Kidde Fire Systems DS Series, Application Manual

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K-76-1000 -18- July 2016
SMOKE DETECTOR SPACING
The DS-PS spot-type smoke detector spacing recommendation of 30 ft. (9.1 m) ±5% or 18 in. (460 mm)
is based upon the detector installation on a smooth ceiling that is 10 ft. (3 m) high. Detector coverage is
typically represented as a square, because most structures have flat sidewalls. Like spot-type heat
detectors, smoke detector coverage is a circle whose radius is 0.7 times the listed spacing. Since all of
the area within the detector’s circle of coverage is suitable for detecting smoke from fire, the shape and
dimensions of the detector coverage “square” may be modified. Note that, although the coverage “square”
is a “rectangle,” the coverage area is within the overall detector circle coverage. (Refer to Figure 3.)
Note: Unlike heat detectors, smoke detectors are not given a listed spacing. It is recommended that
smoke detectors be installed on S = 30 ft. (9.1 m) ±5% or 18 in. (460 mm) installed on “x” centers,
on smooth ceilings. NFPA 72, National Fire Alarm and Signaling Code contains additional infor-
mation regarding spacing adjustments.
Ceilings and Walls
Locate smoke detectors on the ceiling or, if on a sidewall, between the ceiling and 12 in. (300 mm) down
from the ceiling to the top of the detector.
Figure 10. DS-PS Smoke Detector Placement Near Ceiling/Wall Joints
For a smooth ceiling, for every point on the ceiling, locate the detector within a horizontal measurement
no greater than 0.7 times the selected spacing.
1. Smooth ceiling
2. Top of detector is acceptable in this area 3. Wall
4. Floor
2
3
4
12 in. (300 mm) max.
1