Section R. 400.18638 - Air-conditioning and air-handling systemsRule 638.
(1) Air-conditioning, warm air heating, air-cooling systems, and ventilating systems shall be in compliance with the provisions of the national fire protection association pamphlet no. 90-A, 1972 edition, air conditioning and ventilating systems, which is adopted by reference in R 400.18659.(2) If power exhaust ventilation is to be used, there shall be an air supply equal to the amount exhausted, especially in areas that house combustion equipment.(3) Fans and air-handling equipment that are used for recirculating air in more than 1 room or a single area shall be located in a room that is cut off from other portions of the building by construction that has a fire-resistant rating of not less than 1 hour, including fire dampers for duct openings, and a thermostatic device that has a setting of not more than 125 degrees Fahrenheit or an approved automatic smoke detector shall be located in the system at a suitable point in the return air duct ahead of the fresh air intake which, when activated, shall open the electrical circuit that supplies the fan motor. A fan room shall not be designed or used for any other use, except for housing other mechanical equipment.(4) If a duct system serves 2 or more floors, an approved fire damper shall be installed either at each direct outlet or inlet and in each branch duct at the junction with the main vertical duct or at each point where a floor is pierced.(5) If a duct pierces a smoke barrier or a wall or enclosure that is required to have a 1-hour-fire-resistance rating, then a heat-actuated fire damper shall be installed. If a duct pierces a wall that is required to have a 2-hour-or-more-fire-resistance rating, a heat-actuated fire damper shall be installed on both sides of the wall opening through which the duct passes.(6) A required exit corridor shall not be used either as an exhaust plenum or as a return plenum chamber in a heating and ventilating system and an opening shall not be provided in separation walls or doors between rooms and corridors.(7) A duct or plenum space, whether for supply, return, or exhaust, shall be constructed of noncombustible materials. Space between a drop ceiling and the floor above, where the drop ceiling is protection for exposed steel, shall not be used as a plenum.(8) A heat-actuated fire damper shall be listed by an approved independent, nationally-recognized laboratory such as factory mutual or underwriters laboratories, incorporated.Mich. Admin. Code R. 400.18638