Pressure drop in a liquid pipeline
Friction loss by Darcy-Weisbach (friction factor from Colebrook-White, 64/Re in laminar flow) plus the elevation change; the flow velocity and Reynolds number.
d = D − 2t; v = 4 · Q / (π · d²); Re = ρ · v · d / μ1/√λ = −2 · lg(ε / (3.7 · d) + 2.51 / (Re · √λ)); Re < 2300: λ = 64 / ReΔP = λ · (L / d) · ρ · v² / 2 + ρ · g · ΔzA single-phase Newtonian liquid at constant temperature. For 2300 < Re < 4000 the flow is unstable and the turbulent λ is used (conservative). Add fittings and valves to the length as equivalent length. Not for gas-liquid flow or waxy oils near their pour point.
Source: Darcy-Weisbach equation; Colebrook-White formula (1939); Crane TP-410
Inputs
You can change a field's unit: the value is converted to the formula's units automatically.
Negative if the end is lower than the start.
At the flowing temperature.
New steel pipe 0.03–0.05 mm; after a few years in service 0.1–0.2 mm; with deposits and corrosion 0.5–1 mm.
Unit converter for this formulaLiquid rate · Length · Density and °API · Viscosity · Pressure · Velocity
- m³/d1
- m³/h0.0416667
- L/s0.0115741
- L/min0.694444
- m³/min0.000694444
- bbl/d6.28981
- Mbbl/d0.00628981
- ft³/d35.3147
- US gpm0.183453
- bbl/min0.00436792
A day is 24 hours.
- ΔP_f — Friction loss–
- h_f — Friction head loss–
- v — Flow velocity–
- Re — Reynolds number–
- λ — Darcy friction factor–
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Results are engineering estimates from standard formulas; for design decisions check them against the codes, project documents and specialists' calculations. The formulas carried over from the original set are unchanged, and their errors are described in the notes.