System Sensor BEAM1224, BEAM1224S - Manual (Page 3)

DETECTOR PLACEMENT
This section of the manual discusses the placement of projected beam detec-
tors. Though this information is based upon industry expertise, it is intended
to be used only as a technical guide. Always comply with the requirements of
applicable codes and standards such as, NFPA 72, National Fire Alarm Code,
as well as directives of the Authority Having Jurisdiction (AHJ). For general
information on the placement of detectors, read System Sensor’s Projected
Beam Detector Application Guide.
Projected beam detectors are usually located with their beams parallel to the
ceiling. However, they can be mounted vertically or at any angle to protect the
area involved. Since beam detectors sense the smoke buildup over a distance,
they are ideal for locations with high ceilings. They can also be mounted on a
wall or ceiling below the level of a spot type detector, reducing the effects of
air stratification. Some typical locations would include large areas with high
ceilings such as atriums, warehouses, and factories.
NOTE: Projected beam smoke detectors should always be mounted to stable
mounting surfaces. See the MOUNTING LOCATION section for details.
Some fire codes specify spacing on a given center-to-center distance between
detectors under ideal conditions. This spacing is based on rooms with smooth
ceilings and no physical obstructions between the contents being protected
and the detectors. Moreover, they are also based on a maximum ceiling
height, and on the assumption that the value and the combustible nature of
the contents of the room being protected do not warrant greater protection or
closer spacing.
In a room with a smooth ceiling, detectors should be spaced horizontally be-
tween 30 and 60 feet (9.1 to 18.3m). One-half that spacing between the beam
and the sidewall may be used as a guide. See Figure 1. The beam detector
can be mounted with the transmitter/receiver on one wall and the reflector
on the opposite wall, or both suspended from the ceiling, or any wall/ceiling
combination. In the case of the ceiling mount, the distance from the end walls
should not exceed one-quarter of the selected spacing (7.5 ft. [2.3m] maxi-
mum if the spacing is 30 ft. [9.1m]). See Figure 2.
fIgURE 1. SPACINg fOR SMOOTh CEILINg (SIDE vIEw):
1 / 2 S S
12 IN. MIN.
(0.3M)
30’ (9.1M) MAX
TO FIRST
DETECTORS
WALL
10’ (3.0M)
MIN.
TYPICAL
C0254-02
fIgURE 2. SPACINg fOR SMOOTh CEILINg (TOP vIEw):
16 FT. (5M) MINIMUM
328 FT. (100M) MAXIMUM
Tx/Rx REFLECTOR
S
Tx/Rx REFLECTOR
1 /
2
S MAXIMUM
1 /
4
S
MAX.
C0255-00
In the case of peaked or sloped ceilings, codes may specify spacing of detectors
by using horizontal spacing from the peak of the roof or ceiling. Figures 3 and
4 show the spacing for both the shed type and peaked type sloped ceilings.
On smooth ceilings, beam smoke detectors should generally be mounted a
minimum of 12 inches (0.3m) from the ceiling or beneath structural obstruc-
tions such as joists, ducts, etc. See Figure 1 In addition, beam smoke detectors
should be mounted vertically at least 10 feet (3.0 m) from the floor to avoid
common obstructions from normal building usage. In many cases, however,
the location and sensitivity of the detectors shall be the result of an engineer-
ing evaluation that includes the following: ceiling heights above 30 feet (9.1
m) – refer to the “Single-Ended Reflected Beam Smoke Detector” application
guide A05-0095 for more information regarding the effects of stratification,
structural features, size and shape of the room and bays, occupancy and uses
of the area, ceiling height, ceiling shape, surface and obstructions, ventilation,
ambient environment, burning characteristics of the combustible materials
present, and the configuration of the contents in the area to be protected. As
a general rule, reflective objects such as ductwork or windows should be a
minimum of 15 inches (38.1cm) from the path of the beam
fIgURE 3. SLOPED CEILINg (ShED TyPE):
S
3 FT.
(0.9M)MAX.
S
1 /
2 S MAX.
Tx/Rx
REFLECTOR
C0256-00
fIgURE 4. SLOPED CEILINg (PEAkED TyPE):
1 /
2 S
S
S
1 /
2 S
3 FT. (0.9M)
MAX.
3 FT. (0.9M)
MAX.
MOUNT SPOT DETECTOR
ANYWHERE IN THIS
AREA AT LEAST 4 IN. (100 mm)
VERTICALLY FROM PEAK
Tx/Rx
REFLECTOR
C0257-04
MOUNTINg LOCATIONS
Beam detectors require a stable mounting surface for proper operation. A sur-
face that moves, shifts, vibrates, or warps over time will cause false alarm or
trouble conditions. Initial selection of a proper mounting surface will elimi-
nate false alarms and nuisance trouble signals.
Mount the detector on a stable mounting surface, such as brick, concrete,
a sturdy load-bearing wall, support column, structural beam, or other sur-
face that is not expected to experience vibration or movement over time. DO
NOT MOUNT the beam detector on corrugated metal walls, sheet metal walls,
external building sheathing, external siding, suspended ceilings, steel web
trusses, rafters, nonstructural beam, joists, or other such surfaces.
In cases where only one stable mounting surface as defined above can be
used, the transmitter/receiver unit should be mounted to the stable surface
and the reflector should be mounted to the less stable surface. The reflector has
a much greater tolerance for the unstable mounting locations defined above.
D400-73-00 3 I56-2294-006R