NFPA's unit shutdown code

[Rref]

NFPA 72 (5.14) talks about the installation of duct mounted smoke detectors, and may I am just looking all over it and not seeing it, but I don't see the specific code referencing the automatic shut down of heating and air units. I am really looking for the code reference that mentions the size and location of units requiring duct mounted smoke detection.

 

[stookeyfpe]

Chapter 6 of the International Mechanical Code contains the requirements for when air handling systems require smoke detection systems.

For common supply and return air systems, duct smoke detection is required when the air flow volume is > 2000 cubic feet/minute. Return air risers serving two or more stories with a air flow volume of 15,000 CFM or more also requires duct smoke detection. See IMC Sections 606.2.2 & 606.2.3, respecitively.

Shutdown of the equipment is specified in IMC Section 606.4:

606.4 Controls operation. Upon activation, the smoke detectors shall shut down all operational capabilities of the air distribution system in accordance with the listing and labeling of appliances used in the system. Air distribution systems that are part of a smoke control system shall switch to the smoke control mode upon activation of a detector.

 

[cdafd]

maybe NFPA 90a


6.4.2* Location.
6.4.2.1 Smoke detectors listed for use in air distribution systems shall be located as follows:
(1) Downstream of the air filters and ahead of any branch connections in air supply systems having a capacity greater than 944 L/sec (2000 ft3/min)
(2) At each story prior to the connection to a common return and prior to any recirculation or fresh air inlet connection in air return systems having a capacity greater than 7080 L/sec (15,000 ft3/min) and serving more than one story
6.4.2.2 Return system smoke detectors shall not be required where the entire space served by the air distribution system is protected by a system of area smoke detectors.
6.4.2.3 Smoke detectors shall not be required for fan units whose sole function is to remove air from the inside of the building to the outside of the building.