US3733888A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Freeness testing apparatus and method for open containers
Assignee: Bematec SA
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Filing: 1971-04-28
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Granted: 1973-05-22
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Expires: 1991-04-28
Abstract
Abstract A freeness detector of the vertical stand pipe type, used on closed paper stock lines, is combined with an open vessel containing groundwood paper stock or the like with the open intake end of the freeness detector submerged, but the screen above the level of the stock. Sub-atmospheric pressure in the filtrate chamber permits atmospheric pressure to raise filtrate for testing and positive pressure blows the filtrate and mat downwardly. The apparatus preferably also includes an agitator in the stock and back flushing liquid passages in the detector.
Inventors
- 👤 D Danforth
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 11:03
CPC Classifications
G; G01; G01N; G01N11/00; G01N33/00; G01N33/34; G01N33/343
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
192 words
Apparatus for automatically and periodically testing the freeness of paper stock in a container open to the atmosphere, said apparatus comprising: an open container having a bottom and having paper stock, at a predetermined level above said bottom, exposed to atmospheric pressure; a tubular freeness detector, having a transverse screen, for separating fibers from liquid in said paper stock, said screen dividing said detector into a stock intake chamber with an open intake end and a filtrate chamber with a closed end; means supporting said freeness detector on said container at a predetermined level relative to said container bottom, with the open end of said intake chamber submerged below stock level at a spaced distance above said bottom and with said screen and filtrate chamber above stock level; and automatic super atmospheric and sub atmospheric air pressure control means operably connected to said filtrate chamber, for periodically reducing pressure in said chamber below atmospheric pressure to draw filtrate through said screen thereinto for testing while forming a mat on the intake side of said screen and then blowing said mat and filtrate out of said open intake end back into said container.
Claim 2
Dependent Claim
192 words
Apparatus for automatically and periodically testing the freeness of paper stock in a container open to the atmosphere, said apparatus comprising: an open container having a bottom and having paper stock, at a predetermined level above said bottom, exposed to atmospheric pressure; a tubular freeness detector, having a transverse screen, for separating fibers from liquid in said paper stock, said screen dividing said detector into a stock intake chamber with an open intake end and a filtrate chamber with a closed end; means supporting said freeness detector on said container at a predetermined level relative to said container bottom, with the open end of said intake chamber submerged below stock level at a spaced distance above said bottom and with said screen and filtrate chamber above stock level; and automatic super atmospheric and sub atmospheric air pressure control means operably connected to said filtrate chamber, for periodically reducing pressure in said chamber below atmospheric pressure to draw filtrate through said screen thereinto for testing while forming a mat on the intake side of said screen and then blowing said mat and filtrate out of said open intake end back into said container.
Claim 3
Dependent Claim
44 words
Apparatus as specified in claim 1, wherein: said support means includes clamping mechanism for detachably affixing said detector vertically on the rim of an upstanding side wall of said container and for detachably affixing said tubular detector at selected heights in said clamping mechanism.
Claim 4
Dependent Claim
27 words
Apparatus as specified in claim 1, plus: jet spray, back-flushing means built into said detector; and automatic means for supplying flush liquid thereto after each testing cycle.
Claim 5
Dependent Claim
142 words
Apparatus for sampling and testing the freeness of paper stock, said apparatus comprising: and pulse a paper stock container open to the atmosphere and having an upstanding wall and a bottom; a freeness detector, of the vertical stand pipe type, mounted vertically on said wall of said container with the open end thereof below stock level and at a spaced distance above said bottom and the screen and upper end thereof above stock level; and automatic means for periodically connecting the upper end of said detector to a source of sub atmospheric pressure to raise filtrate therein through said screen for testing while forming a mat on the intake side thereof and then connecting said upper end to a source of super atmospheric pressure to blow said filtrate and mat back down through said open end of said detector into said container.
Claim 6
Dependent Claim
142 words
Apparatus for sampling and testing the freeness of paper stock, said apparatus comprising: and pulse a paper stock container open to the atmosphere and having an upstanding wall and a bottom; a freeness detector, of the vertical stand pipe type, mounted vertically on said wall of said container with the open end thereof below stock level and at a spaced distance above said bottom and the screen and upper end thereof above stock level; and automatic means for periodically connecting the upper end of said detector to a source of sub atmospheric pressure to raise filtrate therein through said screen for testing while forming a mat on the intake side thereof and then connecting said upper end to a source of super atmospheric pressure to blow said filtrate and mat back down through said open end of said detector into said container.
Claim 7
Dependent Claim
50 words
Apparatus as specified in claim 4, plus: flushing passages in said detector for jet spraying back flush liquid through said screen and out of said open end; and liquid pressure control means operably connecting said flushing passages to a source of liquid for flushing said detector during each blow-down thereof.
Claim 8
Dependent Claim
37 words
Apparatus as specified in claim 4, plus: agitation means associated with said detector in said container, said agitation means continually urging the paper stock in said container in a predetermined flow path to avoid fiber settlement therein.
Claim 9
Dependent Claim
47 words
Apparatus as specified in claim 4, plus: a power driven agitator, mounted on the wall of said container with an impeller submerged below the level of the stock therein to move said stock past said open end at a speed of at least one foot per second.
Claim 10
Independent Claim
154 words
The method of testing the freeness of groundwood paper stock in an open container by means of a vertical stand pipe freeness detector which comprises the steps of: mounting said stand pipe on said container with its open lower intake end below stock level at a spaced distance above the container bottom and with its screen above stock level; periodically applying sub atmospheric pressure to the upper end of said detector to permit atmospheric pressure to raise filtrate through said screen into the filtrate chamber for testing while forming a fiber mat on the intake side thereof and then applying super atmospheric pressure thereto to blow said filtrate, and the fiber mat on said screen, down and out of said intake end; and agitating said stock in the area of said container proximate said intake end during said testing, to assure an accurate fiber suspension and to disperse any mat created by said testing.
Claim 11
Independent Claim
154 words
The method of testing the freeness of groundwood paper stock in an open container by means of a vertical stand pipe freeness detector which comprises the steps of: mounting said stand pipe on said container with its open lower intake end below stock level at a spaced distance above the container bottom and with its screen above stock level; periodically applying sub atmospheric pressure to the upper end of said detector to permit atmospheric pressure to raise filtrate through said screen into the filtrate chamber for testing while forming a fiber mat on the intake side thereof and then applying super atmospheric pressure thereto to blow said filtrate, and the fiber mat on said screen, down and out of said intake end; and agitating said stock in the area of said container proximate said intake end during said testing, to assure an accurate fiber suspension and to disperse any mat created by said testing.
Claim 12
Dependent Claim
48 words
A method as specified in claim 8, plus the step of: back flushing and jet spraying said detector with clean dilution water through said screen from said filtrate chamber during each said blow-down step to remove any fibers stapled on said screen or trapped elsewhere in said detector.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-05-21 | 1976-11-20 | 1977-05-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-05-21 | 1980-11-20 | 1981-05-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-05-21 | 1984-11-20 | 1985-05-22 | $7700.00 | Window Closed / Lapsed |