Patent ID: 6455854
Filing Date: 2002-09-24
Classification: G01N

Abstract:
An infrared gas detector, said detector monitoring for the presence of one or more of a plurality of target gases comprising volatile, potentially explosive C1-7 alkane compounds having differing infrared absorption spectra, said detector accurately indicating the concentration of such gases in service environments exhibiting differential attenuation of infrared radiation; said detector comprising:an infrared radiation source for transmitting at least one beam of infrared radiation having a wavelength range that includes wavelengths of substantially 2215, 2300, and 2385 nm; a first filter spaced from said radiation source along a beam path in which the one or more target gases are received and which is subjected to the service environment of the detector, said first filter receiving radiation from the beam traversing the beam path, said first filter transmitting radiation in a band having a central wavelength of 2300Â±20 nm and a full width half maximum of 50Â±20 nm to form a first wavelength band for said detector; a dual bandpass, second filter spaced from said radiation source along said beam path, said second filter receiving radiation from the beam and transmitting radiation in a band having a central wavelength of 2215Â±20 nm and a full width half maximum of 25Â±20 nm to form a second wavelength band for said detector, said second filter further transmitting radiation in a band having a central wavelength of 2385Â±20 nm and a full width half maximum of 25Â±20 nm to form a third wavelength band for said detector; a first radiation sensor for sensing the intensity of radiation in said first wavelength band; a second radiation sensor for sensing the intensity of radiation in said second and third wavelength bands; and means responsive to said first and second radiation sensors for indicating the presence of one or more target gases.