Low-pressure gas pipe sizing using the Spitzglass formula. Schedule 40 black iron pipe for natural gas and propane distribution.
| Pipe Size | ID (in) | Capacity (CFH) | Velocity (FPS) | ΔP (in.wc) | Status |
|---|
| Application | Max Velocity | Notes |
|---|---|---|
| Low-pressure gas mains | 30 FPS | NFPA 54 / IFGC recommendation |
| High-pressure gas | 50 FPS | Above 0.5 psig |
| Outdoor underground | — | Pressure drop governs; per utility requirements |
| Typical design target | 20–25 FPS | Leaves headroom for demand diversity |
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