US5477155A
Expired / Lapsed
US
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Current flow integrity test
Assignee: EMD Millipore Corp
•
Filing: 1993-08-11
•
Granted: 1995-12-19
•
Expires: 2013-08-11
Abstract
Abstract A new method and apparatus is described for conducting an integrity test on porous membranes and membrane filters and for conducting a pore-size characterization of membrane. The method and apparatus apply to membrane integrity tests and pore-size characterizations which are based on the dependence on the pore size of the pressure required to intrude a non-wetting, electrically conductive liquid into and through the pores. Electrical-measurement methods are described for identifying the pressure at which intrusion occurs.
Inventors
- 👤 Stephen Proulx
- 👤 John L. Burns, Jr.
- 👤 Scott Emory
- 👤 Richard W. Gray
- 👤 Frank M. Lentine
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 16:36
CPC Classifications
B; B01; B01D; B01D65/00; B01D65/10; B01D65/102; G; G01; G01N; G01N15/00; G01N15/08; G01N15/088
Claims Analysis
Total Claims: 56
Claim 1
Independent Claim
87 words
The process for determining porosity characteristic of an electrically nonconductive ultrafiltration or microporous membrane which comprises: contacting a first surface of said membrane with a second liquid which does not wet said membrane, contacting a second surface of said membrane with a second liquid which does not wet said membrane, increasing pressure on said first liquid to cause said first liquid to intrude said membrane, measuring change in electrical conductivity across said membrane, and correlating said change of electrical conductivity across said membrane with said porosity characteristic.
Claim 2
Dependent Claim
87 words
The process for determining porosity characteristic of an electrically nonconductive ultrafiltration or microporous membrane which comprises: contacting a first surface of said membrane with a second liquid which does not wet said membrane, contacting a second surface of said membrane with a second liquid which does not wet said membrane, increasing pressure on said first liquid to cause said first liquid to intrude said membrane, measuring change in electrical conductivity across said membrane, and correlating said change of electrical conductivity across said membrane with said porosity characteristic.
Claim 3
Dependent Claim
14 words
The process of claim 1 wherein said change of electrical conductivity is measured directly.
Claim 4
Dependent Claim
14 words
The process of claim 1 wherein said change of electrical conductivity is measured indirectly.
Claim 5
Dependent Claim
21 words
The process of any one of claims 1, 2 or 3 wherein said porosity characteristic is intrusion pressure of the membrane.
Claim 6
Dependent Claim
22 words
The process of any one of claims 1, 2 or 3 wherein said porosity characteristic is relative pore size of the membrane.
Claim 7
Dependent Claim
21 words
The process of any one of claims 1, 2 or 3 wherein said porosity characteristic is bubble point of the membrane.
Claim 8
Dependent Claim
27 words
The process of claim 1 wherein a plurality of electrical probes are positioned in said first liquid and said second liquid adjacent opposing surfaces of said membrane.
Claim 9
Dependent Claim
44 words
The process of claim 1 wherein a first electrode is positioned in said first liquid and a second electrode is positioned in said second liquid and wherein at least one of said first electrode or said second electrode is movable relative to said membrane.
Claim 10
Dependent Claim
92 words
The process for determining a porosity characteristic in an electrically nonconductive ultrafiltration or microporous membrane which comprises: contacting a first surface of said membrane with an electrically conductive first liquid which does not wet said membrane, contacting a second surface of said membrane with a second liquid which does not wet said membrane, increasing pressure on said first liquid to cause said first liquid to intrude said membrane, measuring change in electrical conductivity of said second liquid, and correlating said change of electrical conductivity in said second liquid with said porosity characteristic.
Claim 11
Dependent Claim
92 words
The process for determining a porosity characteristic in an electrically nonconductive ultrafiltration or microporous membrane which comprises: contacting a first surface of said membrane with an electrically conductive first liquid which does not wet said membrane, contacting a second surface of said membrane with a second liquid which does not wet said membrane, increasing pressure on said first liquid to cause said first liquid to intrude said membrane, measuring change in electrical conductivity of said second liquid, and correlating said change of electrical conductivity in said second liquid with said porosity characteristic.
Claim 12
Dependent Claim
12 words
The process of claim 9 wherein said electrical conductivity is measured directly.
Claim 13
Dependent Claim
12 words
The process of claim 9 wherein said electrical conductivity is measured indirectly.
Claim 14
Dependent Claim
27 words
The process of claim 9 wherein a plurality of electrical probes are positioned in said first liquid and said second liquid adjacent opposing surfaces of said membrane.
Claim 15
Dependent Claim
44 words
The process of claim 9 wherein a first electrode is positioned in said first liquid and a second electrode is positioned in said second liquid and wherein at least one of said first electrode or said second electrode is movable relative to said membrane.
Claim 16
Dependent Claim
82 words
The process for determining the presence of defects in an electrically nonconductive ultrafiltration or microporous membrane which comprises: contacting a first surface of said membrane with an electrically conductive first liquid which does not wet said membrane contacting a second surface of said membrane with a second liquid which does not wet said membrane, increasing pressure on said first liquid to a pressure less than a characteristic intrusion pressure of said membrane, and measuring change in electrical conductivity of said second liquid.
Claim 17
Dependent Claim
82 words
The process for determining the presence of defects in an electrically nonconductive ultrafiltration or microporous membrane which comprises: contacting a first surface of said membrane with an electrically conductive first liquid which does not wet said membrane contacting a second surface of said membrane with a second liquid which does not wet said membrane, increasing pressure on said first liquid to a pressure less than a characteristic intrusion pressure of said membrane, and measuring change in electrical conductivity of said second liquid.
Claim 18
Dependent Claim
12 words
The process of claim 14 wherein said electrical conductivity is measured directly.
Claim 19
Dependent Claim
12 words
The process of claim 14 wherein said electrical conductivity is measured indirectly.
Claim 20
Dependent Claim
27 words
The process of claim 14 wherein a plurality of electrical probes are positioned in said first liquid and said second liquid adjacent opposing surfaces of said membrane.
Claim 21
Dependent Claim
44 words
The process of claim 14 wherein a first electrode is positioned in said first liquid and a second electrode is positioned in said second liquid and wherein at least one of said first electrode or said second electrode is movable relative to said membrane.
Claim 22
Dependent Claim
81 words
The process for determining the presence of defects in an electrically nonconductive ultrafiltration or microporous membrane which comprises: contacting a first surface of said membrane with an electrically conductive first liquid which does not wet said membrane: contacting a second surface of said membrane with a second liquid which does not wet said membrane, increasing pressure on said first liquid to a pressure less than a characteristic intrusion pressure of said membrane, and measuring change in electrical conductivity across said membrane.
Claim 23
Dependent Claim
81 words
The process for determining the presence of defects in an electrically nonconductive ultrafiltration or microporous membrane which comprises: contacting a first surface of said membrane with an electrically conductive first liquid which does not wet said membrane: contacting a second surface of said membrane with a second liquid which does not wet said membrane, increasing pressure on said first liquid to a pressure less than a characteristic intrusion pressure of said membrane, and measuring change in electrical conductivity across said membrane.
Claim 24
Dependent Claim
12 words
The process of claim 19 wherein said electrical conductivity is measured directly.
Claim 25
Dependent Claim
12 words
The process of claim 19 wherein said electrical conductivity is measured indirectly.
Claim 26
Dependent Claim
27 words
The process of claim 19 wherein a plurality of electrical probes are positioned in said first liquid and said second liquid adjacent opposing surfaces of said membrane.
Claim 27
Dependent Claim
43 words
The process of claim 19 wherein a first electrode is positioned in said first liquid and a second electrode is positioned in said second liquid and wherein at least one of said first electrode or said second electrode movable relative to said membrane.
Claim 28
Dependent Claim
98 words
The process for determining a porosity characteristic of an electrically nonconductive ultrafiltration or microporous membrane which comprises: contacting a first surface of said membrane with an electrically conductive first liquid, contacting a second surface of said membrane with a second liquid, said porous membrane containing a third liquid which prevents said first liquid and said second liquid from wetting said membrane, increasing pressure on said first liquid to cause said first liquid to intrude said membrane, measuring change in electrical conductivity across said membrane, and correlating said change of electrical conductivity across said membrane with said porosity characteristic.
Claim 29
Dependent Claim
98 words
The process for determining a porosity characteristic of an electrically nonconductive ultrafiltration or microporous membrane which comprises: contacting a first surface of said membrane with an electrically conductive first liquid, contacting a second surface of said membrane with a second liquid, said porous membrane containing a third liquid which prevents said first liquid and said second liquid from wetting said membrane, increasing pressure on said first liquid to cause said first liquid to intrude said membrane, measuring change in electrical conductivity across said membrane, and correlating said change of electrical conductivity across said membrane with said porosity characteristic.
Claim 30
Dependent Claim
14 words
The process of claim 24 wherein said change of electrical conductivity is measured directly.
Claim 31
Dependent Claim
14 words
The process of claim 24 wherein said change of electrical conductivity is measured indirectly.
Claim 32
Dependent Claim
21 words
The process of any one of claims 24, 25 or 26 wherein said porosity characteristic is intrusion pressure of the membrane.
Claim 33
Dependent Claim
22 words
The process of any one of claims 24, 25 or 26 wherein said porosity characteristic is relative pore size of the membrane.
Claim 34
Dependent Claim
21 words
The process of any one of claims 24, 25 or 26 wherein said porosity characteristic is bubble point of the membrane.
Claim 35
Dependent Claim
27 words
The process of claim 24 wherein a plurality of electrical probes are positioned in said first liquid and said second liquid adjacent opposing surfaces of said membrane.
Claim 36
Dependent Claim
44 words
The process of claim 24 wherein a first electrode is positioned in said first liquid and a second electrode is positioned in said second liquid and wherein at least one of said first electrode or said second electrode is movable relative to said membrane.
Claim 37
Dependent Claim
100 words
The process for determining a porosity characteristic in an electrically nonconductive ultrafiltration or microporous membrane which comprises: contacting a first surface of said membrane with an electrically conductive first liquid, contacting a second surface of said membrane with a second liquid, said porous membrane containing a third liquid which prevents said first liquid and said second liquid from wetting said membrane, increasing pressure on said first liquid to cause said first liquid to intrude said membrane, measuring change in electrical conductivity of said second liquid, and correlating said change of electrical conductivity in said second liquid with said porosity characteristic.
Claim 38
Dependent Claim
100 words
The process for determining a porosity characteristic in an electrically nonconductive ultrafiltration or microporous membrane which comprises: contacting a first surface of said membrane with an electrically conductive first liquid, contacting a second surface of said membrane with a second liquid, said porous membrane containing a third liquid which prevents said first liquid and said second liquid from wetting said membrane, increasing pressure on said first liquid to cause said first liquid to intrude said membrane, measuring change in electrical conductivity of said second liquid, and correlating said change of electrical conductivity in said second liquid with said porosity characteristic.
Claim 39
Dependent Claim
12 words
The process of claim 32 wherein said electrical conductivity is measured directly.
Claim 40
Dependent Claim
12 words
The process of claim 32 wherein said electrical conductivity is measured indirectly.
Claim 41
Dependent Claim
27 words
The process of claim 32 wherein a plurality of electrical probes are positioned in said first liquid and said second liquid adjacent opposing surfaces of said membrane.
Claim 42
Dependent Claim
35 words
The process of claim 32 wherein a first electrode is positioned in said first liquid and a second electrode is positioned in said second liquid and said second electrode is movable relative to said membrane.
Claim 43
Dependent Claim
89 words
The process for determining the presence of defects in an electrically nonconductive ultrafiltration or microporous membrane which comprises: contacting a first surface of said membrane with an electrically conductive first liquid, contacting a second surface of said membrane with a second liquid, said porous membrane containing a third liquid which prevents said first liquid and said second liquid from wetting said membrane, increasing pressure on said first liquid to a pressure less than a characteristic intrusion pressure said membrane, and measuring change in electrical conductivity of said second liquid.
Claim 44
Dependent Claim
89 words
The process for determining the presence of defects in an electrically nonconductive ultrafiltration or microporous membrane which comprises: contacting a first surface of said membrane with an electrically conductive first liquid, contacting a second surface of said membrane with a second liquid, said porous membrane containing a third liquid which prevents said first liquid and said second liquid from wetting said membrane, increasing pressure on said first liquid to a pressure less than a characteristic intrusion pressure said membrane, and measuring change in electrical conductivity of said second liquid.
Claim 45
Dependent Claim
12 words
The process of claim 37 wherein said electrical conductivity is measured directly.
Claim 46
Dependent Claim
12 words
The process of claim 37 wherein said electrical conductivity is measured indirectly.
Claim 47
Dependent Claim
27 words
The process of claim 37 wherein a plurality of electrical probes are positioned in said first liquid and said second liquid adjacent opposing surfaces of said membrane.
Claim 48
Dependent Claim
35 words
The process of claim 37 wherein a first electrode is positioned in said first liquid and a second electrode is positioned in said second liquid and said second electrode is movable relative to said membrane.
Claim 49
Dependent Claim
89 words
The process for determining the presence of defects in an electrically nonconductive ultrafiltration or microporous membrane which comprises: contacting a first surface of said membrane with an electrically conductive first liquid, contacting a second surface of said membrane with a second liquid, said porous membrane containing a third liquid which prevents said first liquid and said second liquid from wetting said membrane, increasing pressure on said first liquid to a pressure less than a characteristic intrusion pressure of said membrane, and measuring change in electrical conductivity across said membrane.
Claim 50
Dependent Claim
89 words
The process for determining the presence of defects in an electrically nonconductive ultrafiltration or microporous membrane which comprises: contacting a first surface of said membrane with an electrically conductive first liquid, contacting a second surface of said membrane with a second liquid, said porous membrane containing a third liquid which prevents said first liquid and said second liquid from wetting said membrane, increasing pressure on said first liquid to a pressure less than a characteristic intrusion pressure of said membrane, and measuring change in electrical conductivity across said membrane.
Claim 51
Dependent Claim
12 words
The process of claim 42 wherein said electrical conductivity is measured directly.
Claim 52
Dependent Claim
12 words
The process of claim 42 wherein said electrical conductivity is measured indirectly.
Claim 53
Dependent Claim
27 words
The process of claim 42 wherein a plurality of electrical probes are positioned in said first liquid and said second liquid adjacent opposing surfaces of said membrane.
Claim 54
Dependent Claim
35 words
The process of claim 42 wherein a first electrode is positioned in said first liquid and a second electrode is positioned in said second liquid and said second electrode is movable relative to said membrane.
Claim 55
Dependent Claim
28 words
The process of any one of claims 24, 32, 37 and 42 wherein said third liquid is polyethylene glycol and said first liquid is an aqueous salt solution.
Claim 56
Dependent Claim
30 words
The process of any one of claims 24, 32, 37 and 42 wherein said third liquid is polyethylene glycol and said first liquid is an aqueous solution of ammonium sulfate.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1998-12-18 | 1999-06-19 | 1999-12-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-12-18 | 2003-06-19 | 2003-12-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-12-18 | 2007-06-19 | 2007-12-19 | $7700.00 | Window Closed / Lapsed |