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C402.4.5.2 Outdoor Air Intakes and Exhausts
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Outdoor air supply and exhaust openings shall be provided with Class IA motorized dampers with a maximum leakage rate of 4 cfm/ft2 (20.3 L/s • m2) at 1.0 inch water gauge (w.g.) (249 Pa) when tested in accordance with AMCA 500D.
- Gravity (nonmotorized) dampers having a maximum leakage rate of 20 cfm/ft2 (101.6 L/s • m2) at 1.0 inch water gauge (w.g.) (249 Pa) when tested in accordance with AMCA 500D are permitted to be used as follows:
- In buildings for exhaust and relief dampers.
- In buildings less than three stories in height above grade.
- For ventilation air intakes and exhaust and relief dampers in buildings of any height located in Climate Zones 1, 2 and 3.
- Where the design outdoor air intake or exhaust capacity does not exceed 300 cfm (141 L/s).
- Gravity (nonmotorized) dampers for ventilation air intakes shall be protected from direct exposure to wind.
- Dampers smaller than 24 inches (610 mm) in either dimension shall be permitted to have a leakage of 40 cfm/ft2 (203.2 L/s• m2) at 1.0 inch water gauge (w.g.) (249 Pa) when tested in accordance with AMCA 500D.