Honeywell INTELLIKNIGHT 5820XL - Manual (Page 17)

Introduction
151209 1-5
Limitations of Fire Alarm Systems
Manufacturer recommends that smoke and/or heat detectors be located throughout a
protected premise following the recommendations of the current edition of the
National Fire Protection Association Standard 72 (NFPA 72), manufacturer’s
recommendations, State and local codes, and the recommendations contained in
Guide for the Proper Use of System Smoke Detectors, which is made available at no
charge to all installing dealers. A study by the Federal Emergency Management
Agency (an agency of the United States government) indicated that smoke detectors
may not go off or give early warning in as many as 35% of all fires. While fire alarm
systems are designed to provide 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. For example:
• 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.
In general, smoke detectors on one level of a structure cannot be expected to sense
fires developing on another level.
• 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.
• Smoke detectors, even when working properly, have sensing limitations.
Detectors that have photoelectronic sensing chambers tend to detect smoldering
fires better than flaming fires, which have little visible smoke. Detectors that have
ionizing-type sensing chambers tend to detect fast flaming fires better than
smoldering fires. Because fires develop in different ways and are often
unpredictable in their growth, neither type of detector is necessarily best and a
given type of detector may not provide adequate warning of a fire.
• Smoke detectors are subject to false alarms and nuisance alarms and may have
been disconnected by users. For example, a smoke detector located in or near a
kitchen may go into nuisance alarm during normal operation of kitchen
appliances. In addition, dusty or steamy environments may cause a smoke
detector to falsely alarm. If the location of a smoke detector causes an abundance
of false alarms or nuisance alarms, do not disconnect the smoke detector; call a
professional to analyze the situation and recommend a solution.
• Smoke detectors cannot be expected to provide adequate warning of fires caused
by arson, children playing with matches (especially within bedrooms), smoking in
bed, violent explosions (caused by escaping gas, improper storage of flammable