US4365981A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Gas filter
Assignee: Donaldson Co Inc
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Filing: 1981-07-01
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Granted: 1982-12-28
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Expires: 2001-07-01
Abstract
Abstract A gas filter is formed from two uniformly spaced nesting screens extending along a serpentine path, with the space between them filled with granular filtering material. Each screen has laterally spaced areas curved in one direction lengthwise of the serpentine path and alternating with laterally spaced areas curved in the opposite direction and integrally joined thereto to thereby provide the screen with a continuous curvature from end to end of the serpentine path.
Inventors
- 👤 John B. McDonough
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 06:43
CPC Classifications
B; B01; B01D; B01D53/00; B01D53/02; B01D53/04; B01D53/0407; B01D53/0446; B01D46/00; B01D46/10; B01D2253/00; B01D2253/30; B01D2253/34
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
104 words
A gas filter comprising two uniformly spaced nesting screens extending within a frame structure along a serpentine path, each of the screens having laterally spaced areas curved in one direction lengthwise of said path and alternating with laterally spaced areas curved in the opposite direction and integrally joined thereto to thereby provide each of the screens with a continuous curvature without any flat surfaces from end to end of said serpentine path and the lateral ends of the screens being secured to the frame structure, and granular filtering material filling the space between the screens to form a serpentine filter bed of continuous curvature.
Claim 2
Dependent Claim
104 words
A gas filter comprising two uniformly spaced nesting screens extending within a frame structure along a serpentine path, each of the screens having laterally spaced areas curved in one direction lengthwise of said path and alternating with laterally spaced areas curved in the opposite direction and integrally joined thereto to thereby provide each of the screens with a continuous curvature without any flat surfaces from end to end of said serpentine path and the lateral ends of the screens being secured to the frame structure, and granular filtering material filling the space between the screens to form a serpentine filter bed of continuous curvature.
Claim 3
Dependent Claim
34 words
A gas filter according to claim 1, further including bars extending lengthwise across said serpentine filter bed and provided with slots receiving edges of the screens to maintain the screens in their serpentine form.
Claim 4
Dependent Claim
25 words
A gas filter according to claim 2, in which each of said bars is an angle bar with said slots in one of its flanges.
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) | 1985-12-27 | 1986-06-28 | 1986-12-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-12-27 | 1990-06-28 | 1990-12-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-12-27 | 1994-06-28 | 1994-12-28 | $7700.00 | Window Closed / Lapsed |