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Pipe Friction - Darcy-Weisbach

Pipe head-loss from Darcy-Weisbach equation - the fundamental pipe-friction calculation for any fluid system.

Darcy-WeisbachPipeHead loss
Head loss
2.336m
Formula, assumptions, and limits

Friction factor from Moody chart - Re + roughness ε/D. Smooth steel ε ≈ 0.045 mm. Add minor losses (K × v²/2g) for bends, valves, filters.

Symbol legend

SymbolMeaningUnitSource
Pipe lengthmpiping iso
Inside diametermpipe schedule
Mean velocitym/sQ/A
Darcy friction factor - Moody chart