WO1994023292A1 - Detector device - Google Patents
Detector device Download PDFInfo
- Publication number
- WO1994023292A1 WO1994023292A1 PCT/GB1994/000575 GB9400575W WO9423292A1 WO 1994023292 A1 WO1994023292 A1 WO 1994023292A1 GB 9400575 W GB9400575 W GB 9400575W WO 9423292 A1 WO9423292 A1 WO 9423292A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- window
- shielding gas
- gas flow
- source
- sai
- Prior art date
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/62—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating the ionisation of gases, e.g. aerosols; by investigating electric discharges, e.g. emission of cathode
- G01N27/64—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating the ionisation of gases, e.g. aerosols; by investigating electric discharges, e.g. emission of cathode using wave or particle radiation to ionise a gas, e.g. in an ionisation chamber
- G01N27/66—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating the ionisation of gases, e.g. aerosols; by investigating electric discharges, e.g. emission of cathode using wave or particle radiation to ionise a gas, e.g. in an ionisation chamber and measuring current or voltage
Definitions
- This invention relates to detector devices fo gas-borne contaminant.
- One such detector device is described i PCT/GB92/01313 and comprises a sample gas flow passag and a window into said passage for ionising radiation
- the ionised sample gas passes between measurin electrodes.
- the device is very sensitive t low contaminant concentrations, it is also very toleran of high concentrations. A problem arises, however, o contaminant fouling the window which reduces th sensitivity and can give rise to spurious results.
- the present invention alleviates that problem.
- the invention comprises a detector device fo detection of gas-borne contaminant having a sample ga flow passage and a window into said passage for ionisin radiation and shield means interposing a flow o shielding gas between said window and said sample ga f flow against contamination of said window.
- the device may comprise an ionising radiatio source chamber behind said window and shielding gas flo means for shielding gas from said chamber over sai window into said passage.
- Said chamber may have filtered inlet.
- Sample gas flow past said window may draw sai shielding gas flow in train.
- Said shielding gas flow may comprise a thi layer.
- the source of ionising radiation may comprise a ultraviolet source.
- the device may comprise baffle means definin the sample and shielding gas flow paths and which ma comprise radiation-unaffected material such as poly tetrafluoroethylene, which is tolerant of ultraviole radiation and which does not, when subject to suc radiation, emit photoelectrons, which would interfer with measurements.
- radiation-unaffected material such as poly tetrafluoroethylene, which is tolerant of ultraviole radiation and which does not, when subject to suc radiation, emit photoelectrons, which would interfer with measurements.
- the shielding gas may be clean (e.g. filtered air, but the device may comprise a source of shieldin gas such as a reservoir of clean air or nitrogen.
- the detector device illustrated in the drawin comprises a sample gas flow passage 11 through whic sample gas, e.g. air which might carry contaminant, i drawn by a fan 12.
- sample gas e.g. air which might carry contaminant
- the device has a window 13 openin into the passage 11 for ionising radiation which ionise the sample gas.
- the ionised sample gas then passes b an electrode system 14 which detects the ionisatio occasioned by the radiation.
- An ultraviolet source 15 is located behind th window 13 in a chamber 16.
- the source 15 has an en face comprising the window 13 which in use with heavil contaminated samples could itself become coated wit contaminant which will affect its performance - th radiation emitted through the window 13 will b attenuated, and the coating, itself excited by th radiation, could emit photoelectrons that woul interfere with measurement.
- the window 13 is protected by a flow o shielding gas 1J . between the window 13 and the sampl gas flow through the passage 11.
- the chamber 16 is hermetically sealed except fo a filtered inlet 17 and a shielding gas outlet apertur 18a. Sample gas flow past the window 13 (pulled by th fan 12) draws the shielding gas flow in train as a thi layer flow over the window 13.
- a definitive source o shielding gas may be provided as a reservoir, such as pressure cylinder 19 connected through suitable valvin 21 to the chamber 16.
- the shielding gas may then b clean air or it may be nitrogen, which does not absor 10.6 eV UV radiation and does not, on that account affect the sensitivity of the device.
- an air shield would reduce the sensitivity onl by about 20% which is a small price for the longer ter stability of the detector.
- Dilution of the sample gas by the shielding ga need cause a reduction in contaminant concentration o one or two percent at most, which will be of little o no consequence, but can be compensated for in any even during calibration of the device.
- the aperture 18a is in a baffle 22 defining th sample and shielding gas flow paths.
- the aperture 18 can be the same size as or slightly smaller than th window 13 - as it will be subject to some radiation, i is desirably of a material which is not affected. Poly tetrafluoroethylene is tolerant of UV radiation and doe not emit photoelectrons on exposure.
- the face of th baffle 22 in the passage 11 can be metallised an earthed to help define and maintain the electri potential distribution within the detection device.
- the gas shielding arrangement is of cours applicable to any window into the passage, not just window for ionising radiation.
- a detector device ma have several windows into the passage for one reason o another; each window can be shielded in similar fashion.
Landscapes
- Chemical & Material Sciences (AREA)
- Health & Medical Sciences (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- Electrochemistry (AREA)
- Physics & Mathematics (AREA)
- Life Sciences & Earth Sciences (AREA)
- Analytical Chemistry (AREA)
- Toxicology (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Optical Measuring Cells (AREA)
- Investigating Or Analysing Materials By Optical Means (AREA)
- Other Investigation Or Analysis Of Materials By Electrical Means (AREA)
- Measurement Of Radiation (AREA)
- Analysing Materials By The Use Of Radiation (AREA)
Abstract
Description
Claims
Priority Applications (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AU62619/94A AU6261994A (en) | 1993-03-30 | 1994-03-21 | Detector device |
GB9519848A GB2291713A (en) | 1993-03-30 | 1994-03-21 | Detector device |
EP94909993A EP0692095A1 (en) | 1993-03-30 | 1994-03-21 | Detector device |
JP6521787A JPH08508341A (en) | 1993-03-30 | 1994-03-21 | Detector |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB939306556A GB9306556D0 (en) | 1993-03-30 | 1993-03-30 | Detector device |
GB9306556.3 | 1993-03-30 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO1994023292A1 true WO1994023292A1 (en) | 1994-10-13 |
Family
ID=10732963
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/GB1994/000575 WO1994023292A1 (en) | 1993-03-30 | 1994-03-21 | Detector device |
Country Status (5)
Country | Link |
---|---|
EP (1) | EP0692095A1 (en) |
JP (1) | JPH08508341A (en) |
AU (1) | AU6261994A (en) |
GB (2) | GB9306556D0 (en) |
WO (1) | WO1994023292A1 (en) |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE2705185A1 (en) * | 1976-02-27 | 1977-09-01 | Varian Associates | PROCEDURE FOR ANALYZING GAS MIXTURES AND PERFORMING THE PROCESS OF APPROPRIATE ELECTRON TRAP DETECTORS |
EP0147521A1 (en) * | 1983-08-24 | 1985-07-10 | Matter + Siegmann AG | Control method for burning processes |
EP0524022A1 (en) * | 1991-07-19 | 1993-01-20 | The Secretary Of State For Defence In Her Britannic Majesty's Government Of The United Kingdom Of Great Britain And Northern | Gas detection device and method |
-
1993
- 1993-03-30 GB GB939306556A patent/GB9306556D0/en active Pending
-
1994
- 1994-03-21 AU AU62619/94A patent/AU6261994A/en not_active Abandoned
- 1994-03-21 JP JP6521787A patent/JPH08508341A/en active Pending
- 1994-03-21 EP EP94909993A patent/EP0692095A1/en not_active Withdrawn
- 1994-03-21 WO PCT/GB1994/000575 patent/WO1994023292A1/en not_active Application Discontinuation
- 1994-03-21 GB GB9519848A patent/GB2291713A/en not_active Withdrawn
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE2705185A1 (en) * | 1976-02-27 | 1977-09-01 | Varian Associates | PROCEDURE FOR ANALYZING GAS MIXTURES AND PERFORMING THE PROCESS OF APPROPRIATE ELECTRON TRAP DETECTORS |
EP0147521A1 (en) * | 1983-08-24 | 1985-07-10 | Matter + Siegmann AG | Control method for burning processes |
EP0524022A1 (en) * | 1991-07-19 | 1993-01-20 | The Secretary Of State For Defence In Her Britannic Majesty's Government Of The United Kingdom Of Great Britain And Northern | Gas detection device and method |
Also Published As
Publication number | Publication date |
---|---|
GB9519848D0 (en) | 1995-11-29 |
EP0692095A1 (en) | 1996-01-17 |
JPH08508341A (en) | 1996-09-03 |
GB2291713A (en) | 1996-01-31 |
AU6261994A (en) | 1994-10-24 |
GB9306556D0 (en) | 1993-05-26 |
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