GB2221295A - Semi-automatic zeroing of gas measuring system - Google Patents
Semi-automatic zeroing of gas measuring system Download PDFInfo
- Publication number
- GB2221295A GB2221295A GB8914119A GB8914119A GB2221295A GB 2221295 A GB2221295 A GB 2221295A GB 8914119 A GB8914119 A GB 8914119A GB 8914119 A GB8914119 A GB 8914119A GB 2221295 A GB2221295 A GB 2221295A
- Authority
- GB
- United Kingdom
- Prior art keywords
- gas
- concentration
- semi automatic
- incubator
- zeroing system
- 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- Withdrawn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
- 238000010926 purge Methods 0.000 claims description 7
- 238000010586 diagram Methods 0.000 claims description 4
- 238000005259 measurement Methods 0.000 claims description 2
- 230000006641 stabilisation Effects 0.000 claims description 2
- 230000000977 initiatory effect Effects 0.000 abstract description 2
- 230000003213 activating effect Effects 0.000 description 2
- 230000032683 aging Effects 0.000 description 2
- 230000015556 catabolic process Effects 0.000 description 2
- 238000006731 degradation reaction Methods 0.000 description 2
- 230000001143 conditioned effect Effects 0.000 description 1
- 230000003750 conditioning effect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 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
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01L—CHEMICAL OR PHYSICAL LABORATORY APPARATUS FOR GENERAL USE
- B01L1/00—Enclosures; Chambers
- B01L1/02—Air-pressure chambers; Air-locks therefor
-
- 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
- G01N33/0006—Calibrating gas analysers
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2201/00—Features of devices classified in G01N21/00
- G01N2201/12—Circuits of general importance; Signal processing
- G01N2201/127—Calibration; base line adjustment; drift compensation
Abstract
A semi automatic gas zeroing system incorporated in an incubator comprises a microprocessor control which records the CO2 value measured by a CO2 infra red gas detector at the initiation of an operation cycle of an incubator and stores this value in a battery backed RAM. This offset value is then added or substracted from subsequent measured values to produce the correct reading and control point for the CO2 level. The incubator may be purged of CO2 before the initial CO2 offset value is measured. <IMAGE>
Description
"Semi-Automatic Gas Zeroinq System"
This invention relates to a semi automatic gas zeroing system especially but not exclusively for setting C02 levels in incubators or ovens used for example for growing culture samples.
Incubator ovens such as that described in our co-pending
European Patent Application No 87302282.6 have C02 supply systems provided which include gas sensing means which allow a desired level of gas concentration to be obtained. These sensors may be infra red sensors which due to degradation of bulb light intensity, ageing of components and other factors require a user to set the zero C02 point manually to eliminate any errors caused by drift in the system. This is achieved by manually adjusting a control potentiometer which leads to inaccuracies due to the non linear nature of the sensor output. Small errors introduced at the lower end of the scale are magnified at higher C02 levels.
According to the present invention there is provided a semi automatic gas zeroing system comprising gas sensor means for detecting concentration of a specific gas in a closed area, memory means for recording an initially detected gas concentration, means for comparing said recorded concentration with a subsequently detected concentration and display means for displaying the change in gas concentration from said recorded concentration.
Preferably the gas sensor means comprises an infra red CO2 gas detector.
Preferably also the closed area in which gas is to be detected is an incubator.
Preferably also the memory means for recording gas concentration and the means for comparing gas concentrations is a microproccesor control.
Preferably also fan means are provided for purging gas from the closed area prior to the initial concentration measurement.
Preferably also timer means are included to time the purging of the gas from the closed area and to time a stabilisation period following gas purging before initial concentration is detected.
Embodiments of the present invention will now be described, by way of example with reference to the accompanying drawing which is a block functional diagram of a semi automatic gas zeroing system in accordance with the present invention.
Referring to the drawing a functional diagram of a semi automatic gas zeroing system incorporated in an incubator is illustrated. The system comprises a microprocessor control which records the C02 value measured by a CO2 infra red gas detector at the initiation of an operation cycle of an incubator and stores this value in a battery backed RAM.
This offset value is then added or substracted from subsequent measured values to produce the correct reading and control point for the C02 level.
More specifically C02 sensing is achieved in the incubator by using an infra-red detector and conditioning its output with analogue electronic circuitry. The output from this circuit is a non-linear O-10V signal which is fed to the microprocessor based control electronics. The analogue signal is then suitably conditioned and converted to a digital number for processing by the micro-computer which then calculates the actual C02 value.
In time degradation of the bulb light intensity in the infra-red detector, ageing of components in general and other factors lead to errors caused by drift in the system and hence the need to adjust the system to set the zero C02 point.
A simple procedure, which will now be described and which is illustrated in the accompanying block diagram, is followed by an operator to calculate the offset caused by the system drift which then provides the reference point for subsequent measuring.
The first step requires that any concentration of C02 remaining in the incubator be removed so the operator first presses a 0% pushbutton which has the effect of sounding an alarm, if the door is closed, activating a display panel, starting an internal time out timer and activating an internal fan. The alarm sounding alerts the operator to open the door which once open allows the fan to purge the incubator of C02. The display panel displays a 60 second countdown and flashes the actual C02 level every 10 seconds.
At the end of the countdown the incubator will be cleared of C02. The alarm sounds again and the display panel flashes to alert the operator to close the door and at the same time the internal time out counter is activated again.
Provided the operator closes the door promptly the alarm stops and the display panel shows a 15 minute countdown with the acutal C02 value flashing up every 15 seconds. The 15 minute countdown allows the incubator to reach its temperature operating point and ensures that the ambient C02 level has stabilised. At the end of the 15 minute countdown the C02 sensor reading is used to calculate an offset value which is then entered in the memory to be used for future actual C02 level calculation during the operation of the incubator.
Modifications and improvements may be incorporated without departing from the scope of the invention.
Claims (7)
1. A semi automatic gas zeroing system comprising gas sensor means for detecting concentration of a specific gas in a closed area, memory means for recording an initially detected gas concentration, means for comparing said recorded concentration with a subsequently detected concentration and display means for displaying the change in gas concentration from said recorded concentration.
2. A semi automatic gas zeroing system as claimed in Claim 1, wherein the gas sensing means comprises an infra red C02 gas detector.
3. A semi automatic gas zeroing system as claimed in Claim 1 or 2, wherein the closed area in which gas is to be detected is an incubator.
4. A semi automatic gas zeroing system as claimed in any one of the preceding Claims, wherein the memory means for recording gas concentration and the means for comparing gas concentrations is a microprocessor control.
5. A semi automatic gas zeroing system as claimed in any one of the preceding Claims, wherein fan means are provided for purging gas from the closed area prior to the initial concentration measurement.
6. A semi automatic gas zeroing system as claimed in any one of the preceding Claims, wherein timer means are included to time the purging of the gas from the closed area and to time a stabilisation period following gas purging before initial concentration is detected.
7. A semi automatic gas system substantially as hereinbefore described, with reference to and as shown in the accompanying diagram.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB888815039A GB8815039D0 (en) | 1988-06-24 | 1988-06-24 | Semi-automatic gas zeroing system |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB8914119D0 GB8914119D0 (en) | 1989-08-09 |
| GB2221295A true GB2221295A (en) | 1990-01-31 |
Family
ID=10639276
Family Applications (2)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB888815039A Pending GB8815039D0 (en) | 1988-06-24 | 1988-06-24 | Semi-automatic gas zeroing system |
| GB8914119A Withdrawn GB2221295A (en) | 1988-06-24 | 1989-06-20 | Semi-automatic zeroing of gas measuring system |
Family Applications Before (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB888815039A Pending GB8815039D0 (en) | 1988-06-24 | 1988-06-24 | Semi-automatic gas zeroing system |
Country Status (1)
| Country | Link |
|---|---|
| GB (2) | GB8815039D0 (en) |
Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3935459A (en) * | 1974-06-24 | 1976-01-27 | Sun Electric Corporation | Apparatus and method of automatically zeroing an exhaust emission analyzer |
| US3969626A (en) * | 1975-02-18 | 1976-07-13 | E. I. Du Pont De Nemours And Company | Method and apparatus for detecting total reduced sulfur |
| GB1547623A (en) * | 1975-05-06 | 1979-06-27 | Siemens Ag | Respiratory apparatus |
| EP0104463A1 (en) * | 1982-08-31 | 1984-04-04 | Becton Dickinson and Company | Detection of the presence of biological activity utilizing infrared analysis |
| EP0157243A2 (en) * | 1984-04-04 | 1985-10-09 | Cerberus Ag | Method and apparatus for the detection of reducing gases |
| EP0255856A2 (en) * | 1986-06-07 | 1988-02-17 | Ruhrgas Aktiengesellschaft | Method and apparatus for measuring the aldehyde concentration in waste gases |
| GB2204684A (en) * | 1987-05-08 | 1988-11-16 | Mine Safety Appliances Co | Infrared fluid analyzer |
-
1988
- 1988-06-24 GB GB888815039A patent/GB8815039D0/en active Pending
-
1989
- 1989-06-20 GB GB8914119A patent/GB2221295A/en not_active Withdrawn
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3935459A (en) * | 1974-06-24 | 1976-01-27 | Sun Electric Corporation | Apparatus and method of automatically zeroing an exhaust emission analyzer |
| US3969626A (en) * | 1975-02-18 | 1976-07-13 | E. I. Du Pont De Nemours And Company | Method and apparatus for detecting total reduced sulfur |
| GB1547623A (en) * | 1975-05-06 | 1979-06-27 | Siemens Ag | Respiratory apparatus |
| EP0104463A1 (en) * | 1982-08-31 | 1984-04-04 | Becton Dickinson and Company | Detection of the presence of biological activity utilizing infrared analysis |
| EP0157243A2 (en) * | 1984-04-04 | 1985-10-09 | Cerberus Ag | Method and apparatus for the detection of reducing gases |
| EP0255856A2 (en) * | 1986-06-07 | 1988-02-17 | Ruhrgas Aktiengesellschaft | Method and apparatus for measuring the aldehyde concentration in waste gases |
| GB2204684A (en) * | 1987-05-08 | 1988-11-16 | Mine Safety Appliances Co | Infrared fluid analyzer |
Also Published As
| Publication number | Publication date |
|---|---|
| GB8914119D0 (en) | 1989-08-09 |
| GB8815039D0 (en) | 1988-08-03 |
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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) |