US3686835A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Filter cassette with removable capsule
Assignee: MSA Safety Inc
•
Filing: 1970-11-27
•
Granted: 1972-08-29
•
Expires: 1990-11-27
Abstract
Abstract A shallow cup of non-hygroscopic material has a central inlet opening in its base and a filter disc closing its open end, whereby a hollow capsule is formed. A separable two-part cassette contains the capsule, with the marginal area thereof clamped between the two parts. One part contains the cup and has an end wall provided with a central inlet port registering with the cup inlet, and the other part of the cassette covers the filter and has an end wall provided with a central outlet port. The filter forms one wall of a chamber between it and the end wall of the last-mentioned part of the cassette. After a period of filtering, the cassette is opened and the preweighed capsule is removed and weighed again to determine the amount of particulate matter captured by the capsule.
Inventors
- 👤 John P Strange
- 👤 Stanley P Nebash
- 👤 Alexander C Mcinnes
- 👤 Paul W Mcconnaughey
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 14:51
CPC Classifications
G; G01; G01N; G01N1/00; G01N1/02; G01N1/22; G01N1/2202; G01N1/2205; G01N2001/222; G01N2001/2223
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
165 words
A filter unit comprising a shallow cup formed of nonhygroscopic material and having a central inlet opening in its base and an annular shoulder at its open end, a filter disc in the cup seated against said shoulder, a porous retaining disc covering the filter disc, means for securing the discs in place so that a hollow capsule is formed, and a separable two-part cassette removably containing the capsule with said shoulder and marginal areas of the discs clamped between said parts, one of said cassette parts containing said cup and having an end wall provided with a central inlet port registering with said cup inlet, the capsule and cassette engaging each other at the inner end of said inlet port, and the other of the cassette parts covering said discs and having an end wall provided with a central outlet port, the retaining disc forming one wall of a chamber between that disc and the end wall of said other part of the cassette.
Claim 2
Dependent Claim
165 words
A filter unit comprising a shallow cup formed of nonhygroscopic material and having a central inlet opening in its base and an annular shoulder at its open end, a filter disc in the cup seated against said shoulder, a porous retaining disc covering the filter disc, means for securing the discs in place so that a hollow capsule is formed, and a separable two-part cassette removably containing the capsule with said shoulder and marginal areas of the discs clamped between said parts, one of said cassette parts containing said cup and having an end wall provided with a central inlet port registering with said cup inlet, the capsule and cassette engaging each other at the inner end of said inlet port, and the other of the cassette parts covering said discs and having an end wall provided with a central outlet port, the retaining disc forming one wall of a chamber between that disc and the end wall of said other part of the cassette.
Claim 3
Dependent Claim
55 words
A filter unit according to claim 1, in which the open end of one of said cassette parts is provided with an internal annular shoulder and the open end of the other part of the cassette is provided with an annular rib, said cup shoulder and discs being clamped between said cassette shoulder and rib.
Claim 4
Dependent Claim
37 words
A filter unit according to claim 1, in which said cassette is provided around said outlet port with projections in said chamber spacing said retaining disc from the end wall of said other part of the cassette.
Claim 5
Dependent Claim
26 words
A filter unit according to claim 1, including a removable sealing tape encircling the cassette at the joint between its two parts and holding them together.
Claim 6
Dependent Claim
29 words
A filter unit according to claim 1, in which said cup flange is provided with an inwardly projecting tab for easy removal of the capsule from the opened cassette.
Claim 7
Dependent Claim
21 words
A filter unit according to claim 1, in which said cup is provided with an inturned rim around its inlet opening.
Claim 8
Dependent Claim
32 words
A filter unit according to claim 1, in which said cup is made of metal foil and has an integral flange around its open end overlapping the margin of the retaining disc.
Claim 9
Dependent Claim
20 words
A filter unit according to claim 1, in which said cup is conical with its inlet opening at its apex.
Claim 10
Dependent Claim
28 words
A filter unit according to claim 8, in which the inside of said one part of the cassette is conical and conforms to and engages the conical cup.
Claim 11
Dependent Claim
77 words
A filter unit according to claim 8, in which the inside of said one part of the cassette is conical and conforms to and engages the conical cup, the open end of said one part is provided with an internal annular shoulder, the open end of said other part of the cassette is provided with an annular rib opposed to that shoulder, and the marginal area of the capsule is clamped between the cassette shoulder and rib.
Claim 12
Dependent Claim
26 words
A filter unit according to claim 8, including a removable sealing tape encircling the cassette at the joint between its two parts and holding them together.
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) | 1975-08-29 | 1976-02-28 | 1976-08-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-08-29 | 1980-02-28 | 1980-08-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-08-29 | 1984-02-28 | 1984-08-29 | $7700.00 | Window Closed / Lapsed |