Product Overview
TM40/40U Rev. (Af), February 2019
19
2.4
Principles of Operation
This section describes the principles of operation for the 40/40U and UB.
2.4.1
Hydrocarbon Fire Detection
The Model 40/40U and UB Flame Detector is an electronic device designed to
sense the occurrence of fire and flames, and subsequently activate an alarm or
an extinguishing system directly or through a control circuit.
The UV Flame Detector is a single spectrum optical detector sensitive to the UV
radiation spectrum that is present in fires. The detector monitors the protected
volume, by measuring the radiation intensity in it, within the frequency range of
the electromagnetic spectrum, namely the Ultra-Violet (UV).
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
–
0.260µm. 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 workin
g temperature range.
•
Detection Levels
Detection of radiation in the UV channel, with an intensity that exceeds the
detector’s preset warning level results in a:
•
Warning signal
•
Alarm signal
2.4.2
Heated Optics
The SharpEye 40/40 Flame Detector uses 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 ice, 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 from 32°F/0°C to 86°F/30°C. The heating
stops when the temperature is 27°F/15°C above the start temperature.
on page 43.
2.4.3
HART Protocol
The SharpEye 40/40 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.
