US4257448A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Flow cut-off device for insertion in a gas duct
Assignee: Individual
•
Filing: 1978-12-15
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Granted: 1981-03-24
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Expires: 1998-12-15
Abstract
Abstract The device has a gas passage of adjustable flow cross-section through which gas flows in normal use. Inflowing gas also acts on a blocking member, and when the pressure of the inflow gas rises above a certain value, the pressure on the blocking member is sufficient to move the blocking member into the gas passage to block the passage. The blocking member is then retained in position in the passage, blocking the gas flow by the gas pressure. The blocking member can be a ball which is moved against the force of gravity by the pressure of the gas to close the passage.
Inventors
- 👤 Chan K. Shiu
- 👤 Leung W. Kwong
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 21:15
CPC Classifications
F; F16; F16K; F16K17/00; F16K17/20; F16K17/22; F16K17/24; F16K17/28; F16K17/285; F16K17/34; Y; Y10; Y10T; Y10T137/00; Y10T137/7722; Y10T137/7723; Y10T137/7726; Y10T137/7727; Y10T137/7781; Y10T137/7784; Y10T137/7785; Y10T137/7837; Y10T137/7869; Y10T137/7871; Y10T137/7873
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
159 words
A flow cut-off device for insertion in a gas duct, the device comprising an inlet and an outlet, a chamber on the inlet side of the device, a passage leading from the chamber to the outlet and including two mutually rotatable coaxial tubes having a plurality of holes through their walls arranged so that the flow cross-section through the passage can be altered by relative rotation of the tubes, and a seat on the outlet side of said holes; a blocking member subject on one side to the pressure in the chamber and on an opposite side to the pressure at the outlet; and means for guiding the blocking member between a lower non-blocking position and an upper position in which it engages the seat to block the passage and prevent gas flowing through the outlet, said blocking member being arranged to move to said upper position when the pressure differential across the blocking member exceeds a predetermined value.
Claim 2
Dependent Claim
159 words
A flow cut-off device for insertion in a gas duct, the device comprising an inlet and an outlet, a chamber on the inlet side of the device, a passage leading from the chamber to the outlet and including two mutually rotatable coaxial tubes having a plurality of holes through their walls arranged so that the flow cross-section through the passage can be altered by relative rotation of the tubes, and a seat on the outlet side of said holes; a blocking member subject on one side to the pressure in the chamber and on an opposite side to the pressure at the outlet; and means for guiding the blocking member between a lower non-blocking position and an upper position in which it engages the seat to block the passage and prevent gas flowing through the outlet, said blocking member being arranged to move to said upper position when the pressure differential across the blocking member exceeds a predetermined value.
Claim 3
Dependent Claim
31 words
A device as claimed in claim 1, wherein the blocking device is kept in its non-blocking position by gravity unless the pressure differential across the blocking member exceeds said predetermined value.
Claim 4
Dependent Claim
38 words
A device as claimed in claim 1, wherein the blocking member is a ball and the guide means is a vertically oriented tube having a transverse pin across its lower end to retain the ball in the tube.
Claim 5
Dependent Claim
39 words
A device as claimed in claim 1, further comprising a resetting member in the form of a plunger operable from outside the device for pushing the blocking member away from the seat when normal pressure conditions once more prevail.
Claim 6
Dependent Claim
12 words
A device as claimed in claim 4, wherein the plunger is spring-loaded.
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) | 1984-03-23 | 1984-09-22 | 1985-03-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-03-23 | 1988-09-22 | 1989-03-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-03-23 | 1992-09-22 | 1993-03-24 | $7700.00 | Window Closed / Lapsed |