Location And Spacing - Bosch D296 Application Manual

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2.4

Location and Spacing

Section 5.7.3.4.1 NFPA 72, National Fire Alarm
Code (2002 Edition) states: "Projected beam-type
smoke detectors shall be located in accordance with
the manufacturer's documented instructions."
The D296/D297 Series allows a range of 30 ft to
350 ft (9 m to 106 m) and spacing up to 60 ft
(18.3 m). Space the detectors no more than 60 ft
Figure 4: Location and Spacing
¼ S
1 - Transmitters (2)
S = Selected detector spacing
2.5 Ceilings
2.5.1 Flat Ceilings
Projected beam applications have a flat, smooth
ceiling with a height of 12 ft (3.6 m) or lower and
beam or solid joist depths of 1 ft (0.3 m) or less.
Open trusses less than 10% material and 90% open
air do not affect the flow of smoke. Smooth flat
ceiling guidelines apply where the trusses are used.
Figure 5: Flat Ceiling – Example A
1 - Transmitters (5)
S = Selected detector spacing
Bosch Security Systems, Inc. | 01/07 | F01U500951-01
½ S
1
S
2
½ S
1 ½ S
S
1
2 - Receivers (5)
D296/D297 | Application Guide | 2.0 Applications
(18.3 m) between projected beams and no more than
half the spacing between a projected beam and a
sidewall. You can determine other spacing based on
ceiling height, airflow characteristics, and response
requirements. In some cases, mount the transmitter
on one end wall and mount the receiver on the
opposite wall. You can also mount the transmitter
and receiver up to one-quarter of the spacing
distance from the end walls. Refer to Figure 4.
2 - Receivers (2)
Use normal spacing when the projected beams are
running in the direction parallel to the run of the
beams or solid joists. Use half spacing when the
projected beams are running at right angles to the
run of the beams or solid joists. A joist is a support
that is 4 in. (100 mm) or more in depth and 3 ft (0.9
m) or less in spacing. A beam is a support that is 4
in. (100 mm) or more in depth and 3 ft (0.9 m) or
more in spacing. Refer to Figure 5.
½ S
3 - Ceiling beams (joists [2])
2
¼ S
1
2
3
2
5