US4135548A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Liquid nitrogen level controller
Assignee: United States Department of the Air Force
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Filing: 1977-08-11
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Granted: 1979-01-23
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Expires: 1997-08-11
Abstract
Abstract The liquid nitrogen level in a flask is controlled by the degree of immersion of two sensing coils of copper wire in the liquid nitrogen activating a solid state switching circuit which controls a liquid nitrogen inlet flow valve. Manual override and sensor fault indication is provided.
Inventors
- 👤 Daniel Sears
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 23:33
CPC Classifications
F; F16; F16K; F16K21/00; F16K21/04; F16K21/18; F16K21/185; F17; F17C; F17C13/00; F17C13/02; F17C13/021; G; G01; G01F; G01F23/00; G01F23/22; G01F23/24; G01F23/241; F17C2203/00; F17C2203/06; F17C2203/0602; F17C2203/0612; F17C2203/0626; F17C2203/0629; F17C2205/00; F17C2205/03; F17C2205/0302; F17C2205/0323; F17C2205/0326; F17C2205/0329; F17C2221/00; F17C2221/01; F17C2221/014; F17C2223/00; F17C2223/01; F17C2223/0146; F17C2223/0153; F17C2223/0161; F17C2223/03; F17C2223/033; F17C2250/00; F17C2250/03; F17C2250/036; F17C2250/04; F17C2250/0404; F17C2250/0408; F17C2250/0417; F17C2250/06; F17C2250/0605; F17C2250/061; Y; Y10; Y10T; Y10T137/00; Y10T137/7287; Y10T137/7306
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
150 words
A liquid nitrogen level controller for maintaining the level of LN 2 in a flask within a determined range comprising: a. a source of LN 2 ; b. means including a LN 2 valve for conducting LN 2 from the said source to the said flask; c. a first LN 2 sensor; d. a second LN 2 sensor; e. means for positioning the said first and second LN 2 sensors in a substantially vertical upper and lower relationship, respectively, within the said flask; f. means including a dual NAND Schmitt trigger circuit and a four-bit latch circuit cooperating with the said first and second sensors and the LN 2 valve for opening the said LN 2 valve when the said LN 2 level in the flask is below the said lower sensor and closing the said LN 2 valve when the LN 2 level is above the said upper sensor.
Claim 2
Dependent Claim
150 words
A liquid nitrogen level controller for maintaining the level of LN 2 in a flask within a determined range comprising: a. a source of LN 2 ; b. means including a LN 2 valve for conducting LN 2 from the said source to the said flask; c. a first LN 2 sensor; d. a second LN 2 sensor; e. means for positioning the said first and second LN 2 sensors in a substantially vertical upper and lower relationship, respectively, within the said flask; f. means including a dual NAND Schmitt trigger circuit and a four-bit latch circuit cooperating with the said first and second sensors and the LN 2 valve for opening the said LN 2 valve when the said LN 2 level in the flask is below the said lower sensor and closing the said LN 2 valve when the LN 2 level is above the said upper sensor.
References Cited (Backward Citations)
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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) | 1982-01-22 | 1982-07-24 | 1983-01-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-01-22 | 1986-07-24 | 1987-01-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-01-22 | 1990-07-24 | 1991-01-23 | $7700.00 | Window Closed / Lapsed |