APPLICATION
The Det-Tronics U5005 Smoke Detector is a sensitive
yet rugged, state-of-the-art protection device that is
designed for classified areas in hazardous industrial
and commercial locations. The detector is designed
to operate effectively with both slow smoldering and
fast burning fires. Typical applications that use the
U5005 include:
• Combustible storage facilities
• Munitions manufacturing
• Volatile chemical storage
• Chemical processing plants
• Petroleum refineries
• Turbine enclosures.
DESCRIPTION
The photoelectric smoke detector uses a solid state
infrared emitting diode (IRED) and a light sensing
photovoltaic cell arranged in a labyrinth assembly.
The labyrinth permits free access to smoke but
restricts external light. Because of its critical function
to the operation of the detector, each IRED is select-
ed with extreme care and is subjected to rigorous
pre-production testing to ensure long-term reliability
and performance.
During normal operation (no smoke), the detector
samples the air approximately every four seconds for
a period of less than one millisecond. The photo-
voltaic smoke cell, which is placed at an angle to the
pulsed invisible light source, is sensitive to the
infrared light in the specified frequency emitted by
the IRED light source and is designed to receive a
signal only when the pulsed IRED source is activat-
ed. See Figure 1.
When smoke enters the chamber, the light from the
IRED reflects off the smoke particles and reaches the
photovoltaic smoke cell. When the amount of light
reflected by smoke reaches the factory set threshold
level, the smoke alarm circuit is actuated.
The detector will respond to a slow smoldering fire
when smoke in the chamber reaches the pre-set sen-
sitivity setting, typically 2.3%.
If a fast burning fire should occur, including fires in
flammable liquids and other materials such as plas-
tics that generate black smoke, the abnormally rapid
movement of smoke into the detection chamber is
sensed by a special rate compensating circuit. An
increase in smoke within the detection chamber that
exceeds a pre-set rate causes the rate compensation
circuit to increase the intensity of the light source,
which increases detector sensitivity. If the smoke
continues to build at this rate, an amplifier circuit is
triggered and the unit generates an alarm. If not, the
detector reverts to normal sensitivity.
INSTRUCTIONS
Smoke Detector
for Classified Areas
U5005
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