Spectrex 20/20U (UB) - UV Flame Detector - Manual (Page 10)

Spectrex Inc. - SharpEye™ UV Flame Detector Manual – TM 20/20UB Rev. E, August 2004
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2. Technical Description
• Detection Range: Up to 50 ft (15m) for a 1ft x 1ft (0.3m x 0.3m)
Gasoline fire.
• Advanced Digital Processing Of The Dynamic Characteristics Of Fire.
• Single Spectrum: UV radiation
• Multiple Detection Levels: Warning, alarm and saturated signal
• Solar Blind
• Microprocessor Based: Microcontroller performs signal processing
• Built In Test: Manual and automatic BIT for 20/20UB only
(see section 4.5)
• Electrical Interface:
o
Dry contact RELAYS.
o
4-20mA outputs.
2.1 Principles Of Operation
The Model 20/20U, 20/20UB Radiation 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, which present in fires. The detector monitors the protected
volume, by measuring the radiation intensity in it, the frequency range of the
electromagnetic spectrum, namely the UV.
The detector senses one channel in which appropriate detection pulses are
registered and further analyzed for frequency, intensity and duration.
2.2 The 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. Further more; the UV
channel sensitivity is stabilized over the working temperature range.
2.3 Detection Levels
Detection of radiation in the UV channel having an intensity which exceeds
detector’ preset Warning level will result in a Warning signal.
Detection of radiation in the UV channel having an intensity, which exceeds
detector’s preset Alarm level will result in an Alarm signal.