US3848457A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Gaseous fluid monitoring apparatus
Assignee: 3M Co
•
Filing: 1973-05-14
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Granted: 1974-11-19
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Expires: 1993-05-14
Abstract
Abstract Apparatus for determining the extent to which a gaseous fluid is modified by a known material with the extent of such modification being measured with respect to an unacceptable level of modification such as the lower explosive limit for the modified gaseous fluid. Two chambers, each having an electric to acoustic transducer and an acoustic to electric transducer, are used with the acoustic to electric transducers connected in a bridge circuit. One chamber contains the gaseous fluid. It may be sealed in the chamber or received from a source where the gaseous fluid is not subject to modification by the known material. The other chamber receives the gaseous fluid from an area where it is subject to modification by the known material. A constant output oscillator having its frequency determined by the resonant frequency of the chamber receiving the unmodified gaseous fluid is used to energize the electric to acoustic transducers. The output of the bridge varies as the gaseous fluid is modified by the known material to provide an output signal which is measured relative to the output for the unacceptable level of modification of the gaseous fluid by said known material.
Inventors
- 👤 D Behymer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 15:09
CPC Classifications
G; G01; G01N; G01N29/00; G01N29/22; G01N29/30; G01N29/02; G01N29/032; G01N29/34; G01N29/348; G01N2291/00; G01N2291/02; G01N2291/024; G01N2291/02433; G01N2291/10; G01N2291/105
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
228 words
Apparatus for detecting the modification of a gaseous fluid by a known material including a first chamber for receiving the gaseous fluid; a second chamber for receiving the gaseous fluid from an area where it is subject to being modified by a known material; a first and second transducer positioned in each of said first and second acoustic chambers, said first transducer being an electric to acoustic transducer and said second transducer being an acoustic to electric transducer; an oscillator connected for energizing said first transducers with a signal having a frequency that is equal to the resonant frequency of said first chamber; a bridge circuit including said second transducers, said bridge circuit being energized by the acoustic energy received by said second transducers from said first transducers, the acoustic energy received by said second transducer of said second acoustic chamber varying with the modification of the gaseous fluid by the known material; a feedback circuit connected between said bridge circuit and said oscillator for providing said oscillator with an electrical signal proportional to the electrical signal output of said second transducer for said first chamber causing said oscillator to operate at the resonant frequency of said first chamber; and means connected to the output of said bridge circuit and responsive thereto for providing a signal indicative of the modification of the gaseous fluid by the known substance.
Claim 2
Dependent Claim
228 words
Apparatus for detecting the modification of a gaseous fluid by a known material including a first chamber for receiving the gaseous fluid; a second chamber for receiving the gaseous fluid from an area where it is subject to being modified by a known material; a first and second transducer positioned in each of said first and second acoustic chambers, said first transducer being an electric to acoustic transducer and said second transducer being an acoustic to electric transducer; an oscillator connected for energizing said first transducers with a signal having a frequency that is equal to the resonant frequency of said first chamber; a bridge circuit including said second transducers, said bridge circuit being energized by the acoustic energy received by said second transducers from said first transducers, the acoustic energy received by said second transducer of said second acoustic chamber varying with the modification of the gaseous fluid by the known material; a feedback circuit connected between said bridge circuit and said oscillator for providing said oscillator with an electrical signal proportional to the electrical signal output of said second transducer for said first chamber causing said oscillator to operate at the resonant frequency of said first chamber; and means connected to the output of said bridge circuit and responsive thereto for providing a signal indicative of the modification of the gaseous fluid by the known substance.
Claim 3
Independent Claim
214 words
An apparatus for detecting the modification of a gaseous fluid by a known material including a first chamber for receiving the gaseous fluid; a second chamber for receiving the gaseous fluid from an area where it is subject to being modified by a known material; a first and second transducer positioned in each of said first and second acoustic chambers, said first transducer being an electric to acoustic transducer and said second transducer being an acoustic to electric transducer; a constant output oscillator connected for energizing said first transducers with a signal having a frequency that is equal to the resonant frequency of said first chamber; said oscillator including an amplifier which has a degenerative feedback circuit connected between the output and input of said amplifier to help maintain the output of said oscillator constant; a bridge circuit including said second transducers, said bridge circuit being energized by the acoustic energy received by said second transducers from said first transducers, the acoustic energy received by said second transducer of said second acoustic chamber varying with the modification of the gaseous fluid by the known material; and means connected to the output of said bridge circuit and responsive thereto for providing a signal indicative of the modification of the gaseous fluid by the known substance.
Claim 4
Independent Claim
214 words
An apparatus for detecting the modification of a gaseous fluid by a known material including a first chamber for receiving the gaseous fluid; a second chamber for receiving the gaseous fluid from an area where it is subject to being modified by a known material; a first and second transducer positioned in each of said first and second acoustic chambers, said first transducer being an electric to acoustic transducer and said second transducer being an acoustic to electric transducer; a constant output oscillator connected for energizing said first transducers with a signal having a frequency that is equal to the resonant frequency of said first chamber; said oscillator including an amplifier which has a degenerative feedback circuit connected between the output and input of said amplifier to help maintain the output of said oscillator constant; a bridge circuit including said second transducers, said bridge circuit being energized by the acoustic energy received by said second transducers from said first transducers, the acoustic energy received by said second transducer of said second acoustic chamber varying with the modification of the gaseous fluid by the known material; and means connected to the output of said bridge circuit and responsive thereto for providing a signal indicative of the modification of the gaseous fluid by the known substance.
Claim 5
Dependent Claim
23 words
An apparatus in accordance with claim 2 wherein said degenerative feedback circuit includes a thermistor heated by the current in said feedback circuit.
Claim 6
Independent Claim
199 words
An apparatus for detecting the modification of a gaseous fluid by a known material including a first chamber for receiving the gaseous fluid; a second chamber for receiving the gaseous fluid from an area where it is subject to being modified by a known material; a first and second transducer positioned in each of said first and second acoustic chambers, said first transducer being an electric to acoustic transducer and said second transducer being an acoustic to electric transducer; an oscillator connected for energizing said first transducers with a signal having a frequency that is equal to the resonant frequency of said first cHamber; a bridge circuit including said second transducers, said bridge circuit being energized by the acoustic energy received by said second transducers from said first transducers, the acoustic energy received by said second transducer of said second acoustic chamber varying with the modification of the gaseous fluid by the known material; and means connected to the output of said bridge circuit and responsive thereto for providing a signal indicative of the modification of the gaseous fluid by the known substance, said means including two operational amplifiers connected for providing full-wave rectification of the bridge circuit output.
Claim 7
Independent Claim
199 words
An apparatus for detecting the modification of a gaseous fluid by a known material including a first chamber for receiving the gaseous fluid; a second chamber for receiving the gaseous fluid from an area where it is subject to being modified by a known material; a first and second transducer positioned in each of said first and second acoustic chambers, said first transducer being an electric to acoustic transducer and said second transducer being an acoustic to electric transducer; an oscillator connected for energizing said first transducers with a signal having a frequency that is equal to the resonant frequency of said first cHamber; a bridge circuit including said second transducers, said bridge circuit being energized by the acoustic energy received by said second transducers from said first transducers, the acoustic energy received by said second transducer of said second acoustic chamber varying with the modification of the gaseous fluid by the known material; and means connected to the output of said bridge circuit and responsive thereto for providing a signal indicative of the modification of the gaseous fluid by the known substance, said means including two operational amplifiers connected for providing full-wave rectification of the bridge circuit output.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-11-18 | 1978-05-20 | 1978-11-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-11-18 | 1982-05-20 | 1982-11-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-11-18 | 1986-05-20 | 1986-11-19 | $7700.00 | Window Closed / Lapsed |