US 3,944,834 A · Pollution monitor with self-contained calibration and cell-block therefor

Abstract

The embodiment of the pollution monitor described in the specification uses the principle of ultraviolet-induced fluorescence to detect and measure gaseous pollution in air, smokestack exhaust and other fluids. Improved calibration or standardization is effected by the use of one or more calibration cells in which a non-gaseous material simulates the fluorescence of the gaseous species under investigation, by scattering the incident ultraviolet light into a spectral region similar to that of the fluorescence of the gaseous species. Examples of suitable materials have been found to be aluminum, gold, platinum and molybdenum, all of which scatter light in the appropriate spectral region at a level which stays substantially constant with time. In the preferred embodiment, the sample cell and the calibration cells are all formed in a single cell block by drilling holes into solid bar material which holes function as the individual cell cavities. The sample cell has ports for the flow of sample gas therethrough, while in each of the calibration cells, the metallic material is mounted to intercept and scatter the incident ultraviolet light energy. The cell block is constructed to rotate so that the several cells can be individually aligned in the light path between the ultraviolet source and fluorescence detector.

Claims20

Dependent claims

A pollution monitor for detecting the presence of a gaseous pollutant in a gas sample comprising:

A. a sample cell having:
1. a cell cavity,
2. means for flowing a gas sample through the cell cavity,
3. a first window for admitting ultraviolet energy into said cell cavity to cause fluorescence of the gaseous pollutant in said gas sample, and
4. a second window mounted at an angle with respect to said first window for permitting fluorescent energy to emerge from said cell cavity;
B. a calibration cell having:
1. a cell cavity,
2. a first window for admitting ultraviolet energy into said calibration cell cavity,
3. a second window mounted at an angle with respect to said first window of the calibiration cell for permitting scattered energy to emerge from said calibration cell cavity, and
4. a non-gaseous, scattering material mounted in the cavity of said calibration cell to intercept ultraviolet radiation entering said calibration cell and scatter said ultraviolet energy into a spectral region which simulates the fluorescence of the gaseous pollutant, said material being positioned to project the scattered energy out of the second window of the calibration cell;
C. means for projecting a beam of ultraviolet light toward said cells;
D. a detector positioned to detect fluorescent or scattered energy emerging from said cells;
E. said sample cell and said calibration cell being movably mounted with respect to said projecting means and said detector to permit selective movement of said cells into the light path between said source and detector.

10 more elements

A movable cell block having a plurality of cells in which fluorescence can be stimulated by ultraviolet radiation, and designed to be mounted in a pollution monitor between a source of ultraviolet radiation and a fluorescence detector and comprising:

A. a sample cell formed as a cavity in said cell block and having:
1. means for flowing a gas sample through the cell cavity,
2. a first window for admitting ultraviolet energy into the cell cavity to cause fluorescence of the gaseous pollutant in the gas sample, and
3. a second window mounted at an angle with respect to said first window for permitting fluorescent energy to emerge from said cell cavity;
B. at least one calibration cell formed as a cavity in said cell block and having:
1. a first window for admitting ultraviolet energy into said calibration cell cavity,
2. a second window mounted at an angle with respect to said first window of the calibration cell for permitting scattered energy to emerge from said calibration cell cavity, and
3. a non-gaseous, scattering material mounted in the cavity of said calibration cell to intercept ultraviolet radiation entering said calibration cell and scatter the ultraviolet energy into a spectral region which simulates the fluorescence of the gaseous pollutant, said material being positioned to project the scattered energy out of the second window of the calibration cell;
C. means for moving said cell block to position selectively one of the cell cavities in the light path between said ultraviolet source and said detector.

6 more elements

Dependencies are inferred from the claim text.

Pollution monitor with self-contained calibration and cell-block therefor

Life of this patent

Pollution monitor with self-contained calibration and cell-block therefor

Life of this patent

Abstract

Claims20