Filter
Top Products
LSN Peripherals | LSN Smoke | 339
FAP‑420/FAH‑420 Auto-
matic Fire Detectors LSN
improved version
Features
▶
Combination of optical, thermal and chemical sensors
with intelligent evaluation electronics.
▶
Detector properties adapted to cater for room usage
▶
Drift compensation in optical and gas measurement
section
▶
Maintains LSN loop functions in the event of wire
interruption or short-circuit thanks to two integrated
isolators
▶
Extended system parameters of improved LSN
technology
The 420 Series Automatic Fire Detectors combine the
advantages of the improved LSN technology with the
performance characteristics of the proven MAGIC.SENS
Fire Detectors, which are distinguished by superb accuracy
as well as detection speed and precision. These have been
specially designed for connection to the Modular Fire Panel
FPA‑5000 with the significantly improved LSN system
parameters. Integrated turning switches ensure easy
addressing of detectors, either automatically or manually,
as well as with or without autodetection.
System Overview
Operating mode Detector type
FAP-
OTC 420
FAP-OT 420 FAP-
O 420(KKW
)
FAH-
T 420(KKW)
Combined x x - -
Optical x x x -
Thermo-max. x x - x
Thermal
differential
x x - x
Chemical
(+ optical)
x - - -
Functions
Sensor technology and signal processing
The individual sensors can be configured via the LSN
network manually or using a timer.
All sensor signals are analyzed continually by the internal
evaluation electronics and are linked with each other via an
inbuilt microprocessor. The link between the sensors
means that the combined detectors can also be used where
light smoke, steam or dust must be expected during the
course of normal operation.
Only if the signal combination corresponds to that for the
programming of the selected usage site field code will the
alarm be triggered automatically. This results in a higher
level of security against false alarms.
In addition, the time curve for fire and malfunction
detection sensor signals is also analyzed, resulting in
increased reliability of detection for each individual sensor.
In the case of the optical and chemical sensor, the response
threshold (drift compensation) is actively adjusted. Manual
or time-controlled switch-off of individual sensors is
required for adjustment to extreme interference factors.
Optical sensor (smoke sensor)
The optical sensor uses the scattered-light method.
An LED transmits light to the measuring chamber, where it
is absorbed by the labyrinth structure. In the event of a fire,
smoke enters the measuring chamber and the smoke
particles scatter the light from the LED. The amount of light
hitting the photo diode is converted into a proportional
electrical signal.
Thermal sensor (temperature sensor)
A thermistor in a resistance network is used as a thermal
sensor, from which an analog-digital converter measures
the temperature-dependent voltage at regular intervals.
Depending on the specified detector class, the temperature
sensor triggers the alarm status when the maximum
temperature of 54 °C or 69 °C is exceeded (thermal
maximum), or if the temperature rises by a defined amount
within a specified time (thermal differential).
www.boschsecurity.com Bosch Security Systems B.V.
6