Pipe Headloss : Colebrook White Formula

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The Darcy Weisbach Equation for calculating the pipe losses is as below;


In the Darcy–Weisbach Equation, the friction factor f  can be calculated from the equation of Colebrook–White.


 where k is the absolute roughness of the pipe wall (mm), D the inner diameter of the pipe (mm) and Re the Reynolds number .
Pipe Roughness values are as follows;

Pipe Material
Roughness Value (mm)
Mettalic Pipes - Cast Iron and Ductile Iron0.15
Mettalic Pipes - Mild Steel0.06
Asbestos Cement, Cement Concrete, Cement Mortar or Epoxy Lined Steel, CI, DI Pipes0.0350.035
PVC, GRP, and other plastic pipes0.0030.003