Bosch FAS-420-TT Series - Air-Return Pipe for Pressure Areas and Atmospheric Loads

22 en | Technical specifications Aspiration smoke detector LSN improved
2020.04 | 6.1 | F.01U.029.275 Operation guide Bosch Sicherheitssysteme GmbH
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.
If these hoses exceed a maximum of 1m in length, the plan according to Section3Planning
applies. If structural circumstances dictate that lengths in excess of 1m are used, the pipe
system has to be calculated accordingly.
3.6.4 Air-return pipe for pressure areas and atmospheric loads
P1
P2
5
1
FAS / FCS
2
3
4
Principle of air return
P1/P2 Pressure areas 1 and 2
1 Detector module
2 Airflow sensor
3 Aspiration unit
4 Air-return pipe
5 Pipe system
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. The air-
return pipe can serve to equalize pressure or to prevent atmospheric loads (e.g. odors) in
neighboring spaces.
1
2
FAS-420 series
FAS-420 with air-return pipe
1 Smoke aspiration pipe
2 Air-return pipe
The air-return pipe is connected to the air exhaust duct inside the FAS-420 through the
ventilation grille. This requires the pre-punched opening in the protective grille to be broken
out.
!
Caution!
The air-return pipe of the smoke aspiration system should not exceed 2m. Longer returns
must be checked individually.