Results
- Velocity
- — m/s
- Reynolds number
- —
- Darcy friction factor
- —
- Pressure drop
- — bar
- Pressure drop in kPa
- — kPa
How it works
Enter the flow, inside diameter, length, fluid properties and pipe roughness. The tool finds the velocity and Reynolds number, the Darcy friction factor, and the pressure drop ΔP = f · (L/D) · ρ · v² / 2.
Formula
ΔP = f · (L/D) · ρ · v² / 2 · f(Re < 2300) = 64/Re · f = 0.25 / [log₁₀(ε/(3.7D) + 5.74/Re⁰·⁹)]²
Assumptions and limits
For a single-phase incompressible liquid in a full, straight, horizontal pipe: fittings, valves, elevation change, gas compressibility and two-phase flow are not included. The friction factor is 64/Re for laminar flow and the Swamee–Jain equation for turbulent flow (valid for roughly 5 000 < Re < 10⁸ and ε/D from 10⁻⁶ to 10⁻²). Use 0.046 mm for new commercial steel.
For education and quick estimates only. Check the result against the applicable standards and your project data before using it in design, operation or safety decisions.
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