Principle Of Operation - Honeywell FS20X Series User Manual

FS20X Fire and Flame Detectors

Principle of Operation

Honeywell Analytics' Multi-Spectrum, Multi-Spectral, and MultiBand™ infrared (IR)
and ultraviolet (UV) fire and flame detectors are sophisticated, state of the art,
electro-optical digital radiant energy devices that sense the wideband radiant energy
emitted by combustion processes that include the molecular emissions and hot
particulate blackbody emissions in flames. Radiant energy fire detectors respond
much faster to flames and fires at a longer distances than conventional photoelectric
and ionization smoke and heat detectors because a fire radiates energy at the
speed of light. High speed of response is critical for detecting flaming fires in time to
activate suppression systems, close fire doors, etc. Seconds can make the difference
between suppressing a small fire with little or no damage or having a disastrous fire
which overwhelms a suppression system and fails to stop the fire.
Infrared light consists of spectral wavelengths longer than red while ultraviolet light
consists of wavelengths shorter than violet. Much of the IR and UV wavelengths
are invisible to humans. The FS20X™ detector operates from approximately 185.
This includes the visible spectrum, from about 400 to 700 nanometers (0.4 to 0.7
microns.) The visible band is used to discriminate against false alarm sources.
The detector senses radiant energy from both hydrocarbon and non-hydrocarbon
fires. Built-in microprocessors use digital signal processing (DSP) to distinguish
between radiant energy from a real fire and that from a false alarm source.
Honeywell Analytics has developed and refined these complex proprietary and
patented WideBand IR and UV algorithms for 30 years, beginning in 1981. These
patented algorithms perform real-time DSP, and precisely analyze the signals in
high-resolution frequency and time domains. This decision-making process involves
thousands of real-time calculations every second. Honeywell Analytics FSX™
detectors use solid-state high speed quantum sensors (not heat sensors such as
pyroelectric or thermopile) that all respond to the fire's radiant energy emissions. The
quantum sensors convert the rate of photonic energy directly into analog electrical
signals. These analog signals are converted to high resolution digital values for real-
time microprocessor analysis.
The detector microprocessors incorporate random access memory (RAM), read-
only memory (ROM), and non-volatile flash memory. When the microprocessors
determine that a fire has been detected, the pre-alarm digital sensor data (FirePic™)
and the event information are recorded in flash memory. Depending on the
configuration, other actions may include activating one or more status LEDs, relays,
a current loop, or sending digital data such as the RS-485 FireBusII™ and Modbus.
If the microprocessor determines, based on internal and "through-the-window"
testing, that the detector is not operating correctly, it records the fault data in flash
memory and activates the fault outputs and the yellow status LED. The digital data in
the detector can easily be accessed with a PC for analysis and record-keeping using
Honeywell Analytics' Windows -based PC software and FSIM USB Interface Unit.
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