Bosch D285DH User Manual
Fire Alarm Systems | D285DH Photoelectric Duct Smoke Detector Head (12 VDC or 24 VDC)
D285DH Photoelectric Duct Smoke
Detector Head (12 VDC or 24 VDC)
www.boschsecurity.com
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Commercial or residential applications
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Two-wire or four-wire application, depending on
base
base
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Chamber Check rapid-flash LED Automatic Trouble
Indication reports contaminated chamber
Indication reports contaminated chamber
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Flashing LED power indicator
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Steady-On LED alarm indicator
The D285DH duct detector head detects the large
smoke particles which typically result from wood,
paper, and fabric combustion.
The detector is part of a two component system: the
duct detector housing and the duct detector head. The
housing is permanently attached on the duct. The
interchangeable duct detector head quickly detaches
for replacement and cleaning without affecting circuit
wiring. The duct detector head attaches to the
following duct detector housings:
smoke particles which typically result from wood,
paper, and fabric combustion.
The detector is part of a two component system: the
duct detector housing and the duct detector head. The
housing is permanently attached on the duct. The
interchangeable duct detector head quickly detaches
for replacement and cleaning without affecting circuit
wiring. The duct detector head attaches to the
following duct detector housings:
• D340 Two-wire Duct Detector Housing (12 VDC or 24
VDC)
• D341 Four-wire Duct Detector Housing (24 VDC or
120 VAC)
• D342 Four-wire Duct Detector Housing (24 VDC or
220/240 VAC)
Functions
Detection chamber operation
The duct detector uses an infrared (IR) LED light
source and a silicon photodiode to measure light in a
chamber. In normal conditions the light is absorbed in
the chamber. The presence of a significant number of
particulates allows the light to reflect to the
photodiode. After three consecutive measurements
exceeding the basic level, the unit signals an alarm
source and a silicon photodiode to measure light in a
chamber. In normal conditions the light is absorbed in
the chamber. The presence of a significant number of
particulates allows the light to reflect to the
photodiode. After three consecutive measurements
exceeding the basic level, the unit signals an alarm
condition. The detector can be reset from the panel,
after an alarm condition is cleared, by interrupting
power.
The detection chamber, designed for reliable smoke
entry characteristics, is protected by a micro-fine
insect screen to reduce dust accumulation and insect
penetration and minimize nuisance alarms.
after an alarm condition is cleared, by interrupting
power.
The detection chamber, designed for reliable smoke
entry characteristics, is protected by a micro-fine
insect screen to reduce dust accumulation and insect
penetration and minimize nuisance alarms.
Chamber Check Feature
To further reduce nuisance alarms, the detector head
checks its calibration. This Chamber Check feature is
automatic. If the head is out of calibration for a period
exceeding 24 hours, the Trouble-Alarm LED flashes
once per second, three times the normal rate.
checks its calibration. This Chamber Check feature is
automatic. If the head is out of calibration for a period
exceeding 24 hours, the Trouble-Alarm LED flashes
once per second, three times the normal rate.
Testing
Internal diagnostic test
This head has a moisture-proof reed switch that reacts
to an external magnet for testing. The magnet test
simulates a 4% to 6% smoke obscuration, which
places the detector in an alarm condition. This test
results in specific LED and alarm circuit responses
indicating the:
This head has a moisture-proof reed switch that reacts
to an external magnet for testing. The magnet test
simulates a 4% to 6% smoke obscuration, which
places the detector in an alarm condition. This test
results in specific LED and alarm circuit responses
indicating the:
• Detector is within calibration standards
• Detector settings are outside sensitivity standards
• Detector is not operational
• Detector settings are outside sensitivity standards
• Detector is not operational