System Overview; Detector Configuration; Functional Description Of The Sensor Technology; Optical Sensor (Smoke Detector) - Bosch FAP-DO420 Operation Manual

6 en | System Overview
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System Overview

2.1

Detector Configuration

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2.2

Functional Description of the Sensor Technology

2.2.1

Optical Sensor (Smoke Detector)

This optical sensor utilizes the scattered-light method.
An LED sends light into the measuring chamber (see , page 6, item 1), where it is absorbed by
the labyrinth structure. In the event of a fire, smoke enters the measuring chamber. The light
is scattered by the smoke particles and hits the photo diodes, which transform the quantity of
light into a proportional electrical signal.
The DO detectors have a dual optical sensor that uses the different infrared and blue light
wavelengths (Dual Ray technology). This allows fires to be detected early and even the
smallest quantities of smoke (TF1, TF9) to be reliably detected.
Notice!
The FAP-DO420 smoke detector makes an alarm decision based on an intelligent combination
of the following criteria:
i
Amount of smoke density measured
Speed of of smoke density increase
Size of smoke particles (as measured by Dual Ray Technology)
2.2.2

Thermal Sensor (Heat Detector)

A thermistor (see , page 6, item 2) in a resistance network is used as a thermal sensor; an
analog-digital converter measures the temperature-dependent voltage at regular intervals.
Depending on the specified detector class, the thermal 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).
12/2012 | 8.1 | F.01U.003.448
Smoke measurement chamber with
optical sensor
Thermal sensor
Chemical sensor (covered on the cross-
section)
Individual display
PC board with evaluation electronics
MS 400 / MS 400 B Detector Base
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Detector Configuration
Operation Guide
Automatic Fire Detectors LSN
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