SECTION
716 DUCTS AND AIR TRANSFER OPENINGS
716.1 General.
The provisions of this section shall govern the protection
of duct penetrations and air transfer openings in assemblies
required to be protected.
716.1.1
Ducts 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 Section 712.
716.2 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 manufacturer's
installation instructions and the dampers' listing.
716.2.1 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.
716.2.2 Hazardous exhaust ducts. Fire dampers for hazardous
exhaust duct systems shall comply with the International
Mechanical Code.
716.3
Damper testing and ratings. Dampers shall be listed and
bear the label of an approved testing agency indicating compliance
with the standards in this section. Fire dampers shall comply
with the requirements of UL 555. Only fire 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. Smoke dampers shall comply with
the requirements of UL 555S. Combination fire/smoke dampers
shall comply with the requirements of both UL 555 and UL 555S.
Ceiling radiation dampers shall comply with the requirements
of UL 555C.
716.3.1 Fire protection rating. Fire dampers shall have
the minimum fire protection rating specified in Table
716.3.1 for the type of penetration.
716.3.1.1 Fire damper actuating device. The fire
damper actuating device shall meet one of the following
requirements:
1.The
operating temperature shall be approximately 50°F (lO°C)
above the normal temperature within the duct system,
but not less than 160°F (71 DC).
2.The
operating temperature shall be not more than 286°F (l41°C)
where located in a smoke control system complying with
Section 909.
3.Where
a combination fire/smoke damper is located in a smoke
control system complying with Section
909, the operating temperature rating shall be approximately
50°F (lO°C) above the maximum smoke control system designed
operating temperature, or a maximum temperature of 350°F
(l77°C). The temperature shall not exceed the UL 555S
degradation test temperature rating for a combination
fire/smoke damper.
716.3.2 Smoke damper ratings. Smoke damper leakage ratings
shall not be less than Class II. Elevated temperature ratings
shall not be less than 250°F (l21 DC).
716.3.2.1 Smoke damper actuation methods. The smoke
damper shall close upon actuation of a listed smoke detector
or detectors installed in accordance with
Section 907.10 and one of the following methods, as
applicable:
1.Where
a damper is installed within a duct, a smoke detector
shall be installed in the duct within 5 feet (l524 mm)
of the damper with no air outlets or inlets between
the detector 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.
2.Where a damper is installed
above smoke barrier doors in a smoke barrier, a spot-type
detector listed for releasing service shall be installed
on either side of the smoke barrier door opening.
3.Where a damper is installed
within an unducted opening in a wall, a spot-type detector
listed for releasing service shall be installed within
5 feet (1524 mm) horizontally of the damper.
4.Where a damper is installed
in a corridor wall or ceiling, the damper shall be permitted
to be controlled by a smoke detection system installed
in the corridor.
5.Where a total-coverage
smoke detector system is provided within areas served
by a heating, ventilation and air-conditioning (HV AC)
system, dampers shall be permitted to be controlled
by the smoke detection system.
716.4
Access and identification. Fire and smoke dampers shall
be provided with an approved means of access, which 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 0.5 inch (12.7 mm) in
height reading: FIRE/SMOKE DAMPER, SMOKE DAMPER or FIRE DAMPER.
Access doors in ducts shall be tight fitting and suitable
for the required duct construction.
716.5
Where required. Fire dampers, smoke dampers, combination
fire/smoke dampers and ceiling radiation dampers shall be
provided at the locations prescribed in Sections 716.5.1 through
716.5.5. 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 required.
716.5.1 Fire walls. Ducts and air transfer openings
permitted in fire walls in accordance with Section
705.11 shall be protected with listed fire dampers installed
in accordance with their listing.
716.5.2 Fire barriers.
Ducts and air transfer openings of fire barriers shall be
protected with approved fire dampers installed in accordance
with their listing. Ducts and air transfer openings shall
not penetrate exit enclosures and exit passageways except
as permitted by Sections 1020.1.2
and 1021.5, respectively.
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
as part of the fire-resistance rated assembly.
2.Ducts are used as part
of an approved smoke control system in accordance with
Section 909 and where the use of
a fire damper would interfere with the operation of a
smoke control system.
3.Such walls are penetrated by ducted HV AC systems, have
a required fire-resistance rating of 1 hour or less, are
in areas of other than Group Hand 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 HV AC system shall be a duct
system for conveying supply, return or exhaust air as
part of the structure's HV AC system. Such a duct system
shall be constructed of sheet steel not less than 26 gage
thickness and shall be continuous from the air-handling
appliance or equipment to the air outlet and inlet terminals.
716.5.3 Shaft enclosures. 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:
1.1.
Steel exhaust subducts are extended at least 22 inches
(559 mm) vertically in exhaust shafts, provided there
is a continuous airflow upward to the outside; or
1.2.
Penetrations are tested in accordance with ASTM E 119
as part of the rated assembly; or
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; or 104. 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.In Group Band R occupancies, equipped throughout with
an automatic sprinkler system in accordance with Section
903.3.1.1, smoke dampers are not required at penetrations
of shafts where:
2.1.
Kitchen, clothes dryer, bathroom and toilet room exhaust
openings are installed with steel exhaust subducts,
having a wall thickness of at least 0.019 inch (0048
mm); and
2.2.
That extend at least 22 inches (559 mm) vertically;
and
2.3.
An exhaust fan is installed at the upper terminus of
the shaft that is, powered continuously in accordance
with the provisions of Section
909.11, so as to maintain a continuous upward airflow
to the outside.
3.Smoke dampers are not required
at penetration 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 approved 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.
716.5.4 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
partitions are tenant separation or 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
712.
2.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 deck above.
3.The
duct system is constructed of approved materials in accordance
with the International 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 (0.06 m2),
3.2.
The duct shall be constructed of steel a minimum of
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 (305 mm) by 0.060-inch-thick
(1.52 mm) 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
11/2-inch by 11/2-inch
by 0.060-inch (38 mm by 38 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 on all sides.
716.5.4.1
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 corridor enclosure
required to have smoke and draft control doors in accordance
with Section 715.4.3.
Exceptions:
1.Smoke dampers are not required where the building is
equipped throughout with an approved 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.
716.5.5 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 716.3.2.1.
Exception: Smoke dampers are not required where the openings
in ducts are limited to a single smoke compartment and the
ducts are constructed of steel.
716.6
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
707 or shall comply with Sections 716.6.1 through 716.6.3.
716.6.1 Through penetrations. In occupancies other than
Groups 1-2 and 1-3, a duct constructed of approved materials
in accordance with the International 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 712.4.
For air transfer openings, see Exception 7 to Section
707.2.
Exception: A duct is permitted to penetrate three floors
or less without a fire damper at each floor, provided it 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 not less than
0.019 inch (0.48 mm) (26 gage) in thickness.
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 4-inch (102 mm) nominal diameter
and the total area of such ducts shall not exceed 100
square inches (0.065 m2) in any I 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 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 716.6.2.1.
716.6.2 Membrane penetrations.
Ducts and air transfer openings constructed of approved
materials in accordance with the International Mechanical
Code that penetrate the ceiling membrane of a fire-resistance-rated
floor/ceiling or roof/ceiling assembly shall be protected
with one of the following:
1.A shaft enclosure in
accordance with Section 707.
2.A listed ceiling radiation
damper installed at the ceiling line where a duct penetrates
the ceiling of a fire-resistance-rated floor/ceiling
or roof/ceiling assembly.
3.A listed ceiling radiation
damper installed at the ceiling line where a diffuser
with no duct attached penetrates the ceiling of a fire-resistance-rated
floor/ceiling or roof/ceiling assembly.
716.6.2.1 Ceiling radiation dampers. Ceiling radiation
dampers shall be tested in accordance with UL 555C and
installed in accordance with the manufacturer's installation
instructions and listing. Ceiling radiation dampers are
not required where either of the following applies:
1.Tests
in accordance with ASTM E 119 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 712.4.1.2,
are located within the cavity of a wall and do not pass
through another dwelling unit or tenant space.
716.6.3
Nonfire-resistance-rated floor assemblies. Duct systems
constructed of approved materials in accordance with the
International Mechanical Code that penetrate nonfire-resistance-rated
floor assemblies shall be protected by any of the following
methods:
1.A shaft enclosure in accordance
with Section 707.
2.The
duct connects not more than two 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.
3.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.
716.7
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.
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