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Chapter 1: Fire geometry and smoke movement in buildings
Dampers
Dampers in air-moving systems are used to balance and
control airflow, relieve excess pressure, and resist fire or
smoke passage. Fire, smoke, or ceiling dampers are the
three types of dampers used in buildings.
Fire dampers are used for the protection of openings in
walls, partitions, or floors and are rated at 1-1/2 to
3 hours. Fire dampers are installed in accordance with
UL 555, Standard for Safety Fire Dampers. A fire
damper does not prevent the leakage of smoke through
the opening and is normally released by a fusible link.
Smoke dampers resist the passage of smoke and
protect openings in smoke barriers or as a part of
engineered smoke control systems. Smoke dampers are
installed in accordance with UL 555S, Standard for
Safety Leakage Rated Dampers for Use in Smoke
control Systems. Combination fire/smoke dampers will
have a fire resistance rating and meet both UL 555 and
UL 555S.
Ceiling dampers or other methods for protecting
openings in floor/roof-ceiling assemblies are installed in
accordance with UL 555C, Standard for Safety Ceiling
Dampers.
Fire and ceiling dampers are designed to close upon the
operation of a fusible link. When dampers are part of an
engineered smoke control system the temperature rating
of the fusible links must be 50 degrees above the
maximum smoke control system designed operating
temperature with some additional qualifiers found in
UL 555S.
With the remote operation of dampers for the engineered
smoke control system, dampers must have provisions
that allow them to re-close automatically upon reaching
the damper's maximum degradation temperature as
defined in UL 555S.
Completion of smoke damper travel to either the fully
open or the fully closed state must be accomplished
within 75 seconds and be confirmed at the FSCS.
Note:
Local codes may require different response times
for smoke dampers. See "System response time" on
page 42.
Louvers and vents
Various combinations of louvers, vents, and nonrated
dampers can be used as a part of a smoke control
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system. These venting methods are used to prevent
over-pressurization of stairwells, elevator shafts and
smoke zones. Vents can provide relief using barometric
dampers with adjustable counterweights or electric or
pneumatic motor-operated dampers.
Venting in stairwell and some atrium smoke control
systems may use side-swinging doors that open to the
exterior in lieu of louvers or vents. Exterior doors
produce a constant-supply air rate, a recognized
advantage in the design of stair systems on several
fronts, including a requirement in the Supplement to the
National Building Code of Canada. Exterior door opening
is a method of reducing pressure fluctuations in the
stairwell in the same way in which louvers and vents are
used.
Movable louvers may be used in elevator or stairwell
pressurization systems and must be interconnected to
the smoke control system to ensure that they open in the
proper sequence. Movable louvers may also be used for
some building or zoned smoke control systems. For
whichever device is selected, there should be a
capability to close the opening should smoke begin to
enter through it.
Doors for makeup air
The simplest method of introducing makeup air into an
area is via direct openings to the outside using doors
and louvers, which can be opened upon system
activation. For new construction, the architectural
designer, in concert with the smoke control system
designer, can place these opening below the expected
smoke layer. For locations where such openings are
impractical, a powered supply system will likely be used.
Door and wall closers
In the last decade, several manufacturers have
developed rolling or bifold door and wall systems, which
can be used to create a smoke zone, isolate elevator
shafts, lobbies, or areas of refuge.
Smoke barriers, other than side swinging doors, are
supplied by a small number of manufacturers. The
Won-Door Co. has received a door and a wall rating for
their bifold system; McKeon Rolling Door has a
rolling/swinging door combination; and SmokeGuard
Corp. has an elevator opening protective. Listing
directories for buildings materials contain specifics about
these products.
VM-1 Smoke Management Application Guide
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