Patent US3876546A successfully refreshed from Google Patents.
US3876546A
Expired / Lapsed
US
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Four-media filter
Assignee: Neptune Microfloc Inc
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Filing: 1973-12-03
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Granted: 1975-04-08
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Expires: 1993-12-03
Abstract
Abstract A filter bed comprises four filter media of different specific gravities and sizes. The media are intermixed in such a manner that the number of particles continually increases in the direction of fluid flow through the bed. The media comprise coal of two different size ranges and specific gravities, plus silica sand and garnet.
Inventors
- 👤 Andrew K Hsiung
- 👤 Walter R Conley
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 16:43
CPC Classifications
B; B01; B01D; B01D24/00; B01D24/007; B01D39/00; B01D39/02; B01D39/06; B01D2201/00; B01D2201/18; B01D2201/188
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
151 words
IN A FILTER FOR THE FILTRATION OF WATER AND HAVING BACKWASH MEANS AND A BED COMPRISING PARTICLES OF FILTER MEDIA OF DIFFERENT SPECIFIC GRAVITIES, THE PARTICLES OF EACH SPECIFIC GRAVITY BEING WITHIN A DISCRETE SIZE RANGE, THE SIZE RANGE OF SAID PARTICLES BEING INVERSE TO THEIR SPECIFIC GRAVITIES, WHEREUPON SAID FILTER WHEN BACKWASHED ACHIEVES AN ORIENTATION HAVING A CONTINUALLY INCREASING NUMBER OF PARTICLES PER UNIT AREA IN THE DIRECTION OF WATER FLOW THROUGH SAID BED, THE IMPROVEMENT COMPRISING: A FIRST FILTER MEDIUM COMPRISING COAL HAVING A SPECIFIC GRAVITY IN THE RANGE BETWEEN ABOUT 1.30 AND 1.50; A SECOND FILTER MEDIUM COMPRISING COAL HAVING A SPECIFIC GRAVITY IN THE RANGE BETWEEN ABOUT 1.60 AND 1.80; A THIRD FILTER MEDIUM COMPRISING SILICA SAND HAVING A SPECIFIC GRAVITY IN THE RANGE BETWEEN ABOUT 2.60 AND 2.65; AND A FOURTH FILTER MEDIUM COMPRISING PARTICLES SELECTED FROM THE GROUP CONSISTING OF GARNET PARTICLES AND ILMENITE PARTICLES.
Claim 2
Dependent Claim
151 words
IN A FILTER FOR THE FILTRATION OF WATER AND HAVING BACKWASH MEANS AND A BED COMPRISING PARTICLES OF FILTER MEDIA OF DIFFERENT SPECIFIC GRAVITIES, THE PARTICLES OF EACH SPECIFIC GRAVITY BEING WITHIN A DISCRETE SIZE RANGE, THE SIZE RANGE OF SAID PARTICLES BEING INVERSE TO THEIR SPECIFIC GRAVITIES, WHEREUPON SAID FILTER WHEN BACKWASHED ACHIEVES AN ORIENTATION HAVING A CONTINUALLY INCREASING NUMBER OF PARTICLES PER UNIT AREA IN THE DIRECTION OF WATER FLOW THROUGH SAID BED, THE IMPROVEMENT COMPRISING: A FIRST FILTER MEDIUM COMPRISING COAL HAVING A SPECIFIC GRAVITY IN THE RANGE BETWEEN ABOUT 1.30 AND 1.50; A SECOND FILTER MEDIUM COMPRISING COAL HAVING A SPECIFIC GRAVITY IN THE RANGE BETWEEN ABOUT 1.60 AND 1.80; A THIRD FILTER MEDIUM COMPRISING SILICA SAND HAVING A SPECIFIC GRAVITY IN THE RANGE BETWEEN ABOUT 2.60 AND 2.65; AND A FOURTH FILTER MEDIUM COMPRISING PARTICLES SELECTED FROM THE GROUP CONSISTING OF GARNET PARTICLES AND ILMENITE PARTICLES.
Claim 3
Dependent Claim
37 words
The filter of claim 1 in which said first filter medium comprises cannel coal having a specific gravity in the range between about 1.30 and 1.40, and an effective size of between about 1.8 and 2.2 mm.
Claim 4
Dependent Claim
26 words
A filter as in claim 1 in which the relative volumes of said first and second filter media are in the range from 0.1 to 10.0.
References Cited (Backward Citations)
US293745A
Cited
US3343680A
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US3382983A
Cited
US3557961A
Cited
US3704786A
Cited
US3757954A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-04-07 | 1978-10-07 | 1979-04-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-04-07 | 1982-10-07 | 1983-04-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-04-07 | 1986-10-07 | 1987-04-08 | $7700.00 | Window Closed / Lapsed |