US3864960A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Vacuum leak detector
Assignee: National Aeronautics and Space Administration
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Filing: 1973-10-02
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Granted: 1975-02-11
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Expires: 1993-10-02
Abstract
Abstract A leak detector for use with high vacuum seals as used in feedthroughs and hatch covers for manned spacecraft and vacuum systems. Two thermistors are used, one exposed directly to vacuum and the other exposed to a secondary chamber formed by the seal being monitored and a second auxiliary seal. Leakage into the secondary chamber causes an unbalance of an electrical bridge circuit in which the thermistors are connected.
Inventors
- 👤 James C Administrator Fletcher
- 👤 George P Kazokas
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 22:59
CPC Classifications
G; G01; G01M; G01M3/00; G01M3/002; B; B01; B01J; B01J3/00; B01J3/002; G01M3/02; G01M3/04; G01M3/16; G01M3/18; G01M3/184
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
248 words
An apparatus for the detection of vacuum leaks at a main seal between a first member and a second member which together form a barrier between a gaseous atmosphere and a vacuum environment comprising; secondary seal means attached along the expected leak path enclosing a chamber on the vacuum side of the main seal, one boundary of which is the main seal; gas flow exit means connecting said chamber to said vacuum environment; first heat generating means mounted in said vacuum environment within said gas flow exit whereby gas leaking past the main seal vents to the vacuum environment by flowing past said heat generating means; first temperature measurement means mounted adjacent to said first heat generating means whereby the temperature of said first heat generating means is measured; second heat generating means of identical characteristics to said first heat generating means mounted in said vacuum environment whereby said second heat generating means is isolated from said gas flow exit means; second temperature measurement means of identical characteristic to said first temperature measurement means mounted adjacent to said second heat generating means whereby the temperature of said second heat generating means is measured; and temperature comparison means interconnected to said first and second temperature measurement means for comparing the temperatures of said first heat generating means and said second heat generating means indicating the rate of gas flow cooling occuring at first heat generating means and thereby yielding a measure of gas leak rate past said main seal.
Claim 2
Independent Claim
248 words
An apparatus for the detection of vacuum leaks at a main seal between a first member and a second member which together form a barrier between a gaseous atmosphere and a vacuum environment comprising; secondary seal means attached along the expected leak path enclosing a chamber on the vacuum side of the main seal, one boundary of which is the main seal; gas flow exit means connecting said chamber to said vacuum environment; first heat generating means mounted in said vacuum environment within said gas flow exit whereby gas leaking past the main seal vents to the vacuum environment by flowing past said heat generating means; first temperature measurement means mounted adjacent to said first heat generating means whereby the temperature of said first heat generating means is measured; second heat generating means of identical characteristics to said first heat generating means mounted in said vacuum environment whereby said second heat generating means is isolated from said gas flow exit means; second temperature measurement means of identical characteristic to said first temperature measurement means mounted adjacent to said second heat generating means whereby the temperature of said second heat generating means is measured; and temperature comparison means interconnected to said first and second temperature measurement means for comparing the temperatures of said first heat generating means and said second heat generating means indicating the rate of gas flow cooling occuring at first heat generating means and thereby yielding a measure of gas leak rate past said main seal.
Claim 3
Dependent Claim
63 words
An apparatus for the detection of vacuum leaks as in claim 1 wherein a first temperature sensor, which is electrically heated, functions as both the first heat generating means and the first temperature measuring means and a second temperature sensor, which has characteristics identical to the first temperature sensor, functions as both the second heat generating means and the second temperature measurement means.
Claim 4
Dependent Claim
27 words
An apparatus for the detector of vacuum leaks as in claim 2 wherein said first temperature sensor and said second temperature sensor are thermistors of matched characteristics.
Claim 5
Dependent Claim
21 words
An apparatus for the detection of vacuum leaks as in claim 3 wherein said temperature comparison means is a bridge circuit.
Claim 6
Dependent Claim
159 words
An apparatus for the detection of vacuum leaks as in claim 1 wherein the main seal is a hatch seal of a spacecraft comprising: secondary seal means along the expected leak path enclosing a detector chamber, one boundary of which is the hatch seal; gas flow exit means connecting said detector chamber to the vacuum environment outside of the spacecraft; sensing thermistor mounted in the vacuum environment within said gas flow exit whereby gas leaking past said hatch seal vents to the vacuum by flowing past said sensing thermistor; reference thermistor with characteristics identical to said sensing thermistor mounted in the vacuum environment whereby said reference thermistor is isolated from said gas flow exit means; and resistance bridge interconnected with said sensing thermistor and said reference thermistor whereby said thermistors are electrically heated and the temperatures of said thermistors are compared thereby indicating the existance of any difference in cooling rate caused by a leak at the hatch seal.
Claim 7
Independent Claim
248 words
A method for detection of vacuum leaks at a main seal between a first member and a second member which together form a barrier between a gaseous atmosphere and a vacuum environment comprising: placing a secondary seal means along the expected leak patH on the vacuum side of the main seal to enclose a chamber, one boundary of which is the main seal; venting said chamber to said vacuum environment by means of a passageway; mounting a first heat generating means in said passageway in said vacuum environment whereby gas leaking past the main seal vents to the vacuum environment by flowing past said heat generating means; mounting a first temperature sensing means adjacent to said first heat generating means whereby the temperature of said first heat generating means is measured; mounting second heat generating means of identical characteristic to said first heat generating means in said vacuum environment whereby said second heat generating means is isolated from said gas flow exit means; mounting second temperature means of identical characteristics to said first temperature measurement means adjacent to said second heat generating means whereby the temperature of said second heat generating means is measured; interconnecting temperature comparison means to said first and second temperature measurement means to compare the temperature of said first heat generating means and said second heat generating means and to indicate the rate of gas flow cooling occuring at first heat generating means and thereby measuring the gas leak rate past said main seal.
Claim 8
Independent Claim
248 words
A method for detection of vacuum leaks at a main seal between a first member and a second member which together form a barrier between a gaseous atmosphere and a vacuum environment comprising: placing a secondary seal means along the expected leak patH on the vacuum side of the main seal to enclose a chamber, one boundary of which is the main seal; venting said chamber to said vacuum environment by means of a passageway; mounting a first heat generating means in said passageway in said vacuum environment whereby gas leaking past the main seal vents to the vacuum environment by flowing past said heat generating means; mounting a first temperature sensing means adjacent to said first heat generating means whereby the temperature of said first heat generating means is measured; mounting second heat generating means of identical characteristic to said first heat generating means in said vacuum environment whereby said second heat generating means is isolated from said gas flow exit means; mounting second temperature means of identical characteristics to said first temperature measurement means adjacent to said second heat generating means whereby the temperature of said second heat generating means is measured; interconnecting temperature comparison means to said first and second temperature measurement means to compare the temperature of said first heat generating means and said second heat generating means and to indicate the rate of gas flow cooling occuring at first heat generating means and thereby measuring the gas leak rate past said main seal.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-02-10 | 1978-08-12 | 1979-02-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-02-10 | 1982-08-12 | 1983-02-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-02-10 | 1986-08-12 | 1987-02-11 | $7700.00 | Window Closed / Lapsed |