Match Optical Flame Detectors to the Proper Hazards
December 21st, 2009
A scientist would not use a microscope to observe stars in the sky. It’s a misapplication of technology. In the same way, a safety engineer would not use an infrared-spectrum-based flame detector to detect sulfur fires. That’s because certain optical flame detectors are better suited than others to detecting given flame hazards.
Current technologies and algorithms enable detectors to be sensitive to certain fuel fires. The technologies widely used today are based on UV and IR sensors, and combinations of UV and IR sensors. Following is a brief summary of optical flame detectors and the hazards they best detect:
UV detectors provide good response to a broad spectrum of flame hazards. In general, when used indoors in a controlled environment, UV is an economical option. Lightning, the sun, and arc welding can cause false alarms. In addition, the performance of UV detectors might be impaired by certain chemicals that attenuate UV light, such as oils, silicones, ethanol, and ammonia.
IR-based detectors sense IR emissions generated by any material above absolute zero, which includes the sun and people. Tuned into certain regions of the IR spectrum, IR detectors are very suitable for detection of carbon-based fueled fires. IR detectors can be prone to false alarms from chopped or modulated IR sources.
Multispectrum IR detectors offer improved performance over UV and IR detectors by reducing false alarms. These detectors have the greatest on-axis detection ranges (>200ft) of any flame-detection technology.
UV/IR detectors combine UV and IR benefits, thereby reducing false-alarm issues seen with UV and IR detectors.
CCTV is an emerging technology that uses visible light for flame detection. Positive identification of a flame remains a significant challenge for this technology. Ambient light conditions, partially obstructed fires, and pale flames are a few of the issues yet to be overcome.
For more information on matching detectors to their hazards, we invite you to review “Not All Hazards are the Same,” an article published in Asia Pacific Fire magazine.
If you have questions or comments, please contact us at rss@det-tronics.com.
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