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US3742475A
Expired / Lapsed
US
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Gaseous impurity detector employing corona discharge phenomenon
Assignee: TIF INSTRUMENTS INC US
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Filing: 1971-03-16
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Granted: 1973-06-26
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Expires: 1991-03-16
Abstract
Abstract A method is disclosed of detecting gaseous impurities, particularly halogens, in an ambient atmosphere by repeatedly pulsing a pair of electrodes disposed in that atmosphere with a voltage sufficient to cause a corona discharge in the continuous corona region, and detecting the average (d.c.) current component of such discharge, changes in which correspond to changes in the concentration of such gaseous impurities. Apparatus is disclosed for detecting such impurities in concentrations as low as 1 ppm.
Inventors
- 👤 Leonard N Liebermann
- 👤 Stanley H Lai
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 08:18
CPC Classifications
H; H01; H01H; H01H71/00; H01H71/10; H01H71/1045; H02; H02H; H02H3/00; H02H3/02; H02H3/025; G; G01; G01N; G01N27/00; G01N27/62; G01N27/68; G01N27/70
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
55 words
A method of detecting gaseous impurities in an ambient atmosphere, comprising applying voltage pulses across a pair of electrodes disposed in such atmosphere, the voltage being sufficient to cause a corona discharge across said electrodes in the continuous corona region; and detecting the mean corona current of said discharge, which current varies with impurity concentration.
Claim 2
Independent Claim
55 words
A method of detecting gaseous impurities in an ambient atmosphere, comprising applying voltage pulses across a pair of electrodes disposed in such atmosphere, the voltage being sufficient to cause a corona discharge across said electrodes in the continuous corona region; and detecting the mean corona current of said discharge, which current varies with impurity concentration.
Claim 3
Independent Claim
87 words
A method of detecting gaseous impurities in an ambient atmosphere, comprising applying voltage pulses across a pair of electrodes disposed in such atmosphere, the voltage thereof being sufficient to cause a negative corona discharge across said electrodes in the continuous corona region and said pulses being between about 1 to 300 microseconds in length at a pulse rate greater than 10/second, but not so great as to exceed 10 percent duty cycle; and detecting the mean corona current of said discharge, which current varies with impurity concentration.
Claim 4
Independent Claim
87 words
A method of detecting gaseous impurities in an ambient atmosphere, comprising applying voltage pulses across a pair of electrodes disposed in such atmosphere, the voltage thereof being sufficient to cause a negative corona discharge across said electrodes in the continuous corona region and said pulses being between about 1 to 300 microseconds in length at a pulse rate greater than 10/second, but not so great as to exceed 10 percent duty cycle; and detecting the mean corona current of said discharge, which current varies with impurity concentration.
Claim 5
Independent Claim
48 words
A method of detecting gaseous impurities in an ambient atmosphere comprising applying voltage pulses across an asymmetrical electrode pair sufficient in magnitude to cause a corona discharge thereacross in the continuous corona region; and measuring the peak true corona discharge current, which is representative of such impurity concentration.
Claim 6
Independent Claim
48 words
A method of detecting gaseous impurities in an ambient atmosphere comprising applying voltage pulses across an asymmetrical electrode pair sufficient in magnitude to cause a corona discharge thereacross in the continuous corona region; and measuring the peak true corona discharge current, which is representative of such impurity concentration.
Claim 7
Dependent Claim
70 words
Apparatus for detecting gaseous impurities in an ambient atmosphere comprising: an asymmetrical electrode pair disposable in such ambient atmosphere; a source of voltage pulses connected to the electrode pair, the voltage of said pulses being sufficient to cause a corona discharge across the electrode pair in the continuous corona regIon; and means for indicating the mean corona current of said discharge, which is representative of the concentration of such impurity.
Claim 8
Dependent Claim
70 words
Apparatus for detecting gaseous impurities in an ambient atmosphere comprising: an asymmetrical electrode pair disposable in such ambient atmosphere; a source of voltage pulses connected to the electrode pair, the voltage of said pulses being sufficient to cause a corona discharge across the electrode pair in the continuous corona regIon; and means for indicating the mean corona current of said discharge, which is representative of the concentration of such impurity.
Claim 9
Dependent Claim
23 words
Apparatus as defined in claim 4 including a limiting resistor for preventing spark breakdown under all impurity concentration occurring in such ambient atmosphere.
Claim 10
Dependent Claim
117 words
Apparatus for detecting gaseous impurities in an ambient atmosphere comprising: an asymmetrical electrode pair disposable in such ambient atmosphere, one electrode of said electrode pair being pointed; a source of voltage pulses connected to the electrode pair, the voltage of said pulses being sufficient to cause a corona discharge across the electrode pair in the continuous corona region and said pulse source providing negative-polarity pulses to the pointed electrode having a pulse width of about one to 300 microseconds at a pulse rate greater than 10/second but not so great as to exceed 10 percent duty cycle; and means for indicating the mean corona current of said discharge, which is representative of the concentration of such impurity.
Claim 11
Dependent Claim
117 words
Apparatus for detecting gaseous impurities in an ambient atmosphere comprising: an asymmetrical electrode pair disposable in such ambient atmosphere, one electrode of said electrode pair being pointed; a source of voltage pulses connected to the electrode pair, the voltage of said pulses being sufficient to cause a corona discharge across the electrode pair in the continuous corona region and said pulse source providing negative-polarity pulses to the pointed electrode having a pulse width of about one to 300 microseconds at a pulse rate greater than 10/second but not so great as to exceed 10 percent duty cycle; and means for indicating the mean corona current of said discharge, which is representative of the concentration of such impurity.
Claim 12
Dependent Claim
31 words
Apparatus as defined in claim 6 wherein said indicating means includes an R-C circuit in series with the electrode pair for providing an output voltage proportional to the time-average discharge current.
Claim 13
Dependent Claim
40 words
Apparatus as defined in claim 7 wherein said indicating means includes a voltage-controlled multivibrator connected to drive a speaker and connected to be controlled by said output voltage, whereby the frequency of the speaker output is indicative of impurity concentration.
Claim 14
Dependent Claim
30 words
Apparatus as defined in claim 7 wherein said indicating means includes an active amplifier responsive to said output voltage, connected in circuit with an indicating meter for indicating impurity concentration.
References Cited (Backward Citations)
US3460125A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-06-25 | 1976-12-25 | 1977-06-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-06-25 | 1980-12-25 | 1981-06-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-06-25 | 1984-12-25 | 1985-06-26 | $7700.00 | Window Closed / Lapsed |