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Mannings N: table 4
54" diameter to 8" diameter
Manning's n roughness coefficients for open channels and closed conduits — used in hydraulic flow calculations
| section | description | n value | subcategory |
|---|---|---|---|
| table 4 | 54" diameter | 0.023 | 5. Helical 3x1 inch |
| table 4 | 60" diameter | 0.021 | 3. Helical 2.67 x 1/2 inch |
| table 4 | 66" diameter | 0.025 | 5. Helical 3x1 inch |
| table 4 | 72" diameter | 0.026 | 5. Helical 3x1 inch |
| table 4 | 78" diameter and larger | 0.027 | 5. Helical 3x1 inch |
| table 4 | 8" diameter | 0.012 | 2. Helical 1.50 x 1/4 inch |
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