Calibrators for infrared-type gas analyzers
AssigneeCascadia Technology Corporation
InventorsJerry R. Apperson, Paul K. Graham, Leslie E. Mace, James T. Russell, Lawrence L. Labuda, Walter A. Cooke
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Abstract
A method of and device for calibrating infrared radiation transducers. A concentration factor representing the ratio of a data signal to a reference signal for a known concentration of a designated gas in a sample containing that gas is generated. The concentration factor is stored and used during subsequent calibration procedures. The calibration device has a zero cell and a span cell with windows for transmitting infrared radiation and radiation reflecting or absorbing material in the span cell. The span cell therefore provides a known and consistent level of radiation absorption.
Claims23
The combination of:
- a transducer having:
- (a) a source for generating a beam of infrared radiation and propagating the beam along an optical path through a gas sample, and (b) a detector spaced along the optical path, from said source, for generating a signal which is indicative of the attenuation of the beam by a designated gas in said sample and, consequentially, of the concentration of the designated gas;
- memory means for storing a predetermined concentration factor for said transducer, the concentration factor being indicative of the magnitude of the signal generated by the detector for a known concentration of the designated gas;
- calibration means for calculating calibration values for said transducer from:
- (a) the concentration factor, and (b) a zero signal generated by the detector when the designated gas is absent;
- and
- concentration calculation means for subsequently calculating the concentration of the designated gas in the sample from:
- (a) the calibration values, and (b) the magnitude of the signal generated by the detector as the beam of infrared radiation traverses the sample.
A method of calibrating an infrared radiation transducer from:
- (a) the magnitude of a beam of infrared radiation after that radiation has been attenuated by a specimen of a designated gas, and (b) calculated calibration values, said method comprising the steps of:
- generating a concentration factor for the transducer which is to be calibrated, said concentration factor being indicative of the magnitude of the infrared radiation beam as attenuated by a known concentration of the designated gas;
- storing the concentration factor in a non-volatile memory associated with said transducer;
- calculating calibration values from:
- (a) the concentration factor, and (b) a value reflecting the magnitude of the unattenuated infrared radiation beam.
Dependencies are inferred from the claim text.