U.S. patent application number 09/312181 was filed with the patent office on 2001-11-08 for apparatus for high pressure fluid filtration.
This patent application is currently assigned to Therox Inc. Invention is credited to BUHR, MARK S., DAOUD, ADIB G., DAW, DEREK J., MERRITT, JOHN E..
Application Number | 20010037975 09/312181 |
Document ID | / |
Family ID | 23210238 |
Filed Date | 2001-11-08 |
United States Patent
Application |
20010037975 |
Kind Code |
A1 |
BUHR, MARK S. ; et
al. |
November 8, 2001 |
Apparatus for high pressure fluid filtration
Abstract
A bacterial fluid filter includes a filter element supported by
a backing member. The filter element and backing member are sealed,
e.g., with one or more o-ring seals, in a housing to provide a
filter assembly capable of filtering fluid under relatively high
pressure. In one embodiment, a filter element, backing member, and
seal are disposed in a removable and disposable housing that is
sized to fit within a filter housing.
Inventors: |
BUHR, MARK S.; (HUNTINGTON
BEACH, CA) ; DAOUD, ADIB G.; (SAN DIEGO, CA) ;
DAW, DEREK J.; (COSTA MESA, CA) ; MERRITT, JOHN
E.; (SAN CLEMENTE, CA) |
Correspondence
Address: |
THEROX, INC.
2400 MICHELSON DRIVE
IRVINE
CA
92612
US
|
Assignee: |
Therox Inc
|
Family ID: |
23210238 |
Appl. No.: |
09/312181 |
Filed: |
May 14, 1999 |
Current U.S.
Class: |
210/634 ;
210/446; 210/455; 210/490; 210/639 |
Current CPC
Class: |
A61M 2205/7518 20130101;
B01D 2201/34 20130101; B01D 29/05 20130101; B01D 35/02 20130101;
B01D 2201/4046 20130101; A61M 1/3613 20140204; B01D 35/31 20130101;
B01D 61/18 20130101; B01D 63/08 20130101; B01D 29/58 20130101; B01D
29/05 20130101; B01D 29/58 20130101; B01D 35/02 20130101; B01D
35/31 20130101 |
Class at
Publication: |
210/634 ;
210/639; 210/490; 210/455; 210/446 |
International
Class: |
B01D 029/46 |
Claims
What is claimed is:
1. A bacterial fluid filter comprising: a housing having a fluid
passageway extending therethrough; a filter element disposed in the
housing in the fluid passageway; and a backing element disposed
adjacent the filter element in the housing in the fluid passageway
downstream from the filter element.
2. The fluid filter, as set forth in claim 1, wherein the housing
comprises a first portion and a second portion, the first portion
being coupled to the second portion.
3. The fluid filter, as set forth in claim 1, wherein the housing
comprises an inlet lumen positioned upstream from the filter
element and an outlet lumen positioned downstream from the backing
element.
4. The fluid filter, as set forth in claim 2, wherein the housing
comprises an inlet lumen in the first portion positioned upstream
from the filter element and an outlet lumen in the second portion
positioned downstream from the backing element.
5. The fluid filter, as set forth in claim 1, wherein the housing
is adapt ed to be removably disposed in a bulkhead assembly coupled
to a fluid line.
6. The fluid filter, as set forth in claim 1, wherein the filter
element comprises a disk.
7. The fluid filter, as set forth in claim 1, wherein the filter
element comprises at least one of nylon, polyethersulfone, teflon,
polycarbonate, polyester, polytetrafluoroethylene, polypropylene,
cellulose, glass fiber, stainless steel, monel, inconel, silver or
gold.
8. The fluid filter, as set forth in claim 1, wherein the filter
element comprises an absolute path of about 0.22 micron or
less.
9. The fluid filter, as set forth in claim 1, wherein the backing
element comprises a disk.
10. The fluid filter, as set forth in claim 1, wherein the backing
element comprises at least one of sintered metal filter disk made
of at least one of titanium, stainless steel, monel, inconel, and
gold.
11. The fluid filter, as set forth in claim 1, wherein the backing
element comprises a mean path of about 0.5 micron or less.
12. The fluid filter, as set forth in claim 3, comprising a seal
disposed between the inlet of the housing and the filter
element.
13. The fluid filter, as set forth in claim 3, comprising a seal
disposed between the backing element and the outlet of the
housing.
14. The fluid filter, as set forth in claim 13, wherein the housing
includes a portion that protrudes through the seal to support the
backing element.
15. The fluid filter, as set forth in claim 12, wherein the seal
comprises an o-ring.
16. The fluid filter, as set forth in claim 13, wherein the seal
comprises an o-ring.
17. A bacterial fluid filter comprising: a housing having a first
portion and a second portion, the first portion having a fluid
inlet and having a first recess and a second recess, the second
portion having a fluid outlet and being coupleable to the first
portion; a first o-ring seal disposed in the first recess of the
first portion of the housing; a filter element disposed adjacent
the first o-ring seal; a backing element disposed adjacent the
filter element; and a second o-ring seal disposed in the second
recess of the first portion of the housing adjacent the backing
element.
18. The fluid filter, as set forth in claim 17, wherein the filter
element comprises a disk.
19. The fluid filter, as set forth in claim 17, wherein the filter
element comprises at least one of nylon, polyethersulfone, teflon,
polycarbonate, polyester, polytetrafluoroethylene, polypropylene,
cellulose, glass fiber, stainless steel, monel, inconel, silver or
gold.
20. The fluid filter, as set forth in claim 17, wherein the filter
element comprises an absolute path of about 0.22 micron or
less.
21. The fluid filter, as set forth in claim 17, wherein the backing
element comprises a disk.
22. The fluid filter, as set forth in claim 17, wherein the backing
element comprises at least one of sintered metal filter disk made
of at least one of titanium, stainless steel, monel, inconel, and
gold.
23. The fluid filter, as set forth in claim 17, wherein the backing
element comprises a mean path of about 0.5 micron or less.
24. The fluid filter, as set forth in claim 17, wherein the second
portion of the housing comprises a portion that protrudes through
the second o-ring seal to support the backing element.
25. The fluid filter, as set forth in claim 17, wherein the second
portion of the housing comprises a recess sized to accept the first
portion of the housing therein.
26. A bacterial fluid filter comprising: a filter housing having a
removable filter disposed therein, wherein the filter housing
comprises: a bulkhead portion having a fluid inlet; a seal disposed
about the fluid inlet; and a plug portion having a fluid outlet,
the plug portion being coupleable to the bulkhead portion; and
wherein the filter comprises: a housing having a fluid inlet and a
fluid outlet; an o-ring seal disposed about the fluid inlet of the
housing; at least one filter element disposed adjacent the o-ring
seal; and a backing element disposed adjacent the at least one
filter element.
27. The fluid filter, as set forth in claim 26, wherein the filter
element comprises a disk.
28. The fluid filter, as set forth in claim 26, wherein the filter
element comprises at least one of nylon, polyethersulfone, teflon,
polycarbonate, polyester, polytetrafluoroethylene, polypropylene,
cellulose, glass fiber, stainless steel, monel, inconel, silver or
gold.
29. The fluid filter, as set forth in claim 26, wherein the filter
element comprises an absolute path of about 0.22 micron or
less.
30. The fluid filter, as set forth in claim 26, wherein the backing
element comprises a disk.
31. The fluid filter, as set forth in claim 26, wherein the backing
element comprises at least one of sintered metal filter disk made
of at least one of titanium, stainless steel, monel, inconel, and
gold.
32. The fluid filter, as set forth in claim 26, wherein the backing
element comprises an absolute path of about 0.5 micron or less.
33. The fluid filter, as set forth in claim 26, wherein the seal
disposed about the fluid inlet of the bulkhead portion comprises a
deformable ring formed integral with the bulkhead portion.
34. The fluid filter, as set forth in claim 26, wherein the seal
disposed about the fluid inlet of the bulkhead portion comprises an
o-ring seal.
35. The fluid filter, as set forth in claim 26, wherein the
bulkhead portion and the plug portion of the filter housing are
threadably engageable.
36. The fluid filter, as set forth in claim 26, wherein the seal is
formed by an o-ring.
37. A method of filtering a fluid comprising the acts of: providing
a filter assembly including a housing having a fluid passageway
extending therethrough, a filter element disposed in the housing in
the fluid passageway, and a backing element disposed adjacent the
filter element in the housing in the passageway downstream from the
filter element.
38. The method, as set forth in claim 37, further comprising the
acts of: providing within the fluid passageway a high pressure
fluid.
39. The method, as set forth in claim 38, wherein the high pressure
fluid includes a solvent including a volume of dissolved gas
normalized to standard temperature and pressure of between about
0.5 and about 3 times the volume of the solvent.
40. The method, as set forth in claim 38, wherein the high pressure
fluid comprises a fluid to be provided at a given site in a
gas-supersaturated state.
Description
FIELD OF THE INVENTION
[0001] The present invention relates generally to an apparatus for
filtering a high pressure fluid stream and, more particularly, to a
filter assembly for removing bacteria and other foreign materials
from high pressure physiologic fluid streams.
BACKGROUND OF THE INVENTION
[0002] In many applications it is desirable to remove bacteria and
other foreign materials from fluids prior to delivery of the fluids
to a particular desired location. For example, in the medical
field, fluids routinely are filtered for sterilization in
conjunction with their delivery to catheters for infusion into a
patient. Typically, such filtering is accomplished by the placement
of a filter media comprising a porous membrane in the fluid flow
path.
[0003] There are many different types of commercially available
filter media, e.g., nylon, polyethersulfone, teflon, polycarbonate,
polyester, polytetrafluoroethylene, polypropylene, cellulose, glass
fiber, stainless steel, monel, inconel, silver and gold. A filter
membrane generally may be described by its "mean path," i.e., the
average size of the pores in the filter media, and/or its "absolute
path," i.e., the size of the largest pores in the filter media. A
filter membrane's absolute path corresponds to the size of the
smallest particle that can be filtered out of a fluid flow path by
the filter membrane. For medical applications in which absolute
sterilization is required, a filter membrane having an absolute
path of not greater than about 0.2 micron typically is
required.
[0004] Filter membranes come in a variety of shapes and sizes.
Filter membranes may be mounted in line or in panel, and they are
typically disposed within a filter holder, either alone or in
combination with additional pre-filters, screens, etc. For examples
of commercially available filter devices, see, e.g., the 1995
Microfiltration & Laboratory Products Catalog, Poretics
Corporation, Livermore, Calif.
[0005] Many fluids to be infused into patients are not delivered
from a high pressure source, e.g., pressures up to about 5500
p.s.i. or higher. For that reason, conventional fluid filtering
devices such as those referred to above typically are not designed
to withstand high pressure environments. Under high pressure
conditions, the porous membranes of conventional filter devices may
burst, allowing bacteria and other unwanted materials to pass.
Accordingly, there remains a need for a filter assembly capable of
removing bacteria and other foreign materials from high pressure
fluid streams.
[0006] The present invention may address one or more of the
problems set forth above.
SUMMARY OF THE INVENTION
[0007] Certain aspects commensurate in scope with the disclosed
embodiments are set forth below. It should be understood that these
aspects are presented merely to provide the reader with a brief
summary of certain forms the invention might take and that these
aspects are not intended to limit the scope of the invention.
Indeed, the invention may encompass a variety of aspects that may
not be set forth below.
[0008] The copending U.S. patent application entitled "Filtration
of Gas-Containing Fluids" filed on Apr. 30, 1999, by James Richard
Spears, Serial No. Unassigned, is hereby incorporated by reference
herein for all purposes.
[0009] In one embodiment of the present invention, an apparatus for
filtering a high pressure fluid stream is provided. Advantageously,
the high pressure fluid stream comprises a flow of a fluid in which
a gas (e.g., oxygen, nitrogen, carbon dioxide, air) is dissolved.
Advantageously, the dissolved gas volume normalized to standard
temperature and pressure is between about 0.5 and about 3 times the
volume of the solvent. The fluid passing through the filtering
apparatus advantageously comprises a fluid to be provided at a
given site in a gas-supersaturated state. Examples (without
limitation as to the scope of the present invention) include fluids
that are to be delivered into blood, infused into a patient,
brought into contact with tissues, etc., such as
oxygen-supersaturated fluids.
[0010] The apparatus comprises a filter assembly stack disposed
within a filter housing assembly. The filter assembly stack
comprises a first o-ring, a filter membrane, a membrane backing
member, and a second o-ring. The filter housing comprises a
bulkhead and a cap.
[0011] The filter assembly stack and the housing assembly
advantageously are adapted and assembled so that when the cap and
bulkhead are joined, e.g., by threaded engagement, with an
adhesive, etc., the o-rings are compressed, so as to create a
sealed continuous fluid flow path through the filter assembly stack
and filter housing assembly. Advantageously, the first o-ring, the
filter membrane, and the membrane backing member are disposed
between the bulkhead and cap, with the filter membrane disposed
between the first o-ring and the membrane backing member, so that a
portion of the cap (e.g., a generally centrally disposed annular
shoulder region) presses against part of the membrane backing
member so as to compress the first o-ring to create a first seal
between the bulkhead and the filter membrane. A second seal
advantageously is created by compression of the second o-ring
between the bulkhead and cap.
[0012] The membrane backing member advantageously comprises a
filter frit having a mean path about equal in size to the absolute
path of the filter membrane, e.g., advantageously about 0.2 micron.
Advantageously, the filter frit comprises a sintered metal filter
disk made of titanium, stainless steel, monel, inconel, gold, or
another suitable filter material. The frit is disposed downstream
of the filter membrane, so as to provide backing support to prevent
the filter membrane from bursting under high fluid pressures. A
mesh, screen, or other fluid permeable device for providing
support, or any combination of one or more of such devices, also
may be used instead of or in addition to a filter or a frit as a
filter membrane backing member. Advantageously, the filter membrane
backing member comprises a relatively smooth member free of sharp
edges or rough surfaces that would compromise the filter it backs
under pressure.
[0013] In an alternate embodiment, the filter assembly stack
comprises a filter frame, an o-ring, one or more filter membranes,
a membrane backing member, and a filter frame cap. The filter
assembly stack advantageously comprises two filter membranes
disposed between an o-ring and a membrane backing member. The
o-ring, filter membranes, and membrane backing member
advantageously are held together between the filter frame and the
filter frame cap, with a portion of the filter frame cap pressing
against part of the membrane backing member so as to compress the
o-ring to form a seal with the filter membrane. The joint between
the filter frame and filter frame cap may be sealed with an
adhesive, e.g., a UV adhesive. Thus, a sealed fluid pathway through
the filter assembly stack is provided. The filter assembly stack is
disposed within the filter housing with one or more seals, such as
o-rings, disposed between the filter assembly stack and the filter
housing bulkhead and cap, to ensure a sealed fluid pathway through
the entire assembly. Alternatively, the filter housing bulkhead and
cap are adapted with one or more embossed surfaces (raised
portions, e.g., formed by one or more ridges or by one or more
grooves in the assemblies) that contact the filter frame or filter
frame cap upon assembly. Advantageously, the contacting portions of
the ridges and/or filter stack are made of deformable materials
that compress to form a seal when the filter housing bulkhead and
filter housing cap are joined, so that the filter assembly is
self-sealing. Alternatively, the filter frame and/or filter frame
cap may be adapted to include one or more of such ridges so that
the filter assembly is self-sealing, or an o-ring or other such
sealing device may be used.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] Further objects and advantages of the present invention will
become apparent upon reading the following detailed description and
upon referring to the accompanying drawings in which:
[0015] FIG. 1 is an exploded, cross-sectional view of an exemplary
high pressure fluid filter system in accordance with the present
invention.
[0016] FIG. 2 is an exploded, cross-sectional view of an alternate
exemplary high pressure fluid filter system in accordance with the
present invention.
[0017] FIG. 2A is a detail view of a portion of FIG. 2
DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS
[0018] The description below illustrates embodiments of the present
invention. For the sake of clarity, not all features of an actual
implementation of the present invention are described in this
specification. It should be appreciated that in connection with
developing any actual embodiment of the present invention many
application-specific decisions must be made to achieve specific
goals, which may vary from one application to another. Further, it
should be appreciated that any such development effort might be
complex and time-consuming, but would still be routine for those of
ordinary skill in the art having the benefit of this
disclosure.
[0019] For the sake of clarity and convenience, the various
embodiments are described herein in the context of applications
generally involving the filtering of high pressure fluid streams
for medical applications. However, the present invention may also
be useful in other, non-medical applications.
[0020] Turning now to the drawings, a system is provided for
filtering a high pressure fluid stream, i.e., a fluid provided to
the filter system at pressures from about 1000 p.s.i. to about 5500
p.s.i. or higher. As shown in FIG. 1, the system includes a filter
housing assembly including a bulkhead 10 and cap 12. The exact size
and shape of the bulkhead 10 and cap 12 may vary depending upon the
circumstances involved in a particular desired application. In the
embodiment shown in FIG. 1, the bulkhead 10 comprises a generally
cylindrically-shaped block assembly including a continuous fluid
pathway comprising a lumen 18 between a fluid inlet 14 and fluid
outlet 16. The downstream face 20 of bulkhead 10 advantageously
includes a generally cylindrical inner recess 22 within which a
first o-ring 24 is positioned to form a seal about the fluid outlet
16. The filter 28 impinges upon the first o-ring 24, so the o-ring
24 provides a first seal between the bulkhead 10 and the filter
28.
[0021] The filter 28 advantageously comprises a thin disk of filter
media with an absolute path of about 0.5 micron or less, and
advantageously of about 0.22 micron or less. For example, a filter
media absolute path of about 0.2 micron or less may prove to be
particularly advantageous. The filter 28 may be made of nylon,
polyethersulfone, teflon, polycarbonate, polyester,
polytetrafluoroethylene, polypropylene, cellulose, glass fiber,
stainless steel, monel, inconel, silver or gold. Of course, the
exact pore size and material selected for use as the filter 28 may
vary depending upon the circumstances involved in a particular
desired application.
[0022] A filter backing member 30 is positioned downstream from the
filter 28 to provide backing support to prevent the filter 28 from
bursting under high fluid pressures. The filter backing member 30
advantageously comprises a filter frit or disk having a mean path
about equal in size to the absolute path of the filter membrane,
e.g., advantageously about 0.2 micron or less. The filter backing
member 30 may be a sintered metal filter disk made of titanium,
stainless steel, monel, inconel, gold, or another suitable filter
material. A mesh, screen, or other fluid permeable device for
providing support, or any combination of one or more of such
devices, also may be used instead of or in addition to the frit as
a filter backing member. The filter backing member 30
advantageously does not compromise the filter 28 under
pressure.
[0023] The downstream face 20 of bulkhead 10 advantageously
includes a generally cylindrical outer recess 26 within which a
second o-ring 32 is positioned outside of the filter backing member
30 to form a second seal between the bulkhead 10 and cap 12. The
second o-ring 32 advantageously forms the second seal about the
continuous fluid pathway between the fluid outlet 16 and the fluid
exit lumen 34 through cap 12. It should be mentioned that the
o-rings 24 and 32 advantageously are standard-size o-rings made of
70 shore A durometer silicone rubber, although the exact size,
shape, hardness, and other properties or characteristics of the
o-rings may vary depending upon the particular circumstances
involved in a desired application.
[0024] The cap 12 advantageously includes a slot or recess 38
adapted to receive the bulkhead 10. The cap 12 and bulkhead 10 may
be secured together by threaded engagement, by an adhesive, or by
any other suitable joining means. As shown in FIG. 1, the cap 12
also includes a raised shoulder 36 adapted to engage at least a
portion of the filter backing member 30 to provide additional
support to the filter 28 and the backing member 30. Advantageously,
both the first o-ring 24 and the second o-ring 32 are compressed
and form seals upon the joining of the cap 12 and bulkhead 10.
Thus, a continuous sealed fluid pathway through the filter 28 and
filter backing a member 30 is provided.
[0025] In an alternate embodiment, as shown in FIG. 2, a high
pressure fluid bacterial filter assembly is provided comprising a
filter assembly stack 40 disposed within a filter housing. Unlike
the embodiment of FIG. 1, the filter assembly stack 40 comprises a
discrete, disposable filtering unit that may be easily removed from
the filter housing and replaced. The filter assembly stack 40
advantageously includes one or more filter membranes 42 disposed
between an o-ring 44 and a membrane backing member 46.
Advantageously, the membrane backing member does not compromise the
filtering ability of the membranes 42 under pressure. A filter
frame 48 including a generally centrally disposed lumen 50 is
adapted to receive the o-ring 44, the filter membrane(s) 42, the
membrane backing member 46, and a shoulder portion 53 of a filter
frame cap 52. The cap 52 also includes a generally centrally
disposed lumen 54. Advantageously, upon the joining of the filter
frame 48 and filter frame cap 52, the o-ring 44 is compressed so as
to create a sealed fluid pathway through the filter assembly stack
40. The filter frame 48 and the filter cap 52 are advantageously
sealed together, with an adhesive, for instance, such as a UV
adhesive. Also, to ensure that the stack 40 is properly positioned
for fluid flow, the frame 48 and/or the cap 52 may include a key or
key way (not shown) that corresponds to a complementary key way or
key (not shown) in the bulkhead 56 and/or the plug 58.
[0026] The filter assembly stack 40 advantageously is disposed
within the filter housing which comprises a bulkhead 56 and a plug
or nut 58. The filter housing 56 includes a generally centrally
disposed lumen 60 adapted to receive a supply of high pressure
fluid. Also, one or more ridges 62 are disposed about the lumen 60
and positioned to contact the filter frame 48. Advantageously, the
ridges 62 and/or the filter frame 48 are made of a deformable
material, such as polyethersulfone, polycarbonate, polyester or
other suitable material, so that when the nut 58 is joined with the
bulkhead 56 the filter frame 48 is forced against the ridges 62 to
form one or more seals about the continuous fluid pathway running
through lumens 50,60. The nut 58 includes a generally centrally
disposed fluid exit lumen 64, and also may include one or more
ridges 62 (see FIG. 2A) positioned to contact the filter cap 52.
Thus, upon the joining of the filter housing 56 and the nut 58, a
continuous sealed fluid pathway is provided through the filter
assembly stack and the filter housing. Of course, another suitable
seal, such as an o-ring, may be used along with or instead of the
ridges 62.
[0027] The present invention may be susceptible to various
modifications and alternative forms. Specific embodiments of the
present invention are shown by way of example in the drawings and
have been described herein in detail. It should be understood,
however, that the description set forth herein of specific
embodiments is not intended to limit the present invention to the
particular forms disclosed. Rather, all modifications,
alternatives, and equivalents falling within the spirit and scope
of the invention as defined by the appended claims are intended to
be covered.
* * * * *