18-28-606.1 Control.

   Air distribution systems shall be equipped with smoke detectors listed and labeled for installation in air distribution systems, as required by this section.

18-28-606.2 Where required.

   Smoke detectors shall be installed where indicated in Sections 18-28-606.2.1 through 18-28-606.2.3.

   Exception: Smoke detectors shall not be required where air distribution systems are incapable of spreading smoke beyond the enclosing walls, floors and ceilings of the room or space in which the smoke is generated.

18-28-606.2.1 Return air systems.

   Smoke detectors shall be installed in return air systems with a design capacity greater than 2,000 cfm (0.9 m 3 /s), in the return air duct or plenum upstream of any filters, exhaust air connections, outdoor air connections, or decontamination equipment and appliances.

   Exception: Smoke detectors are not required in the return air system where the space served by the air distribution system is protected by a system of area smoke detectors in accordance with Chapter 15-16 of this Code. The area smoke detector system shall comply with Section 18-28-606.4.

(Amend Coun. J. 11-9-16, p. 36266, § 36)

18-28-606.2.2 Common supply and return air systems.

   Where multiple air-handling systems share common supply or return air ducts or plenums with a combined designed capacity greater than 2,000 cfm (0.9 m 3 /s), the return air system shall be provided with smoke detectors in accordance with Section 18-28-606.2.1.

   Exception: Individual smoke detectors shall not be required for each variable air volume (VAV) zone unit or VAV-type fan-powered terminal unit, provided that such units do not have an individual design capacity greater than 2,000 cfm (0.9 m3/s) and will be shut down by activation of one of the following:

      1.   Smoke detectors required by Sections 18-28-606.2.1 and 18-28-606.2.3.

      2.   An approved area smoke detector system located in the return air plenum serving such units.

      3.   An area smoke detector system as prescribed in the exception to Section 18-28-606.2.1.

   In all cases, the smoke detectors shall comply with Sections 18-28-606.4 and 18-28-606.4.1.

18-28-606.2.3 Return air risers.

   Where return air risers serve two or more stories and are part of a return air system having a design capacity greater than 15,000 cfm (7.1 m 3 /s), smoke detectors shall be installed at each story. Such smoke detectors shall be located upstream of the connection between the return air riser and any air ducts or plenums.