US4862907A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Check valve
Assignee: Thermo Instrument Systems Inc
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Filing: 1988-09-07
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Granted: 1989-09-05
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Expires: 2008-09-07
Abstract
Abstract An improved liquid flow check valve using a ball and seat wherein the seat is made of sintered ceramic. The improved valve will operate in an environment of acetonitrile and water without sticking shut, thereby providing more stable liquid flow rates in liquid chromatography systems.
Inventors
- 👤 Marvin L. Ledtje
- 👤 Aubrey D. Long, Jr.
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 18:37
CPC Classifications
F; F16; F16K; F16K15/00; F16K15/02; F16K15/04; F16K15/042; Y; Y10; Y10T; Y10T137/00; Y10T137/0318; Y10T137/7722; Y10T137/7837; Y10T137/7838; Y10T137/7904; Y10T137/7908; Y10T137/7909; Y10T137/791
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
34 words
A method of restricting the direction of a flow of a liquid mixture containing one or more amines and water at high pressure by using a check valve with a seat comprising amorphic ceramic.
Claim 2
Independent Claim
34 words
A method of restricting the direction of a flow of a liquid mixture containing one or more amines and water at high pressure by using a check valve with a seat comprising amorphic ceramic.
Claim 3
Dependent Claim
22 words
A method as in claim 1 wherein said liquid mixture contains a proportion of acetonitrile contaminated with said one or more amines.
Claim 4
Dependent Claim
19 words
A method as in claim 2 wherein said proportion of acetonitrile is in a range between 60% and 100%.
Claim 5
Dependent Claim
24 words
A method as in claim 3 wherein said proportion of acetonitrile is controllably varied across said range during an interval of approximately one-half hour.
Claim 6
Dependent Claim
19 words
A method as in claim 1 of using a check valve wherein said amorphic ceramic comprises sintered alumina oxide.
Claim 7
Independent Claim
35 words
A method of restricting the direction of a flow of a liquid mixture containing proportions of acetonitrile and water at high pressure by using a check valve with a seat comprising sintered alumina oxide ceramic.
Claim 8
Independent Claim
35 words
A method of restricting the direction of a flow of a liquid mixture containing proportions of acetonitrile and water at high pressure by using a check valve with a seat comprising sintered alumina oxide ceramic.
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) | 1992-09-04 | 1993-03-06 | 1993-09-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-09-04 | 1997-03-06 | 1997-09-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-09-04 | 2001-03-06 | 2001-09-05 | $7700.00 | Window Closed / Lapsed |