Digital multi-frequency infrared flame detector

An optical flame detection apparatus with ability to detect fires, comprising:

• first and second infrared detectors, said first detector sensitive to a wavelength emitted by combustion of hydrocarbons and other carbon containing materials, said second detector sensitive to infrared wavelengths present in sunlight and emitted by artificial radiation sources, said second detector insensitive to said wavelength emitted by combustion of hydrocarbons and other carbon containing materials;
• a first low frequency bandpass filter coupled to an output of said first infrared detector;
• a second low frequency bandpass filter coupled to an output of said second infrared detector;
• a high frequency bandpass filter coupled to said output of said first infrared detector;
• a data acquisition system coupled to outputs of said first and second low frequency bandpass filter and said high frequency bandpass filter, said system adapted to analyze and interpret the signals generated by the two infrared detectors to detect radiation from a fire while distinguishing sunlight and artificial radiation sources.

A flame detection system, comprising:

• a central controller;
• a plurality of remotely located programmable optical flame detection apparatus;
• a digital data bus connecting said central controller and said plurality of flame detection apparatus to exchange data including programming data instructions between said central controller and said plurality of flame detection apparatus;
• wherein each of said optical flame detection apparatus includes:
• first and second infrared detectors, said first detector sensitive to a wavelength emitted by combustion of hydrocarbons and other carbon containing materials, said second detector sensitive to infrared wavelengths present in sunlight and emitted by artificial radiation sources;
• a data acquisition system coupled to outputs of said first and second infrared detectors, said system adapted to analyze and interpret the signals generated by the two infrared detectors to detect radiation from a fire while distinguishing sunlight and artificial radiation sources, said system including a first channel coupled to a first detector output of said first detector for analyzing the flicker rate of low frequency components of said first detector output to detect amplitude fluctuations characteristic of small fires, and a second channel coupled to said first detector output for analyzing the flicker rate of high frequency components of said first detector output to detect amplitude fluctuations characteristic of large fires.

An optical flame detection apparatus with ability to detect fires, comprising:

• first and second infrared detectors, said first detector sensitive to a wavelength emitted by combustion of hydrocarbons and other carbon containing materials, said second detector sensitive to infrared wavelengths present in sunlight and emitted by artificial radiation sources, said second detector insensitive to said wavelength emitted by combustion of hydrocarbons and other carbon containing materials;
• a first low frequency amplifier and a high frequency amplifier for amplifying respective low and high components of the signals generated by the second detector;
• a second low frequency amplifier for amplifying low frequency components of the signals generated by the first detector;
• a microprocessor based data acquisition system, said system to analyze and interpret the amplified signals generated by the two infrared detectors;
• a digital communication link to an external central processor.