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# Pressure loss

in a straight pipe

Calculation of Pressure loss:
1. Enter volume flow.
2. Enter density and dynamic viscosity.
3. Enter inner diameter and pipe walls roughness.
4. Enter pipe length.
Pressure loss will be calculated for constant density. Pressure loss decreases quadratically with the diameter. Doubling the diameter will drop pressure loss by 75%. Calculation distinguishes between laminar flow (Re < 2320) und turbulent flow (Re > 2320). Since laminar flow can be observed up to Re=8000 pressure loss may be overestimated in the transition zone.

Pressure loss [bar/10m]
Values for water at ambient temperature
(1000 kg/m³, 1 mPas, k=0.1 mm)
 5 m³/h 10 m³/h 20 m³/h 40 m³/h DN25 (d=28mm) 0.267 1.033 4.076 16.13 DN50 (d=55mm) 0.009 0.032 0.121 0.470 DN100 (d=108mm) < 0.001 0.001 0.004 0.015

 Means of Calculation Steel Pipe Plastic pipe
 Plant Fluid Temperature ºC Volume flow* m³/h Density* kg/m³ Dyn. Viscosity * (Newton) mPas Internal Diameter  d * mm Roughness  k * mm Pipe length* m
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