606.4.2 Fan shutdown for recirculating air systems.
MC § 606.4.2
When any building or floor is provided with an air system designed to use recirculated air and is protected by an automatic sprinkler system or an automatic fire alarm system, the fans recirculating air serving the affected area shall automatically stop when sprinkler water flow or a fire condition is detected in the area. For the purposes of this section, 100 percent outdoor air systems shall not be considered recirculating systems. Exceptions: 1. Activation of a manual pull station shall not be required to automatically stop the fans.
2.Systems having a capacity of 2,000 cfm (0.9 m 3 /s) or less or serving not more than one floor.
3.In Group R-2 and R-3 occupancies with energy recovery systems complying with Section 514.4 and not serving public corridors.
