Spectrex 40/40M Multi IR Flame Detector - Manual (Page 17)

TM 40/40M, Rev (6) July 2013
Principles of Operation 5
The detector's principle of operation is based on the patented spectral
analysis technology that identifies the IR spectral signature of fire products,
namely the hot CO
2
spectral emission band at 4.2-4.7 microns and the hot
water (H
2
O) spectral emission band at 2.7-3.0 microns. Additional spectral
bands (above and below these bands) are analyzed for background
interferences.
The spectral analysis incorporates several detection algorithms, according to
several types of fire events, taking into account simultaneous detection of
both CO
2
and H
2
O peaks, or only one of them, as well as flickering analysis
at frequencies typical to these flames. Only when all the parameters of the
spectral analysis and the flickering analysis meet the predetermined values,
is a fire condition identified and the fire alarm is issued.
When exposed to non-fire radiation sources, these parameters do not
identify a fire condition and the detector does not react.
1.4.2 Heated Optics
The SharpEye 40/40 Flame Detectors use heated optics. The heater
increases the temperature of the optical surface by 5-8°F (~3-5°C) above
the ambient temperature to improve performance in icing, condensation and
snow conditions.
The heated optics can be set to one of the following:
 Not operated
 On continuously
 Automatic, per temperature change (default): you can define the start
temperature below which the window is heated. (The default is 41°F
(5°C).) This temperature can be defined between 32°F (0°C) to 122°F
(50°C). The heating stops when the temperature is 27°F (15°C) above
the start temperature.
For more information, see Configuring your Detector on page 29.
1.4.3 HART Protocol
The SharpEye40/40 Flame Detectors use the HART protocol.
HART Communication is a bi-directional industrial field communication
protocol used to communicate between intelligent field instruments and host
systems. HART is the global standard for smart process instrumentation and
the majority of smart field devices installed in plants worldwide are HART-
enabled. HART is available in wiring options 2 and 3, see Table 1, page 3.
HART technology is easy to use and very reliable.
Through the HART connection, you are able to perform:
 Detector set-up
 Detector troubleshooting
 Detector health and status
For more details, refer to the HART Manual TM 777030.