Uv/ir fire detector with dual wavelength sensing ir channel

Abstract

A system for automatically detecting fires fueled by hydrocarbons and certain non-organics including hydrogen, hydrazine, magnesium, aluminum, potassium, ammonia and silane, which system has a low incidence of false alarms from incident radiation emitted by non-fire radiation sources such as the sun. The system includes a UV sensor assembly that both senses UV radiation in a predetermined spectral bandwidth and generates a first signal corresponding to the sensed radiation; an IR sensing assembly consisting of a single IR sensor that simultaneously senses IR radiation in two predetermined spectral bandwidths and generates a second signal corresponding to the IR radiation in at least one of the spectral regions; and a signal processor. The UV spectral bandwidth is such that the UV sensing assembly is responsive to UV radiation emitted by hydrocarbons and certain non-organics but non-responsive to solar UV radiation. The IR spectral bandwidths are selected so that one spectral region is responsive to IR radiation emitted by hydrocarbons and certain non-organics while the other is responsive to hydrocarbons only. Both IR spectral regions are selected so as to be largely non-responsive to solar IR radiation. The signal processor processes the first and second signals and generates a fire signal when the processed signals are indicative of a fire.