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INSPECTION & INSTALLATION
4.3 Bends
When making bends to flexible air ducts or air connectors, the diameter of the bend shall be greater than or equal to one (1) duct diameter (see Figures 8 & 9). If the bends are less than one (1) duct diameter this can significantly increase pressure drop throughout the system resulting in a reduction in the overall system efficiency and performance. For bends made prior to or after a metal connection, extend the duct straight for at least one duct diameter length before and after the connection points. This avoids potential damage to the duct from the fitting edges while also improving the airflow.
For proper support, place strapping both before and after a 90 degree bend that is made in the middle of a duct run.
CORRECT BENDS
13
Figure 9
Figure 8
Figure 10
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