Bosch D296 Application Manual page 6

D296/D297 | Application Guide | 2.0
Place the detectors in every ceiling beam pocket when the ceiling beams (joists) exceed 1 ft (.03 m), the spacing
between the beams exceeds 8 ft (2.4 m), or the ceiling height exceeds 12 ft (3.6 m).
If you expect the fire size to exceed 1 MW (1000 kW), the ceiling height can be up to 28 ft before each beam
pocket must be treated separately. Review Section B-2 Performance-Based Approach to Designing and Analyzing Fire
Detection Systems in NFPA 72, National Fire Alarm Code (2002 Edition) to determine the potential fire size at the
location. Refer to Figure 6.
Figure 6: Flat Ceiling – Example B
1
1 - Transmitters (5)
2 - Receivers (5)
2.5.2 Sloped Ceilings
Use the spacing for flat beamed ceilings in installations with beams running parallel to (up) the slope. The ceiling
height is the average height over the slope. For slopes greater than 10°, detectors at half the spacing from the low
end are not required. Spacing is measured along a horizontal projection of the ceiling.
Use the spacing for flat beamed ceilings in installations with the beams running perpendicular to (across) the
slope. One set of beams must be within 3 ft (1 m) measured horizontally of the high point of the ceiling (Figure 7).
Figure 7: Sloped Ceilings
2
S
°
1 - Slope 10 or less
2 - 3 ft (1 m) maximum
S = Selected detector spacing
6
Applications
3
4
S
3
3 - Ceiling beams (joists [2])
2
S
3 - Slope greater than 10
4 - Detector at ½ S not required
Bosch Security Systems, Inc. | 01/07 | F01U500951-01
2
1
S ½ S
°