Spectrex 40/40U-UB - UV Flame Detector - Manual (Page 17)

TM 40/40U, Rev (7) July 2013
Principles of Operation 5
The detector senses one channel in which appropriate detection pulses are
registered, and further analyzed for frequency, intensity and duration.
 Sensing Element
The UV sensor is sensitive to radiation over the range of 0.185-0.260
micron. The UV channel incorporates a special logic circuit that
eliminates false alarms caused by solar radiation and other non-fire UV
sources. Furthermore, the UV channel’s sensitivity is stabilized over the
working temperature range.
 Detection Levels
Detection of radiation in the UV channel having an intensity that exceeds
the detector’s preset warning level results in a:
 Warning signal
 Alarm signal
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.