US4801383A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Selective twist filtration roving
Assignee: Pall Filtration and Separations Group Inc
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Filing: 1984-11-19
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Granted: 1989-01-31
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Expires: 2004-11-19
Abstract
Abstract This invention relates to a filtration roving with the cross section of the roving exhibiting portions more tightly twisted than the remainder of the roving.
Inventors
- 👤 Michael A. Hoffmann
- 👤 Robert J. Schmitt
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 07:36
CPC Classifications
D; D01; D01H; D01H4/00; D01H4/04; D01H4/16; B; B01; B01D; B01D29/00; B01D29/11; B01D29/111; B01D39/00; B01D39/14; B01D39/16; B01D39/1607; B01D39/1615; B01D39/1623; B01D2239/00; B01D2239/06; B01D2239/069; B01D2239/0695; B01D29/13; B01D29/15; B01D29/21; B01D29/216; B01D29/50; B01D29/56; B01D29/58
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
60 words
A filter comprising rigid pervious core means through which fluid to be filtered can flow, filter media means for filtering the fluid, the filter media means covering a portion of said core means, the filter media means comprising filtration roving consisting of a twisted unitary strand which, in crosssection, exhibits portions more tightly twisted than the remainder of the roving.
Claim 2
Dependent Claim
60 words
A filter comprising rigid pervious core means through which fluid to be filtered can flow, filter media means for filtering the fluid, the filter media means covering a portion of said core means, the filter media means comprising filtration roving consisting of a twisted unitary strand which, in crosssection, exhibits portions more tightly twisted than the remainder of the roving.
Claim 3
Dependent Claim
23 words
The filter of claim 1 wherein the filtration roving has an inner portion that is more tightly twisted than the remaining outer portion.
Claim 4
Dependent Claim
26 words
The filter of claim 1 wherein the filtration roving has an inner and an outer portion which are more tightly twisted than the remaining middle portion.
Claim 5
Dependent Claim
26 words
The filter of claim 1 wherein the filtration roving has an inner and a middle portion which are more tightly twisted than the remaining outer portion.
Claim 6
Dependent Claim
79 words
A filter comprising rigid pervious core means through which fluid to be filtered can flow, filter media means for filtering the fluid, the filter media means covering a portion of said core means, and the filter media means comprising a twisted unitary strand filtration roving in which selected fibers comprising selected portions of the roving are subjected to greater negative pressure between spinning drums used to make the roving than other fibers comprising the non-selected portions of the roving.
Claim 7
Dependent Claim
79 words
A filter comprising rigid pervious core means through which fluid to be filtered can flow, filter media means for filtering the fluid, the filter media means covering a portion of said core means, and the filter media means comprising a twisted unitary strand filtration roving in which selected fibers comprising selected portions of the roving are subjected to greater negative pressure between spinning drums used to make the roving than other fibers comprising the non-selected portions of the roving.
Claim 8
Dependent Claim
70 words
In a filter comprising a rigid, pervious core and filter media surrounding at least a portion of said core, said filter media composed of filtration roving wound around the core, the improvement wherein said roving consists of a twisted unitary strand and, in cross-section, is characterized by an outer region of comparatively bulky twisted fiber and an inner region formed of fibers more tightly twisted than said outer region fibers.
Claim 9
Dependent Claim
70 words
In a filter comprising a rigid, pervious core and filter media surrounding at least a portion of said core, said filter media composed of filtration roving wound around the core, the improvement wherein said roving consists of a twisted unitary strand and, in cross-section, is characterized by an outer region of comparatively bulky twisted fiber and an inner region formed of fibers more tightly twisted than said outer region fibers.
Claim 10
Dependent Claim
26 words
The filter of claim 6, in which the degree of twist from the outermost region fibers to the innermost region fibers increases in a continuous manner.
Claim 11
Dependent Claim
66 words
The filter of claim 6, in which said roving is produced by feeding fibers into a valley-shaped space formed between parallel aligned, closely spaced, counter-rotated suction drums, each of which contains an axially extending suction slot which faces said valley-shaped space, and restricting the portion of said suction slots near which the roving exits from said drums, to produce the bulky outer region of the roving.
Claim 12
Dependent Claim
23 words
The filter of claim 8, in which approximately one to two inches of the suction slot is restricted at the right end thereof.
Claim 13
Dependent Claim
13 words
The filter of claim 8, in which said slot portion is completely blocked.
Claim 14
Dependent Claim
18 words
The filter of claim 9, in which said approximately one to two inches of slot is completely blocked.
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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) | 1992-01-31 | 1992-08-01 | 1993-01-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-01-31 | 1996-08-01 | 1997-01-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-01-31 | 2000-08-01 | 2001-01-31 | $7700.00 | Window Closed / Lapsed |