Where To Place Detectors And Sensors; Proper Locations For Detectors And Sensors - Simplex 4098 Applications Manual

Where to Place Detectors and Sensors

Proper Locations
IMPORTANT: The guidelines in this section are adapted from standards
for Detectors
and Sensors
To provide effective early warning of a developing fire situation, smoke detectors/sensors should
be installed in all areas of the protected premises. Total coverage as defined by NFPA 72 should
include all rooms, halls, storage areas, basements, attics, lofts, and spaces above suspended
ceilings including plenum areas utilized as part of the HVAC system. In addition, this should
include all closets, elevator shafts, enclosed stairways, dumbwaiter shafts, chutes and other
subdivisions and accessible spaces.
Fire detection systems installed to meet local codes or ordinances may not be adequate for early
warning of the fire. Some codes or ordinances have minimum objectives such as capturing
elevators or preventing circulation of smoke through HVAC systems instead of early detection of
fire.
You should weigh the costs against the benefits of installing a complete fire detection system
when any detection system is being installed. The location, quantity and zoning of
detectors/sensors should be determined by what objectives are desired rather than the minimum
requirements of any local codes or ordinances.
Detectors/sensors may be omitted from combustible blind spaces when any of the following
conditions prevail:
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Detectors/sensors may also be omitted from below open grid ceilings where all of the following
conditions are met:
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published by the National Fire Protection Association, Quincy,
Massachusetts, U. S. A. These standards include NFPA 72,
"National Fire Alarm Code"; NFPA 70, "National Electrical Code",
Article 760; and NFPA 90A, "Standard for the Installation of
Air Conditioning and Ventilating Systems."
Where the ceiling is attached directly to the underside of the supporting beams of a
combustible roof or floor deck.
Where the concealed space is entirely filled with noncombustible insulation. (In solid joist
construction, the insulation need only fill the space from the ceiling to the bottom edge of the
joist of the roof or floor deck.)
Where there are small concealed spaces over rooms, provided the space in question does not
exceed 50 square feet (4.6 square meters).
In spaces formed by sets of facing studs or solid joists in walls, floors, or ceilings where the
distance between the facing studs or solid joists do not exceed 6 inches (15 cm).
The openings of the grid are at least 1/4 inch (6 mm) in the smallest dimension.
The thickness of the material does not exceed the smallest of the grid openings.
The openings constitute at least 70% of the area of the ceiling material.
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