Infrared leak detector

Abstract

A leak detector using an infrared emitter and pyroelectric sensor to form an instrument for identifying the presence and concentration of a selected material type gas compound, such as a refrigerant gas compound within a given sample, such as a sample of ambient air. For the detection, a radiation flux coming from an infrared emitter penetrates the sample, which is analyzed spectrally, and results in a wave length-specific signal being generated at the output of the detector. By controlling the type of optical filter, the radiation energy is controlled at a selected wavelength, to ensure coverage of all selected compounds. For refrigerants, the selected wavelength can be between approximately 8 to approximately 10 microns in the wavelength range. This selected wavelength obscures other signals, thus minimizing false alarms. By not chopping or pulsing the emitter, the leak detector has a faster response time with no adverse impacts on the accuracy of the compound material being detected. To further minimize false alarms and to ensure that the emitter does not come in contact with the sample gas, an additional filter can be positioned in the optical path. For refrigerant compounds, the filter can block out signals below approximately 6 microns. For detecting refrigerants, two filters can be used: 1) a broadband filter to allow detection of all refrigerants currently on the market, and 2) a narrowband filter to limit detection only to R134 which possesses a narrow wavelength, so that detection of other compounds (or contaminants) can be minimized.