Circular Duct Sizes
Dimensions of circular ventilation air ducts
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Circular Duct Dimensions - Metric Units
Common circular duct sizes used in air handling ventilation systems:
| Nominal Diameter (mm) | Outside Diameter (mm) | Inside Diameter (mm) |
| 63 | 63 - 63.5 | 61.8 - 62.3 |
| 80 | 80 - 80.5 | 78.8 - 79.3 |
| 100 | 100 - 100.5 | 98.8 - 99.3 |
| 125 | 125 - 125.5 | 123.8 - 124.3 |
| 160 | 160 - 160.6 | 158.7 - 159.3 |
| 200 | 200 - 200.7 | 198.6 - 199.3 |
| 250 | 250 - 250.8 | 248.5 - 249.3 |
| 315 | 315 - 315.9 | 313.4 - 314.3 |
| 400 | 400 - 401.0 | 398.3 - 399.3 |
| 500 | 500 - 501.1 | 498.2 - 499.3 |
| 630 | 630 - 631.2 | 628.1 - 629.3 |
| 800 | 800 - 801.6 | 798.0 - 799.3 |
| 1000 | 1000 - 1002.0 | 997.9 - 999.3 |
| 1250 | 1250 - 1252.5 | 1247.8 - 1249.3 |
Circular Galvanized Steel Ducts - Areas and Weights - Imperial Units
| Diameter (inches) | Surface Area (ft2/ft) | Gage | ||
| 26 | 24 | 22 | ||
| Weight (lbs/ft) | ||||
| 5 | 1.05 | 1.02 | 1.36 | 1.59 |
| 5 | 1.31 | 1.25 | 1.67 | 1.95 |
| 6 | 1.57 | 1.49 | 1.98 | 2.32 |
| 7 | 1.83 | 1.72 | 2.30 | 2.69 |
| 8 | 2.09 | 1.96 | 2.61 | 3.06 |
| 9 | 2.36 | 2.20 | 2.93 | 3.42 |
| 10 | 2.62 | 2.51 | 3.34 | 3.91 |
| 11 | 2.88 | 2.74 | 3.66 | 4.28 |
| 12 | 3.14 | 2.98 | 3.97 | 4.64 |
| 13 | 3.40 | 3.21 | 4.28 | 5.01 |
| 14 | 3.67 | 3.45 | 4.60 | 5.38 |
| 15 | 3.93 | 3.68 | 4.91 | 5.75 |
| 16 | 4.19 | 3.92 | 5.23 | 6.12 |
| 17 | 4.45 | 4.16 | 5.54 | 6.48 |
| 18 | 4.72 | 4.39 | 5.85 | 6.85 |
| 19 | 4.98 | 4.63 | 6.17 | 7.22 |
| 20 | 5.24 | 4.94 | 6.58 | 7.70 |
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Related Topics
- Ventilation - Systems for ventilation and air handling - air change rates, ducts and pressure drops, charts and diagrams and more
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Related Documents
- Air Ducts Friction Loss Diagram - Major loss diagram air ducts - SI units
- Air Ducts Velocity Diagram - Air flow volume, duct size, velocity and dynamic pressure
- Duct Velocity - Calculate velocities in circular and rectangular ducts - imperial and SI-units - online calculator
- Equal Friction Method - The equal friction method of sizing ducts is easy and straightforward to use
- Rectangular Air Ducts Velocity Diagram - Velocity diagram rectangular air ducts
- Velocities in Ventilation Ducts - Recommended velocities in ventilation ducts
