Patent ID: 8143580

Claim:
A Non-Dispersive Infrared (“NDIR”) gas sensor, comprising: an infrared source compartment containing an infrared source; a sample chamber; a detector compartment, said sample chamber being located optically between the infrared source compartment and the detector compartment, said detector compartment comprising: a first detection channel comprising a first narrow band pass filter hermetically sealed with a non-absorbing gas that does not have an absorption band overlapping a first gas or water vapor, said first detection channel having a first output modulated by presence of the first gas and water vapor in the sample chamber; a second detection channel comprising a second narrow band pass filter hermetically sealed with the first gas and a water cell located optically between the infrared source and the second narrow band pass filter, said second detection channel having a second output that is independent of any amount of the first gas in the sample chamber and partially responsive to the amount of the water vapor in the sample chamber; and a third detection channel comprising a third narrow band pass filter hermetically sealed with the first gas, said third detection channel having a third output that is independent of the amount of the first gas in the sample chamber; and electronics for processing signals from the first detection channel, the second detection channel and the third detection channel and for calculating a detected concentration of the first gas in a gas sample comprising a combination of the first gas and water vapor in the sample chamber based upon the first output, the second output, the third output and a set of calibration data for the NDIR gas sensor; and wherein the first narrow band pass filter, the second narrow band pass filter and the third narrow band pass filter have a central wavelength and a full width half-maximum bandwidth that are identical and the central wavelength falls within an absorption band of the first gas and water vapor.