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Patent US4498333A successfully refreshed from Google Patents.
US4498333A
Expired / Lapsed
US
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Carbon granule probe microphone for leak detection
Assignee: National Aeronautics and Space Administration
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Filing: 1983-06-01
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Granted: 1985-02-12
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Expires: 2003-06-01
Abstract
Abstract A microphone which is not subject to corrosion is provided by employing carbon granules to sense sound waves. The granules are packed into a ceramic tube and no diaphragm is used. A pair of electrodes are located in the tube adjacent the carbon granules and are coupled to a sensing circuit. Sound waves cause pressure changes on the carbon granules which results in a change in resistance in the electrical path between the electrodes. This change in resistance is detected by the sensing circuit. The microphone is suitable for use as a leak detection probe in recovery boilers, where it provides reliable operation without corrosion problems associated with conventional microphones.
Inventors
- 👤 Shakkottai P. Parthasarathy
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 06:53
CPC Classifications
G; G01; G01M; G01M3/00; G01M3/02; G01M3/04; G01M3/24
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
111 words
A fluid container system including means for detecting leaks therein, comprising: a fluid container; a ceramic tube having an open end adapted for insertion into the interior of the container, said tube having a closed end located on the outside of the container; a plurality of carbon granules packed within the closed end of the tube; a plug contained within the tube for maintaining the carbon granules in their packed condition, said plug allowing the passage of sound waves therethrough; and detection means for detecting resistance changes of a fixed length path through the carbon granules resulting from pressure changes on the carbon granules caused by sound waves entering the tube.
Claim 2
Dependent Claim
111 words
A fluid container system including means for detecting leaks therein, comprising: a fluid container; a ceramic tube having an open end adapted for insertion into the interior of the container, said tube having a closed end located on the outside of the container; a plurality of carbon granules packed within the closed end of the tube; a plug contained within the tube for maintaining the carbon granules in their packed condition, said plug allowing the passage of sound waves therethrough; and detection means for detecting resistance changes of a fixed length path through the carbon granules resulting from pressure changes on the carbon granules caused by sound waves entering the tube.
Claim 3
Dependent Claim
45 words
A system as in claim 1 wherein the detection means includes first and second spaced apart electrodes located in the interior of the housing adjacent the carbon granules and circuit means for detecting resistance changes in the path through the carbon granules between the electrodes.
Claim 4
Dependent Claim
43 words
A system as in claim 2 wherein the circuit means comprises a battery and resistor connected in series across the electrodes, wherein changes in the resistance in the path through the carbon granules will result in variation of the voltage across the resistor.
Claim 5
Dependent Claim
36 words
A system as in claim 1 including means for providing a flow of air from the interior of the tube to the open end thereof to prevent the entry of dust and fumes into the tube.
Claim 6
Dependent Claim
13 words
A system as in claim 1 wherein the container is a recovery boiler.
References Cited (Backward Citations)
US1296683A
Cited
US1634210A
Cited
US2171793A
Cited
US2548947A
Cited
US3831561A
Cited
US4309576A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-02-12 | 1988-08-13 | 1989-02-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-02-12 | 1992-08-13 | 1993-02-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-02-12 | 1996-08-13 | 1997-02-12 | $7700.00 | Window Closed / Lapsed |