U.S. patent application number 14/472714 was filed with the patent office on 2014-12-18 for adsorbent cartridge assembly with end cap.
The applicant listed for this patent is Micropore, Inc.. Invention is credited to J. Anthony DelNegro, Nicholas J. Dunlop, Douglas B. McKenna.
Application Number | 20140366738 14/472714 |
Document ID | / |
Family ID | 45932946 |
Filed Date | 2014-12-18 |
United States Patent
Application |
20140366738 |
Kind Code |
A1 |
McKenna; Douglas B. ; et
al. |
December 18, 2014 |
ADSORBENT CARTRIDGE ASSEMBLY WITH END CAP
Abstract
This invention relates to an adsorbent cartridge assembly having
at least one end cap, and systems related thereto, for removing
gaseous contaminants from the air or other gases.
Inventors: |
McKenna; Douglas B.;
(Avondale, PA) ; DelNegro; J. Anthony;
(Wilmington, DE) ; Dunlop; Nicholas J.;
(Wilmington, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Micropore, Inc. |
Elkton |
MD |
US |
|
|
Family ID: |
45932946 |
Appl. No.: |
14/472714 |
Filed: |
August 29, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13273854 |
Oct 14, 2011 |
8821619 |
|
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14472714 |
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61393273 |
Oct 14, 2010 |
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Current U.S.
Class: |
96/154 |
Current CPC
Class: |
B01D 2251/404 20130101;
B01D 2253/116 20130101; Y02C 10/08 20130101; Y02C 20/40 20200801;
B01D 2251/302 20130101; Y02C 10/04 20130101; B01D 2257/504
20130101; B01D 2253/1124 20130101; B01D 2259/4533 20130101; B01D
53/62 20130101; B01D 53/0415 20130101 |
Class at
Publication: |
96/154 |
International
Class: |
B01D 53/04 20060101
B01D053/04 |
Claims
1-45. (canceled)
46. An integrated, self-supporting adsorbent cartridge assembly for
removing gaseous contaminants, comprising: (a) an adsorbent
cartridge, comprising an adsorbent sheet wound into a roll, wherein
the adsorbent sheet is formed from a mixture comprising a polymer
and an adsorbent, wherein the sheet is spaced to form multiple
layers by ribs protruding from the sheet and molded directly out of
the adsorbent sheet, wherein said sheet wound into a roll comprises
a first open end face, a second open end face, and an outer
portion; wherein: the adsorbent comprises calcium hydroxide,
lithium hydroxide, molecular sieves, or mixtures thereof; the
adsorbent cartridge does not comprise a rigid outer housing; the
open end faces are at opposite ends of the cartridge; said layers
are disposed orthogonally with respect to the open end faces; and
said layers are mechanically spaced so as to allow gas flow between
said layers; and (b) an end cap secured around said first open end
face, wherein said end cap allows gas flow through said first open
end face, comprising: an outer sleeve circumscribing the outer
portion of one end of the cartridge adjacent to said first open
face; wherein said outer sleeve has a portion protruding beyond
said one end of the cartridge; and the protruding portion comprises
an inner surface; wherein the assembly has mechanical integrity
during transportation and installation.
47. The assembly of claim 46, wherein said outer sleeve further
comprises one or more supporting members extending from the inner
surface of the protruding portion of the outer sleeve and
protruding at least partially over the first open end face.
48. The assembly of claim 46, wherein the one or more supporting
members is a single member circumscribing the inner surface of the
protruding portion of the outer sleeve.
49. The assembly of claim 46, wherein said plurality of radial ribs
are arranged substantially equidistant from each other.
50. The assembly of claim 46, wherein the end cap is secured to
said first open end face by any method chosen from the group of:
ultrasonic welding, shrink-wrapping, adhesives, and molding.
51. The assembly of claim 46, wherein the end cap is secured to the
first open end face by a shrink wrap covering the outer portion of
the cartridge and at least a portion of the outer sleeve.
52. The assembly of claim 46, wherein the end cap is made from
materials capable of absorbing shocks and/or contains flexible
material suitable for making sealing attachment of the end cap to
the cartridge.
53. The assembly of claim 46, wherein the adsorbent is molecular
sieves.
54. The assembly of claim 46, wherein the polymer is ultra high
molecular weight polyethylene.
55. The assembly of claim 46, further comprising a second end cap
secured around the second open end face, comprising: an outer
sleeve circumscribing the outer portion of an end of the cartridge
adjacent to said second open face; wherein said outer sleeve has a
portion protruding beyond the end of the cartridge adjacent to said
second open face; and the protruding portion comprises an inner
surface.
56. The assembly of claim 46, wherein the cartridge assembly is
suitable for medical applications.
Description
[0001] This application claims the benefit of priority of U.S.
Provisional Appl. 61/393,273, filed Oct. 14, 2010, which is
incorporated herein by reference in its entirety.
TECHNICAL FIELD
[0002] This invention relates to an adsorbent cartridge assembly
having at least one end cap, and systems related thereto, for
removing gaseous contaminants from the air or other gases.
BACKGROUND
[0003] A carbon dioxide removal system maintains carbon dioxide
(CO.sub.2) concentration at a safe level. Maintaining CO.sub.2 at
safe levels can be accomplished by passing exhaled or inhaled gases
through a canister filled with a chemical adsorbent, such as soda
lime or anhydrous lithium hydroxide (LiOH). Several manufacturers
make these adsorbents and use their own special mixes. For example,
SODASORB.RTM., manufactured by W. R. Grace & Co., is composed
of a mixture of sodium hydroxide, calcium hydroxide, and potassium
hydroxide.
[0004] Adsorbents are typically in the form of small granules that
are generally sized between 0.04 to 0.25 inches (1.0 to 6.5 mm; 1
to 18 mesh) in diameter. The granules may be poured directly into a
canister for scrubbing CO.sub.2. The gas to be scrubbed is forced
through the granules either by lung power or by fan supplied power.
Due to the generation of airborne caustic dust, the handling or
pouring of granules in confined spaces is an undesirable
operation.
[0005] Pre-filled granular cartridges offer the ease of use
characteristics over loose granules, but these pre-filled canisters
still have issues with shipping and handling or in-use shock and
vibration, which causes chemical dusting of the adsorbent, settling
of adsorbent which changes pressure drop, channeling of gases
around the adsorbent (along the outer wall), all of which result in
variable adsorbent performance. Pre-filled cartridges are installed
into a canister/outer housing for use within equipment for
scrubbing of CO.sub.2.
[0006] An alternative to granular adsorbent is the ExtendAir.RTM.
adsorbent cartridge (Micropore Inc.). This technology as generally
described in U.S. Pat. No. 5,964,221 solves all of the
aforementioned issues which granular adsorbents have, while also
providing the ease of use characteristics desired.
[0007] For many applications, an ExtendAir.RTM. adsorbent sheet is
wound on a cylindrical core, but is sometimes stacked to form a
cube or other shapes. The adsorbent is prevented from unwinding or
losing shape by using an inexpensive polymer film wrapped around
the exterior of the cartridge. This cartridge has ease of handling
advantages offered by the pre-filled granular canisters and reduces
or eliminates dusting, without the added manufacturing cost and
bulk, of a completely enclosing plastic or metal housing.
[0008] However, the ends of the adsorbent cartridge assembly may
become damaged during shipping, handling or even in-use. Further,
the size or shape of the cartridge may not allow use of the
cartridge with canisters of different shapes or sizes than that of
the cartridge. In addition, for certain applications, the adsorbent
material of the cartridge may be incompatible with direct contact
with the canister material. Finally, it is desirable to produce an
assembly that enables a uniform end seal or perimeter seal surface,
without blocking perimeter flow channels. In the case of a
cylindrical adsorbent cartridge, the seal would have to accommodate
the step in the spirally wound cartridge, resulting from the
outermost layer of the adsorbent sheet material.
[0009] Hence, there is a need for improved adsorbent cartridges to
meet these needs. This invention addresses these needs and
others.
SUMMARY
[0010] The present invention provides, inter alia, an adsorbent
cartridge assembly for removing gaseous contaminants,
comprising:
[0011] (a) one or more adsorbent surfaces arranged in multiple
layers with edges of the layers forming two open end faces of a
three-dimensional cartridge, wherein the open end faces are at
opposite ends of the cartridge; and wherein the layers are
mechanically spaced to allow gas flow between the layers from one
open end face of the cartridge to the other open end face of the
cartridge;
[0012] (b) an end cap extending about and covering at least
portions of an outer surface of the cartridge adjacent to one open
end face of the cartridge.
[0013] In some embodiments, the end cap protrudes beyond the
cartridge so as to extend beyond the outer portion of the cartridge
in a direction of flow through the assembly, the end cap having an
inner surface.
[0014] The present invention further provides an adsorbent
cartridge assembly for removing gaseous contaminants,
comprising:
[0015] (a) an adsorbent cartridge, comprising one or more adsorbent
surfaces arranged in multiple layers, wherein said surfaces
arranged in multiple layers comprise a first open end face, a
second open end face, and an outer portion; wherein:
[0016] the open end faces are at opposite ends of the
cartridge;
[0017] said layers are disposed orthogonally with respect to the
open end faces; and
[0018] said layers are mechanically spaced so as to allow gas flow
between said layers; and
[0019] (b) an end cap secured around said first open end face,
comprising:
[0020] an outer sleeve circumscribing the outer portion of one end
of the cartridge adjacent to said first open face; wherein said
outer sleeve has a portion protruding beyond said one end of the
cartridge; and the protruding portion comprises an inner
surface.
[0021] In some embodiments, the end cap further comprises an inner
sleeve inserted into the inner core of the roll; and a plurality of
radial ribs arranged substantially equidistant from each other
connecting the inner sleeve to the inner surface of the protruding
portion of the outer sleeve.
[0022] In some embodiments, the end cap further comprises a sealing
ring molded to the inner surface of the protruding portion of the
outer sleeve, the sealing ring surrounding the entire inner
circumference of the outer sleeve.
[0023] In some embodiments, the sealing ring is co-molded to the
inner surface and is of a different material than the remainder of
the end cap.
[0024] In some embodiments:
[0025] the cartridge comprises one adsorbent surface wound into a
roll to form the multiple layers mechanically spaced by ribs
disposed on the adsorbent surfaces; wherein the roll has an inner
core, parallel to gas flow and perpendicular to the open end faces,
said inner core being coaxial to the outer portion of the roll;
[0026] the end cap further comprises an inner sleeve inserted into
the inner core of the roll; and a plurality of radial ribs arranged
substantially equidistant from each other connecting the inner
sleeve to the inner surface of the protruding portion of the outer
sleeve;
[0027] wherein the end cap further comprises a sealing ring
co-molded to the inner surface of the protruding portion of the
outer sleeve, the sealing ring surrounding the entire inner
circumference of the outer sleeve, wherein the sealing ring is of a
different material than the remainder of the end cap.
[0028] This invention offers the advantages of providing a uniform
end seal or perimeter seal surface, without blocking perimeter flow
channels. The perimeter seal is possible with the end cap even
though there is a step in the spirally wound cartridge. The sealing
surface can be made more rigid than one might choose if sealing
directly to the adsorbent cartridge surface, separating superior
adsorbent material properties, from superior sealing material
properties. The end cap can protect the ends of the adsorbent
cartridge from damage during shipping, handling or even in-use.
Further, use of an end cap which is chemically compatible with
caustics with a cartridge that eliminates chemical dusting can
allow for the canister to be made of materials that may not be
compatible with the adsorbent chosen. The cartridge assembly allows
full use of the adsorbent (flow through outer channels), while
allowing the outlet of the cartridge assembly to be a different
shape or size to that of the adsorbent cartridge (e.g., to convert
from a 6 inch to 5 inch diameter, or vice versa; to convert from a
cylindrical cartridge to a square outlet or inlet, or vice
versa).
[0029] The details of one or more embodiments of the invention are
set forth in the accompanying drawings and the description below.
Other features, objects, and advantages of the invention will be
apparent from the description and drawings, and from the
claims.
DESCRIPTION OF DRAWINGS
[0030] FIG. 1(a) is a three-quarter perspective view of an
adsorption cartridge of the present invention where the cartridge
is cylindrical and the sheets are spiral.
[0031] FIG. 1(b) is a cross-section top view of the adsorption
canister of FIG. 1(a) where the sheets inside the canister have a
spiral configuration.
[0032] FIG. 1(c) is an enlargement of the circular area of the
cross-section shown in FIG. 1(b) showing the sheets separated by a
separating means.
[0033] FIG. 1(d) is a cross-section view of an adsorption sheet of
the present invention where the sheet is formed of expanded
polytetrafluoroethylene with adsorbent particles encapsulated
within.
[0034] FIG. 1(e) is a cross-section view of an adsorption sheet of
the present invention where the sheet of FIG. 1(d) is surrounded by
an outer membrane.
[0035] FIG. 1(f) is a cross-section view of an adsorption sheet of
the present invention where adsorbent material is attached to an
internal screen and outer membranes are attached to the adsorbent
particles.
[0036] FIG. 1(g) is a cross-section view of an adsorption sheet of
the present invention where outer membranes are attached to an
internal screen and the interstices in the screen contain adsorbent
material.
[0037] FIGS. 1(h) through 1(k) are three-quarter elevation views of
a method for forming the sheet of FIG. 1(g).
[0038] FIG. 1(l) is a scanning electron micrograph (SEM), enlarged
5,000 times, of a cross section of an adsorbent sheet of the
present invention were the adsorbent powder is formed into a
microporous sheet by thermally induced phase separation of
polyethylene.
[0039] FIG. 1(m) is a three-quarter top elevation view of an
adsorbent sheet for use in the present invention, in which
separating ribs have been molded on one side of the sheet out of
the adsorbent itself.
[0040] FIG. 1(n) is a cross-section view of the adsorbent sheet
shown in FIG. 1(m).
[0041] FIG. 1(o) is a three-quarter top elevation view of another
embodiment of an adsorbent sheet for use in the present invention,
in which separating ribs have been molded in an angular fashion on
one side of the adsorbent sheet.
[0042] FIG. 1(p) is a three-quarter side elevation view of still
another embodiment of an adsorbent sheet for use in the present
invention, in which separating ribs have been molded in an angular
fashion on both sides of the adsorbent sheet.
[0043] FIG. 1(q) is a detailed view of the adsorbent sheet
illustrated in FIG. 1(p).
[0044] FIG. 2(a) is an embodiment of an adsorbent cartridge
assembly with end caps.
[0045] FIG. 2(b) shows a plastic sleeve wrapped around an adsorbent
cartridge assembly.
[0046] FIG. 2(c) shows a flow cone attached to an end cap.
[0047] FIG. 2(d) shows an embodiment of an end cap with two
opposing core plugs arranged so that two or more cartridges can be
stacked together using the end cap.
[0048] FIG. 3(a) shows an embodiment of the adsorbent cartridge
assembly with a cap.
[0049] FIG. 3(b) shows a cross-sectional view of the cartridge
assembly shown in FIG. 2(a).
[0050] FIG. 4(a) shows an embodiment of the cartridge assembly
using two flow cones which are snapped on to the end caps of the
cartridge. A thin film shrink wraps around the cartridge and end
caps to secure the whole assembly.
[0051] FIG. 4(b) shows a detailed view of the mechanism through
which the flow cone of FIG. 3(a) is attached onto the end cap.
[0052] FIG. 5(a) shows another embodiment of the cartridge assembly
with an end cap.
[0053] FIG. 5(b) shows a detailed view of an end cap having a ledge
around its inner protruding side.
[0054] FIG. 6(a) shows an adsorbent cartridge assembly with an end
cap that further includes a flow cone.
[0055] FIG. 6(b) shows an end cap with a circumscribed groove on
its outer sleeve.
[0056] FIG. 7 shows an embodiment in which air flow is directed to
exit a cartridge assembly through the same open end face from which
the air flow entered, by the use of a dome shaped end cap.
[0057] FIG. 8 shows a cross-section of an embodiment of the
assembly as a cross-section, whereby an end cap being held by
shrink wrap in addition to various sizes using different number of
ribs (spokes) and inclusive of an integral core plug.
[0058] FIG. 9 shows an embodiment whereby the canister body is
sealed to the flow cone 111 by O-ring 801, and the flow cone 111 is
sealed to the end cap 803 by O-ring 802.
[0059] FIG. 10 shows an embodiment whereby the flow cone 901 is
sealed to the end cap 902 by O-ring 903. Noting the flow cone is
sealed to the canister body in another location.
[0060] FIG. 11-13 show another embodiment of the adsorbent
cartridge assembly with an end cap and a flow cone.
[0061] FIG. 14 shows two embodiments of end caps having different
geometry allowing for different methods of grip on the cartridge
which may eliminate the need for an outer wrap to secure the end
cap to the cartridge.
[0062] FIG. 15 shows an embodiment of a cartridge assembly.
[0063] FIG. 16 shows a co-molded end cap with a sealing ring.
[0064] Like reference symbols in the various drawings indicate like
elements.
DETAILED DESCRIPTION
[0065] The present invention provides, inter alia, an adsorbent
cartridge assembly that is designed to provide efficient
adsorption, mechanical resistance to the adsorbent cartridge
against shocks and vibrations, help reduce or eliminate air
by-passing the cartridge, and prevent damages due to caustic
reaction between the cartridge and inner walls of a canister. As
the mechanism for removing gaseous contaminants from a gas is
dependent on the particular material chosen, the use of the word
"adsorption" in this specification is meant to include adsorption,
absorption, chemisorption, physisorption, catalysis etc.
[0066] Accordingly, disclosed herein, inter alia, is an adsorbent
cartridge assembly for removing gaseous contaminants,
comprising:
[0067] (a) one or more adsorbent surfaces arranged in multiple
layers with edges of the layers forming two open end faces of a
three-dimensional cartridge, wherein the open end faces are at
opposite ends of the cartridge; and wherein the layers are
mechanically spaced to allow gas flow between the layers from one
open end face of the cartridge to the other open end face of the
cartridge;
[0068] (b) an end cap extending about and covering at least
portions of an outer surface of the cartridge adjacent to one open
end face of the cartridge.
[0069] In some embodiments, the end cap protrudes beyond the
cartridge so as to extend beyond the outer portion of the cartridge
in a direction of flow through the assembly, the end cap having an
inner surface. In some embodiments, the outer surface of the end
cap may be of larger dimensions than the outer surface of the
cartridge. In some embodiments, the outer surface of the end cap
may be of different shape than the outer surface of the
cartridge.
[0070] In some embodiments, the present invention provides an
adsorbent cartridge assembly comprising:
[0071] (a) an adsorbent cartridge, comprising one or more adsorbent
surfaces arranged in multiple layers, wherein said surfaces
arranged in multiple layers comprise a first open end face, a
second open end face, and an outer portion; wherein:
[0072] the open end faces are at opposite ends of the
cartridge;
[0073] said layers are disposed orthogonally with respect to the
open end faces; and
[0074] said layers are mechanically spaced so as to allow gas flow
between said layers; and
[0075] (b) an end cap secured around said first open end face,
comprising:
[0076] an outer sleeve circumscribing the outer portion of one end
of the cartridge adjacent to said first open face; wherein said
outer sleeve has a portion protruding beyond said one end of the
cartridge; and the protruding portion comprises an inner
surface.
[0077] In some embodiments, the outer sleeve further comprises one
or more supporting members extending from the inner surface of the
protruding portion of the outer sleeve and protruding at least
partially over the first open end face.
[0078] In some embodiments, the one or more supporting members is a
single member circumscribing the inner surface of the protruding
portion of the outer sleeve.
[0079] In some embodiments:
[0080] the end cap further comprises an inner hub aligned over the
center of said first open end face; and
[0081] the one or more supporting members comprise a plurality of
radial ribs connecting the inner hub to the inner surface of the
protruding portion of the outer sleeve.
[0082] In some embodiments, the plurality of radial ribs are
arranged substantially equidistant from each other.
[0083] In some embodiments, the inner hub is a disc.
[0084] In some embodiments, the inner hub is a ring.
[0085] In some embodiments, the cartridge comprises one adsorbent
surface wound into a roll to form the multiple layers; wherein said
roll has an outer portion.
[0086] In some embodiments, the roll has an inner core, parallel to
gas flow and perpendicular to the open end faces; wherein said
inner core is coaxial to the outer portion of the roll.
[0087] In some embodiments, the inner core is solid.
[0088] In some embodiments, the inner core is hollow.
[0089] In some embodiments: [0090] the end cap further comprises a
hub centered over the inner core; and [0091] the one or more
supporting members comprise a plurality of radial ribs connecting
the inner hub to the inner surface of the protruding portion of the
outer sleeve.
[0092] In some embodiments:
[0093] the hub comprises a ring arranged concentrically to the
outer sleeve; and
[0094] the one or more supporting members comprise a plurality of
radial ribs connecting the inner ring to the inner surface of the
protruding portion of the outer sleeve.
[0095] In some embodiments, the assembly further comprises a plug
inserted into the ring.
[0096] In some embodiments, the assembly further comprises core
plugs inserted into the ring in opposing directions so as to
connect more than one cartridge in series.
[0097] In some embodiments:
[0098] the hub comprises a disc arranged concentrically to the
outer sleeve; and
[0099] the one or more supporting members comprise a plurality of
radial ribs connecting the inner ring to the inner surface of the
protruding portion of the outer sleeve.
[0100] In some embodiments:
[0101] the inner core is hollow;
[0102] the inner hub comprises an inner sleeve inserted into the
inner core; and
[0103] the one or more supporting members comprise a plurality of
radial ribs connecting the inner sleeve to the inner surface of the
protruding portion of the outer sleeve.
[0104] In some embodiments:
[0105] the inner core is hollow;
[0106] the inner hub comprises a plug inserted into the inner core;
and
[0107] the one or more supporting members comprise a plurality of
radial ribs connecting the plug to the inner surface of the
protruding portion of the outer sleeve.
[0108] In some embodiments, the hub has substantially the same
dimension as the inner core of the roll.
[0109] In some embodiments, the cartridge further comprises a foam
or sealing material covering at least a portion of an outer layer
of the roll.
[0110] In some embodiments, the cartridge further comprises a foam
or sealing material inserted under an outer layer of the roll.
[0111] In some embodiments, the layers are spaced by ribs disposed
on the adsorbent surfaces.
[0112] In some embodiments, the layers are spaced by separating
screens between the adsorbent surfaces.
[0113] In some embodiments, the end cap is secured to said first
open end face by any method chosen from the group of: ultrasonic
welding, shrink-wrapping, adhesives, and molding.
[0114] In some embodiments, the end cap is secured to the first
open end face by a shrink wrap covering the outer portion of the
cartridge and at least a portion of the outer sleeve.
[0115] In some embodiments, the outer sleeve tapers in the
direction of the protruding portion allowing the end cap to be
secured to the cartridge without any external securer.
[0116] In some embodiments, the outer sleeve further comprises a
groove circumscribing the outer portion of the outer sleeve.
[0117] In some embodiments, the end cap is secured to said first
open end face by a shrink wrap covering the outer portion of said
cartridge and extending into the groove.
[0118] In some embodiments, the assembly further comprises a cone
secured around the outer sleeve, wherein said cone comprises an
opening with a smaller diameter than the first open end face.
[0119] In some embodiments, the outer sleeve further comprises a
groove circumscribing the inner surface of the protruding portion
of the outer sleeve; and the cone further comprises a protrusion on
an outer surface of the cone, which locks into the groove.
[0120] In some embodiments, the assembly further comprises a
sealant disposed between the cone and the inner surface of the
protruding portion of the outer sleeve.
[0121] In some embodiments, the sealant is an o-ring.
[0122] In some embodiments, the inner core is hollow; and wherein
said assembly further comprises a dome secured around the outer
sleeve.
[0123] In some embodiments, the end cap is made from materials
capable of absorbing shocks and/or contains flexible material
suitable for making sealing attachment of the end cap to the
cartridge.
[0124] In some embodiments, the cartridge has more than one axially
extended channel within its interior through which gas can
flow.
[0125] In some embodiments, the end cap further comprises means to
promote a uniform flow of air across a cross-sectional surface of
the cartridge. In some embodiments, means is selected from the
group of a flow deflector plate, a filter, a ring with sloping ribs
and a disc.
[0126] In some embodiments, the assembly further comprises a second
end cap secured around the second open end face, comprising:
[0127] an outer sleeve circumscribing the outer portion of an end
of the cartridge adjacent to said second open face; wherein said
outer sleeve has a portion protruding beyond the end of the
cartridge adjacent to said second open face; and the protruding
portion comprises an inner surface.
[0128] In some embodiments, the present invention provides a
gaseous contaminant removal system, comprising: [0129] (a) the
assembly of any one of one of the aforementioned embodiments, or
combination thereof; and [0130] (b) a canister for housing said
cartridge;
[0131] wherein:
[0132] said canister comprises an inlet through which gas can flow
to contact the adsorbent cartridge; and an outlet for gas flow;
wherein one of the open end faces of the cartridge is adjacent to
the inlet.
[0133] In some embodiments, the second open end face is adjacent to
the inlet.
[0134] In some embodiments, the assembly further comprises a
sealant disposed between the inner wall of the canister and the
protruding portion of the outer sleeve, so that air is directed
into and does not by-pass the cartridge.
[0135] In some embodiments, the term "open end faces are at
opposite ends of the cartridge" means one open end provides an
inlet for gas flow and the other open end provides for outlet for
gas flow through the cartridge. In some embodiments, the open end
faces are parallel to each other at opposite ends of the cartridge.
In some embodiments, the open end faces are not parallel to each
other, wherein the cartridge has curvature.
[0136] In general, the adsorbent cartridges of the invention do not
require a rigid outer housing. The adsorbent cartridge has the
advantage of instead using a less expensive end cap to interconnect
the cartridge to the inlet and/or outlet of the gas system (e.g.,
the canister). Preferably, this allows the end cap to interconnect
the cartridge to the gas system (e.g., canister) without need of
fastening to the inlet and/or outlet of the gas system (e.g.,
without need of adhesive or mechanical fasteners between the
cartridge and the canister inlet or outlet).
[0137] The cartridge and end cap are described in more detail
below.
[0138] Adsorbent Cartridge
[0139] The cartridges include, but are not limited to,
ExtendAir.RTM. cartridges and those described in U.S. Pat. No.
7,329,307, U.S. Pat. No. 7,326,280, and U.S. Pat. No. 5,964,221,
each of which is incorporated herein by reference in its
entirety.
[0140] The adsorbent cartridge includes adsorbent surfaces that are
arranged in multiple layers. Generally, the surfaces are
mechanically spaced (e.g., by ribs or other spacers, screens, etc.)
where the spacers are in contact with the next adjacent sheet. In
some embodiments, the spacers are parallel to the direction of air
flow. In some embodiments, the sheets may be flat, or pleated, or
contain ribs therein.
[0141] In some embodiments, the sheets are wound into a cylinder
but the cartridge may also be of other geometries. In the wound
embodiments, the sheet 30 is spiraled (i.e., arranged in a
continuous helix or as separate rings or helixes arranged
concentrically) as shown as illustrated in FIG. 1(a). Air flow
through the cartridge can be from both directions (top to bottom,
or bottom to top) and is parallel to the spiraled adsorbent sheet
surfaces. FIG. 1(b) shows a top view of cylindrical cartridge 20 of
FIG. 1(a) with adsorbent sheet 30 arranged in a "spiral"
configuration where the sheet is wrapped around the center. FIG.
1(c) shows separating screens 32 positioned between the spirally
positioned sheets 30.
[0142] In some embodiments, the sheets are stacked into a cube or
rectangular shape (90 degree corners on all sides but length, width
and depth may or may not be identical). In some embodiments, the
adsorbent surfaces are planar. The term "planar" used to describe
surfaces means that the adsorbent surfaces are substantially
without curvature (e.g., the surfaces are not rolled). A sealing
material (foam or rigid) may be used to seal two or more sides of
the cube or rectangle, leaving two open end faces (to allow for air
flow), two outer surfaces formed by the adsorbent sheets, and two
foam surfaces.
[0143] In some embodiments, each adsorbent surface comprises the
same type of adsorbent. In other embodiments, each adsorbent
surface is independently selected from various adsorbents.
[0144] The Manufacture of Adsorbent Surfaces
[0145] In some embodiments, the gaseous contaminant is carbon
dioxide. In some embodiments, the adsorbent material used in the
adsorbent surfaces is calcium hydroxide or lithium hydroxide.
[0146] Further description of LiOH adsorbent sheets can be found
in, for example, Hrycak et al. in U.S. Pat. No. 7,329,307 and U.S.
Pat. No. 7,326,280, each of which is incorporated herein by
reference in its entirety. Further description of Ca(OH).sub.2
adsorbent sheets and other types of adsorbent sheets can be found
in, for example, in McKenna, U.S. Pat. No. 5,964,221, which is
incorporated herein by reference in its entirety.
[0147] In one embodiment shown in FIG. 1(d), sheet 30 is formed of
an adsorbent filled expanded porous PTFE sheet having a
microstructure of nodes 40 interconnected with fibrils 41 wherein
adsorbent material 39 is present in the voids of the PTFE structure
as taught by U.S. Pat. No. 4,985,296 issued to Mortimer, Jr.,
incorporated herein by reference in its entirety. This sheet is
water repellent, but air-permeable. Ideally, particles 39 are
packed in a multi-modal (e.g., bi-modal or tri-modal) manner, with
particles of different sizes interspersed around one another to
fill as much of the available void space between particles as is
possible so as to maximize the amount of active material contained
in the sheet. This technique also allows more than one type of
adsorbent particle to be filled into a single sheet.
[0148] By using filled porous expanded polytetrafluoroethylene
(PTFE) as sheet 30, a number of additional advantages are further
imparted. Expanded PTFE is a non-linting, non-out-gassing inert
material that effectively reduces dusting of adsorbent material
during manufacturing and during the life of the filter.
Additionally, processing advantages of this material include the
ability to make a relatively thin material that can be produced in
a wide sheet and then cut (or cut and pleated) into desired
configurations.
[0149] The properties of CO.sub.2 adsorbent filled PTFE sheet are
such that no other supporting fabric or material is needed to
maintain structural integrity. In fact, not only can this filled
PTFE sheet withstand flexing, pleating and mechanical vibration
under dry conditions, the hydrophobicity of the PTFE offers this
structural durability even while subjected to direct liquid water
contact. Another embodiment of sheet 30 is shown in FIG. 1(e),
where filled PTFE sheet 30 is encapsulated between two hydrophobic
gas-permeable membranes 42. These outer membranes 42 add extra
protection to ensure that adsorption material 40 is contained
within sheet 30 while preventing water from reaching the adsorbent
contained in the sheet. Membranes 42 must have a high degree of
filtration efficiency to prevent adsorbent particles from escaping
into the breathing atmosphere. These membranes 42 preferably
comprise porous expanded polytetrafluoroethylene (PTFE), because it
is hydrophobic and offers high particulate filtration
efficiency.
[0150] A third embodiment of the sheet is shown in cut-away FIG.
1(f) where an internal screen 43 is encapsulated by adsorbent
material 39 that is surrounded by two hydrophobic gas-permeable
membranes 42.
[0151] A fourth embodiment of the sheet 30 is shown in FIG. 1(g)
where an internal screen 44 is attached to two hydrophobic
gas-permeable membranes 42 and adsorbent material 39 is positioned
in the voids between screen members 44.
[0152] FIGS. 1(h) thorough 1(k) illustrate a method for making
sheet 30 of FIG. 1(g) having an internal screen 44, adsorbent
material 39, and outer membranes 42. FIG. 1(h) depicts internal
screen 44. Next, in FIG. 1(i), internal screen 44 is attached to a
membrane 42 by a lamination process. Subsequently, in FIG. 1(j),
adsorbent material 39 is added into the open cells of internal
screen 44. Afterwards, in FIG. 1(k), a second membrane 42 is
laminated to the top of the internal screen 44, thereby
encapsulating adsorbent material 40 within.
[0153] FIG. 1(l) is a scanning electron micrograph of another
embodiment of sheet 30 used in the cartridges described herein.
This structure is produced by way of thermally induced phase
separation, such as in the following manner.
[0154] A water repellent polymer, such as ultra high molecular
weight polyethylene, is combined with a gas adsorbent material,
such as calcium hydroxide powder. This combination may be
accomplished by combining the two materials together in an
extruder. By conveying this mixture through the extruder and mixing
with a lubricant, such as mineral oil, the polymer dissolves in the
lubricant and become uniformly mixed with the adsorbent and
lubricant. This mixture can then be extruded into a composite sheet
or other shape.
[0155] The composite sheet may be calendared to further flatten the
sheet if desired. The lubricant may then be extracted out of the
resulting sheet using a solvent, such as hexane. The solvent may
then be removed, such as through use of a dry nitrogen purge.
[0156] The resulting structure is highly micro-porous, allowing for
the diffusion of CO.sub.2 or other gases, and yet is able to be
produced with very high adsorbent powder loadings per unit volume.
Additionally, if a very strong polymer, such as Ultra High
Molecular Weight Polyethylene is used, a very small amount of
polymer is required to make the sheet structurally stable, which
allows for even higher adsorbent loadings per unit volume. While
typical powder loadings for this type of manufacturing process are
on the order of 50 to 60% filler powder after process oil
extraction, loadings well above 60% may be possible. In some
embodiments, adsorbent loading is greater or equal to about 90% by
weight. In some embodiments, adsorbent loading is greater or equal
to about 97%. Additionally, in some embodiments, the material is
molded into any desired shape, and thus, the separating means may
be accomplished by molding separating ribs onto the surface of the
sheet.
[0157] Various embodiments of this molded structure are illustrated
in FIGS. 1(m) through 1(q). By molding the separating elements 33
(or "ribs") directly out of adsorbent material, not only is the
adsorbent cartridge easier to produce, but, because of its
self-separating properties, the total amount of adsorbent in the
filter can be increased by 10 to 30 percent.
[0158] End Cap
[0159] The use of a uniform end cap to which an adsorbent cartridge
can seal, helps to overcome problems associated with 1) air by-pass
due to physical gaps between the cartridge and the housing
canister, 2) damage due to caustic reaction between the cartridge
and the inner walls of the housing canister, and 3) mechanical
fragility of unprotected cartridges. An example of an adsorbent
suitable for medical applications is the Eclipse.TM. CO.sub.2
Adsorbent, which includes end caps.
[0160] FIGS. 2(a) and 2(b) show embodiments of an assembled
cartridge 100, a wound adsorbent cartridge 101 with foam 102 either
covering the end of the cartridge or wound partially under the last
wrap of adsorbent materials. The actual size and position of foam
102 can be tailored to specific applications. Foam 102 aids in
preventing airflow from by-passing the cartridge. An end cap 103
can then be attached on one or more open end faces of the
cartridge. Surfaces of the adsorbent materials are arranged in
multiple layers 116 in cartridge 101. First open end face 104 is
parallel to second open end face 115, both end faces are at
opposite ends of the cartridge. Besides the two open end faces,
cartridge 101 also includes an outer portion 121. Multiple layers
116 are arranged orthogonally with respect to both open end faces.
Multiple layers 116 are mechanically spaced from one another such
that gas flow between the layers is not obstructed. In some
embodiments, the mechanical spacing is provided by ribs 33 as shown
in FIG. 1(m). End cap 103 includes an outer sleeve 107, which forms
a protruding portion 117 when end cap 103 is secured around open
end face 104 of cartridge 101. Protruding portion 117 also includes
an inner surface 118, these features are more clearly illustrated
in FIG. 3(b). In some embodiments, end cap 103 contains supporting
members in the form of radial ribs 109 that support an inner hub
108 through which a core plug 106 can be engaged. Wound cartridge
101 has an inner core 105 into which core plug 106 can be inserted.
Core plug 106 can be incorporated both as an integrated core plug
and end cap assembly 120 or it may be part of an assembly formed in
a unitary fashion.
[0161] Plastic, rubber and co-molded materials (e.g.
plastic/rubber) can be used to fabricate end caps. Material choices
are determined based on the intended applications of the end caps
and are not limited to the materials listed above. The actual
manufacturing method used to produce the end cap can also vary.
Manufacturing based on molded parts may be suitable for certain
embodiments and applications. The adopted manufacturing method is
based on the applications and constraints imposed by the choice of
material.
[0162] End cap 103 can be partially or completely formed from
flexible materials that are able to seal elastically to cartridges,
even cartridges with variability in their diameters. Sealing can be
done independently of the cartridge diameter by inserting core plug
106 on end cap 103 into inner core 105 of wound cartridge 101. In
general, end cap 103 is designed to be placed onto one end of
cartridge such that the end cap makes a snug fit to the outer rim
or perimeter of the cartridge. In this manner, the foam materials
surrounding the cartridge can also be secured. Correct positioning
of the end cap can be ensured through the contact of radial ribs
109 with open end face 104 of the cartridge or through a fitting
notch incorporated in the end cap profile. Ribs 109 can also ensure
protection against telescoping of cartridge material.
[0163] A polymer (e.g. plastic) film 110 can be applied to seal
assembly 100 around the outer surface of the cartridge, including
the perimeter surfaces of the end caps, as shown in FIG. 2(b). For
certain applications, polymer film 110 can be heat sealed to the
assembly. In some embodiments, polymer film 110 extends over the
outer edges of each end cap when the assembly is wrapped. In some
embodiments, end cap 103 has a groove 520 (shown in FIG. 6(b)
around the outer perimeter along the rim of end cap 103 to
facilitate in securing film 110. Sealing materials do not fully
encase end caps so that airflow through open end faces 104 and 115
of cartridge is not obstructed.
[0164] Besides its use in sealing the outer surface of the
cartridges, polymer film 110 also enables a cartridge to attach to
an end cap such that the cartridges with variability in diameter
can be accommodated within the cross-sectional surface of the end
cap.
[0165] In some applications as shown in FIGS. 3(a) and 3(b), gas
flow through inner core 105 of cartridge 101 can be eliminated by
the insertion of core plug 106 into the ends of inner core 105
after the cartridge and end caps are assembled. Besides eliminating
gas flow, core plug 106 may also assists in securing the end caps.
Based on the application, one or both end caps can be designed to
have a core plug that is either integrated into the end cap or
formed in a unitary fashion. Further as shown in FIG. 14, the
design of the end cap may allow for instances where the outer wrap
is not required. For example, the protruding portion of the end cap
may taper (1401) and thereby eliminate the need for a groove within
end cap design. The length of the end cap can be tailored to adjust
the grip of the end cap to the cartridge. In addition, the outside
ring can be angled in, or shaped in multiple ways to increase the
grip on the cartridge, to thus eliminate the need for an outer
shrink wrap.
[0166] In some applications as shown in FIG. 16, an end cap 1600
can be co-molded, in which a body 1601 of the end cap 1600 is
fabricated from one material and a seal section 1602 is made of
another material. The body 1601 may include an outer sleeve 1603,
radial ribs 1604 and an inner hub 1605. The sealing section 1602
may be disposed at one side of an inner surface 1606 of the outer
sleeve 1603 and surrounds the entire circumstance of the one side
of the inner surface 1606. The sealing section 602 may protrude
from outer sleeve 1603. In some applications, high density
polyethylene (HDPE) may be used for the body 1061 of the end cap
1600 and a thermoplastic rubber (e.g., a crosslinked mixture of
polypropylene and EPDM (ethylene-propylene-diene monomer) rubber,
such as Santoprene.TM.) for the seal section 1602 of the end cap
1600. Other combinations of materials for the body 1601 sealing
section 1602 may be used, depending on the desired application.
[0167] Flow Cones
[0168] FIG. 2(c) shows a flow cone 111 with a tapered end 112
through which pre-treated and treated gas can be directed into or
out of the flow cone respectively. In some embodiments, the
combination of flow cone 111 with end cap 103 can be used to
connect breathing devices that have a smaller standard tubing
connection. Wider end 113 of flow cone 111 can be fitted onto (e.g.
snapped on) end cap 103 to form assembly 114 shown in FIG. 2(c). In
some embodiments, the flow cone and end cap assembly can be
designed in an integrated fashion. The extended radial ribs in the
end cap can help to direct gas flow to open end face 104 of the
cartridge. Sealing is required between the end cap, the flow cone
and the canister housing to eliminate gas flow that by-passes the
cartridge.
[0169] A groove 520 (in FIG. 6 (b)) on the outer perimeter along
the rim of end cap 103 allows a sealing film to be attached to the
end cap. FIG. 6 (a) shows an example in which groove 520 can be
used to allow the latching of a flow cone 111 to the cartridge
assembly. In some embodiments, this combination of flow cone 111
with end cap 103 can be used in cases where a housing canister body
is not required. Such applications may include adsorbent systems
that are designed for one time use.
[0170] One example in which a canister housing is not required is
the REMO2.RTM. application, an embodiment of which is shown in FIG.
4(a). In these applications, the cartridge may not be perfectly
sealed. Instead, a film 301 is wrapped around the cartridge to help
keep the tension in the wound cartridge and prevent gas entering
from the sides of the cartridge. Two flow cones 302 are attached to
open end faces of cartridge 101. The structural requirements for
the housing element in such applications may be less stringent than
those required in a typical canister. FIG. 4(b) shows the
attachment mechanism of flow cone 302 to end cap 303.
[0171] The design of the flow cone can be tailored to specific
applications. In some embodiments, as shown in FIG. 10, flow cone
901 can be inserted to fit the inner diameter of the end cap 902. A
single O-ring 903 fits into notch 904 and is used to provide
mechanical sealing to ensure air flow through the cartridge (and
eliminating by-pass of the cartridge). In embodiments, in which
only a single O-ring is used, the end cap can be slipped more
easily onto the O-ring.
[0172] Gas Flow Optimization
[0173] The embodiments described in this document can be modified
in several ways to optimize gas flow through the adsorbent
cartridge. In some embodiments, flow deflector plates can be
inserted into end cap 103 to ensure a good and even gas flow across
the entire open end face 104 of the cartridge. In some embodiments,
a screen (which can affect the flow rate and flow distribution) can
be placed near the top of the end cap to deflect the gas flow and
average the flow across the whole face of the cartridge. In some
embodiments, the extended radial ribs may be sloped instead of
being arranged in a horizontal plane. These contoured ribs may help
to deflect the gas flow and even out the distribution of gas flow
across the cartridge. In some embodiments, a flat disc is inserted
in a portion of the end cap assembly to evenly distribute gas flow
by moving the gas stream to cover entire bounds of the
cartridge.
[0174] Sealing Options Using O-Rings
[0175] In some embodiments, as shown from a cross-sectional view in
FIG. 9, two O-rings are used as sealants to seal an assembly
featuring a cartridge, end cap, and flow cone installed in a
housing canister. In these embodiments, flow cone 111 is latched
onto an end cap 803. A sealant O-ring 801 is used to seal and
prevent the airflow from going around the cartridge such that
by-pass of airflow can be minimized or eliminated. A second sealant
O-ring 802 seals the end cap and the flow cone to ensure that all
airflow going through the flow cone passes through into the
cartridge.
[0176] In some embodiments, the canister housing might already have
sealing capabilities, thus sealing may not be required at some or
all perimeter surfaces between the flow cone and the end cap, and
between the end cap and the cartridge. In some embodiments, O-rings
are used to form seals between mating surfaces defined as the
surfaces between the cartridge and the top end of the lower end
cap, and the surface between the cartridge and the lower end of the
upper end cap. The necessity and use of seals for these surfaces
are application specific.
[0177] In some embodiments, end caps may be attached to cartridges
by means of adhesives (e.g. glues) that are inert to both the
adsorbent materials and the gas flowing through the cartridge. The
adhesives may be applied around the rim of a cartridge so that an
end cap can be attached to the cartridge while not obstructing the
flow of gas across open end face 104 of the cartridge.
[0178] Different configurations of adsorbent systems require the
use of adsorbent cartridges having different sizes. These
differently sized cartridges in turn require end caps of different
dimensions and configurations. In some embodiments, as shown in
FIG. 5(a), end cap 401 does not have extended radial ribs. Instead
of having radial ribs as supporting members, end cap 401 has a
ledge 119 around inner surface 118 of protruding portion 117, as
shown in FIG. 5(b).
[0179] In this configuration, a shrink wrap 403 made from, for
example, polypropylene, polyolefin and polyethylene can be used to
secure cartridge 101 and ends caps 401 around the rims and outer
surface of the cartridge and end caps. Plug 402 with a loop can be
engaged directly into inner core 105 of cartridge 101, which can be
used as a means to pull the cartridge from the canister
assembly.
[0180] Mechanical/Structural Protection of Cartridges
[0181] The integrated cartridge and end cap assembly is more robust
against handling and shipping damages due to the shock absorbing
capability and mechanical resistance afforded by the end caps. End
caps may be fabricated from flexible materials or combinations of
rigid and flexible materials that are able to absorb shocks. Since
cartridges are often packaged in multiples with the cartridges
arranged side by side, the ability to absorb shocks and vibrations
along a vertical dimension across which at least one end cap is
secured is useful in reducing damages on the cartridges incurred
during shipment, without requiring the use of more expensive
packaging materials. With the additional protection provided by the
end caps, simple packaging techniques involving only standard metal
foil composites bags placed inside a standard box could be utilized
for shipping purposes. In addition, the end-user of the cartridges
most commonly imparts vertical shocks and vibrations to the
cartridge by subjecting the cartridges to vertical drops when the
cartridges are installed in a canister. End caps thus help to
ensure the integrity of cartridges both during shipment and
installation of the cartridge by providing additional mechanical
resistance against shocks to the adsorbent cartridges.
[0182] In some embodiments, end caps can be designed to have a
thicker section for the rim and/or rib portions. Such a design
would be more symmetric, which is more impact resistant and
provides greater mechanical stability for the cartridge assembly.
FIG. 12 illustrates an example of an end cap 1101 with thicker rim
portion, which is engaged to a flow cone 1102.
[0183] Although end caps are generally used for wound cartridges,
they can be used as means to reduce shipping and handling damages
to non-cylindrical cartridges (e.g. square, rectangular, or oval)
as well.
[0184] Inlet and Outlet of Airflow from the Same Face of a
Cartridge
[0185] In some embodiments, particularly those in which the
available physical space for the adsorbent system is limited, gas
flow may be required to enter and exit the adsorbent cartridge from
the same end face. An example of such an embodiment is illustrated
in FIG. 7. End cap 601 is domed-shaped and sealed on one end. Gas
flows into the cartridge through core 105 of the cartridge. End cap
601 redirects the incoming gas in the reverse direction through the
adsorbent cartridge such that the processed gas exits the same open
end face 602 of the cartridge as the inflow of gas. End cap 601 is
sealed to cartridge 603. End cap 601 may contain additional
features and components such as gas deflector plates, flow discs
and filters to help channel and make the gas flow through the
cartridge more uniform. In some embodiments, the gas flow is in the
reverse direction, depending on the application.
[0186] In the embodiments shown in FIG. 2, cartridge 101 has one
inner core 105. In some embodiments, the cartridge may have more
than one core. The additional cores can serve as channels through
which gas may flow.
[0187] FIG. 8 shows both a top view and a cross sectional view of
the adsorbent cartridge and endcap 701 with 3 spokes, the number of
spokes will vary based on specific application and dimensions. The
core plug 704 of the end cap is first used to engage the end cap to
the cartridge before wrapping film 703 is secured to the cartridge
and end cap together. Wrapping film 703 shrinks to the outside
perimeter of the cartridge and the stepped face 702 provided on the
end cap 701, in some applications the end cap many have a tapered
face to facilitate the attachment of the wrapping film.
[0188] In the embodiments shown in FIG. 13, end cap 1201 with a
symmetric design is shown. Such a symmetric design of the end cap
allows ambidextrous installation of the end-cap and cartridge
assembly, at the same time allowing a simpler mold design that may
be advantageous in the manufacturing/production of these end
caps.
[0189] In some embodiments, multiple cartridges are stacked. Each
of the multiple cartridges can have its own housing canisters, or
the different cartridges can be joined by end cap 103 having two
opposing core plugs 106 as illustrated in FIG. 2(d) to connect the
ends of different cartridges. An exemplary application of these
embodiments can be for an application in which airflow or other
gases is first passed through a cartridge containing molecular
sieves to remove its moisture content before the processed gas
enters another cartridge arranged in series to have carbon dioxide
removed from it. Even though cartridges can be used to treat gas
flow entering the open end faces in both directions, when symmetric
end caps suitable for ambidextrous installation are used, safety
features need to be in place to ensure that once installed, the
direction of airflow is clearly indicated. For example,
cylindrical/circular cartridges are typically installed into
tapered canister housing in which the direction of airflow can be
easily identified.
Example 1
Cartridge Assembly
[0190] The prototype cartridge assembly consists of a spirally
wound cartridge and a single end cap, both of which are cylindrical
although as previously noted a wound cartridge will not be
perfectly cylindrical due to the step from the outer edge of the
adsorbent sheet. The end cap in the prototype is designed and
manufactured with a number of spokes and an integral plug. When
attaching the end cap to the cartridge the integral plug slides
into the central hollow core of the cartridge, which secures the
end cap to the cartridge and also stops any flow of gas through the
hollow core when installed (e.g., in a breathing device). The end
cap attaches to the cartridge around its perimeter. The endcap is
made of a rubber material and is designed to be of a smaller
diameter than the cartridge, so that when installed the end cap
fits around the cartridge perimeter snugly. With this design, it
has not been necessary to have an outer shrink wrap to hold the
end-cap when assembled. The chosen durometer of the prototype is 80
which allows for some elasticity of the end cap to help when
attaching to the cartridge. The rubber end cap also allows for a
means to seal the cartridge assembly in the canister and thus
minimizes by-pass of the adsorbent material. In some embodiments,
the cartridge assembly is substantially as shown in FIG. 15.
[0191] A number of embodiments of the invention have been
described. Nevertheless, it will be understood that various
modifications may be made without departing from the spirit and
scope of the invention. Accordingly, other embodiments are within
the scope of the following claims.
* * * * *