = Hstatic + Hfriction + Hvelocity + Hresidual
Estimating friction loss
In a 100 m galvanised steel line at 20 m³/h, a DN80 pipe loses about 8–10 m. Bends and valves add equivalent pipe length.
Note
On long runs friction can outweigh static lift — never size by measuring height alone.Measure for accuracy
For retrofit projects especially, measure the real system curve with a flow meter and gauges.
| Parameter | Symbol | Unit |
|---|---|---|
| Static lift | Hgeo | m |
| Friction loss | Hf | m |
| Residual pressure | Hr | m |
Add the three and you have the required total head.