6/28/2011 DOC.NO.: 150D - 1
P/N RE 150D Rev. No. 1
2
Fire Alarm System Limitations
An automatic fire alarm system
–typically made up of smoke
detectors, heat detectors, manual Call Points, audible warning
devices, and a fire alarm control with remote notification capability–
can provide early warning of a developing fire. Such a system,
however, does not assure protection against property damage or loss
of life resulting from a fire. The Manufacturer recommends that smoke
and/or heat detectors be located throughout a protected premise
following the recommendations of of IS 2189: 1999 and any other local
codes of practice that are applicable. While fire alarm systems are
designed to provide early warning against fire, they do not guarantee
warning or protection against fire. A fire alarm system may not provide
timely or adequate warning, or simply may not function, for a variety
of reasons:
Smoke detectors
may not sense fire where smoke cannot reach the
detectors such as in chimneys, in or behind walls, on roofs, or on the
other side of closed doors. Smoke detectors also may not sense a fire
on another level or floor of a building. A second-floor detector, for
example, may not sense a first-floor or basement fire.
Particles of combustion or "smoke"
from a developing fire
may not reach the sensing chambers of smoke detectors because:
• Barriers such as closed or partially closed doors, walls,
or chimneys may inhibit particle or smoke flow.
• Smoke particles may become "cold," stratify, and not
reach the ceiling or upper walls where detectors are
located.
• Smoke particles may be blown away from detectors by
air outlets.
• Smoke particles may be drawn into air returns before
reaching the detector.
The amount of "smoke" present may be insufficient to alarm smoke
detectors. Smoke detectors are designed to alarm at various levels of
smoke density. If such density levels are not created by a developing
fire at the location of detectors, the detectors will not go into alarm.
