Hazen-Williams C-Factors Reference
Hazen-Williams C-factors (roughness coefficients) for all pipe materials supported by Plumbing Booster.
Introduction
Hazen-Williams C-Factors by Pipe Material
| Material | C-Factor | Condition | Typical Use |
|---|---|---|---|
| PPR (Polypropylene Random) | 150 | New / smooth | Hot and cold water supply |
| PEX (Cross-linked PE) | 150 | New / smooth | Residential water supply |
| CPVC | 150 | New / smooth | Hot and cold water supply |
| UPVC | 150 | New / smooth | Cold water, drainage |
| Copper (Type L) | 140 | New / smooth | Hot and cold water supply |
| HDPE | 150 | New / smooth | Water mains, drainage |
| PVC (Schedule 40/80) | 150 | New / smooth | Cold water, drainage |
| Steel (galvanized, new) | 120 | Fairly smooth | Water supply (legacy) |
| Steel (galvanized, old) | 80 | Fairly rough | Water supply (aged) |
| Cast iron (new) | 130 | Fairly smooth | Water mains (legacy) |
| Cast iron (old) | 100 | Fairly rough | Water mains (aged) |
| Cast iron (very old) | 60 | Rough | Water mains (very aged) |
IPC Roughness Categories
| Category | C-Factor Range | Typical Materials |
|---|---|---|
| Smooth | 140-150 | PPR, PEX, CPVC, UPVC, Copper, HDPE |
| Fairly smooth | 120-130 | New steel, new cast iron |
| Fairly rough | 80-100 | Old steel, old cast iron |
| Rough | 60-80 | Very old cast iron, corroded pipe |
Notes
- • C-factors decrease over time as pipes age and corrode.
- • Plumbing Booster uses the material-specific C-factor automatically.
- • For IPC pressure analysis, select the roughness category in System Structure.
- • Hazen-Williams equation: hf = 10.67 x L x Q^1.852 / (C^1.852 x d^4.87)
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