Bosch FAS-420-TM - Ceiling Lead-Through; Air-Return Pipe for Pressure Areas and Atmospheric Loads

FAS-420-TM Aspirating Smoke Detector Technical Specifications | en 25
Bosch Sicherheitssysteme GmbH Operation Guide F.01U.088.878 | 4.1 | 2010.11
2.6.3 Ceiling Lead-through
A concealed pipe system for area monitoring can be realized by installing in a false ceiling.
This requires the use of ceiling lead-throughs in the false ceiling. The ceiling lead-through can
be used with a false ceiling thickness of up to approx. 35 mm.According to the planning and
design guidelines, the ceiling lead-throughs are fitted with aspiration reducing film sheets
with defined air sampling openings and connected to the pipe system by means of aspiration
hoses (see Figure 2.20).
If these hoses exceed a maximum of 3 m in length, the plan according to Section 3 Planning,
page 33 applies.If structural circumstances dictate that lengths in excess of 3 m are used, the
pipe system has to be calculated accordingly.
2.6.4 Air-Return Pipe for Pressure Areas and Atmospheric Loads
If the aspirating smoke detectors and the pipe system are installed in areas with varying air
pressure, the aspirated air must be returned to the pressure area of the pipe system (see
Figure 2.21). The air-return pipe can serve to equalize pressure or to prevent atmospheric
loads (e.g. odors) in neighboring spaces.
Figure 2.20 Ceiling lead-throughs
1Ceiling
2T-fitting
3 Pipe system
4
Complete ceiling lead-
through
5 Aspiration hose for ceiling
lead-through
6 False ceiling
7 Knurled nut
8 Aspiration reducing film sheet
9Aspiration
1
2
3
4
6
7
8
9
5
Figure 2.21 Principle of air return
P1/P2 Pressure areas 1 and 2
1 Air-return pipe
2 Pipe system
2
FAS / FCS
1
P1
P2