Friction Loss Calculator (Hazen-Williams)

Your details

Switch all inputs and outputs between metric and imperial units.
Total straight-run length of the pipe section being analysed.
m
Internal (bore) diameter of the pipe, not the outer diameter.
mm
Volumetric flow rate through the pipe. Must be below about 3 m/s (10 ft/s) for Hazen-Williams to be accurate.
L/s
Select the pipe material. The Hazen-Williams C coefficient will be set automatically.
Friction head lossNormal velocity
0.404m

Energy lost to pipe friction, expressed as a height of water column

Pressure drop3.96
Flow velocity0.637
Head loss per 100 units0.404
Hazen-Williams C150
0.637 m/s
Too slow<0.3Normal0.3-1.5High1.5-3Excessive3+

0.404 m friction head loss at 0.64 m/s average velocity.

  • The pipe loses 0.404 m of head (3.96 kPa) over 100 m.
  • Friction head loss per 100 m of pipe is 0.404 m.
  • Flow velocity (0.64 m/s) is within the acceptable design range for Hazen-Williams.

Next stepTo reduce head loss: increase pipe diameter (D appears in the denominator to the 4.87 power, so small increases have a large effect), shorten the pipe run, or select a smoother material with a higher C value.

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