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Mannings N: closed conduits
Galvanized to PVC, smooth
Manning's n roughness coefficients for open channels and closed conduits — used in hydraulic flow calculations
| section | description | n max (dimensionless) | n min (dimensionless) | n normal (dimensionless) | subcategory |
|---|---|---|---|---|---|
| closed conduits | Galvanized | 0.017 | 0.013 | 0.016 | 4. Wrought Iron: |
| closed conduits | Glazed | 0.015 | 0.011 | 0.013 | 10. Brickwork: |
| closed conduits | HDPE, corrugated (full profile) | 0.025 | 0.018 | 0.022 | Plastic: |
| closed conduits | HDPE, smooth interior | 0.015 | 0.009 | 0.012 | Plastic: |
| closed conduits | Laminated, treated | 0.02 | 0.015 | 0.017 | 8. Wood: |
| closed conduits | Lined with cement mortar | 0.017 | 0.012 | 0.015 | 10. Brickwork: |
| closed conduits | Lockbar and welded | 0.014 | 0.01 | 0.012 | 2. Steel: |
| closed conduits | Mortar | 0.015 | 0.011 | 0.013 | 6. Cement: |
| closed conduits | Neat Surface | 0.013 | 0.01 | 0.011 | 6. Cement: |
| closed conduits | PVC, smooth | 0.011 | 0.009 | 0.01 | Plastic: |
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