Ductwork - Supports
The support distance for ductwork is typical based upon deflection, stress and cylinder buckling analysis.
For sheet metal duct work the space between the hangers should not exceed the distances listed below:
Horizontal Ductwork
| Ducts Size | Maximum Spacing (ft, m) | |
|---|---|---|
| Area (ft2, m2) | Diameter (in, mm) | |
| less than 4 (0.4) | less than 5 (125) | 8 (2.5) |
| 4 (0.4) to 10 (1) | 5 (125) to 38 (1000) | 6 (2) |
| more than 10 (1) | more than 38 (1000) | 4 (1.2) |
Vertical Ductwork
| Ducts Type | Maximum Spacing (ft, m) |
|---|---|
| round | 12 (3.6) |
| rectangular | 10 (3) |
- 1 ft2 = 0.0929 m2 = 144 in2
- 1 ft (foot) = 0.3048 m = 12 in
Note! Support systems for ductwork may provide restraint in three directions against displacement and rotation. Consideration must be given with restraining ducts to avoid development of excessive internal duct stresses caused by expansion or contraction due to temperature variations.
Related Topics
• Ventilation
Systems for ventilation and air handling - air change rates, ducts and pressure drops, charts and diagrams and more.
Related Documents
Ducts - Sheet Metal Gauges
Thickness of sheet metal used in ductwork.
Ducts Sizing - the Velocity Reduction Method
The velocity reduction method can be used when sizing air ducts.
Ductwork - Seal Classes
Ductwork air leakage classes.
Horizontal Pipe Hanger Supports - Spacing and Rod Size
Recommended maximum support span between hangers - and rod sizes for straight horizontal pipes.