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Fire detection system with IR and UV ratio detector

  • US 4,455,487 A
  • Filed: 10/30/1981
  • Issued: 06/19/1984
  • Est. Priority Date: 10/30/1981
  • Status: Expired due to Term
First Claim
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1. Means for automatically detecting flames in a preselected zone with an extremely low incidence of false alarms due to naturally occurring and man-made background radiation not generated by a flame comprising:

  • means for detecting ultraviolet (UV) radiation eminating from said preselected zone and generating a first signal corresponding to said UV radiation incident upon said UV detecting means;

    means for detecting infrared (IR) radiation also eminating from said preselected zone and occurring in a narrow band, and generating a second signal corresponding to said IR radiation incident upon said IR detecting means;

    electronic means for processing said first signal to produce a normalized UV signal;

    electronic means for processing said second signal to produce a normalized IR signal; and

    electronic means for forming a ratio of said normalized UV signal to said normalized IR signal, comparing said ratio to a known range of values that is characteristic of the flames being detected, and generating a fire signal if said ratio falls within said range.

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