GB2248929A - Optical sensor for acidic/basic substances - Google Patents

Optical sensor for acidic/basic substances Download PDF

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Publication number
GB2248929A
GB2248929A GB9118549A GB9118549A GB2248929A GB 2248929 A GB2248929 A GB 2248929A GB 9118549 A GB9118549 A GB 9118549A GB 9118549 A GB9118549 A GB 9118549A GB 2248929 A GB2248929 A GB 2248929A
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GB
United Kingdom
Prior art keywords
color
thin film
sensor
prism
indication material
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.)
Granted
Application number
GB9118549A
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GB9118549D0 (en
GB2248929B (en
Inventor
Susumu Sato
Yoshihiro Togashi
Norio Ito
Koichi Ishii
Shinji Yasuda
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Mitsubishi Electric Corp
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Mitsubishi Electric Corp
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Publication date
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Publication of GB9118549D0 publication Critical patent/GB9118549D0/en
Publication of GB2248929A publication Critical patent/GB2248929A/en
Application granted granted Critical
Publication of GB2248929B publication Critical patent/GB2248929B/en
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Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02B—BOARDS, SUBSTATIONS OR SWITCHING ARRANGEMENTS FOR THE SUPPLY OR DISTRIBUTION OF ELECTRIC POWER
    • H02B13/00—Arrangement of switchgear in which switches are enclosed in, or structurally associated with, a casing, e.g. cubicle
    • H02B13/02—Arrangement of switchgear in which switches are enclosed in, or structurally associated with, a casing, e.g. cubicle with metal casing
    • H02B13/035—Gas-insulated switchgear
    • H02B13/055—Features relating to the gas
    • 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
    • G01N21/75—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated
    • G01N21/77—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated by observing the effect on a chemical indicator
    • G01N21/78—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated by observing the effect on a chemical indicator producing a change of colour
    • G01N21/783—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated by observing the effect on a chemical indicator producing a change of colour for analysing gases
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H33/00—High-tension or heavy-current switches with arc-extinguishing or arc-preventing means
    • H01H33/02—Details
    • H01H33/53—Cases; Reservoirs, tanks, piping or valves, for arc-extinguishing fluid; Accessories therefor, e.g. safety arrangements, pressure relief devices
    • H01H33/56—Gas reservoirs
    • H01H2033/567—Detection of decomposition products of the gas

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Analytical Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Plasma & Fusion (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Power Engineering (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Investigating Or Analysing Materials By The Use Of Chemical Reactions (AREA)
  • Investigating Or Analysing Materials By Optical Means (AREA)

Abstract

A sensor 5 optically detects a colour reaction in a thin film 4 of colour indication material by means of transmitted light and reflected light to thereby detect the absence or presence of an acidic substance or a basic substance. Solid material constituting the thin film is vapour-deposited on a surface of a prism and the thickness of the thin film is in the range 100 ANGSTROM - 600 ANGSTROM . The sensor is applicable to electrical apparatus with gaseous (SF6) insulation, to detect decomposition of the gas as a result of arcing etc. <IMAGE>

Description

SENSOR The present invention relates to-a sensor for detecting an acidic substance or a basic substance, in particular, to detect fluid which exhibits acidity or basicity.
A so-called gas filled insulation apparatus wherein SF6 gas or the like having excellent insulating and quenching performance is used as an insulating and cooling medium, has been used for an electric apparatus or appliance such as a transformer, an interrupter, a bus bar or the like. If an abnormal state takes place in such electric apparatus or appliance, and when arcing or corona discharges occur or a short circuit takes place due to a fault at-an electrically contacting portion, for instance, such abnormality can not be easily detected from the outside because the electric apparatus or appliance is usually covered by a metallic casing.
On the other hand, in a case that an abnormal state occurs in the SF6 gas, gas resulted from the decomposition of the SF6 gas is produced. Accordingly, if an abnormality detecting device to detect such decomposed gas with good sensitivity is provided, it is possible to diagnose the abnormality in an electric apparatus or appliance.
As such abnormality detecting device, there is a proposal as disclosed in Japanese Patent Application No.
305074/1989, for instance. According to the proposal, a color indication material such as crystal violet is fixed in an insulating medium, and a color reaction resulted from the contact of the color indication material with an acidic gas such as HF (hydrogen fluoride) which is produced by the reaction between gas produced by the decomposition of the SF6 gas and a water component slightly remaining in the electric apparatus, is optically detected.
Figure 4 is a diagram showing the basic construction of the abnormality detecting device described in Japanese Patent Application No. 305074/1979 wherein reference numeral 1 designates a grounded vessel in an electric apparatus, numeral 2 designates a metallic conductor, numeral 3 designates SF6 gas, numeral 4 designates a color indication material, numeral 5 designates a prism for fixing the color indication material 4 in the electric apparatus, numeral 6 designates a light source, numeral 7 designates a spectroscope, numeral 8 designates a photomultiplier tube, numeral 9 designates a diagnosis device, and numeral 10 designates optical fibers.
Figure 5 is a diagram which shows in more detail a sensing section comprising the color indication material 4 and the prism 5.
The principle of detecting abnormality is as follows.
When a decomposed gas such as HF is produced in the electric apparatus, the color of the color indication material 4 is changed by a color reaction. In this case, there is a color having a wavelength which shows the greatest sensitivity, i.e. a wavelength showing the greatest change among colors. An amount of change in the reflection light showing the greatest change, which is reflected from the surface of the prism, is examined through the spectroscope 7 and the photomultiplier tube 8, and if there is a change, judgement of the abnormality of the electric apparatus is made by means of the diagnosis device 9.
The sensor is constituted by coating the water solution of the color indication material 4 on the surface of the prism 5, followed by drying and fixing it on the surface Of the prism 5.
However, the method of coating the water solution of the color indication material on the surface of a solid material such as the prism, followed by drying and fixing the color indication material had some difficulties in the determination of the concentration of the water solution and on the way to coat the color indication material on the prism. Thus, it has been practically difficult to provide a sensor having good sensitivity.
Further, there has been expected to produce such sensor having good sensitivity in an industrial scale.
It is an object of the present invention to eliminate the above-mentioned problems and to provide a sensor having good sensitivity, which is suited for a large scale production and is produced in a stable manner.
In accordance with the present invention, there is provided a sensor to optically detect a color reaction in a thin film of color indication material by means of a transmitted light and a reflected light to thereby detect the absence or presence of an acidic substance or a basic substance characterized in that a solid material constituting that thin film is on a surface of a prism and the thickness of the thin film is in a range of 100 A-600 A.
Further, in accordance with the present invention, the sensor having a thin film formed by a vapor deposition is used.
In drawings: Figure 1 is a diagram showing an embodiment of the sensor according to the present invention; Figures 2a, 2b and 2c are graphs showing the relation between the film thickness of a color indication material and the transmittance, and an amount of change in transmittance respectively; Figure 3 is a graph showing the relation between an amount of a color indication material in a crucible and the film thickness on the prism; Figure 4 is a diagram showing how the conventional sensor is used; and Figure 5 diagram showing a conventional sensor.
Preferred embodiments of the sensor according to the present invention will be described.
As the color indication material, such a color indication material that a state of electrons in the molecules of the material is influenced by an acidic substance or a basic substance, and the spectra of light by the absorption and reflection is changed to thereby show a color reaction, is usable. Accordingly, by detecting the change of the spectrum of light with good sensitivity, it is possible to detect a color reaction which has not been able to distinguish the reaction through naked eyes.
In accordance with the above-mentioned principle, a color indication material is placed in the neutral atmosphere; the color indication material is irradiated with light from a light source including a wavelength of light which is changed by a color reaction inherent in the color indication material, and analysis of the wavelength of light reflected or absorbed is conducted whereby the presence or absence of the color reaction, namely, the-presence or absence of an acidic substance or a basic substance and a degree of an acidic atmosphere or a basic atmosphere can be detected.
The detection of a color reaction with use of a prism as a substance to fix the color indication material is conducted as follows. The prism is generally understood in that incident light is entirely reflected at wall surfaces (side surfaces) of the prism. However, in fact, light slightly leaks from the side faces of the prism to the outside and the leaking light again enters into the prism. Accordingly, by attaching the color indication material. to the side faces of the prism, it is possible to detect a color reacion in the color indication material, if any, when light which has entered in the prism and has been reflected in it becomes output light.
Then, a change in the light absorption characteristics of the color indication material can be detected. In this case, when the film thickness of the color indication material is large, light passing through the prism does not pass through a portion where the color reaction takes place (because the color reaction occurs at a surface side of the film), whereby the color reaction can not detected at all. On the other hand, when the film thickness is small, the quantity of the color reaction is small and, therefore, sensitivity becomes low.
Accordingly, there is the optimum value in the film thickness of the color indication material. If a film of color indication material having the optimum thickness and uniform thickness is obtained, the sensitivity in detecting optically the color reaction is excellent.
The film thickness of the color indication material is preferably in a range of 100 A- 600 A. In particular, it was confirmed experimentally that the optimum value of the film thickness was a range of about 300 A-400 A. In order to form a thin film of color indication material on the prism, a vacuum deposition method is preferably used.
Thus, in accordance with the present invention, sensors having good sensitivity can be stably produced at a large scale production rate.
In accordance with the present invention, a sensor wherein a color indication material in- a form of a thin film which is sufficient to and necessary for the detection of a color reaction is formed on the surface of a prism is used, wherein light which has leaked from the surface of the prism is reflected and transmitted in the prism. The light reflected and transmitted in the prism is subjected to a spectral analysis so as to measure the intensity of light for each spectram. The intensity of light measured is converted into an electric output, which is calculated in the diagnosis device, whereby the presence or absence of a color reaction, namely, the presence or absence of an acidic substance or basic substance is judged.
Preferred embodiments of the sensor of the present invention will be described with reference to the drawings.
In Figure 1, reference numeral 5 designates a prism and numeral 11 designates a color indication material having a film thickness in a range of 100 A-600 A.
Figure 2 shows a result of examination as to the transmittance of light passing through the prism, i.e.
the ratio of the intensity of an incident light entering in the prism to the intensity of an output light from the prism, at different wavelengths before and after the color reaction wherein crystal violet is used as a color indication material and the thickness of the thin film of crystal violet on the prism as shown in Figure 1 is changed.
In Figures 2a, 2b and 2c, the abscissa denotes the film thickness of the color indication material and the ordinate denotes the transmittance at wavelengths of 680 nm, 550 nm and 440 nm respectively. In the Figures, symbols 0 represent values before the color reaction, symbols O represent values after the color reaction and symbols A represent amounts of change of the transmittance between before and after the color reaction. Further, the Figures show the reaction of the crystal violet to an acidic substance as a change of the transmittance at several spectra wherein each of the wavelengths represents the portion exhibiting the greatest change in the reaction color of the crystal violet. Figures 2a, 2b and 2c clearly show that the change of the transmittance exhibits the greatest value in each of the wavelengths in a range of film thickness of 300 A-400 A.Namely, by using the above-mentioned film thickness, a slight amount of an acidic substance can be detected with good sensitivity.
Figures 2a-2c, however, clearly show that use of the film thickness in a range of 100 A-600 A permits observation of a change of the transmittance for each of the wavelengths, it is possible to detect an acidic substance or a basic substance.
In the above-mentioned embodiments, the thin film of color indication material is formed on the surface of the prism by means of a vacuum deposition method. The nature of the thin film of color indication material formed by vapor depositing is determined depending on the thickness of the thin film, an evaporating material used and a process of vapor deposition. An organic material can be used for the color indication material. Since the organic material has a low decomposition temperature of molecules, a high evaporation temperature can not be expected. The crystal violet in a case that the crystalline contains no water exhibits entirely different colors from a case that it contains water, and the crystalline containing water exhibits a violet color.In consideration of the above-mentioned conditions and in order to prepare a thin film of crystal violet in a stable manner, the inventors of the present application have developed the measures as follows.
A color indication material is dissolved in an organic solvent; the organic solvent is dried to recrystallize the color indication material, and the recrystalline of the material is subjected to a vapor deposition method to thereby form a thin film of color indication material. By using the above-mentioned method, the color indication material having a desired thickness can be formed on the surface of the prism.
Thus, by controlling the film thickness of the color indication material, a sensor capable of detecting an acidic substance or a basic substance with good sensitivity can be provided.
In the above-mentioned method, since the color indication material is dissolved in the organic solvent and the solution is dried to recrystallize the material, the crystalline of the color indication material can be small, whereby the evaporation temperature can effectively be suppressed to be low, and the characteristics of the thin film formed by vacuum deposition can be improved.
Figure 3 is a graph showing the relation of the weight of the color indication material in a crucible to the thickness of a thin film of color indication material which is formed on the surface of a glass plate by vapor deposition under the condition that the degree of vacuum and the evaporation temperature are constant in a vacuum metallizing furnace. The thickness of the thin film of color indication material on the glass plate is measured with an interference microscope. Figure 3 shows a linear characteristic which passes the origin. Accordingly, it is understood from the above-mentioned graph that the thickness of the thin film can be easily controlled.
In accordance with the present invention, a sensor capable of detecting optically a color reaction in a thin film of color indication material in an optical manner by using a transmission light and a reflection light to thereby detect an acidic substance or a basic substance, wherein a solid material constituting the thin film is formed on the surface of a prism, and the film thickness of the thin film is determined in a range of 100 A-600 A.
Accordingly, the acidic substance or a basic substance can be detected with good sensitivity.
Although the crystal violet is used as the color indication material in the above-mentioned description, bromocresol purple can also be used. Further, another color indication material may be used depending on the object of detection and usage.
In accordance with the present invention, since the thin film is formed by using a vacuum deposition method, a desired film thickness can be correctly obtained, whereby a sensor capable of detecting an acidic substance or a basic substance with good sensitivity can be produced in a stable manner and large scale production.
Further, the present invention is applicable to the detection of water pollution or air pollution other than the abnormality diagnosis of an electric apparatus or appliance described above.

Claims (7)

CLAIMS:
1. A sensor to optically detect a color reaction in a thin film of color indication material by means of transmitted light and reflected light to thereby detect the absence or presence of an acidic substance or a basic substance characterized in that a solid material constituting said thin film is on a surface of a prism and the thickness of said thin film is in the range 100 - 600A.
2. An optical sensing element for the optical sensing of ambient conditions by means of color change, comprising an optical element having a surface to be exposed to the ambient conditions to be sensed, and on the said surface, a thin film of color indication material adapted to change color in response to change in ambient conditions, the said thin film having a thickness in the range 100 - 600A.
3. A sensor as claimed in claim 1 or claim 2 in which the film thickness is in the range 300 - 400A.
4. A sensor according to claim 1, 2 or 3 in which the thin film is a vapour-deposited film.
5. An optical color-indication sensor, substantially as herein described with reference to Figures 1 to 3 of the accompanying drawings.
6. Optical detection apparatus comprising a sensor as claimed in any of claims 1 to 5 in combination with means for optically analysing the color of the thin film material.
7. A method of making a sensor as claimed in claim 1 or 2 comprising disolving the color indication material in a solvent, drying the solution to recrystallize the color indication material, and vapour-depositing the recrystallized material on the said prism or optical element.
GB9118549A 1990-08-29 1991-08-29 Sensor Expired - Fee Related GB2248929B (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP22761190A JPH04109151A (en) 1990-08-29 1990-08-29 Sensor

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GB9118549D0 GB9118549D0 (en) 1991-10-16
GB2248929A true GB2248929A (en) 1992-04-22
GB2248929B GB2248929B (en) 1994-10-05

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GB (1) GB2248929B (en)
HK (1) HK39895A (en)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113670988B (en) * 2021-08-11 2024-09-03 山东智微检测科技有限公司 Dual-mode gas sensing device with color and conductivity and preparation and use methods thereof

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3998591A (en) * 1975-09-26 1976-12-21 Leeds & Northrup Company Spectrochemical analyzer using surface-bound color reagents
US4200110A (en) * 1977-11-28 1980-04-29 United States Of America Fiber optic pH probe
GB2054844A (en) * 1979-07-10 1981-02-18 Hellige Gmbh Transcutaneous photometric measurement of blood component
WO1986005589A1 (en) * 1985-03-20 1986-09-25 Monash University Fibre optic chemical sensor
EP0434893A2 (en) * 1989-11-24 1991-07-03 Mitsubishi Denki Kabushiki Kaisha Abnormality detecting device

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5724844A (en) * 1980-07-21 1982-02-09 Mitsubishi Electric Corp Detecting device for abnormality of gas
JPS6228418A (en) * 1985-07-23 1987-02-06 Nippon Spindle Mfg Co Ltd Spinning ring
JPS62123401A (en) * 1985-11-22 1987-06-04 Nippon Kogaku Kk <Nikon> Optical thin film for far ultraviolet rays
JPS6415703A (en) * 1987-07-09 1989-01-19 Nikon Corp Optical thin film for infra red ray

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3998591A (en) * 1975-09-26 1976-12-21 Leeds & Northrup Company Spectrochemical analyzer using surface-bound color reagents
US4200110A (en) * 1977-11-28 1980-04-29 United States Of America Fiber optic pH probe
GB2054844A (en) * 1979-07-10 1981-02-18 Hellige Gmbh Transcutaneous photometric measurement of blood component
WO1986005589A1 (en) * 1985-03-20 1986-09-25 Monash University Fibre optic chemical sensor
EP0434893A2 (en) * 1989-11-24 1991-07-03 Mitsubishi Denki Kabushiki Kaisha Abnormality detecting device

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Publication number Publication date
JPH04109151A (en) 1992-04-10
GB9118549D0 (en) 1991-10-16
HK39895A (en) 1995-03-31
GB2248929B (en) 1994-10-05

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746 Register noted 'licences of right' (sect. 46/1977)

Effective date: 19950810

PCNP Patent ceased through non-payment of renewal fee

Effective date: 19990829