September 30, 2010
Carl Schmidt, Bristolite
Smoke and heat vents, working in conjunction with draft curtains, have long been
used as an effective fire protection measure. They can typically be found installed
in warehouses, stores and malls. They provide a pre-established path for hot gases
and smoke to exit a building and offer several key benefits:
- Minimize structural damage
By preventing heat from mushrooming over the fire area and heating other materials
to the point of ignition, fire venting has a marked effect on reducing the lateral
spread of fire
- Improve fire-fighting efficiency and safety
Fire vents allow arriving firefighters to quickly determine the approximate interior
location of the fire by observing the exterior location of the smoke plume from
the open vents. Prompt venting has also been proven to reduce dangerous heat, vision-obscuring
smoke and toxic or potentially explosive products of combustion.
- Enhance occupant life safety
Raising the smoke layer inside a burning building not only improves visibility of
exit paths, it helps save lives given that the vast majority of fire fatalities
are due to smoke inhalation.
These benefits are essentially why building codes have mandated the use of smoke/heat
vents in large-area single-level buildings (i.e.; warehouses, discount centers,
manufacturing facilities, etc.) for many years.
Current standards governing the acceptance, listing and approval of smoke and heat
vent products are primarily UL 793-08, Standards for Automatically
Operated Roof Vents for Smoke and Heat, National Fire Protection Association
(NFPA) 204-07, Standard for Smoke and Heat Venting,
FM Global 4430 (2007), Approval Standard for Smoke and Heat
Vents and ICC-ES AC331-2008, Acceptance Criteria for
Smoke and Heat Vents. There are cross-references among these standards
(for example, UL-793 is referenced within ICC-ES AC331), and various code requirements
are based on them, including applicable provisions of NFPA 204-07, the International
Building Code (IBC) and the International Fire Code (IFC). There are also allied
standards, such as NFPA 92B, Standard for Smoke Management
Systems in Malls, Atria and Large Spaces and the international standards
ISO 21927-2:2006, Smoke and heat control systems -- Part
2: Specification for natural smoke and heat exhaust ventilators and ISO
21927-1:2008, Smoke and heat control systems -- Part 1: Specification
for smoke barriers, but the UL, FM and ICC standards most often govern
in the U.S.
In general, once the performance tests have been completed as specified within each
document, the product may be “listed” by UL, “approved” by FM Global or “recognized”
by the ICC Evaluation Service. Product labels may be specified. However, it is virtually
always left up to the Authority Having Jurisdiction (AHJ) – such as the local Building
Department – to specify which standards must be met and which identification methods
must be used.
Smoke and Heat Vent Standards table summarizes the current requirements
of these standards for dome or metal lid mechanically operated units. These are
mechanically-opened vents consisting primarily of a body frame, one or more damper
covers or hatches and operating mechanisms, which generally include a heat responsive
device and spring(s).
AAMA’s Smoke Vent Task Group has been at work over the last several years to foster
research testing that has helped shape these standards and influence code changes
to reflect actual in-field performance and interaction of building fire protection
systems. The task group will continue to monitor standards and code activities and
develop educational information to ensure the standards are of practical use to
project specifiers, owners, fire authorities, code officials and others involved
in the field.