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Method and apparatus for determining gas concentration

  • US 20030134427A1
  • Filed: 01/08/2003
  • Published: 07/17/2003
  • Est. Priority Date: 01/11/2002
  • Status: Active Grant
First Claim
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1. A method for measuring the concentration of a marker gas in a gas mixture comprising steps of;

  • obtaining a gas mixture sample initially including said marker gas and a calibration gas having an independently known concentration and inherently present in said gas mixture for a gas mixture sampling interval;

    providing a spectrometer including a spectrometer light source, a spectrometer gas sample cell, a spectrometer detector and a spectrometer computer;

    placing said gas mixture sample in said spectrometer gas sample cell;

    illuminating said gas mixture sample with said spectrometer light source;

    detecting a transmitted light beam which has passed through said gas mixture sample with said spectrometer detector to produce a detector electronic signal sequence;

    transmitting said detector electronic signal sequence to said spectrometer computer wherein said computer includes an executable program;

    acquiring said detector electronic signal sequence using said spectrometer computer for a signal acquisition interval to obtain a gas mixture spectrum;

    storing said gas mixture spectrum;

    analyzing said gas mixture spectrum using said spectrometer computer said step of analyzing further including steps of;

    identifying a marker gas absorption feature and a calibration gas absorption feature, determining a marker gas absorption feature intensity and a calibration gas absorption feature intensity, storing said marker gas absorption feature intensity and storing said calibration gas absorption feature intensity as a function of time over said gas mixture sampling interval;

    repeating said steps of acquiring and analyzing for multiple signal acquisition intervals to identify a single signal acquisition interval wherein a known concentration calibration gas absorption feature which corresponds to an independently known calibration gas concentration and a simultaneous marker gas absorption feature occur;

    calculating a ratio of said simultaneous marker gas absorption feature intensity to said known concentration calibration gas absorption feature intensity and multiplying said ratio by a proportionality constant to determine concentration of said marker gas.

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