UV/IR fire detector with dual wavelength sensing IR channel

A fire detection system for automatically detecting fires fueled by hydrocarbons and by certain non-organics, where the certain non-organics includes hydrogen, hydrazine, magnesium, aluminum, potassium, ammonia and silane, the system having a low incidence of false alarms from incident ultraviolet (UV) and infrared (IR) radiation emitted by non-fire radiation sources, comprising:

• a first optical sensing channel being configured so as to sense UV wavelength radiation in a predetermined UV spectral region and generating a first signal corresponding to the sensed UV radiation, said UV spectral region having a predetermined bandwidth selected such that said first optical sensing channel is both responsive to the incident UV radiation emitted by the fires fueled by the hydrocarbons and responsive to the incident UV radiation emitted by the fires fueled by the certain non-organics but non-responsive to both the incident UV radiation emitted by the sun and to the incident UV radiation emitted by the non-fire radiation sources having wavelength emissions greater than 275 nanometers;
• a second optical sensing channel being configured so as to simultaneously sense IR radiation in a first IR spectral region and a second IR spectral region and to generate a second signal corresponding to the IR radiation sensed in at least one of said spectral regions, said first and second IR spectral regions each being defined by predetermined bandwidths that are separate and distinct from each other;
• wherein the predetermined bandwidth for said first IR spectral region is selected such that said second optical channel is both responsive to the incident IR radiation emitted from the fires fueled by the certain non-organics and responsive to the incident IR radiation emitted from the fires fueled by the hydrocarbons;
• wherein the predetermined bandwidth for said second IR spectral region is selected such that said second optical sensing channel senses the incident IR radiation emitted from the fires fueled by the hydrocarbons;
• wherein the predetermined bandwidths of said first and second IR spectral regions are also established such that said second optical sensing channel is essentially non-responsive to the incident IR radiation emitted by the sun;
• and
• signal processing circuitry both for processing said first and said second signals and for generating a fire signal when the processed first and second signals are indicative of a fire.

An infrared (IR) detector for detecting IR radiation emitted by fires fueled by hydrocarbons and by certain non-organics, where the certain non-organics includes hydrogen, hydrazine, magnesium, aluminum, potassium, ammonia and silane, comprising:

• an IR optical dual bandpass filter being tuned to pass IR radiation in both a first and second IR spectral region, said first and second spectral regions each being defined by predetermined bandwidths that are separate and distinct from each other;
• a filter window that filters the incident IR radiation emitted by the fire and the non-fire radiation sources so only a predetermined bandwidth of the incident IR radiation passes therethrough to said IR duel bandpass filter, the predetermined bandwidth of said filter window is established so that at least IR radiation in both the predetermined bandwidths of said first and second spectral regions is passed, said filter window being disposed in front of said IR duel bandpass filter;
• and
• an IR sensing element, disposed behind said IR dual bandpass filter, being at least responsive to the IR radiation in the predetermined bandwidths of said first and second IR spectral regions and generating a signal proportional to the incident IR radiation, filtered by said filter window and said IR optical dual bandpass filter, sensed in at least one of said IR spectral regions, wherein the predetermined bandwidth for said first IR spectral region is selected such that said IR sensing element is both responsive to the incident IR radiation emitted from the fires fueled by the certain non-organics and responsive to the incident IR radiation emitted from the fires fueled by the hydrocarbons, the predetermined bandwidth for said second IR spectral region is selected such that said IR sensing element is responsive to the incident IR radiation emitted from the fires fueled by the hydrocarbons, the predetermined bandwidths of said first and second IR spectral regions are also established such that said IR sensing element is essentially non-responsive to the incident IR radiation emitted by the sun.

A fire detection system for automatically detecting fires fueled by hydrocarbons and by certain non-organics, where the certain non-organics includes hydrogen, hydrazine, magnesium, aluminum, potassium, ammonia and silane, the system having a low incidence of false alarms from incident ultraviolet (UV) and infrared (IR) radiation emitted by non-fire radiation sources, comprising:

• a first optical sensing channel being configured so as to sense UV wavelength radiation in a predetermined UV spectral region and generating a first signal corresponding to the sensed UV radiation, said UV spectral region having a predetermined bandwidth selected such that said first optical sensing channel senses both the incident UV radiation emitted by the fires fueled by the hydrocarbons and the incident UV radiation emitted by the fires fueled by the certain non-organics but is essentially non-responsive to both the incident UV radiation emitted by the sun and to the incident UV radiation emitted by the non-fire radiation sources having wavelength emissions greater than 275 nanometers;
• a second optical sensing channel being configured to sense IR radiation in a first IR spectral region and to generate a second signal corresponding to the sensed IR radiation, said first IR spectral region being defined by a predetermined bandwidth, wherein the predetermined bandwidth for said first IR spectral region is selected such that said second optical channel senses both the incident IR radiation emitted from the fires fueled by the certain non-organics and the incident IR radiation emitted by the fires fueled by the hydrocarbons;
• a third optical sensing channel being configured to sense IR radiation in a second IR spectral region, and to generate a third signal corresponding to the sensed IR radiation, said second IR spectral region being defined by a predetermined bandwidth separate and distinct from the bandwidth for said first IR spectral region, wherein the predetermined bandwidth for said second IR spectral region is selected such that said third optical sensing channel senses the incident IR radiation emitted from the fires fueled by the hydrocarbons;
• wherein the predetermined bandwidths of said first and second IR spectral regions are also established such that said second and third optical sensing channels are essentially non-responsive to the incident IR radiation emitted by the sun;
• and
• signal processing circuitry both for processing said first, said second and said third signals and for generating a fire signal when the processed first and second signals are indicative of a fire fueled by the certain non-organics or when the processed first, second and third signals are indicative of a fire fueled by the hydrocarbons.

A method for automatically detecting fires fueled by hydrocarbons and by certain non-organics, where the certain non-organics includes hydrogen, hydrazine, magnesium, aluminum, potassium, ammonia and silane, the method having a low incidence of false alarms from incident ultraviolet (UV) and infrared (IR) radiation emitted by non-fire radiation sources, comprising the steps of:

• sensing UV wavelength radiation in a predetermined UV spectral region having a predetermined bandwidth, the bandwidth being established such that the incident UV radiation emitted by the fires fueled by the hydrocarbons and the incident UV radiation emitted by the fires fueled by the certain non-organics is sensed but the incident UV radiation emitted by both the sun and by the non-fire radiation sources having wavelength emissions greater than 275 nanometers is excluded;
• generating a first signal corresponding to the incident UV radiation sensed;
• selectively filtering the incident IR radiation emitted by the fire and non-fire radiation sources into a first and second IR spectral region, the first and second spectral regions each being defined by predetermined bandwidths that are separate and distinct from each other;
• wherein said selectively filtering further includes selecting predetermined bandwidths for the first and second spectral regions so that said selectively filtering of the incident IR radiation in a first spectral region filters the incident IR radiation emitted so that only predetermined IR spectra emitted by the fires fueled by the certain non-organics and the fires fueled by the hydrocarbons is transmitted and so that said selectively filtering of the incident IR radiation in a second spectral region filters the incident IR radiation emitted so that only predetermined IR spectra emitted by the fires fueled by the hydrocarbons is transmitted;
• simultaneously sensing the selectively filtered IR radiation and generating a second signal corresponding to the incident IR radiation sensed in at least one of said spectral regions;
• processing the first and the second signals;
• and
• generating a fire signal when the processed first and second signals are indicative of a fire.