Patent US3623828A successfully refreshed from Google Patents.
US3623828A
Expired / Lapsed
US
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Trap for preventing diffusion pump backstreaming
Assignee: National Aeronautics and Space Administration
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Filing: 1968-12-31
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Granted: 1971-11-30
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Expires: 1988-12-31
Abstract
Abstract An oil-backstreaming trap is located in a vacuum line between an oil diffusion pump and the evacuated system so that gases from the system are drawn through the trap on the way to the pump. First and second baffle plates extend partially across the crosssectional area of the trap and are spaced apart from each other along the direction of gas flow. The surface of the baffle plate closest to the evacuated system is smooth. The other baffle plate surfaces are roughened to form a large plurality of raised and depressed portions such as are formed by milling the roughened surfaces to form a large plurality of pyramid-shaped elements. In this manner, oil vapor from the diffusion pump which tends to backstream into the evacuated system, is coalesced on the roughened surfaces to form oil drops which then fall back into the diffusion pump.
Inventors
- 👤 Harold Shapiro
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 20:18
CPC Classifications
F; F04; F04F; F04F9/00; F04F9/06
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
189 words
Apparatus for preventing backstreaming oil molecules from a diffusion pump from entering a system being evacuated said apparatus comprised of: a conduit located between and connecting said pump and said system being evacuated thereby; a first impervious baffle plate extending from one side of said conduit toward an opposite side partially across and over the major portion of the cross-sectional area of said conduit; a second impervious baffle plate extending partially across and over the major portion of said cross-sectional area of said conduit from said opposite side toward said one side, said second baffle plate being spaced apart from said first baffle plate in the direction from said evacuated system to said diffusion pump; each of said baffle plates having a first surface thereof facing said evacuated system and a second surface thereof facing said diffusion pump; said second surfaces being roughened surfaces formed of an arrangement of closely spaced projections defining alternate raised and depressed portions forming a plurality of closely spaced small pockets for trapping the oil molecules and coalescing said backstreaming oil molecules from said diffusion pump to form drops thereof in said small pockets.
Claim 2
Dependent Claim
189 words
Apparatus for preventing backstreaming oil molecules from a diffusion pump from entering a system being evacuated said apparatus comprised of: a conduit located between and connecting said pump and said system being evacuated thereby; a first impervious baffle plate extending from one side of said conduit toward an opposite side partially across and over the major portion of the cross-sectional area of said conduit; a second impervious baffle plate extending partially across and over the major portion of said cross-sectional area of said conduit from said opposite side toward said one side, said second baffle plate being spaced apart from said first baffle plate in the direction from said evacuated system to said diffusion pump; each of said baffle plates having a first surface thereof facing said evacuated system and a second surface thereof facing said diffusion pump; said second surfaces being roughened surfaces formed of an arrangement of closely spaced projections defining alternate raised and depressed portions forming a plurality of closely spaced small pockets for trapping the oil molecules and coalescing said backstreaming oil molecules from said diffusion pump to form drops thereof in said small pockets.
Claim 3
Dependent Claim
18 words
The apparatus of claim 1 wherein said roughened surface is comprised of a large plurality of pyramid-shaped elements.
Claim 4
Dependent Claim
19 words
The apparatus of claim 1 wherein said roughened surface is comprised of a large plurality of conical shaped elements.
Claim 5
Dependent Claim
13 words
The apparatus of claim 1 wherein said roughened surface comprises a waffle pattern.
Claim 6
Dependent Claim
42 words
The apparatus of claim 1 wherein said first baffle plate declines from said one side of said conduit toward said diffusion pump at a slope of about 5 percent and extends across about 70 percent of the cross-sectional area of said conduit.
Claim 7
Dependent Claim
51 words
The apparatus of claim 1 wherein the surfaces of said second baffle plate are roughened; said second baffle plate declines from said another side of said conduit downwardly toward said diffusion pump at a slope of about 3 percent; and extends across about 75 percent of cross-sectional area of said conduit.
Claim 8
Dependent Claim
41 words
The apparatus of claim 6 wherein said first baffle plate declines from said one side of said conduit toward said diffusion pump at a slope of about 5 percent and covers about 70 percent of the cross-sectional area of said conduit.
Claim 9
Dependent Claim
18 words
The apparatus of claim 7 wherein said roughened surfaces are comprised of a large plurality of pyramid-shaped elements.
Claim 10
Dependent Claim
19 words
The apparatus of claim 7 wherein said roughened surfaces are comprised of a large plurality of conical shaped elements.
Claim 11
Dependent Claim
13 words
The apparatus of claim 7 wherein said roughened surfaces comprise a waffle pattern.
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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) | 1974-11-29 | 1975-05-31 | 1975-11-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-11-29 | 1979-05-31 | 1979-11-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-11-29 | 1983-05-31 | 1983-11-30 | $7700.00 | Window Closed / Lapsed |