Colebrook White Pipe Design Spreadsheet

Colebrook White Pipe Design Spreadsheet

Under the British Standards and the Eurocodes it is recommended that the Colebrook-White formula is used to determine the velocity and flow of water from a pipe running full subject only to gravity. The Colebrook-White formula is given below;

V = Water Velocity (m/s)

Q = Flow (m³/s)

g = Acceleration Due to Gravity (m/s²)

D = Internal Diameter of Pipe (m)

S = Hydraulic Gradient (m/m)

ks = Roughness Coefficient (m)

v = Kinematic Viscosity (m²/s)

A = Cross Sectional Area of Pipe (m²)



This spreadsheet uses the Colebrook-White and Darcy-Weisbach formulas to calculate the flow conditions in a circular pipe acting under gravity only. As such it is compliant with the requirements of the British Standards and Eurocodes for gravity drainage pipes. It includes the following functions;

  • Calculates the maximum flow of a liquid through a circular pipe under gravity
  • User can alter all parameters including;
  • Can model any circular pipe diameter or hydraulic gradient
  • Liquids other than water can be modelled by altering the kinematic viscosity
  • Output
    • Gives flow of pipe running full in l/s and m³/s
    • Flow of pipe running full is plotted on a chart alongside other hydraulic gradients and standard pipe diameters allowing the designer to quickly see how these parameters affect the flow
    • Gives flow velocity of pipe running full in m/s
    • Also calculates the maximum possible flow and maximum flow velocity for circular pipes running partially full and gives the liquid height at these conditions
    • Allows the user to calculate the flow and velocity when pipe is running partially full at any percentage

Plots a chart showing the maximum flow, maximum velocity and user specified results so the designer can easily see the flow conditions at any stage

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