Method and means for blended multi-component gas calibration and diagnosis of multiple gas analyzers

• US 5,835,974 A
• Filed: 08/22/1994
• Issued: 11/10/1998
• Est. Priority Date: 08/22/1994
• Status: Expired due to Fees

• Current Assignee: General Motors Corporation (General Motors Company)
• Original Assignee: General Motors Corporation (General Motors Company)
• Inventors: Nagy, Donald B.
• Primary Examiner(s): RAEVIS, ROBERT R
• Application Number:
  US08/293,630
• Time in Patent Office: 1,541 Days
• Field of Search: 73/1 G, 73/1 R, 73/1.06, 137/602, 137/605, 137/606, 137/597
• US Class Current: 73/1.06
• CPC Class Codes: G01N 33/00 Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00

Abstract

A gas flow system for an emission analysis bench includes a source of blended calibration span gas using a single span tree connected with all the analyzers so that a method of simultaneous calibration or diagnosis of all the analyzers may be carried out and the need for multiple span trees connected with various separate span gases is avoided. The method includes concurrent delivery of one or more divisions of the span gases to all the analyzers to obtain intermediate data points from the analyzers. A further step of using a precalibrated or linear analyzer, such as the flame ionization detector (FID hydrocarbons analyzer) of the system, to accurately determine the percentage ratio of intermediate divide points obtained by mixing various amounts of zero gas with the span gas simplifies the calibration procedure and eliminates the need for an expensive gas divider.

Claims

1. In a method for calibrating or diagnosing multiple engine exhaust gas analyzers responsive to HC, NOx, CO and CO2 constituent gases, the steps of:

providing a blended span gas comprising a known mixture of a zero gas with said constituent gases; and

simultaneously supplying to all of said analyzers sequential samples of said blended span gas and selected divisions thereof for obtaining a series of simultaneous readings of the multiple analyzers for calibration or diagnostic purposes.

2. In a method for calibrating or diagnosing multiple engine exhaust gas analyzers responsive to NOx, CO and CO2 constituent gases, wherein an additional analyzer has an accurate known response, the steps of:

providing a blended span gas comprising a known mixture of a zero gas with said constituent gases;

simultaneously supplying to all of said analyzers sequential samples of said blended span gas and selected divisions thereof for obtaining a series of simultaneous readings of the multiple analyzers for calibration or diagnostic purposes;

preparing said divisions of the blended span gas to approximate proportions with a diluter; and

utilizing the readings of said additional analyzer to accurately determine the proportions of the constituent gases in the various divisions of the blended span gas.

3. The steps of claim 2 wherein said accurate known response is obtained by precalibration of said additional analyzer.

4. The steps of claim 2 wherein said additional analyzer has a linear response.

5. The steps of claim 4 wherein said additional analyzer is a flame ionization detector for measuring hydrocarbon emissions.

6. In a method for calibrating or diagnosing multiple engine exhaust gas analyzers responsive to HC, NOx, CO and CO2 constituent gases, the steps of:

providing a blended span gas comprising a known mixture of a zero gas with said constituent gases; and

simultaneously supplying to all of said analyzers at least one sample comprising a selected division of said blended span gas for obtaining simultaneous readings of the multiple analyzers for calibration or diagnostic purposes.

7. In a method for calibrating or diagnosing multiple engine exhaust gas analyzers responsive to HC, NOx, CO and CO2 constituent gases, wherein an additional analyzer has an accurate known response, the steps of:

providing a blended span gas comprising a known mixture of a zero gas with said constituent gases; and

simultaneously supplying to all of said analyzers at least one sample comprising a selected division of said blended span gas for obtaining simultaneous readings of the multiple analyzers for calibration or diagnostic purposes

preparing said division of the blended span gas to approximate proportions with a diluter; and

utilizing the reading of said additional analyzer to accurately determine the proportions of the constituent gases in the division of the blended span gas.

8. The steps of claim 7 wherein said accurate known response is obtained by precalibration of said additional analyzer.

9. The steps of claim 7 wherein said additional analyzer has a linear response.

10. The steps of claim 9 wherein said additional analyzer is a flame ionization detector for measuring hydrocarbon emissions.