Honeywell AUTOMATIC CONTROL SI Edition, Инструкция по эксплуатации

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ENGINEERING MANUAL OF AUTOMATIC CONTROL
SMOKE MANAGEMENT FUNDAMENTALS
172
INTRODUCTION
This section describes objectives, design considerations,
design principles, control applications, and acceptance testing
for smoke management systems. A smoke management system
modifies the movement of smoke in ways to provide safety for
the occupants of a building, aid firefighters, and reduce property
damage. References are at the end of this section which include
smoke control codes.
Smoke is a highly toxic agent. Information from U.S. Fire
Administration estimates that in 1989 approximately 6,000 fire
fatalities occurred in the United States, and 80 percent of these
deaths were from inhalation of smoke. Furthermore, an
additional 100,000 individuals were injured, and fire damage
exceeded $10,000,000,000.
Long term effects on humans from repeated exposure to
smoke and heat is a major concern. According to the National
Institute of Building Sciences, “The significance of time of
human exposure is the fact that brief exposure to a highly toxic
environment may be survived, while a lengthy exposure to a
moderately toxic environment can lead to incapacitation,
narcosis, or death.”
1 The primary toxic agent produced in
building fires is carbon monoxide. Other toxic agents include
hydrogen cyanide, hydrogen chloride, sulphur dioxide, acrolein,
aldehydes, carbon dioxide, and a variety of airborne particulates
carrying heavy metals (antimony, zinc, chromium, and lead).
Early smoke management systems used the concept of passive
control to limit the spread of fire and smoke. This method
evolved from early fire containment methods used in high rise
buildings. With passive control, HVAC fans were shut down
and dampers were used to prevent smoke from spreading
through ductwork. This application required very-low-leakage
dampers. Fire walls or barriers, used to prevent the spread of
fire, were enhanced to prevent the spread of smoke.
In the late 1960s, the concept of active smoke control was
created. With active control, the HVAC fans activate to prevent
smoke migration to areas outside of fire zones. This method
includes pressurized stairwells and a technique sometimes
called the pressure sandwich or zoning in which the floors
adjacent to the fire floor are pressurized and the fire floor is
exhausted.
DEFINITIONS
AHJ: Authority Having Jurisdiction. (There may be more than
one authority.)
ASHRAE: American Society of Heating, Refrigerating and
Air-Conditioning Engineers, Inc.
Atrium: A large volume space within a floor opening or series
of floor openings connecting two or more stories,
covered at the top of the series of openings, and used
for purposes other than an enclosed stairway, elevator
hoistway, escalator opening, or utility shaft.
Buoyancy: The tendency of warmer air or smoke to rise when
located in cooler surrounding air. Caused by the
warmer air being less dense than the cooler air,
resulting in pressure differences.
Combination fire and smoke damper: A device that resists
the passage of air, fire, and smoke and meets the
requirements of UL 555, Standard for Fire Dampers,
and UL 555S, Standard for Leakage Rated Dampers
for Use In Smoke Control Systems.
Covered mall: A large volume space created by a roofed-over
common pedestrian area, in a building, enclosing a
number of tenants and occupancies such as retail stores,
drinking establishments, entertainment and amusement
facilities, and offices. Tenant spaces open onto, or directly
communicate with, the pedestrian area.
Expansion: The increase in the volume of smoke and gas
caused by the energy released from a fire.
Fire damper: A damper that meets the requirements of UL
555, Standard for Fire Dampers, and resists the passage
of air or fire.
FSCS: Firefighters’ Smoke Control Station.
Large volume space: An uncompartmented space, generally two
or more stories in height, within which smoke from a
fire, either in the space or in a communicating space,
can move and accumulate without restriction. Atria and
covered malls are examples of large volume spaces.
NFPA: National Fire Protection Association.
Pressure sandwich: An application where only the zones
adjacent to a smoke zone are pressurized and the fire
zone is exhausted to limit the spread of smoke.
Smoke: The airborne solid and liquid particulates and gases
developed when a material undergoes pyrolysis or
combustion, together with the quantity of air that is
entrained or otherwise mixed into the mass.
Smoke Control System: A system that modifies the movement
of smoke in ways to provide safety for the occupants of
a building, aid firefighters, and reduce property damage.