Friction Loss Calculator
Calculate pipe friction loss for water using the Hazen-Williams equation. Supports common pipe materials and sizes.
Pipe & Flow Parameters
hf = 10.67 × L × Q1.852 / (C1.852 × d4.8704)
Results
Total Head Loss
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Pressure Drop
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Loss per 100 ft
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Velocity
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Flow Area
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Velocity Check
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How this was calculated
Hazen-Williams: Empirical formula for friction losses in water piping. Only valid for water at 40-75F. Not for other fluids or very high velocities.
C factor: Roughness coefficient. Higher = smoother pipe. Values decrease with pipe age and corrosion.
Velocity: Recommended max is 5-8 ft/s for most water distribution systems to limit erosion and water hammer.
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Book a free strategy call →Understanding Friction Loss in Pipes
The Hazen-Williams equation is the most widely used empirical formula for calculating friction loss in water distribution systems. Unlike Darcy-Weisbach, it does not require Reynolds number calculation, making it practical for routine pipe sizing. However, it is only valid for water near ambient temperature and turbulent flow conditions.
The C factor is critical -- new PVC pipe (C=150) has roughly half the friction loss of corroded steel (C=80) at the same flow rate. Pipe age, tuberculation, and biofilm growth all reduce C over time.
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