N.Y.C. Admin. Code § BC 717: Section BC 717: Ducts and Air Transfer Openings

717.1 General.

The provisions of this section shall govern the protection of duct penetrations and air transfer openings in assemblies required to be protected and duct penetrations in nonfire-resistance-rated floor assemblies.

717.1.1 Ducts and air transfer openings.

Ducts transitioning horizontally between shafts shall not require a shaft enclosure provided that the duct penetration into each associated shaft is protected with dampers complying with this section.

717.1.2 Ducts that penetrate fire-resistance-rated assemblies without dampers.

Ducts that penetrate fire-resistance-rated assemblies and are not required by this section to have dampers shall comply with the requirements of Sections 714.2 through 714.3.3. Ducts that penetrate horizontal assemblies not required to be contained within a shaft and not required by this section to have dampers shall comply with the requirements of Sections 714.4 through 714.5.2.

717.1.2.1 Ducts that penetrate nonfire-resistance-rated assemblies.

The space around a duct penetrating a nonfire-resistance-rated floor assembly shall comply with Section 717.6.3.

717.2 Installation.

Fire dampers, smoke dampers, combination fire/smoke dampers and ceiling radiation dampers located within air distribution and smoke control systems shall be installed in accordance with the requirements of this section, the New York City Mechanical Code, the manufacturer's instructions and the damper's listing.

717.2.1 Smoke control system.

Where the installation of a fire damper will interfere with the operation of a required smoke control system in accordance with Section 909, approved alternative protection shall be utilized. Where mechanical systems including ducts and dampers utilized for normal building ventilation serve as part of the smoke control system, the expected performance of these systems in smoke control mode shall be addressed in the rational analysis required by Section 909.4.

717.2.1.1 Remote control.

Provisions for operation by remote control of combination fire/smoke dampers shall be in accordance with Section 607.2.1.1 of the New York City Mechanical Code.

717.2.2 Hazardous exhaust ducts.

Fire dampers for hazardous exhaust duct systems shall comply with the New York City Mechanical Code.

717.2.3 Supply air systems.

Smoke dampers in supply air-handling systems having a capacity equal to or greater than 15,000 cfm (7.1 m

3

/s) shall be installed in accordance with Section 607.2.3 of the New York City Mechanical Code.

717.3 Damper testing, ratings and actuation.

Damper testing ratings and actuation shall be in accordance with Sections 717.3.1 through 717.3.3.

717.3.1 Damper testing.

Dampers shall be listed and labeled in accordance with the standards in this section.

1. Fire dampers shall comply with the requirements of UL 555. Only fire dampers and ceiling radiation dampers labeled for use in dynamic systems shall be installed in heating, ventilation and air-conditioning systems designed to operate with fans on during a fire.

2. Smoke dampers shall comply with the requirements of UL 555S.

3. Combination fire/smoke dampers shall comply with the requirements of both UL 555 and UL 555S.

4. Ceiling radiation dampers shall comply with the requirements of UL 555C or shall be tested as part of a fire-resistance-rated floor/ceiling or roof/ceiling assembly in accordance with ASTM E 119 or UL 263.

717.3.2 Damper rating.

Damper ratings shall be in accordance with Sections 716.3.2.1 through 716.3.2.3.

717.3.2.1 Fire damper ratings.

Fire dampers shall have the minimum fire protection rating specified in Table 717.3.2.1 for the type of penetration.

Table 717.3.2.1 Fire Damper Rating

Type of Penetration

Minimum Damper Rating (hour)

Less than 3-hour fire-resistance-rated assemblies

1.5

3-hour or greater fire-resistance-rated assemblies

3

717.3.2.2 Smoke damper ratings.

Smoke damper leakage ratings shall be Class I or II. Elevated temperature ratings shall be not less than 250°F (121.1°C).

717.3.2.3 Combination fire/smoke damper ratings.

Combination fire/smoke dampers shall have the minimum fire protection rating specified for fire dampers in Table 717.3.2.1 for the type of penetration and shall have a minimum smoke damper rating as specified in Section 717.3.2.2.

717.3.3 Damper actuation.

Damper actuation shall be in accordance with Sections 717.3.3.1 through 717.3.3.4 as applicable.

717.3.3.1 Fire damper actuation device.

The fire damper actuation device shall meet one of the following requirements:

1. The operating temperature shall be approximately 50°F (10°C) above the normal temperature within the duct system, but not less than 160°F (71.1°C).

2. The operating temperature shall be not more than 350°F (176.7°C) where located in a smoke control system complying with Section 909.

717.3.3.2 Smoke damper actuation.

The smoke damper shall close upon actuation of a listed smoke detector or detectors installed in accordance with Section 907.3 and one of the following methods, as applicable:

1. Where a smoke damper is installed within a duct, a smoke detector shall be installed inside the duct or outside the duct with sampling tubes protruding into the duct. The detector or tubes within the duct shall be within 5 feet (1524 mm) of the damper. Air outlets and inlets shall not be located between the detector or tubes and the damper. The detector shall be listed for the air velocity, temperature and humidity anticipated at the point where it is installed. Other than in mechanical smoke control systems, dampers shall be closed upon fan shutdown where local smoke detectors require a minimum velocity to operate.

Exceptions:

1. Duct smoke detectors will not be required at each fire smoke damper where the supply fan shall shut down and all the fire smoke dampers associated with the supply system automatically close upon actuation of an automatic alarm initiating device on the floor(s).

2. Duct smoke detectors will be required within 5 feet (1524 mm) downstream of any electric duct reheat coil.

3. Non-ducted return air systems shall have a smoke detector located within 5 feet (1524 mm) upstream of each return air protected opening in a 2 hour fire rated barrier.

4. Ducted return air systems shall have a duct smoke detector located within 5 feet (1524 mm) of a smoke damper; additional smoke detectors will not be required at fire smoke dampers located downstream where there are no additional return air inlets.

2. Where a smoke damper is installed above smoke barrier doors in a smoke barrier, a spot-type detector shall be installed on either side of the smoke barrier door opening. The detector shall be listed for releasing service if used for direct interface with the damper.

3. Where a smoke damper is installed within an unducted opening in a wall, a spot-type detector shall be installed within 5 feet (1524 mm) horizontally of the damper. The detector shall be listed for releasing service if used for direct interface with the damper.

4. Where a smoke damper is installed in a corridor wall, the damper shall be permitted to be controlled by a smoke detection system installed in the corridor.

5. Where a smoke detection system is installed in all areas served by duct in which the damper will be located, the smoke dampers shall be permitted to be controlled by the smoke detection system.

6. Smoke dampers that are part of an engineered smoke control system shall be controlled in accordance with Section 607.3.3.2 of the New York City Mechanical Code.

717.3.3.3 Combination fire/smoke damper actuation.

Combination fire/smoke damper actuation shall be in accordance with Sections 717.3.3.1 and 717.3.3.2. Combination fire/smoke dampers installed in smoke control system shaft penetrations shall not be activated by local area smoke detection unless it is secondary to the smoke management system controls.

717.3.3.4 Ceiling radiation damper actuation.

The operating temperature of a ceiling radiation damper actuation device shall be 50°F (10°C) above the normal temperature within the duct system, but not less than 160°F (71.1°C).

717.4 Access and identification.

Fire and smoke dampers shall be provided with an approved means of access that is large enough to permit inspection and maintenance of the damper and its operating parts. The access shall not affect the integrity of fire-resistance-rated assemblies. The access openings shall not reduce the fire-resistance rating of the assembly. Access points shall be permanently identified on the exterior by a label having letters not less than 1/2 inch (12.7 mm) in height reading: FIRE/SMOKE DAMPER, SMOKE DAMPER or FIRE DAMPER followed by an identification marking that is individual and unique to the damper accessed.

717.5 Where required.

Fire dampers, smoke dampers, combination fire/smoke dampers, and ceiling radiation dampers shall be provided as specified in Sections 717.5.1 through 717.5.7 and 717.6. Where an assembly is required to have both fire dampers and smoke dampers, combination fire/smoke dampers or a fire damper and a smoke damper shall be provided.

Exception: Ducts 20 square inches (12 903.2 mm

2

) or less passing through fire-resistance rated assemblies shall not require fire dampers or fire smoke dampers.

717.5.1 Fire walls.

Ducts and air transfer openings permitted in fire walls in accordance with Section 706.11 shall be protected with listed fire dampers and smoke dampers installed in accordance with their listing.

Exception: Smoke dampers shall not be required in ducts where the air continues to move and the air-handling system installed is arranged to prevent recirculation of exhaust or return air under fire emergency conditions. The air-handling system shall be continuously monitored to ensure continuous airflow at a constantly attended location and be inspected and maintained in accordance with the system manufacturer's instructions.

717.5.1.1 Horizontal exits.

A listed smoke damper designed to resist the passage of smoke shall be provided at each point that a duct or air transfer opening penetrates a fire wall that serves as a horizontal exit.

717.5.2 Fire barriers.

Ducts and air transfer openings that penetrate fire barriers (horizontal and wall assemblies) shall be protected with listed fire dampers installed in accordance with their listing. Ducts and air transfer openings shall not penetrate enclosures for interior exit stairways and ramps and exit passageways, except as permitted by Sections 1023.5 and 1024.6, respectively. In addition, smoke dampers shall be installed in penetrations of public corridor and horizontal exit walls in accordance with Sections 717.5.2.1 and 717.5.2.2.

Exception: Fire dampers are not required at penetrations of fire barriers where any of the following apply:

1. Penetrations are tested in accordance with ASTM E 119 or UL 263 as part of the fire-resistance-rated assembly.

2. Ducts are used as part of an engineered smoke control system in accordance with Sections 717.2.1 and 909 of this code where the use of a fire damper would interfere with the operation of a smoke control system.

3. Such walls are penetrated by ducted HVAC systems, have a required fire-resistance rating of 1 hour or less, are in areas of other than Group H and are in buildings equipped throughout with an automatic sprinkler system in accordance with Section 903.3.1.1 or Section 903.3.1.2 of this code. For the purposes of this exception, a ducted HVAC system shall be a duct system for conveying supply, return or exhaust air as part of the structure's HVAC system. Such a duct system shall be constructed of sheet steel not less than No. 26 gage thickness and shall be continuous from the air-handling appliance or equipment to the air outlet and inlet terminals.

717.5.2.1 Horizontal exits.

A listed smoke damper designed to resist the passage of smoke shall be provided at each point a duct or air transfer opening penetrates a fire barrier that serves as a horizontal exit.

717.5.2.2 Public corridors.

A listed smoke damper designed to resist the passage of smoke shall be provided at each point a duct or air transfer opening penetrates a public corridor wall or floor constructed as a fire barrier.

Exceptions:

1. Smoke dampers are not required where the building is equipped throughout with an engineered smoke control system in accordance with Section 909, and smoke dampers are not necessary for the operation and control of the system.

2. Smoke dampers are not required in corridor penetrations where the duct is constructed of steel not less than 0.019-inch (0.48 mm) in thickness and there are no openings serving the corridor.

3. Smoke dampers are not required in corridor penetrations in Group R-2 buildings and Public Corridors serving R-2 spaces in mixed use buildings.

4. Smoke dampers shall not be required in ducts where the air continues to move and the air-handling system installed is arranged to prevent recirculation of exhaust or return air under fire emergency conditions. The air-handling system shall be continuously monitored to ensure continuous airflow at a constantly attended location and be inspected and maintained in accordance with the system manufacturer's instructions.

717.5.3 Shaft enclosures.

Ducts and air transfer openings shall not penetrate a shaft serving as an exit enclosure except as permitted by Section 1023.5. Shaft enclosures that are permitted to be penetrated by ducts and air transfer openings shall be protected with approved fire and smoke dampers installed in accordance with their listing.

Exceptions:

1. Fire dampers are not required at penetrations of shafts where any of the following criteria are met:

1.1. In buildings equipped throughout with an automatic sprinkler system in accordance with Chapter 9, steel exhaust subducts having minimum thickness of 0.0187 inch (0.4712 mm) (No. 26 gage) extend not less than 22 inches (558.8 mm) vertically in exhaust shafts provided that there is a continuous airflow upward to the outdoors whenever the building is occupied.

1.2. Penetrations are tested in accordance with ASTM E 119 or UL 263 as part of the fire-resistance-rated assembly.

1.3. Ducts are used as part of an approved smoke control system designed and installed in accordance with Section 909 and where the fire damper will interfere with the operation of the smoke control system.

1.4. The penetrations are in parking garage exhaust or supply shafts that are separated from other building shafts by not less than 2-hour fire-resistance-rated construction.

2. Smoke dampers are not required in exhaust ducts or shafts where the exhaust fan is maintained in operation whenever the building is occupied, in bathrooms and toilet room exhausts.

3. Smoke dampers are not required at penetrations of exhaust or supply shafts in parking garages that are separated from other building shafts by not less than 2-hour fire-resistance-rated construction.

4. Smoke dampers are not required at penetrations of shafts where ducts are used as part of an engineered mechanical smoke control system designed in accordance with Section 909 and where the smoke damper will interfere with the operation of the smoke control system.

5. Fire dampers and/or smoke dampers are not required at a shaft where the shaft is acting as an extension of the mechanical equipment room that it serves and the shaft and mechanical equipment room maintain fire and smoke separation required by the greater of the two spaces from the occupied portions of the building and meet the requirements of Sections 713.11 and 713.12.

6. Smoke dampers are not required to be located within a prescribed distance of a fire-rated enclosure within which the air handling equipment is located and where isolation smoke dampers are used in air-handling equipment in accordance with Section 607.2.3 of the New York City Mechanical Code.

7. Smoke dampers are not required in ducts where the air continues to move and the air-handling system installed is arranged to prevent recirculation of exhaust or return air during a fire emergency condition. Such fans shall be provided with standby power in accordance with Chapter 27.

717.5.3.1 Limitations.

Shafts that constitute air ducts shall be limited in accordance with Section 607.5.5.2 of the New York City Mechanical Code.

717.5.4 Fire partitions.

Ducts and air transfer openings that penetrate fire partitions shall be protected with listed fire dampers installed in accordance with their listing.

Exceptions: In occupancies other than Group H, fire dampers are not required where any of the following apply:

1. The fire partitions are for tenant separation or interior corridor walls in buildings equipped throughout with an automatic sprinkler system in accordance with Section 903.3.1.1 or 903.3.1.2 and the duct is protected as a through-penetration in accordance with Section 714.

2. The fire partitions are for tenant partitions in covered mall buildings where the walls are not required by provisions elsewhere in the code to extend to the underside of the floor or roof sheathing, slab or deck above.

3. The duct system is constructed of approved materials in accordance with the New York City Mechanical Code and the duct penetrating the wall complies with all of the following requirements:

3.1. The duct shall not exceed 100 square inches (64 516 mm

2

).

3.2. The duct shall be constructed of steel not less than 0.0217 inch (0.55 mm) in thickness.

3.3. The duct shall not have openings that communicate the corridor with adjacent spaces or rooms.

3.4. The duct shall be installed above a ceiling.

3.5. The duct shall not terminate at a wall register in the fire-resistance-rated wall.

3.6. A minimum 12-inch-long (304.8 mm) by 0.060-inch (1.52 mm) thick steel sleeve shall be centered in each duct opening. The sleeve shall be secured to both sides of the wall and all four sides of the sleeve with minimum 1 1/2-inch by 1 1/2-inch by 0.060-inch (38.1 mm by 38.1 mm by 1.52 mm) steel retaining angles. The retaining angles shall be secured to the sleeve and the wall with No. 10 (M5) screws. The annular space between the steel sleeve and the wall opening shall be filled with mineral wool batting or approved equivalent on all sides.

4. Such walls are penetrated by ducted HVAC systems, have a required fire-resistance rating of 1 hour or less, and are in buildings equipped throughout with an automatic sprinkler system in accordance with Section 903.3.1.1 or 903.3.1.2. For the purposes of this exception, a ducted HVAC system shall be a duct system for conveying supply, return or exhaust air as part of the structure's HVAC system. Such a duct system shall be constructed of sheet steel not less than No. 26 gage thickness and shall be continuous from the air-handling appliance or equipment to the air outlet and inlet terminals.

717.5.5 Smoke barriers.

A listed smoke damper designed to resist the passage of smoke shall be provided at each point a duct or air transfer opening penetrates a smoke barrier. Smoke dampers and smoke damper actuation methods shall comply with Section 717.3.3.2.

Exceptions:

1. Smoke dampers are not required where the openings in ducts are limited to a single smoke compartment and the ducts are constructed of steel.

2. Smoke dampers are not required in ducts where the air continues to move and the air-handling system installed is arranged to prevent recirculation of exhaust or return air under fire emergency conditions.

3. Smoke dampers are not required in smoke barriers required by Section 407.5 for Group I-2, Condition 2 where the HVAC system is fully ducted in accordance with Section 603 of the New York City Mechanical Code and where buildings are equipped throughout with an automatic sprinkler system in accordance with Section 903.3.1.1 and equipped with quick-response sprinklers in accordance with Section 903.3.2.

717.5.6 Exterior walls.

Ducts and air transfer openings in fire-resistance-rated exterior walls required to have protected openings in accordance with Section 705.10 shall be protected with listed fire dampers installed in accordance with their listing.

717.5.7 Smoke partitions.

A listed smoke damper designed to resist the passage of smoke shall be provided at each point that an air transfer opening penetrates a smoke partition. Smoke dampers and smoke damper actuation methods shall comply with Section 717.3.3.2.

Exception: Where the installation of a smoke damper will interfere with the operation of a required smoke control system in accordance with Section 909, approved alternative protection shall be utilized.

717.6 Horizontal assemblies.

Penetrations by ducts and air transfer openings of a floor, floor/ceiling assembly or the ceiling membrane of a roof/ceiling assembly shall be protected by a shaft enclosure that complies with Section 713 or shall comply with Sections 717.6.1 through 717.6.3.

717.6.1 Through-penetrations.

In occupancies other than Groups I-2 and I-3, a duct constructed of approved materials in accordance with the New York City Mechanical Code that penetrates a fire-resistance-rated floor/ceiling assembly that connects not more than two stories is permitted without shaft enclosure protection, provided a listed fire damper is installed at the floor line or the duct is protected in accordance with Section 714.4. For air transfer openings, see Section 712.1.9.

Exception: A duct serving a dwelling unit is permitted to penetrate three floors or less without a fire damper at each floor, provided such duct meets all of the following requirements.

1. The duct shall be contained and located within the cavity of a wall and shall be constructed of steel having a minimum wall thickness of 0.0187 inches (0.4749 mm) (No. 26 gage).

2. The duct shall open into only one dwelling or sleeping unit and the duct system shall be continuous from the unit to the exterior of the building.

3. The duct shall not exceed 5-inch (127 mm) nominal diameter and the total area of such ducts shall not exceed 100 square inches (0.065 m

2

) in any 100 square feet (9.3 m

2

) of floor area.

4. The annular space around the duct is protected with materials that prevent the passage of flame and hot gases sufficient to ignite cotton waste where subjected to ASTM E 119 or UL 263 time-temperature conditions under a minimum positive pressure differential of 0.01 inch (2.49 Pa) of water at the location of the penetration for the time period equivalent to the fire-resistance rating of the construction penetrated.

5. Grille openings located in a ceiling of a fire-resistance-rated floor/ceiling or roof/ceiling assembly shall be protected with a listed ceiling radiation damper installed in accordance with Section 717.6.2.1 of this code.

717.6.2 Membrane penetrations.

Ducts and air transfer openings constructed of approved materials in accordance with the New York City Mechanical Code that penetrate the ceiling membrane of a fire-resistance-rated floor/ceiling assembly or roof/ceiling assembly shall be protected with one of the following:

1. A shaft enclosure in accordance with Section 713.

2. A listed ceiling radiation damper and firestopping is installed at the ceiling line where a duct penetrates the ceiling of a fire-resistance-rated floor/ceiling assembly or roof/ceiling assembly.

3. A listed ceiling radiation damper and firestopping is installed at the ceiling line where a diffuser with no duct attached penetrates the ceiling of a fire-resistance-rated floor/ceiling assembly or roof/ceiling assembly.

717.6.2.1 Ceiling radiation dampers.

Ceiling radiation dampers shall be tested in accordance with Section 717.3.1. Ceiling radiation dampers shall be installed in accordance with the details listed in the fire-resistance-rated assembly and the manufacturer's instructions and the listing. Ceiling radiation dampers are not required where one of the following applies:

1. Tests in accordance with ASTM E 119 or UL 263 have shown that ceiling radiation dampers are not necessary in order to maintain the fire-resistance rating of the assembly.

2. Where exhaust duct penetrations are protected in accordance with Section 714.4.2 of this code, are located within the cavity of a wall and do not pass through another dwelling unit or tenant space.

3. Where duct and air transfer openings are protected with a duct outlet protection system tested as part of a fire-resistance-rated assembly in accordance with ASTM E 119 or UL 263.

717.6.3 Non- fire-resistance-rated floor assemblies.

Duct systems constructed of approved materials in accordance with the New York City Mechanical Code that penetrate non- fire-resistance-rated floor assemblies shall be protected by any of the following methods:

1. A shaft enclosure in accordance with Section 713.

2. The duct connects not more than two stories and the annular space around the penetrating duct is protected with a listed noncombustible material that resists the free passage of flame and the products of combustion.

3. In floor assemblies composed of noncombustible materials, a shaft shall not be required where the duct connects not more than three stories, the annular space around the penetrating duct is protected with an approved noncombustible material that resists the free passage of flame and the products of combustion and a fire damper is installed at each floor line.

Exception: Fire dampers are not required in ducts within individual residential dwelling units.

717.7 Flexible ducts and air connectors.

Flexible ducts and air connectors shall not pass through any fire-resistance-rated assembly. Flexible air connectors shall not pass through any wall, floor or ceiling.