Flame Detection Design: A Balancing Act
Detection
Capability
Interference
Rejection
• Range
• Fuel
• Resistance level
• Impact on Flame
Detection
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Flame Detection
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Solar radiation
Wavelength (microns)
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Typical interference
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UV detectors
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Ultraviolet Sensor Operating Principle
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Solar blind 1850 to 2450
UV photons strike tube cathode
Cathode releases electron
Electron strikes gas molecule
Cascade effect occurs to anode
Discharge is quenched, creates pulse
(count) output
Pulse output measured in CPS
(counts per second)
Plastic
housing
Cathode
Anode
Quartz
Envelope
Oi
Test Source
circuit board
connectors
(a,b,c,d)
De t-Tr onics UV Se ns or
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Ultraviolet Flame Detector
• Enhanced Arc Rejection
• Faster and more false alarm
resistant
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IR detectors
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IR Sensor Operating Principle
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Optical filter mounted to sensor
4.45 micron band-pass
Flicker modulation required
Steady state IR sources ignored
Infrared
Energy
Optical
Bandpass
Filter
Pyroelectric
Infrared
Sensor
Flicker
Filter
Circuitry
Output
Circuitry
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TDSA
• Analyzes the raw IR sensor signal “randomness”
• Rejects signals that do not meet randomness criteria
No Fire Alarm
Fire Alarm!
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Single Frequency Infrared Flame Detector
• TDSA IR signal processing
• Quick fire response
• Heated optic
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UV/IR detectors
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Ultraviolet Infrared Flame Detector
• ARC UV and TDSA IR signal processing
• High Speed
• Heated IR optic sensor
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Ultraviolet Infrared Signal Processing
• Dual Spectral Processing
– Arc rejection UV sensor
– TDSA IR sensor
• UV sensor (and gated) with the IR sensor
• Alarm only when processing time is met by both sensors
simultaneously
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Multi-spectrum IR detector
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Spectral Analysis
• Determine unique spectral features of sources
• Use multiple Infrared bandwidths to optimize desired
capabilities
• Develop algorithms to identify signatures
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Typical signal/reference band multi
IR
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X33AF Multispectrum Infrared Flame Detector
• Patents
– Wavelength
– Algorithm
– Digital signal Processing
• Extended Cone of Vision
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X33AF IR3
X33AF Multi-spectrum63m‘
UV/IR
SFIR
UV/IR
SFIR
COV Test data for
1’ * 1’ gasoline fire
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30m
25m