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FIRE AND SMOKE PROTECTION FEATURES 3.2. The duct shall be constructed of steel a point a duct or air transfer opening penetrates a smoke bar- minimum of 0.0217 inch (0.55 mm) in rier. Smoke dampers and smoke damper actuation meth- thickness. ods shall comply with Section 717.3.3.2. 3.3. The duct shall not have openings that Exception: Smoke dampers are not required where the communicate the corridor with adjacent openings in ducts are limited to a single smoke corn- spaces or rooms. partment and the ducts are constructed of steel. 3.4. The duct shall be installed above a ceil- 717.5.6 Exterior walls.Ducts and air transfer openings in ing. fire-resistance-rated exterior walls required to have pro- 3.5. The duct shall not terminate at a wall reg- tected openings in accordance with Section 705.10 shall ister in the fire-resistance-rated wall. be protected with listed fire dampers installed in accor- dance with their listing. 3.6. A minimum 12-inch-long (305 mm) by 717.5.7 Smoke partitions. A listed smoke damper 0.060-inch-thick (1.52 mm) steel sleeve designed to resist the passage of smoke shall be provided shall be centered in each duct opening. The sleeve shall be secured to both sides at each point that an air transfer opening penetrates a of the wall and all four sides of the sleeve smoke partition.Smoke dampers and smoke damper actua- tion methods shall comply with Section 717.3.3.2. with minimum 1'/2-inch by 14,inch by 0.060-inch (38 mm by 38 nun by 1.52 Exception: Where the installation of a smoke damper mm) steel retaining angles. The retaining will interfere with the operation of a required smoke angles shall be secured to the sleeve and control system in accordance with Section 909, the wall with No. 10 (M5) screws. The approved alternative protection shall be utilized. annular space between the steel sleeve 717.6 Horizontal assemblies. Penetrations by ducts and air and the wall opening shall be filled with transfer openings of a floor, floor/ceiling assembly or the mineral wool batting on all sides. ceiling membrane of a roof/ceiling assembly shall be pro- 4. Such walls are penetrated by ducted HVAC sys- tected by a shaft enclosure that complies with Section 713 or tems, have a required fire-resistance rating of 1 shall comply with Sections 717.6.1 through 717.6.3. hour or less, and are in buildings equipped 717.6.1 Through penetrations.In occupancies other than throughout with an automatic sprinkler system in Groups I-2 and I-3,a duct constructed of approved materi- accordance with Section 903.3.1.1 or 903.3.1.2. als in accordance with the Mechanical Code that pene- [ ] For the purposes of this exception, a ducted trates a fire-resistance-rated floor/ceiling assembly that �/ HVAC system shall be a duct system for convey- connects not more than two stories is permitted without ing supply, return or exhaust air as part of the shaft enclosure protection,provided a listed fire damper is structure's HVAC system. Such a duct system installed at the floor line or the duct is protected in accor- shall be constructed of sheet steel not less than dance with Section 714.4. For air transfer openings, see No. 26 gage thickness and shall be continuous Section 712.1.8. from the air-handling appliance or equipment to Exception:A duct is permitted to penetrate three floors the air outlet and inlet terminals. or less without a fire damper at each floor, provided 717.5.4.1 Corridors. A listed smoke damper designed such duct meets all of the following requirements: to resist the passage of smoke shall be provided at each I. The duct shall be contained and located within point a duct or air transfer opening penetrates a corn- the cavity of a wall and shall be constructed of dor enclosure required to have smoke and draft control steel having a minimum wall thickness of 0.0187 doors in accordance with Section 716.5.3. inches(0.4712 min)(No. 26 gage). Exceptions: 2. The duct shall open into only one dwelling or 1. Smoke dampers are not required where the sleeping unit and the duct system shall be contin- building is equipped throughout with an uous from the unit to the exterior of the building. approved smoke control system in accordance 3. The duct shall not exceed 4-inch(102 mm)nomi- with Section 909, and smoke dampers are not nal diameter and the total area of such ducts shall necessary for the operation and control of the not exceed 100 square inches (0.065 m') in any system. 100 square feet(9.3 m')of floor area. 2. Smoke dampers are not required in corridor 4. The annular space around the duct is protected penetrations where the duct is constructed of with materials that prevent the passage of flame steel not less than 0.019 inch (0.48 nun) in and hot gases sufficient to ignite cotton waste thickness and there are no openings serving where subjected to ASTM E 119 or UL 263 time- the corridor. temperature conditions under a minimum posi- 717.5.5 Smoke barriers.A listed smoke damper designed tive pressure differential of 0.01 inch(2.49 Pa)of / to resist the passage of smoke shall be provided at each water at the location of the penetration for the 150 2014 OREGON STRUCTURAL SPECIALTY CODE