Pressure-modulated infrared gas analyzer and method
US4975582A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 16, 1989 |
| Grant date | Dec 4, 1990 |
| Priority date | — |
| Expiry date | Mar 16, 2009 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N2021/3536
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A gas analyzer (10) for detecting low concentrations of a specific gas which has a sample chamber comprising passages (14, 30, and 32) through which radiant energy is directed and which is pressure modulated by a loud speaker (36) both of which provide a radiant energy signal which is detected by a beam splitter (82) having a measurement channel (86) directed to a measurement detector (92) and a reference channel (84) with a reference cell (94), containing gas of the type being analyzed, directed to a reference detector (90). Both detectors (92, 90) produce a signal, and these signals and a cross channel normalization constant are processed by an algorithm. The loudspeaker (36) is isolated from the sample chamber by a flexible diaphragm (42) to eliminate phase changes in the pressure modulated output of the loud speaker (36). Means are provided for measuring the modulation or AC pressure and the steady state or DC pressure in the sample chamber, the radiant energy modulation, the humidity in the sample chamber and the temperature of the analyzer as parameters for processing by the algorithm. Also disclosed is a method of detecting low concentration of a specific gas.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.