GB2164743A - Detecting the presence or concentration of a fluid component - Google Patents
Detecting the presence or concentration of a fluid component Download PDFInfo
- Publication number
- GB2164743A GB2164743A GB08423670A GB8423670A GB2164743A GB 2164743 A GB2164743 A GB 2164743A GB 08423670 A GB08423670 A GB 08423670A GB 8423670 A GB8423670 A GB 8423670A GB 2164743 A GB2164743 A GB 2164743A
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- United Kingdom
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- radiation
- fluid
- filter
- detector
- wavelength
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- 239000012530 fluid Substances 0.000 title claims abstract description 104
- 230000005855 radiation Effects 0.000 claims abstract description 135
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical group [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 claims description 16
- 229910002091 carbon monoxide Inorganic materials 0.000 claims description 16
- 238000000034 method Methods 0.000 claims description 12
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 claims description 6
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 claims description 3
- 229910052697 platinum Inorganic materials 0.000 claims description 3
- 239000004698 Polyethylene Substances 0.000 claims description 2
- 229910000510 noble metal Inorganic materials 0.000 claims description 2
- -1 polyethylene Polymers 0.000 claims description 2
- 229920000573 polyethylene Polymers 0.000 claims description 2
- 239000003870 refractory metal Substances 0.000 claims description 2
- 238000012216 screening Methods 0.000 claims description 2
- 239000007789 gas Substances 0.000 description 28
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 6
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 6
- 238000010521 absorption reaction Methods 0.000 description 5
- 238000005259 measurement Methods 0.000 description 4
- 229920000742 Cotton Polymers 0.000 description 3
- 229910002092 carbon dioxide Inorganic materials 0.000 description 3
- 239000001569 carbon dioxide Substances 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 229910000623 nickel–chromium alloy Inorganic materials 0.000 description 3
- 239000004033 plastic Substances 0.000 description 3
- 229920003023 plastic Polymers 0.000 description 3
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- 239000011248 coating agent Substances 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000011521 glass Substances 0.000 description 2
- 239000013618 particulate matter Substances 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 239000004411 aluminium Substances 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- WUKWITHWXAAZEY-UHFFFAOYSA-L calcium difluoride Chemical compound [F-].[F-].[Ca+2] WUKWITHWXAAZEY-UHFFFAOYSA-L 0.000 description 1
- 229910001634 calcium fluoride Inorganic materials 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 239000011651 chromium Substances 0.000 description 1
- 238000009833 condensation Methods 0.000 description 1
- 230000005494 condensation Effects 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000011109 contamination Methods 0.000 description 1
- 229930195733 hydrocarbon Natural products 0.000 description 1
- 150000002430 hydrocarbons Chemical class 0.000 description 1
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 1
- 229920001684 low density polyethylene Polymers 0.000 description 1
- 239000004702 low-density polyethylene Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 239000011236 particulate material Substances 0.000 description 1
- 238000007747 plating Methods 0.000 description 1
- 238000010926 purge Methods 0.000 description 1
- 238000002310 reflectometry Methods 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 230000000087 stabilizing effect Effects 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
- 238000009423 ventilation Methods 0.000 description 1
- 239000002918 waste heat Substances 0.000 description 1
- 210000002268 wool Anatomy 0.000 description 1
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
- G01N21/3504—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light for analysing gases, e.g. multi-gas analysis
-
- 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
- G01N21/01—Arrangements or apparatus for facilitating the optical investigation
- G01N21/03—Cuvette constructions
- G01N21/031—Multipass arrangements
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
Apparatus for detecting whether a fluid contains a predetermined fluid component and/or for measuring the concentration of the fluid component in the said fluid, comprises a container (1) adapted to contain the said fluid; a radiation source (4) a portion of whose radiation is of a wavelength or wavelengths absorbed by said fluid component, at least a part (2,3) of the container (1) being transparent to the said wavelength or wavelengths; a radiation filter (7) substantially all the filtered radiation from which is at the said wavelength or wavelengths; a detector (11) responsive to the filtered radiation; and means (6,10) for directing radiation from the radiation source (4) onto the detector (11) after the radiation has passed through both the filter (7) and the said part (2,3) of the container (1), the means (6,10) focussing the radiation from the radiation source (4) onto the filter (7). <IMAGE>
Description
SPECIFICATION
Method and apparatus for detecting the presence or concentration of a fluid component
This invention concerns a method and apparatus for detecting the presence or concentration of a fluid component and, although the invention is not so restricted, it is more particularly concerned with a method and apparatus for determining the concentration of carbon monoxide in automobile exhaust gas.
The measurement of the carbon monoxide concentration in automobile exhaust gas is an important element of engine tuning since a typical carbon monoxide concentration in the exhaust gas can vary considerably, e.g. from 2% to 10%.
In order to effect such measurement, it is obviously essential to be able to distinguish between the carbon monoxide present in the exhaust gas and other gas components such as carbon dioxide, unburnt hydrocarbons, and water vapour. One method employed to effect such measurement is to pass infra-red radiation through a sample of the exhaust gas so as to determine the extent to which this infrared radiation is absorbed.This is an effective method of measuring the carbon monoxide concentration since the absorption of the infrared radiation by the carbon monoxide content of the exhaust gas is particularly marked in the region of 4.7 to 4.8,um. In particular, the infra-red radiation absorption band for carbon monoxide is from 4.48,ztm to 4.83jim. This, however, is very close to the corresponding absorption band for carbon dioxide which is from 4.17,ttm to 4.41tm and consequently it is essential that the infra-red radiation which is passed through the exhaust gas is filtered so as to be within a narrow band.This in turn means that an expensive filter needs to be employed, and the cost of this filter constitutes a significant proportion of the whole cost of the apparatus used for determining the concentration of the carbon monoxide.
Although, therefore, the present invention is primarily directed to any novel integer or step, or combination of integers or steps, as herein disclosed and/or as shown in the accompanying drawing, nevertheless, according to one particular aspect of the present invention, to which, however, the invention is in no way restricted, there is provided apparatus for detecting whether a fluid contains a predetermined fluid component and/or for measuring the concentration of the fluid component in the said fluid, the said apparatus comprising a fluid container adapted to contain the said fluid, a radiation source a portion of whose radiation is of a wavelength or wavelengths absorbed by said fluid component, at least a part of the fluid container being transparent or translucent to the said wavelength or wavelengths, a radiation filter substantially all the filtered radiation from which is at the said wavelength or wavelengths; a detector responsive to the filtered radiation; and radiation directing means for directing radiation from the radiation source onto the detector after the radiation has passed through both the filter and the said part of the fluid container, the radiation directing means focussing the radiation from the radiation source onto the filter.
Since the radiation from the radiation source is focussed onto the filter, the size of the latter can be reduced and consequently its cost can be kept as low as possible.
As will be appreciated, the term "wavelength or wavelengths" is intended inter alia to conver a countinuum of wavelengths extending from a minimum to a maximum wavelength.
The transparency of the said part of the container is preferably such as to produce minimum absorption and minimum defocussing of the said radiation.
The radiation is preferably passed through the filter before being passed through the said part of the fluid container.
The radiation which has passed through the said part of the fluid container is preferably passed back therethrough before being directed onto the detector. Since the amount of radiation absorbed by the fluid component depends on the length of the path of radiation through the fluid, and since the accuracy of measurement depends upon this length, such passing of the radiation back through the fluid container effectively doubles the length of the radiation path and therefore enables the size of the fluid container to be reduced. This allows the size, and consequently the cost, of the apparatus as a whole to be reduced.
The filtered radiation is preferably focussed onto the detector.
Preferably there are first radiation directing means comprising a first concave mirror which focusses radiation from the radiation source onto the filter, the first concave mirror being disposed on one side of the fluid container, and second radiation directing means comprising a second concave mirror which is disposed on the opposite side of the fluid container and which reflects the filtered radiation which has passed through the said part of the fluid container back through the said part of the fluid container so as to focus it onto the detector. The radiation source, moreover, is preferably disposed adjacent the centre of curvature of the first concave mirror. Furthermore, the radiation source, the filter and the detector are preferably disposed adjacent to each other but are heat shielded from each other.
The first concave mirror preferably produces a cone of radiation whose apex angle is substantially 32". Means, moreover, may be provided for restricting the cone of radiation col lected by the first concave mirror.
The radiation source may comprise a filament of a refractory metal plated with a noble metal.
The radiation source thus preferably comprises a filament of molybdenum wire plated with platinum.
Means are preferably provided for protecting the radiation source from draughts.
The filter is preferably an interference filter.
The fluid container may be a conduit through which in operation there is a flow of the said fluid or, alternatively, the fluid container may be a closed container.
The fluid container may be an opaque container provided on opposite sides thereof with windows which are transparent to the said wavelength or wavelengths. In this case, each window may be constituted by a polyethylene sheet.
The detector is preferably a thermopile detector.
The said wavelength or wavelengths are preferably in the infra-red.
Means may be provided for screening the filter and the detector from direct radiation from the radiation source.
The invention also comprises a method of detecting whether a fluid contains a predetermined fluid component and/or for measuring the concentration of the fluid component in the said fluid, the said method comprising introducing the fluid into a fluid container at least a part of which is transparent to a wavelength or wavelengths absorbed by said fluid component; employing apparatus comprising a radiation source a portion of whose radiation is of the said wavelength or wavelengths, a radiation filter substantially all the filtered radiation from which is at the said wavelength or wavelengths, and a detector responsive to the filtered radiation; and employing radiation directing means to direct the radiation from the radiation source onto the detector after the radiation has passed through both the filter and the said part of the fluid container, the radiation directing means focussing the radiation from the radiation source onto the filter.
The said fluid is preferably a gas in which case the said fluid may be automobile exhaust gas and the said fluid component may be carbon monoxide, the said wavelength or wavelengths being in the range 4.48 to 4.83item.
The invention is illustrated, merely by way of example, in the accompanying diagrammatic drawing which shows an apparatus according to the present invention for determining the concentration of carbon monoxide in automobile exhaust gas.
Terms such as "left", and "right", as used in the description below, are to be regarded as referring to directions as seen in the accompanying drawing.
Referring to the drawing, an apparatus for determining the concentration of carbon monoxide in automobile exahaust gas comprises a fluid container 1 which may be constituted either by a conduit through which, in operation, there is a flow of automobile exhaust gas, or by a closed container which is arranged to receive, when required, a supply of exhaust gas from an automobile. The fluid container 1 is an opaque container which is provided on opposite sides thereof with windows 2, 3 which are transparent to the infrared radiation mentioned below. Such windows may, if desired, be formed of calcium fluoride, but since the latter material is expensive it is preferred to make the windows 2, 3 of low density polyethylene sheeting having a thickness not exceeding 0.05mm.Such sheeting is such as to absorb not more than 30% of the infra-red radiation, and is preferably such as to absorb only 15% thereof.
Adjacent to and on the left hand side of the fluid container 1 is a filament 4 which constitutes an infra-red radiation source. A portion of the radiation produced by the filament 4 is in the wavelength band 4.48 to 4.48m at which, as explained above, the infra-red radiation is absorbed by the carbon monoxide content of the exhaust gas.
The filament 4 may be constituted by a coil of wire made of a nickel-chromium alloy, the wire diameter being, for example, 0.4mm and the coil having, for example, a diameter of 4mm and a length of 4mm. A nickel-chromium alloy is a particularly good source of appropriate radiation since it can withstand being heated to a temperature of 900"C in air for long periods. This is because a thin, tenacious oxide film is formed in operation on the wire, and this oxide film, once formed, protects the underlying alloy from further oxidation. Such a nickel-chromium alloy typically contains 20% chomium and 1.5% silicon, the balance being nickel.
The filament 4 is preferably, however, made of molybdenum wire with a thin (e.g. 1,um) plating of platinum, since this has improved life and resistance characteristics.
The output of the filament 4 is controlled by an electronic control 5 whose purpose is either to ensure that the electrical supply to the filament 4 does not vary (e.g. is maintained at 3 volts) or to ensure that there is compensation for any change in the heat loss conditions from the filament 4 e.g. due to a change in ventilation or in ambient temperature.
Means (not shown) are provided for protecting the filament 4 from draughts.
The filament 4 is mounted adjacent the centre of curvature of a first concave mirror 6 which focusses radiation from the filament 4 onto an interference filter 7 through which passes only the radiation falling within the 4.48 to 4.83tm band.
The filter 7 is a relatively expensive item per unit area. However, since the infra-red radia tion from the filament 4 is focussed by the first concave mirror 6 onto the filter 7, the latter can be of very small size and therefore of low cost.
The infra-red radiation which has passed through the filter 7 is transmitted through the windows 2, 3 of the fluid container 1 so as to fall onto a second concave mirror 19 which is on the right hand side of the fluid container 1. Thus the first and second concave mirrors 6, 10 are disposed on opposite sides of the fluid container 1, while the radiation from the filament 4 is passed through the filter 7 before being passed through the fluid container 1. The second concave mirror 10 reflects the filtered radiation which has passed through the windows 2, 3, back therethrough so as to focus it onto a thermopile detector 11 which is mounted adjacent the centre of curvature of the second concave mirror 10, the detector 11 being responsive to this filtered radiation.
Each of the concave mirrors 6, 10 may be a front-surfaced mirror formed, for example, of a glass or plastics substrate having a reflective deposit thereon. It will be noted that the concave mirrors 6, 10 are provided externally of the fluid container 1 which ensures that the mirrors 6, 10 cannot be contaminated by the exhaust gas. The concave mirrors 6, 10 are ideally toroidal in shape but, provided the separations between the filament 4 and the filter 7 and between the filter 7 and the detector 11 are kept small, spherical mirrors are satisfactory and are less expensive to manufacture.
The mirrors 6, 10 may be injection-moulded in a hard plastics material prior to being coated.
The coating itself may be aluminium or chromium and may be evaporated onto a hard plastics material, such a coating having a reflectivity of substantially 95% at the wavelength range employed.
As will be seen from the drawing, the filament 4 and the filter 7, both of which are disposed adjacent the focus of the first concave mirror 6, are also adjacent to the detector 11 which is itself disposed adjacent to the focus of the second concave mirror 10. However, these parts are heat-shielded from each other by a radiation screen 12, which shields the filter 7 and detector 11 from direct radiation from the filament 4, and by an enclosure
13 which substantially encloses the detector 11.
The disposition of the filament 4 and the filter 7 adjacent the centre of curvature of the first concave mirror 6, and the disposition of the detector 11 adjacent the centre of curvature of the second concave mirror 10 maximises the optical efficiency of the apparatus as a whole and consequently enables the power supply to the filament 4 to be reduced. Moreover, the construction is such as to enable the filament 4, filter 7 and detector 11 to be disposed extremely close to each other, thus producing a compact device whose size, and therefore cost, may be reduced as much as possible.
The output signal from the detector 11 passes to the electronic control 5 in which the signal is amplified, the electronic control 5 passing a signal to a meter 15. The meter 15 is calibrated so as to give a zero indication when there is a zero concentration of carbon monoxide in the fluid container 1, the meter indication increasing in reponse to an increase in the amount of infra-red radiation absorbed by the exhaust gas and thus in relation to the concentration of the carbon monoxide in the exhaust gas.
The electronic control 5, in addition to stabilizing the light output from the filament 4, also stabilizes the output to the meter 15 and ensures that the apparatus can be operated over the normal range of output voltages from a car battery of 10 to 15 volts.
As indicated at 17, waste heat from the electronic control 5 may be used to warm the incoming gas stream which passes into the fluid container 1 so as to raise the temperature of this gas stream above the dew point and so as to warm up the surfaces of the fluid container 1 and prevent condensation of water vapour thereon.
Moreover, because exhaust gas not only contains a large proportion of water vapour but also contains particulate material such as carbon and rust, it is desirable to filter the gas line before the gas reaches the fluid container 1 so as to avoid contamination of the windows 2, 3. Such a filter (not shown) may be constituted by a 150mm glass vessel which is loosely packed with non-absorbent cotton wool. The cotton wool will remove any condensed water vapour as well as particulate matter, and the water which collects at the bottom of the filter can be drained off therefrom. This will ensure that the cotton wool does not become soggy and will have a good lifetime.It is desirable in this connection to ensure that whatever filter is used to remove water vapour and particulate matter should offer a low impedance to the gas flow therethrough since it is desirable to arrange that this flow is achieved by using the positive pressure in the end of an automobile exhaust pipe, excessive back pressure in the exhaust manifold being undesirable since it affects engine performance. The arrangement may be such that the passage of the exhaust gas through the fluid container 1 is at the rate of 200mls/min.
It will be noted that the exhaust gas is admitted to one end of the fluid container 1 and passes out through the opposite end thereof and this arrangement is of importance since it helps to ensure that the gas thoroughly purges the fluid container 1 of whatever gas occupied it before the test started, this being desirable in order to produce an accurate reading on the meter 15.
As stated above, the filter 7 is an interference filter and the passband of an interference filter varies with the angle of incidence thereon. Consequently it is desirable to arrange that the filter passband and the angle of the cone of radiation is such that no radiation in the carbon dioxide absorption band can reach the detector 11. Thus if a large angle cone of radiation were employed, only radiation very near to 4.83m could be used. Similarly, if the whole wavelength band applicable to carbon monoxide, i.e. 4.48 to 4.83jim were to be employed, then only a very narrow angle cone could be used. For this reason it is desirable, as shown, to employ a radiation screen 16 so as to restrict the cone of radiation collected by the first concave mirror 6 and to arrange that the cone of radiation produced by the first concave mirror 6 has an apex angle of substantially 32".
Claims (27)
1. Apparatus for detecting whether a fluid contains a predetermined fluid component and/or for measuring the concentration of the fluid component in the said fluid, the said apparatus comprising a fluid container adapted to contain the said fluid; a radiation source a portion of whose radiation is of a wavelength or wavelengths absorbed by said fluid component, at least a part of the fluid container being transparent to the said wavelength or wavelengths; a radiation filter substantially all the filtered radiation from which is at the said wavelength or wavelengths; a detector responsive to the filtered radiation; and radiation direction means for directing radiation from the radiation source onto the detector after the radiation has passed through both the filter and the said part of the fluid container, the radiation directing means focussing the radiation from the radiation source onto the filter.
2. Apparatus as claimed in claim 1 in which the radiation is passed through the filter before being passed through the said part of the fluid container.
3. Apparatus as claimed in claim 1 or 2 in which the radiation which has passed through the said part of the fluid container is passed back therethrough before being directed onto the detector.
4. Apparatus as claimed in claim 2 or 3 in which the filtered radiation is focussed onto the detector.
5. Apparatus as claimed in any preceding claim in which there are first radiation directing means comprising a first concave mirror which focusses radiation from the radiation source onto the filter, the first concave mirror
being disposed on one side of the fluid container, and second radiation directing means comprising a second concave mirror which is disposed on the opposite side of the fluid container and which reflects the filtered radiation which has passed through the said part of the fluid container back through the said part of the fluid container so as to focus it onto the detector.
6. Apparatus as claimed in claim 5 in which the radiation source is disposed adjacent the centre of curvature of the first concave mirror.
7. Apparatus as claimed in claim 5 or 6 in which the radiation source, the filter and the detector are disposed adjacent to each other but are heat shielded from each other.
8. Apparatus as claimed in any of claims 5-7 in which the first concave mirror produces a cone of radiation whose apex angle is substantially 32".
9. Apparatus as claimed in any of claims 5-8 comprising means for restricting the cone of radiation collected by the first concave mirror.
10. Apparatus as claimed in any preceding claim in which the radiation source comprises a filament of a refractory metal plated with a noble metal.
11. Apparatus as claimed in any preceding claim in which the radiation source comprises a filament of molybdenum wire plated with platinum.
12. Apparatus as claimed in any preceding claim comprising means for protecting the radiation source from draughts.
13. Apparatus as claimed in any preceding claim in which the filter is an interference filter.
14. Apparatus as claimed in any preceding claim in which the fluid container is a conduit through which in operation there is a flow of the said fluid.
15. Apparatus as claimed in any of claims
1-13 in which the fluid container is a closed container.
16. Apparatus as claimed in any preceding claim in which the fluid container is an opaque container provided on opposite sides thereof with windows which are transparent to the said wavelength or wavelengths.
17. Apparatus as claimed in claim 16 in which each window is constituted by a polyethylene sheet.
18. Apparatus as claimed in any preceding claim in which the detector is a thermopile detector.
19. Apparatus as claimed in any preceding claim in which the said wavelength or wavelengths are in the infra-red.
20. Apparatus as claimed in any preceding claim comprising means for screening the filter and the detector from direct radiation from the radiation source.
21. Apparatus for detecting whether a fluid contains a predetermined fluid component and/or for measuring the concentration of the fluid component in the said fluid substantially as hereinbefore described with reference to and as shown in the accompanying drawings.
22. A method of detecting whether a fluid contains a predetermined fluid component and/or for measuring the concentration of the fluid component in the said fluid, the said method comprising introducing the fluid into a fluid container at least a part of which is transparent to a wavelength or wavelengths absorbed by said fluid component; employing apparatus comprising a radiation source a portion of whose radiation is of the said wavelength or wavelengths, a radiation filter substantially all the filtered radiation from which is at the said wavelength or wavelengths, and a detector responsive to the filtered radiation; and employing radiation directing means to direct the radiation from the radiation source onto the detector after the radiation has passed through both the filter and the said part of the fluid container, the radiation directing means focussing the radiation from the radiation source onto the filter.
23. A method as claimed in claim 22 in which the said fluid is a gas.
24. A method as claimed in claim 23 in which the said fluid is automobile exhaust gas and the said fluid component is carbon monoxide, the said wavelength or wavelengths being in the range 4.48 to 4.83/cm.
25. A method of detecting whether a fluid contains a predetermined fluid component and/or for measuring concentration of the fluid component in the said fluid substantially as hereinbefore described with reference to the accompanying drawings.
26. Apparatus for detecting whether a fluid contains a predetermined fluid component and/or for measuring the concentration of the fluid component in the said fluid, the said apparatus comprising a fluid container adapted to contain the said fluid; a radiation source a portion of whose radiation is of a wavelength or wavelengths absorbed by said fluid component, at least a part of the fluid container being transparent to the said wavelength or wavelengths; a radiation filter substantially all the filtered radiation from which is at the said wavelength or wavelengths; a detector responsive to the filtered radiation; and radiation directing means for directing radiation from the radiation source through the said part of the container and then back through said part so as to direct it onto the detector.
27. Any novel integer or step, or combination of integers or steps hereinbefore described and/or as shown in the accompanying drawings, irrespective of whether the present claim is within the scope of or relates to the same or a different invention from that of the preceding claims.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB08423670A GB2164743A (en) | 1984-09-19 | 1984-09-19 | Detecting the presence or concentration of a fluid component |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB08423670A GB2164743A (en) | 1984-09-19 | 1984-09-19 | Detecting the presence or concentration of a fluid component |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB8423670D0 GB8423670D0 (en) | 1984-10-24 |
| GB2164743A true GB2164743A (en) | 1986-03-26 |
Family
ID=10566939
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08423670A Withdrawn GB2164743A (en) | 1984-09-19 | 1984-09-19 | Detecting the presence or concentration of a fluid component |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2164743A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2013088289A1 (en) * | 2011-12-16 | 2013-06-20 | Koninklijke Philips Electronics N.V. | System and method of monitoring composition of a flow of breathable gas using a detector and emitter positioned on the same side of the flow of breathable gas |
-
1984
- 1984-09-19 GB GB08423670A patent/GB2164743A/en not_active Withdrawn
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2013088289A1 (en) * | 2011-12-16 | 2013-06-20 | Koninklijke Philips Electronics N.V. | System and method of monitoring composition of a flow of breathable gas using a detector and emitter positioned on the same side of the flow of breathable gas |
| CN103998920A (en) * | 2011-12-16 | 2014-08-20 | 皇家飞利浦有限公司 | System and method of monitoring composition of a flow of breathable gas using a detector and emitter positioned on the same side of the flow of breathable gas |
| JP2015505045A (en) * | 2011-12-16 | 2015-02-16 | コーニンクレッカ フィリップス エヌ ヴェ | System and method for monitoring the composition of respiratory gas flow using a detector and radiator located on the same side of the flow of respiratory gas |
| US9267883B2 (en) | 2011-12-16 | 2016-02-23 | Koninklijke Philips N.V. | System and method of monitoring composition of a flow of breathable gas using a detector and emitter positioned on the same side of the flow of breathable gas |
| CN103998920B (en) * | 2011-12-16 | 2016-11-09 | 皇家飞利浦有限公司 | Use the detector being positioned on the same side of breathable gas stream and transmitter to monitor the system and method for the composition of described breathable gas stream |
Also Published As
| Publication number | Publication date |
|---|---|
| GB8423670D0 (en) | 1984-10-24 |
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