GB2048465A - A non-dispersive infra-red gas analyser - Google Patents
A non-dispersive infra-red gas analyser Download PDFInfo
- Publication number
- GB2048465A GB2048465A GB8008345A GB8008345A GB2048465A GB 2048465 A GB2048465 A GB 2048465A GB 8008345 A GB8008345 A GB 8008345A GB 8008345 A GB8008345 A GB 8008345A GB 2048465 A GB2048465 A GB 2048465A
- Authority
- GB
- United Kingdom
- Prior art keywords
- gas
- measured
- radiation path
- cuvette
- absorption
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
- 230000005855 radiation Effects 0.000 claims abstract description 47
- 238000010521 absorption reaction Methods 0.000 claims abstract description 30
- 238000005259 measurement Methods 0.000 claims description 14
- 230000035945 sensitivity Effects 0.000 claims description 8
- 230000000694 effects Effects 0.000 claims description 6
- 230000002452 interceptive effect Effects 0.000 claims description 4
- 239000000203 mixture Substances 0.000 claims description 4
- 239000003990 capacitor Substances 0.000 claims description 2
- 239000000945 filler Substances 0.000 claims description 2
- 239000012528 membrane Substances 0.000 claims description 2
- 229920006395 saturated elastomer Polymers 0.000 claims description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 2
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
- G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
- G01N21/35—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light
- G01N21/37—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light using pneumatic detection
Landscapes
- Physics & Mathematics (AREA)
- Spectroscopy & Molecular Physics (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Investigating Or Analysing Materials By Optical Means (AREA)
Abstract
A non dispersive infra red gas analyser comprises a measuring radiation path (1) with a cuvette (4) charged with the sample gas an adjustable interference filter (6), a comparison path II having a filter but smaller cuvette (5) charged with the sample gas, an adjustable interference filter (7) with an absorption band in the overlap region and a cuvette (8) filter with the gas component to be measured, a modulation device (3) for both beams of rays and a radiation receiving device (9, 10, 11) having the absorption properties of the gas component to be measured and forming the difference between the amplitudes corresponding to the two beams of rays as a measure of the concentration of the gas component to be measured. <IMAGE>
Description
SPECIFICATION
A non-dispersive infra red gas analyser
The invention is an improvement of the non dispersive infra red gas analyser described and claimed in our prior (Patent Application 79/2131 5), which is so constructed that the effect of gas components with absorption bands overlapping the absorption band of the gas component to be measured is largely suppressed. This effect, if not suppressed would falsify the measured value and is known as the cross sensitivity of the analyser.
A cuvette charged with sample gas is provided in the comparison radiation path, and is shorter than that in the measuring radiation path, and moreover an interference filter is arranged in the measuring radiation path, the interference filter having an absorption edge in the overlapping region, and allowing passage in the rest of the absorption range of the gas component to be measured. By suitably selecting the length of the cuvettes in the comparison radiation path, and by selecting and tilting an interference filter suitable for the respective task of measurement, the cross sensitivity may be considerably reduced.
If however, the overlapping region of an interference component extends over the entire absorption band of the gas component to be measured, then with this arrangement the effect of the interfering gas component cannot be sufficiently suppressed.
The invention seeks, in these cases, to largely eliminate the cross sensitivity which still exists by additional means.
According to the invention, there is provided a non dispersive infra-red gas analyser comprising a measuring radiation path, in which are arranged a cuvette charged with the sample gas and an adjustable interference filter, a comparison radiation path, in which is located another but shorter cuvette charged with the sample gas, a modulation device for both means of rays and a radiation receiving device having the absorption properties of the gas component to be measured, and forming the difference between the signal amplitudes corresponding to the two beams of rays as a measure of the concentration of the gas component to be measured, wherein an adjustable interference filter with an absorption band in the overlap region and a cuvette filled with the gas component to be measured are also arranged in the comparison radiation path.
The invention will now be described in greater detail, by way of example, with reference to the drawing, the single figure of which shows one embodiment of an infra red gas analyser constructed in accordance with the invention
In this embodiment, a measuring radiation path I and a comparison radiation path II are formed by a radiation conducting device 1 which has an infra red light source 2. A diaphragm disc 3, which rotates periodically, interrupts the beam of rays in both radiation paths. The mixture of sample gas to be measured flows through the cuvettes 4 and 5 in the radiation paths. The cuvette 5 in the comparison radiation path is substantially shorter than the cuvette 4 in the measuring radiation path.In interference filter 6, or 7, respectively follows the two cuvettes in each radiation path and another covette 8 filled with the gas component to be measured follows in the comparison radiation path. The two beams of rays pass into chambers 8 and 10 of a conventional radiation receiving device in which absorption of radiation takes place due to the filler gas containing the gas component to be measured, and the difference in pressure between the two chambers is measured by a membrane capacitor 11. Both interference filters are selected so that an absorption edge in each case lies in the overlapping region between the bands of the interference gas components, and of the gas component which is to be measured.
By appropriately setting and dimensioning the two interference filters and the cuvettes, good adjustment of the cross sensitivity may be achieved for a sample gas which contains interference gas components the absorption bands of which completely overlap the absorption band of the component to be measured.
For example, it has proved that with a measurement range of 500 ppm No, and interfering gas concentrations of ten per cent
CO, 16% CO2 and saturated water vapour in a gas mixture of 24 degrees C the measurement error is < 1% for the end value of the measurement range. Thus complete overlapping of the absorption band of the NO by the
H2O band is provided for. As compared to this, the corresponding measurement with the original arrangement produced a measurement error of up to 20% of the end value of the measurement range.
1. A non dispersive infra-red gas analyser comprises a measuring radiation path, in which are arranged a cuvette charged with the sample gas and an adjustable interference filter, a comparison radiation path, in which is located another but shorter cuvette charged with the sample gas, a modulation device for both beams of rays and a radiation receiving device having the absorption properties of the gas component to be measured, and forming the difference between the signal amplitudes corresponding to the two beams of rays as a measure of the concentration of the gas component to be measured, wherein an adjustable interference filter with an absorption band in the overlap region and a cuvette filled with the gas component to be measured are also
**WARNING** end of DESC field may overlap start of CLMS **.
Claims (2)
1. A non dispersive infra-red gas analyser comprises a measuring radiation path, in which are arranged a cuvette charged with the sample gas and an adjustable interference filter, a comparison radiation path, in which is located another but shorter cuvette charged with the sample gas, a modulation device for both beams of rays and a radiation receiving device having the absorption properties of the gas component to be measured, and forming the difference between the signal amplitudes corresponding to the two beams of rays as a measure of the concentration of the gas component to be measured, wherein an adjustable interference filter with an absorption band in the overlap region and a cuvette filled with the gas component to be measured are also arranged in the comparison radiation path.
2. A non dispersive infra red gas analyser substantially as described herein with reference to the drawing.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19792909688 DE2909688A1 (en) | 1979-03-12 | 1979-03-12 | NON-DISPERSIVE INFRARED GAS ANALYZER |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB2048465A true GB2048465A (en) | 1980-12-10 |
Family
ID=6065179
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8008345A Withdrawn GB2048465A (en) | 1979-03-12 | 1980-03-12 | A non-dispersive infra-red gas analyser |
Country Status (2)
| Country | Link |
|---|---|
| DE (1) | DE2909688A1 (en) |
| GB (1) | GB2048465A (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE2952464C2 (en) * | 1979-12-27 | 1986-03-27 | Siemens AG, 1000 Berlin und 8000 München | Non-dispersive infrared gas analyzer |
| JPS5892843A (en) * | 1981-11-26 | 1983-06-02 | Horiba Ltd | Nondispersion type infrared analyzer for measurement of two components |
| FI101429B (en) * | 1995-09-29 | 1998-06-15 | Instrumentarium Oy | Correction of collision propagation in non-dispersive absorption measurement of gases |
| CN103900961B (en) * | 2014-03-17 | 2016-02-24 | 西安交通大学 | A kind of three air chamber switching apparatus of spectrometer and the online spectrum test method of gas |
-
1979
- 1979-03-12 DE DE19792909688 patent/DE2909688A1/en not_active Withdrawn
-
1980
- 1980-03-12 GB GB8008345A patent/GB2048465A/en not_active Withdrawn
Also Published As
| Publication number | Publication date |
|---|---|
| DE2909688A1 (en) | 1980-09-18 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |