Hazen-Williams Pipe Friction Loss Calculator

Calculate pipe friction loss using the Hazen-Williams formula with C-factor for fire protection water supply piping per NFPA 13/24

Input Parameters

Results

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Friction Loss
psi
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Friction Loss
ft head
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Flow Velocity
ft/s
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Unit Friction Loss
psi/ft
Note: The Hazen-Williams formula is the standard method for fire protection hydraulic calculations per NFPA 13 and NFPA 24. C-factor accounts for pipe roughness and age. NFPA 13 Table 23.4.1.1 specifies C-factors for various pipe materials.

Reference

Hazen-Williams Friction Loss Formula: p = 4.52 × Q^1.85 / (C^1.85 × d^4.87) p = pressure loss per foot (psi/ft) Q = flow (gpm), d = internal diameter (in), C = roughness coefficient Common C-factors: 150 (plastic/copper), 140 (new steel), 120 (old steel/cast iron) Velocity = 0.4085 × Q / d²