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8
en | System Overview
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 dual-optical detectors make an alarm decision based on an intelligent combination of the
i
following criteria:
Amount of smoke density measured
Speed of smoke density increase
Size of smoke particles (as measured by Dual Ray technology)
2.2.2
Thermal Sensor (Heat Detector)
A thermistor 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 category, 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).
2.2.3
Chemical Sensor (Gas Sensor)
The chemical sensor detects mainly the carbon monoxide
(CO) that a fire produces. The chemical sensor also detects
hydrogen (H) and nitrogen monoxide (NO).
The underlying measurement principle is CO oxidation and the
measurable current that it creates. The sensor signal value is
proportional to the concentration of gas.
The chemical sensor gives additional information. Therefore
the chemical sensor is essential to suppress disturbance
variables reliably.
CO fire sensors can react promptly to smoldering fires. In many case they are better suited to
applications where other fire detection techniques are prone to false alarms. As a result, CO-
detection helps to support an even more reliable fire detection and leads in parallel to a
higher false alarm stability. This behavior is described in the guidelines VdS 6017, VdS 6018,
VdS 6019.
2.3
Two-color LED
The LSN improved detector has one centrally positioned two-color LED that flashes red when
indicating an alarm. When the alarm is canceled through the fire panel, then the detector
returns to its operating condition.
In operating condition the LED is off by default. Showing the operating condition can be
enabled with FSP-5000-RPS. Then, the LED flashes green to indicate the operating condition.
2.4
Features
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–
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2023-06 | 07 | F.01U.283.550
Active self-monitoring of the sensors, with display on the fire panel:
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Active adjustment of the threshold (drift compensation) if the optical sensor
becomes contaminated.
–
Active adjustment of the threshold (drift compensation) of the chemical sensor.
At up to 50 V/m, the EMC is significantly higher than the normative requirements.
Preservation of LSN loop functions in the event of wire break or short-circuit of a detector
through integrated isolators.
User manual
AVENAR detector 4000
3
Chemical sensor
Bosch Sicherheitssysteme GmbH
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