Calculator
Pipe Pressure Drop Calculator
Calculate the pressure drop in a steam pipe due to friction. Based on the Darcy-Weisbach equation — enter flow rate, pipe size, length, and steam pressure.
Interactive toolUpdated July 2026
Inputs
Results
Pressure Drop
0.14 bar
Over 100 m of pipe
Pressure Drop per 100m
0.14 bar
Target: 0.1–0.3 bar/100m
Steam Velocity
11.14 m/s
Should be below 40 m/s
The Darcy-Weisbach Equation
ΔP = (f × L × ρ × v²) / (2 × D)
Where: f = friction factor, L = pipe length (m), ρ = density (kg/m³), v = velocity (m/s), D = pipe ID (m)
This is a simplified calculation. For precise results, include fitting equivalent lengths (elbows, valves, tees) and use accurate steam properties from steam tables.
Acceptable Pressure Drop
- Steam mains: 0.1–0.3 bar per 100 metres
- Steam branches: 0.3–0.5 bar per 100 metres
- Compressed air: Below 0.5 bar total (including all fittings and components)
- If the pressure drop exceeds the target, upsize the pipe or reduce the flow