Defining The Response Sensitivity - Bosch FAS-420-TM-R Operation Manual

34 en | Planning
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Air pressure differences
There must be equal air pressure along the length of the aspiration pipe.
Notice!
If the aspirating smoke detectors and the pipe system are positioned in areas with different
air pressures, the air aspirated by the FAS-420-TM must be returned to the pressure area of
the pipe system (see Air-return pipe for pressure areas and atmospheric loads, page 23 ).
Notice!
FAS-420-TM series detectors with active fire source identification must be installed outside
the areas to be monitored and without an air-return pipe.
Notice!
As an air-return pipe needs to be provided when the FAS-420-TM series is used in areas with
varying air pressures, and given that no air-return pipe is possible with ROOM·IDENT, it is not
possible to use the FAS-420-TM series with ROOM·IDENT in areas with varying or fluctuating
air pressures.
4.4

Defining the Response Sensitivity

The sensitivity of smoke aspiration systems can be divided into certain fire sensitivity classes
in accordance with EN 54‑20 or ISO 7240-20. These fire sensitivity classes describe specific
examples of ways in which the systems can be applied. The permissible system plans given in
Standard pipe planning, page 36 can be determined for each classification.Smoke aspiration
systems with a higher fire sensitivity class according to EN 54‑20 or ISO 7240-20 also satisfy
the requirements of the lower classes.
Class
A
B
C
Notice!
Depending on the number of air sampling openings, fire sensitivity classes A, B and C can all
be achieved with the detection modules available.
The table shows the sensitivities you can choose from
2020.04 | 5.1 | F.01U.088.878
planning was carried out in accordance with "single-hole monitoring" (see Planning with
single-hole monitoring, page 40 ),
the airflow sensor was calibrated dependent on air pressure ( Air-Pressure-Dependent
Calibration, page 75 )
and no larger airflow fluctuations can occur.
Description
Aspirating smoke detector with
extremely high sensitivity
Aspirating smoke detector with
increased sensitivity
Smoke aspiration system with normal
sensitivity
Application example
Very early detection: significant smoke
dilution through air conditioning in IT
areas
Early detection: significant time gains
thanks to very early fire detection
(without air condition)
Normal detection: fire detection with the
advantages of smoke aspiration systems
Operation guide
Aspiration smoke detector LSN improved
Bosch Sicherheitssysteme GmbH