Fire Sentry Corporation

Owen D Parham

David A Castleman

Theodore Raymond Lapp

A process and system for flame detection includes a microprocessor-controlled detector with a first sensor for sensing temporal energy in a first optical frequency range, and a second sensor for sensing temporal energy in a second optical frequency range. The temporal energy sensed in the respective first and second optical frequency ranges are transformed into respective first and second spectra of frequency components. A compensated spectrum of frequency components is generated by performing a frequency bin subtraction of the first and second spectra of frequency components. The compensated spectrum represents the energy emitted from the environment with energy emitted from false alarm sources. An average amplitude and centroid of the compensated spectrum are obtained and used to determine if a monitored phenomenon represents an unwanted fire situation. The compensated spectrum can be compared to reference compensated spectra of frequency components generated from known unwanted fire sources and known false alarm sources.

Fire detector with electronic frequency analysis

A process and system for flame detection includes a microprocessor-controlled detector with an array of sensors for sensing radiant energy from a fire or other heat source. A wide band infrared sensor is used as the primary detector, with near band and visible band sensors serving to detect false-alarm energy from non-fire sources. A narrow band sensor, such as a 4.3-micron sensor, may also be employed in the sensor array, and assists in the detection of hydrocarbon fires. Digital signal processing is used to analyze sensed data and discriminate against false alarms. A modulation index of one of the sensors (preferably the wideband IR sensor) is calculated by the microprocessor using measurements of the signal extremes (i.e., maxima and minima). A fire situation is not declared unless the modulation index falls within a prespecified range, such as between 5% and 85%. A multistage alarm system can be provided, which is selectively triggered by the microprocessor. Spectral recording and analysis of prefire data is provided for. The detector can be housed in an enclosed, sealed, removable, plastic housing that may include an integral plastic window lens.

Fire detector with modulation index measurement

A process and system for flame detection includes a microprocessor-controlled detector with a first sensor for sensing temporal energy in a first optical frequency range, and a second sensor for sensing temporal energy in a second optical frequency range. The temporal energy sensed in the respective first and second optical frequency ranges are transformed into respective first and second spectra of frequency components. A compensated spectrum of frequency components is generated by performing a frequency bin subtraction of the first and second spectra of frequency components. The compensated spectrum of frequency components represents the energy emitted from the environment with energy emitted from false alarm sources. An average amplitude and centroid of the compensated spectrum of frequency components are obtained and used to determine if a monitored phenomenon represents an unwanted fire situation. The compensated spectrum of frequency components can be compared to reference compensated spectra of frequency components generated from known unwanted fire sources and known false alarm sources. This comparison can be facilitated by constructing a frequency space scatter plot from respective average amplitudes and centroids obtained from the reference compensated spectra. A fire detection boundary can be defined, which excludes substantially all of the false alarm sources. Inclusion of the unknown phenomenon within the fire detection boundary is indicative of an unwanted fire situation.

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La Habra, CA, United States of America

Owen D Parham