Honeywell International Inc.

Fire Sentry Corporation

Fire Sentry Systems, Inc.

Theodore Raymond Lapp

David A Castleman

Owen D Parham

Chris A Selstad

A flame detector incorporates visible and near infrared sensors in common with processing circuits to form processed instantaneous, dc type, signal values minus an average value and peak-to-peak ranges of values of ac-type signals over a measurement time interval on the order of three seconds. The resulting values are further processed to determine the presence of a fire condition by comparing them to a predetermined threshold.

Flame detector having visible light related processing circuits and infrared related circuits respectively coupled to photodiodes to establish instantaneous dc related signal changes and peak-to-peak ac signals over a predetermined time interval

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

The present invention provides a highly sensitive, intelligent, reliable, and effective process and system for detecting fire, which may be used in any industrial or other environment. The process and system for flame detection in accordance with the present invention features wide infrared spectrum sensitivity, which facilitates increased sensitivity to any sign of a flame or fire. The process and system of the present invention utilizes digital processing and analysis of data, calibration of operation parameters from temperture data, an intelligent controller (microprocessor) for discriminating against false alarms, and an elaborate multi-stage alarm system, selectively triggered by the controller.

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Coto de Caza, CA, United States of America

Theodore Raymond Lapp