Principle Of Operation - Honeywell FS20X Series User Manual

FS20X Fire and Flame Detectors
Product Overview
The model FS20X™ fire and flame detector senses the ultraviolet and wideband infrared radiant energy
of blackbody particulate and molecular emissions generated by both hydrocarbon and non-hydrocarbon
flames and fires� The wideband spectral radiant energy wavelengths sensed by its four sensors span
approximately 0�185 to 0�26 microns and 0�7 to 3�5 microns�
The detector is designed and Factory Mutual approved for use in Class I, Division 1 and 2, Class II, and
Class III; AEX d/Ex d IIC, and ATEX/IECEx Ex db IIC, Ex tb IIIC hazardous locations�
Figure 1� FS20X detectors; aluminum enclosure (left), stainless steel enclosure (right)
The detector is available in a copper-free aluminum enclosure or a 316 stainless steel enclosure (see
Figure 1)�
Figure 2� EN54 enclosure
The EN54 version is shown in Figure 2�
The detector's electro-optical electronics module is a replaceable hard black enclosure of anodized
aluminum that provides ruggedness, handling, ease of installation, and protection against electromagnetic
interference and radio-frequency interference (EMI/RFI)�
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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 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� IR and UV wavelengths are invisible to humans� The FS20X™ detector
operates from approximately 185nm to 260nm� Additionally, the detector monitors 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 over 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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