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Mannings N: closed conduits
Paved invert, sewer, smooth bottom to Uncoated
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 | Paved invert, sewer, smooth bottom | 0.02 | 0.016 | 0.019 | 10. Brickwork: |
| closed conduits | Polypropylene (PP), smooth | 0.011 | 0.009 | 0.01 | Plastic: |
| closed conduits | Riveted and spiral | 0.017 | 0.013 | 0.016 | 2. Steel: |
| closed conduits | Rubble masonry, cemented | 0.03 | 0.018 | 0.025 | 10. Brickwork: |
| closed conduits | Sanitary sewers coated with sewage slime with bends and connections | 0.016 | 0.012 | 0.013 | 10. Brickwork: |
| closed conduits | Sewer with manholes, inlet, etc., straight | 0.017 | 0.013 | 0.015 | 7. Concrete: |
| closed conduits | Stave | 0.014 | 0.01 | 0.012 | 8. Wood: |
| closed conduits | Stormdrain | 0.03 | 0.021 | 0.024 | 5. Corrugated Metal: |
| closed conduits | Subdrain | 0.021 | 0.017 | 0.019 | 5. Corrugated Metal: |
| closed conduits | Uncoated | 0.016 | 0.011 | 0.014 | 3. Cast Iron: |
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