Fire Suppression
Sprinkler Pipe Sizing (Hazen-Williams)
Quick pipe sizing for a sprinkler branch by NFPA 13's Hazen-Williams formula. Preliminary only — full design needs hydraulic software.
⚠ Preliminary sizing only
Real sprinkler design uses node-by-node hydraulic calculation (HASS, AutoSPRINK). This tool gives friction loss across a single pipe run \u2014 not a system design.
FAQ
What's the Hazen-Williams C? +
A coefficient for pipe roughness. Newer/smoother pipe = higher C = lower friction. NFPA 13 specifies C-values; do not invent your own.
Why is steel C lower than CPVC? +
Steel develops scale over time. NFPA 13 assumes wet-pipe steel at C=100, dry-pipe steel at C=100 (slightly lower in older spec), CPVC stays smooth at C=150.
Branch vs cross-main? +
Branch pipes feed individual sprinklers (typically 1" or 1.25"). Cross-mains feed branches (2" to 6"). Risers feed multiple floors and are typically 4-8".