Technical data

Automatic Fire Detectors LSN improved
version
Programming | en 13
Bosch Sicherheitssysteme GmbH Product Information F.01U.003.449 | 7.2 | 2010.05
4.4 FAH-T 420/FAH-T 420-KKW
Sensitivity classes as per EN 54 Part 5
With the detector types FAH-T 420 and FAH-T 420-KKW, it is possible to set one of the
sensitivity classes listed above in line with planning.
In the sensitivity classes A1, A2S and BS, the FAH-T 420 or FAH-T 420-KKW is operated purely
as a thermal maximum detector. In this case, the detector does not activate at below 54 °C in
class A2S, and not below 69 °C in class BS.
The sensitivity classes A2S and BS are therefore particularly suitable for applications where
higher temperature rates-of-rise occur over a longer period, e.g. in kitchens or boiler rooms.
The sensitivity classes A1R, A2R and BR indicate that the thermal differential unit is active in
addition to the thermal maximum unit.
These sensitivity classes are especially well-suited for use in unheated buildings where the
ambient temperature can vary greatly but high temperature rates-of-rise do not last long.
The thermal differential unit enables class A1R/A2R detectors to respond at T<54 °C and class
BR detectors at T<69 °C.
The selection of the sensitivity class also depends on the installation height of the detector.
To maintain the greatest possible security against false alarms, classes A1 and A1R should not
be selected for room heights below 6 m, although these classes are in theory permitted.
Furthermore, the expected application temperature must be taken into consideration.
EDP room High
High storage warehouse without vehicle traffic with combustion
engine
High
Office (day mode) Medium
Installation locations Selectable sensitivity
Selectable installation locations in the programming software (WinPara and
FSP-5000-RPS)
§ A2R Typical application temperature: 25 °C, T
max
+ T
diff
, height up to 6 m
A2S Typical application temperature: 25 °C, only T
max
, height up to 6 m
A1R Typical application temperature: 25 °C, T
max
+ T
diff
, height 6 m to 7.5 m
A1 Typical application temperature: 25 °C, only T
max
, height 6 m to 7.5 m
BR Typical application temperature: 40 °C, T
max
+ T
diff
, height up to 6 m
BS Typical application temperature: 40 °C, only T
max
, height up to 6 m
§ = Basic setting in the WinPara and FSP-5000-RPS programming software
Temperature
rate-of-rise [K
min
-1
]
Response time for detectors in the
sensitivity class A1R
Response time for detectors in the
sensitivity classes A2R/BR
Lower limiting
value [min/sec]
Upper limiting
value [min/sec]
Lower limiting
value [min/sec]
Upper limiting
value [min/sec]
10 1min 4min 20s 2min 5min 30s
20 30 s 2 min 20 s 1 min 3 min 13 s
30 20 s 1 min 40 s 40 s 2 min 25 s