WO1990010212A1 - Environmental monitoring device and method - Google Patents
Environmental monitoring device and method Download PDFInfo
- Publication number
- WO1990010212A1 WO1990010212A1 PCT/AU1990/000076 AU9000076W WO9010212A1 WO 1990010212 A1 WO1990010212 A1 WO 1990010212A1 AU 9000076 W AU9000076 W AU 9000076W WO 9010212 A1 WO9010212 A1 WO 9010212A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- concentration
- environment
- sensing means
- true
- environmental
- Prior art date
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
- G01N33/0004—Gaseous mixtures, e.g. polluted air
- G01N33/0009—General constructional details of gas analysers, e.g. portable test equipment
- G01N33/0027—General constructional details of gas analysers, e.g. portable test equipment concerning the detector
- G01N33/0031—General constructional details of gas analysers, e.g. portable test equipment concerning the detector comprising two or more sensors, e.g. a sensor array
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
- G01N33/0004—Gaseous mixtures, e.g. polluted air
- G01N33/0009—General constructional details of gas analysers, e.g. portable test equipment
- G01N33/0027—General constructional details of gas analysers, e.g. portable test equipment concerning the detector
- G01N33/0036—Specially adapted to detect a particular component
- G01N33/004—Specially adapted to detect a particular component for CO, CO2
Definitions
- the present invention relates to an environmental monitor and to a method for monitoring environmental conditions.
- the present invention relates to a device and a method for sensing the presence of gaseous substances within an environment.
- the present invention relates to a carbon dioxide (CO 2 ) measurement device and method which may be utilised separately or in conjunction with an environmental monitor for measuring the concentration of CO 2 in an environment.
- CO 2 carbon dioxide
- the present invention also relates to a methane
- Typical parameters which are measured by such devices and methods include temperature, pressure, air velocity and gas concentration.
- the invention detailed herein relates to complementary gas detection techniques which are interdependent although each is in itself a novel idea. The techniques are aimed particularly at solving two particular problems, those of the lack of a suitably compact and inexpensive personal carbon dioxide sensor and the fact that adequate methane detectors consume a lot of energy and are a battery life and bulk problem.
- the technique embodied herein also include a cost effective calibration technique which makes viable the proposed improvement in methane detection and the proposed novel carbon dioxide measuring technique.
- oxygen sensors which are available and to which the invention may utilise are in general self-powered, diffusion limited, metal-air batteries. They contain an anode, electrolyte and an air cathode to which the
- Oxygen is reduced to Hydroxy1 ions which in turn oxidise the metal anode.
- the electrical current between the anode and cathode is proportional to the rate of consumption of oxygen.
- the rate at which oxygen can get to the electrode through the diffusion barrier is proportional to the concentration of oxygen in the
- the current through, or voltage across a suitable resistor is therefore directly related to the concentration of oxygen in the air.
- the traditional diffusion barrier has been a very thin plastic membrane.
- Plastic membranes have a very high temperature and pressure coefficient, with suitable temperature compensation, sensors fitted with such a barrier are sensitive primarily to the partial pressure of
- Gaseous Diffusion Barrier takes the form of a simple capillary.
- Diffusion Barrier has the characteristics of making the sensor insensitive to atmospheric pressure as well as greatly reducing the temperature sensitivity of the device.
- This device has become known as a "Volumetric” or “Concentration” sensor, its main characteristic is that of insensitivity to atmospheric pressure.
- the volumetric oxygen sensor has another
- the present invention seeks to provide a CO 2 sensor using essentially two oxygen sensors, one which exhibits a CO 2 or acid gas enhancement effect and another which does not exhibit this effect.
- difference in derived signal from the two sensors can be calibrated to give a reading of CO 2 concentration.
- the present invention seeks to provide a device and a method for monitoring environmental conditions which overcomes the disadvantages of prior art monitoring devices by providing a device and method which is adapted to sense a plurality of environmental
- microprocessor together with extensive memory capacity, is able to correlate the data from said sensors, compute and indicate to an operator, relevant information relating to the environmental conditions.
- the present invention also seeks to provide a device for monitoring environmental conditions which is compact and functional, lending itself to be worn on the belt of an operator, for instance, in mines and chemical plants, to provide an alarm to said operator in the event of an emergency or hazardous situation.
- the present invention also seeks to provide a device and a method for monitoring environmental conditions, and in particular, the presence of gases such as CH 4 , O 2 , CO 2 CO, NO, H 2 S and H 2 to correlate data relating to such gases, and to provide information to an operator to indicate such conditions explosibility, toxicity and O 2 deficiency, together with information relating to
- the present invention also seeks to provide a device and a method for monitoring environmental conditions wherein, by undergoing a calibration procedure, the parameters of various environmental conditions of a test environment may be monitored and stored in memory for comparison and correlation with the environment conditions of an unknown environment, such that, utilising regression analysis, information may be supplied to an operator to indicate qualitative and/or quantitative indications relative to said environmental conditions.
- the present invention provides a CO 2 concentration measurement device, comprising:
- volumetric sensing means adapted to measure volume % of O 2 in an environment, said volumetric sensing means having a CO 2 enhancement effect;
- partial pressure sensing means adapted to measure the partial pressure of O 2 , said partial pressuring sensing means having substantially non CO 2 enhancement effect;
- processsing means adapted to:
- the present invention seeks to provide a CH. measurement device consisting of:
- thermistor thermal conductivity sensing filament whereby, each of said filaments are individually powered such that the concentration of CH 4 is calculated from the change in electrical properties of the filaments.
- the present invention provides an environmental monitor, comprising:
- At least one sensor adapted to sense a gaseous substance and to provide sensor data indicative of the concentration of said gaseous substance
- memory means adapted to store calibration information obtained from said sensor data during a calibration proce d ure of said device after monitoring a plurality of test environments;
- processing means adapted to process said sensor data obtained during monitoring of an environment, and perform correlation and regression analysis techniques on said sensor data and said calibration information to provide an indication to an operator regarding the nature and
- the present invention provides a method for monitoring the nature
- environmental conditions therein are adapted to be sensed, and data corresponding thereto is compared and correlated to said calibration parameters, such that an indication relative to the nature and concentration of gaseous substances and other environmental conditions within said unknown environment may be indicated to an operator.
- Fig. 1 shows an environmental monitoring device in accordance with the present invention
- Fig. 2 illustrates a system diagram showing the calibration step of basic operational procedure of the environmental monitoring system
- Fig. 3 illustrates a block diagram of the CO 2
- Fig. 4 illustrates a schematic representation of the CH. measurement technique in accordance with the present invention.
- Fig. 1 is shown a preferred embodiment of an environmental monitoring device, in accordance with the present invention.
- the monitoring device generally designated by the numeral 1, is of cylindrical shape with a LCD display panel 2, a plurality of push buttons 3, and a plurality of warning LED's on one end of the cylindrical device 1.
- a sensor sealing cover 4 which surrounds the main body 5.
- the sealing cover 4 is partially slidable around the main body 5, such that, in a first position, the cover 4 exposes a slot which provides environmental access to the sensors contained within the main body 5, allowing remote sampling with sample tube entry and gas exit revealed, in a second position, the slot is fully open and operational to expose the sensors to ambient gas diffusion, and, in a third position, the monitor is switched off and sealed to watertight standard.
- the monitor is preferably constructed in a cylindrical shape, allowing a compact construction which enhances performance due to close proximity of sensors, and allows flexibility of expansion by increasing the height thereof. Consequently, by such construction, no separate attachments are required to operate the device.
- the monitoring device 1 is therefore of lightweight construction and is provided with its own power supply sufficient to operate the LED and LCD displays 4 and 2 together with audible alarms.
- the monitoring device 1 is also adapted to be connected to a serial data link
- Fig. 2 is illustrated a system diagram showing the calibration step and basic operational procedure of the environmental monitoring system in accordance with the present invention.
- the system comprises a computer processing means 6, which is adapted to control the remainder of the system components, record the data derived therefrom, correlate said data and perform
- the method of monitoring the environmental condition is comprised of two core steps.
- the first step is the calibration step wherein the monitoring device undergoes a learn or
- the second step is the monitoring step, wherein the
- monitoring device is placed in an unknown environment, and, utilising the parameters previously recorded in the calibration step, the environmental conditions are sensed and indicated to the operator.
- the processing means 6 is adapted to control the emission of a plurality of gases from a gas supply means 7 into a gas blender 8, the output of the gas blender being supplied to an enclosed test environment 9, in which the environment monitor 1, under test, is provided. At this time, the environmental monitor 1 is connected by suitable
- the interfacing means for instance, an RS232 data link, to the processing means 6.
- the processing means 6 is also adapted to control other environmental conditions of the test environment 9, for instance, the temperature by means of a heating/cooling device 10.
- the computer processing means 6 is adapted to control the physical conditions set up in the test environment, including the concentrations of various gases,
- a plurality of conditions are separately established in the test environment 9 whilst the monitoring device 1 senses data corresponding
- This sensed data is recorded in the memory of the computer processing means and correlated with data pertaining to the established environmental test
- the raw data may be processed by the processing means utilising regression analysis, such that mathematical formulae may be devised characteristic of the monitoring device 1, and in particular, to the actual sensors provided therein. Consequently, the monitoring device 1 is thus calibrated, the mathematical function then being stored in memory within the device 1.
- the monitoring step wherein the parameters of an unknown environment may be determined, may then be
- the monitoring device 1 is able to be provided within any environment, and, utilising the mathematical function stored in memory within the device 1 during the calibration step, the parameters, such as the
- concentrations of gases and the temperature and pressure of the environment may be determined and indicated to the operator.
- the technique of the present invention not only allows monitoring of a plurality of physical parameters by utilisation of a plurality of sensors, but enables the correlation or cross-sensitivity of the physical
- a composite environment can be monitored by the cross-correlation of the individual data.
- the present invention may be applied to monitor the environmental conditions of any environment, however, a particularly useful application is that of monitoring the environment in the coal mining industry. That is, the present invention may be utilised to measure the concentration of various gases such as
- a range of toxic gas sensors can be included in the monitoring device, for example, to sense CO, NO, H 2 and H2S, statistical data correlation techniques are utilised wherein the derived data is based on all of the
- each sensor being provided to sense the presence of a particular gas or other environmental parameter.
- particular sensors may be embodied to suit the parameter to be monitored.
- Fig 3 is illustrated a schematic diagram of a measurement technique utilised for measuring CO 2
- An oxygen reference subsystem 15 is therefore provided which gives a sufficiently accurate indication of oxygen over a sufficiently wide range of temperature and pressure. While this is the way the
- a volumetric oxygen sensor 14 which is subject to the said CO 2 enhancement affect, a partial pressure oxygen sensor 11 which is not subject to or has a significantly smaller CO 2 enhancement effect, an absolute pressure sensor 12 and a temperature sensor 13 are each provided.
- Each of the sensors is provided with a basic electronic circuit which is designed to amplify the signal and offset any undesirable baseline outputs from the sensor to a level which is suitable for input to a microprocessor based data acquisition system 16. The exact electronic circuit used is unimportant and should in general be based on suggested circuit layouts proposed by the suppliers of the individual sensors used.
- microprocessor based data acquisition system The
- microprocessor applies equations and algorithms to
- implementation of this invention is the use of regression analysis of the data from the four sensors, this method being explained in more detail hereinafter.
- the invention could optionally be implemented with a future available oxygen sensor which could
- Th e tradi t ion al arr ang emen t for detecting flammable gases is a pair of electrically heated filaments in a wheatstone bridge.
- the filaments are, firstly the
- the output of the bridge is a
- millivolt signal which is proportional to the gas concentration over the 0 to 2 or 3 percent level.
- catalytic filament is damaged if powered for any
- the measurement is based on the difference in thermal
- Fig. 4 is illustrated how this invention provides a way of applying the catalytically active filament or
- the invention employs a
- sensing filament 18 which is operative over the range of
- One interfering gas is CO 2 which has a significant thermal conductivity affect.
- the pair of thermistors 17 and 18 whose combined energy dissipation is well under that of the conventional compensating filament, is each separately input to the microprocessor 16 or operational amplifier subsystem.
- One of the thermistors 18 is self heating, that is it
- the other thermistor 17 is not self heating and is designed to measure the ambient temperature. Rather than relying on complex circuits, the data is imputted from the individual thermistors and the catalytically active methane filament to the
- regression anaylsis is used to extract the data and hence the calibration in volumetric units which is required.
- Another means is to not use a self heated thermistor but rather to rely on data from other sensors regarding significant background gas concentrations for example the CO 2 measurement technique based on the interdependency between a number of individually novel ideas which further enhances the usefulness of the whole, in this case the thermistor used to measure ambient temperature for the CO 2 technique can double as an output to the CH 4
- subsystem could provide the data to compensate for the thermal conductivity effects of this most likely high concentration of diluting gas.
- Fig. 4 therefore shows the interdependency of the
- incorporating this invention is able to infer methane concentration below 5% on basis of thermal conductivity in the event of loss of catalytic filament.
- each gas sensor and each temperature compensation element being within a certain tolerance band of normal performance over the entire gas or temperature range.
- the temperature compensation was often compensating temperature effects in the circuit as well as in the sensor. Given the normal tolerance of available components and sensors, it is difficult to achieve very high precision of measurement for such instruments. An accuracy, taking into account linearity and temperature affects, of 5% is considered good, greater accuracy than this adds significant cost as a degree of customisation of each manufactured item is required.
- This invention also provides a method of manufacture which employs a radical new approach to deriving accurate data from the sensors.
- the technique is based on the following.
- each sensor is surrounded by the simplest possible circuit without any attempt to achieve
- the circuits are designed to optimise repeatability and long term drift stability.
- the microprocessor thus has the raw data from a number of sensors as input.
- the final stage of manufacture involves a fully automated, systematic test of each mechanically and electrically complete gas sensing product or subsystem over the gas concentration and temperature ranges in which it is expected to operate. This is carried out in the "Automated Calibration Environment”.
- the ACE computer carries out a systematic regression analysis of the applied (independent) and derived (dependent) variables contained in the body of data resulting from the automated test, computes
- the final performance of the instrument is totally independent from any differences in performance of any electronic component or sensor element due to
- the technique allows effects such as the cross sensitivity of an oxygen sensor to carbon dioxide to be efficiently converted into a real data output without any special circuit design. It further makes such a cross sensitivity based measurement feasible where conceivably the effect is particularly variable between different sensors or is particularly temperature sensitive.
- the technique is also of great value as it allows a fast product development path due to circuit simplicity while allowing the complex interrelation problems to be solved later by standard, systematic mathematical techniques.
- the implementation of the present invention consists of a temperature controlled chamber, whose temperature may be remotely programmed by computer, a gas mixing device, capable of mixing at least two gases with air which is also able to be remotely controlled by computer, and a computer which has analog outputs with which to control the temperature and gas concentrations applied to the instrument under test and a means of accepting data from the instrument under test. Data is able to be received (and returned) over a single serial data link, and
- Software in the ACE computer is adapted to program a systematic, time sequenced array of varying gas
- Regression analysis as a calibration technique is a means whereby a multiplicity of observations consisting of sets of raw data from one or more sensors in a measuring AMD/0170a product are recorded. In general one set of observations of raw data is recorded for each set of applied known
- CO 2 concentrations of 0,1,2,3,4,5,6,7,7,9 and 10 percent may be applied to the device and for each CO 2
- the regression technique is a means whereby an equation is proposed which may relate to observed dependant variables x1,x2 to xn which may include functions of x1 and/or x2 such as x1 2 or x1*x2/(1-x2) to the independent, known variable "y" which is the true applied gas concentration.
- the equation for example;
- the present invention provides a device wherein the calibration environment be built and used to apply a programmed array of independent variables to each manufactured product and that each product carry with it those unique equations and coeffiecients which are developed for it by means of regression analysis.
- the present invention therefore provides a device and a method for monitoring environmental conditions wherein, by initially undergoing a calibration procedure, the parameters of various environmental conditions of a test environment may be monitored and stored in memory, such that they can then be compared and correlated with the parameters of the
- the present invention also provides specific novel arrangements for measuring concentrations of CO 2 and CH 4 .
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- Medicinal Chemistry (AREA)
- Physics & Mathematics (AREA)
- Combustion & Propulsion (AREA)
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- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
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- Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)
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Abstract
Description
Claims
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AUPJ289389 | 1989-02-23 | ||
AUPJ2893 | 1989-02-23 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO1990010212A1 true WO1990010212A1 (en) | 1990-09-07 |
Family
ID=3773735
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/AU1990/000076 WO1990010212A1 (en) | 1989-02-23 | 1990-02-23 | Environmental monitoring device and method |
Country Status (3)
Country | Link |
---|---|
EP (1) | EP0460029A4 (en) |
AU (1) | AU630169B2 (en) |
WO (1) | WO1990010212A1 (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5272907A (en) * | 1990-06-08 | 1993-12-28 | Instrumentarium Corporation | Method for the identification of gases |
CN116818023A (en) * | 2023-08-29 | 2023-09-29 | 南京浦蓝大气环境研究院有限公司 | Atmospheric environment monitoring emergency early warning device |
Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3647392A (en) * | 1967-01-27 | 1972-03-07 | Westinghouse Electric Corp | Carbon dioxide sensor |
EP0004184A1 (en) * | 1978-03-08 | 1979-09-19 | British Gas Corporation | Gas sensing element and method for its production |
EP0062466A1 (en) * | 1981-04-04 | 1982-10-13 | English Electric Valve Company Limited | Combustible-gas detectors |
US4481804A (en) * | 1981-09-04 | 1984-11-13 | Hoffmann-La Roche Inc. | Method and apparatus for calibration of sensors |
US4854153A (en) * | 1986-12-05 | 1989-08-08 | Sumitomo Electric Industries, Ltd. | Automatic calibration apparatus for a partial gas pressure measuring sensor |
-
1990
- 1990-02-23 AU AU51742/90A patent/AU630169B2/en not_active Ceased
- 1990-02-23 WO PCT/AU1990/000076 patent/WO1990010212A1/en not_active Application Discontinuation
- 1990-02-23 EP EP19900903717 patent/EP0460029A4/en not_active Withdrawn
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3647392A (en) * | 1967-01-27 | 1972-03-07 | Westinghouse Electric Corp | Carbon dioxide sensor |
EP0004184A1 (en) * | 1978-03-08 | 1979-09-19 | British Gas Corporation | Gas sensing element and method for its production |
EP0062466A1 (en) * | 1981-04-04 | 1982-10-13 | English Electric Valve Company Limited | Combustible-gas detectors |
US4481804A (en) * | 1981-09-04 | 1984-11-13 | Hoffmann-La Roche Inc. | Method and apparatus for calibration of sensors |
US4854153A (en) * | 1986-12-05 | 1989-08-08 | Sumitomo Electric Industries, Ltd. | Automatic calibration apparatus for a partial gas pressure measuring sensor |
Non-Patent Citations (2)
Title |
---|
A.C. STERN, 'Air Pollution' Volume 3, published 1976, by Academic Press (USA) see Chapters 4,9,12, especially pages 164-166, 386-387, 460-461, 481-484. * |
Measurement and Control, Volume 19, No. 7, issued 1986 September (London) W.R. SIMONS 'Development in Flammable Gas Monitoring', see pages 27-32. * |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5272907A (en) * | 1990-06-08 | 1993-12-28 | Instrumentarium Corporation | Method for the identification of gases |
CN116818023A (en) * | 2023-08-29 | 2023-09-29 | 南京浦蓝大气环境研究院有限公司 | Atmospheric environment monitoring emergency early warning device |
CN116818023B (en) * | 2023-08-29 | 2023-11-07 | 南京浦蓝大气环境研究院有限公司 | Atmospheric environment monitoring emergency early warning device |
Also Published As
Publication number | Publication date |
---|---|
AU5174290A (en) | 1990-09-26 |
EP0460029A1 (en) | 1991-12-11 |
EP0460029A4 (en) | 1993-08-04 |
AU630169B2 (en) | 1992-10-22 |
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