Where To Place Detectors/Sensors - Simplex 4098 Applications Manual

WHERE TO PLACE DETECTORS/SENSORS

Important: The guidelines in this section are adapted from standards 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."
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:
•
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).
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