U.S. patent application number 11/722331 was filed with the patent office on 2009-01-22 for method and system for installing a water storage device.
Invention is credited to Steven John Wiggins.
Application Number | 20090020532 11/722331 |
Document ID | / |
Family ID | 36602015 |
Filed Date | 2009-01-22 |
United States Patent
Application |
20090020532 |
Kind Code |
A1 |
Wiggins; Steven John |
January 22, 2009 |
Method and System for Installing a Water Storage Device
Abstract
The present invention relates to a method and system for
correctly installing a flexible liner in a tank for water storage.
The present invention in the preferred form relates to the use of a
substantially rigid outlet (20) in the flexible liner (12) that is
received in a tank aperture (22) when the liner (12) is correctly
installed in the tank (14).
Inventors: |
Wiggins; Steven John;
(Wellington, NZ) |
Correspondence
Address: |
LEWIS, RICE & FINGERSH, LC;ATTN: BOX IP DEPT.
500 NORTH BROADWAY, SUITE 2000
ST LOUIS
MO
63102
US
|
Family ID: |
36602015 |
Appl. No.: |
11/722331 |
Filed: |
December 21, 2005 |
PCT Filed: |
December 21, 2005 |
PCT NO: |
PCT/NZ05/00336 |
371 Date: |
March 4, 2008 |
Current U.S.
Class: |
220/495.05 ;
222/105; 29/522.1 |
Current CPC
Class: |
B65D 2590/046 20130101;
Y10T 29/49938 20150115; B65D 90/046 20130101; F24H 1/183
20130101 |
Class at
Publication: |
220/495.05 ;
29/522.1; 222/105 |
International
Class: |
B65D 90/04 20060101
B65D090/04; F24H 1/18 20060101 F24H001/18 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 21, 2004 |
NZ |
537340 |
Claims
1. A method of installing a flexible liner into a tank for water
storage, wherein each of the liner and tank has a base, the method
comprising the steps of: providing at least one substantially rigid
extension attached to and extending outwardly from the liner base;
providing at least one aperture in the tank base; locating the
liner inside the tank; and inserting the substantially rigid
extension through the tank aperture, wherein the substantially
rigid extension and aperture are positioned such that the liner is
correctly positioned in the tank once the extension is inserted
through the aperture.
2. The method of installing a flexible liner as claimed in claim 1
wherein the substantially rigid extension allows fluid
communication into or out of the liner.
3. The method of installing a flexible liner as claimed in claim 2
wherein the substantially rigid extension is a length of pipe or
tube attached to the liner.
4. The method of installing a flexible liner as claimed in any
preceding claim wherein the substantially rigid extension is
located substantially in the centre of the liner base, and the
aperture is located substantially in the centre of the tank
base.
5. The method of installing a flexible liner as claimed in any
preceding claim wherein two or more extensions and apertures are
provided.
6. The method of installing a flexible liner as claimed in claim 5
wherein at least one extension functions as a water inlet and at
least another extension functions as a water outlet.
7. A method of installing a flexible liner into a tank for water
storage, wherein each of the liner and tank has a base, the liner
base having a substantially rigid extension extending outwardly and
the tank base having an aperture to receive the substantially rigid
extension, the method comprising the steps of: locating the liner
inside the tank; and inserting the substantially rigid extension
through the tank aperture, wherein the substantially rigid
extension and aperture are positioned such that the liner is
correctly positioned in the tank once the extension is inserted
through the aperture.
8. The method of installing a flexible liner as claimed in claim 7
wherein the substantially rigid extension allows fluid
communication into or out of the liner.
9. The method of installing a flexible liner as claimed in claim 8
wherein the substantially rigid extension is a length of pipe or
tube attached to the liner.
10. The method of installing a flexible liner as claimed in any one
of claims 7 to 9 wherein the substantially rigid extension is
located substantially in the centre of the liner base, and the
aperture is located substantially in the centre of the tank
base.
11. The method of installing a flexible liner as claimed in any one
of claims 7 to 10 wherein two or more extensions and apertures are
provided.
12. The method of installing a flexible liner as claimed in claim
11 wherein at least one extension functions as a water inlet and at
least another extension functions as a water outlet.
13. A method of installing a flexible liner into a tank for water
storage, wherein each of the liner and tank has a wall, the method
comprising the steps of: providing at least one substantially rigid
extension attached to and extending outwardly from the liner wall;
providing at least one aperture in the tank wall; locating the
liner inside the tank; and inserting the substantially rigid
extension through the tank aperture, wherein the substantially
rigid extension and aperture are positioned such that the liner is
correctly positioned in the tank once the extension is inserted
through the aperture.
14. The method of installing a flexible liner as claimed in claim
13 wherein the substantially rigid extension allows fluid
communication into or out of the liner.
15. The method of installing a flexible liner as claimed in claim
14 wherein the substantially rigid extension is a length of pipe or
tube attached to the liner.
16. The method of installing a flexible liner as claimed in any one
of claims 13 to 15 wherein two or more extensions and apertures are
provided.
17. The method of installing a flexible liner as claimed in claim
16 wherein at least one extension functions as a water inlet and at
least another extension functions as a water outlet.
18. A method of installing a flexible liner into a tank for water
storage, wherein each of the liner and tank has a wall, the liner
wall having a substantially rigid extension extending outwardly and
the tank wall having an aperture to receive the substantially rigid
extension, the method comprising the steps of: locating the liner
inside the tank; and inserting the liner extension through the tank
aperture, wherein the substantially rigid extension and aperture
are positioned such that the liner is correctly positioned in the
tank once the extension is inserted through the aperture.
19. The method of installing a flexible liner as claimed in claim
18 wherein the substantially rigid extension allows fluid
communication into or out of the liner.
20. The method of installing a flexible liner as claimed in claim
19 wherein the substantially rigid extension is a length of pipe or
tube attached to the liner.
21. The method of installing a flexible liner as claimed in any one
of claims 18 to 20 wherein two or more extensions and apertures are
provided.
22. The method of installing a flexible liner as claimed in claim
21 wherein at least one extension functions as a water inlet and at
least another extension functions as a water outlet.
23. The method of installing a flexible liner as claimed in any one
of the above claims wherein the substantially rigid extension is
detachably received in a fitting that is attached to the liner.
24. The method of installing a flexible liner as claimed in claim
23 wherein the fitting is provided with an aligning means to
receive the substantially rigid extension.
25. A water storage system comprising: a tank having a base, the
tank base having at least one aperture; and a flexible liner having
a base and positioned in the tank to store water, the liner base
having at least one substantially rigid extension attached to and
extending outwardly from the liner base; wherein the substantially
rigid extension extends through the tank aperture to correctly
position the liner in the tank.
26. The water storage system as claimed in claim 25 wherein the
substantially rigid extension allows fluid communication into or
out of the liner.
27. The water storage system as claimed in claim 26 wherein the
substantially rigid extension is a length of pipe or tube attached
to the liner.
28. The water storage system as claimed in any one of claims 25 to
27 wherein the liner extension is located substantially in the
centre of the liner base, and the aperture is located substantially
in the centre of the tank base.
29. The water storage system as claimed in any one of claims 25 to
28 wherein two or more extensions and apertures are provided.
30. The water storage system as claimed in claim 29 wherein at
least one extension functions as a water inlet and at least another
extension functions as a water outlet.
31. A water storage system comprising: a tank having a wall, the
tank wall having at least one aperture; and a flexible liner having
a wall and positioned in the tank to store water, the liner wall
having at least one substantially rigid extension attached to and
extending outwardly from the liner wall; wherein the substantially
rigid extension extends through the tank aperture to correctly
position the liner in the tank.
32. The water storage system as claimed in claim 31 wherein the
substantially rigid extension allows fluid communication into or
out of the liner.
33. The water storage system as claimed in claim 32 wherein the
substantially rigid extension is a length of pipe or tube attached
to the liner.
34. The water storage system as claimed in any one of claims 31 to
33 wherein two or more extensions and apertures are provided.
35. The water storage system as claimed in claim 34 wherein at
least one extension functions as a water inlet and at least another
extension functions as a water outlet.
36. The water storage system as claimed in any one claims 25 to 35
wherein the substantially rigid extension is detachably received in
a fitting that is attached to the liner.
37. The water storage system as claimed in claim 36 wherein the
fitting is provided with an aligning means to receive the
substantially rigid extension.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a method and system for
correctly installing a flexible liner in a tank for water storage.
In particular, although not exclusively, the invention relates to
the use of an outlet in the flexible liner that is received in a
tank aperture when the liner is correctly installed.
BACKGROUND TO THE INVENTION
[0002] The use of a flexible liner to store hot water is described
in New Zealand Patent No. 244107. The flexible liner is ideally
constructed from plastic or polymer material(s) and is located in
the interior of a rigid tank structure. The liner functions to
store hot water while the rigid tank provides structural integrity
to the construction as a whole. This construction reduces heat loss
from the stored water and, in combination with the use of
cost-efficient plastics and composite material in its construction,
is an advantageous alternative to conventional hot water
cylinders.
[0003] However due to the flexibility of the liner, precise
installation of the liner within the tank is difficult. Without
proper liner installation, the risk of failure of the water storage
greatly increases. For instance, the liner may remain displaced to
one side of the tank once installed. In an incorrect position such
as this, excessive stress can be placed on the joints and seams of
the liner when the liner is filled with water. This stress often
leads to premature liner failure.
[0004] It is therefore an object of the present invention to
address the above problem or at least to provide the public with a
useful choice.
SUMMARY OF THE INVENTION
[0005] As used herein, the term `substantially rigid extension`
denotes an extension that is rigid or semi-rigid in at least one
part of the extension. The entirety of the extension need not be
rigid. It is sufficient for one part, for instance the base of the
extension, to be rigid or semi-rigid.
[0006] In one aspect the invention comprises a method of installing
a flexible liner into a tank for water storage, wherein each of the
liner and tank has a base, the method comprising the steps of:
[0007] providing at least one substantially rigid extension
attached to and extending outwardly from the liner base; [0008]
providing at least one aperture in the tank base; [0009] locating
the liner inside the tank; and [0010] inserting the substantially
rigid extension through the tank aperture, [0011] wherein the
substantially rigid extension and aperture are positioned such that
the liner [0012] is correctly positioned in the tank once the
extension is inserted through the aperture.
[0013] In another aspect the invention comprises a method of
installing a flexible liner into a tarik for water storage, wherein
each of the liner and tank has a base, the liner base having a
substantially rigid extension extending outwardly and the tank base
having an aperture to receive the substantially rigid extension,
the method comprising the steps of: [0014] locating the liner
inside the tank; and [0015] inserting the liner extension through
the tank aperture, [0016] wherein the substantially rigid extension
and aperture are positioned such that the liner is correctly
positioned in the tank once the extension is inserted through the
aperture.
[0017] In another aspect the invention comprises a method of
installing a flexible liner into a tank for water storage, wherein
each of the liner and tank has a wall, the method comprising the
steps of: [0018] providing at least one substantially rigid
extension attached to and extending outwardly from the liner wall;
[0019] providing at least one aperture in the tank wall; [0020]
locating the liner inside the tank; and [0021] inserting the
substantially rigid extension through the tank aperture, [0022]
wherein the substantially rigid extension and aperture are
positioned such that the liner is correctly positioned in the tank
once the extension is inserted through the aperture.
[0023] In another aspect the invention comprises a method of
installing a flexible liner into a tank for water storage, wherein
each of the liner and tank has a wall, the liner wall having a
substantially rigid extension extending outwardly and the tank wall
having an aperture to receive the substantially rigid extension,
the method comprising the steps of: [0024] locating the liner
inside the tank; and [0025] inserting the liner extension through
the tank aperture, [0026] wherein the substantially rigid extension
and aperture are positioned such that the liner is correctly
positioned in the tank once the extension is inserted through the
aperture.
[0027] Preferably the liner extension allows fluid communication
into and/or out of the liner. In this form the substantially rigid
extension may function as a water inlet/outlet of the liner. Most
preferably, the substantially rigid extension functions as a water
outlet of the liner.
[0028] Preferably the liner extension is located substantially in
the centre of the liner base, and the aperture is located
substantially in the centre of the tank base.
[0029] In one form, two or more extensions and apertures may be
provided. Where two extensions and apertures are provided, one
extension functions as a water inlet and the other extension
functions as a water outlet.
[0030] Preferably the liner includes a fitting that detachably
receives the substantially rigid extension.
[0031] Preferably the fitting includes an aligning means to receive
the substantially rigid extension.
[0032] In a further aspect, the invention comprises a water storage
system comprising [0033] a tank having a base, the tank base having
at least one aperture; and [0034] a flexible liner having a base
and positioned in the tank to store water, the liner base having at
least one substantially rigid extension attached to and extending
outwardly from the liner base; [0035] wherein the substantially
rigid extension extends through the tank aperture to correctly
position the liner in the tank.
[0036] In a still further aspect, the invention comprises a water
storage system comprising [0037] a tank having a wall, the tank
wall having at least one aperture; and [0038] a flexible liner
having a wall and positioned in the tank to store water, the liner
wall having at least one substantially rigid extension attached to
and extending outwardly from the liner wall; [0039] wherein the
substantially rigid extension extends through the tank aperture to
correctly position the liner in the tank.
[0040] Preferably the liner extension allows fluid communication
into and/or out of the liner. In this form, the substantially rigid
extension may be a water inlet/outlet. Most preferably, the
substantially rigid extension functions as a water outlet of the
liner.
[0041] Preferably the liner extension is located substantially in
the centre of the liner base, and the aperture is located
substantially in the centre of the tank base.
[0042] In one form, two or more extensions and apertures may be
provided. Where two extensions and apertures are provided, one
extension functions as a water inlet and the other extension
functions as a water outlet.
[0043] Preferably the liner includes a fitting that detachably
receives the substantially rigid extension.
[0044] Preferably the fitting includes an aligning means to receive
the substantially rigid extension.
[0045] The term `comprising` as used in this specification and
claims means `consisting at least in part of`, that is to say when
interpreting statements in this specification and claims which
include that term, the features, prefaced by that term in each
statement, all need to be present but other features can also be
present.
[0046] This invention may also be said broadly to consist in the
parts, elements and features referred to or indicated in this
specification, individually or collectively, and any or all
combinations of any two or more said parts, elements or features.
Where specific integers are mentioned herein that have known
equivalents in the art to which this invention relates, such known
equivalents are deemed to be incorporated herein as if individually
set forth.
BRIEF DESCRIPTION OF THE FIGURES
[0047] Preferred forms of the method and system of the invention
will now be described with reference to the accompanying figures in
which:
[0048] FIG. 1 is an exploded view of the water storage system;
[0049] FIG. 2 shows the flexible liner installed inside the
tank;
[0050] FIGS. 3A-3F show variants of the interior tank base shape
and aperture layout;
[0051] FIG. 4 is an exploded view of another form of the water
storage system;
[0052] FIG. 5 shows the flexible liner installed inside the tank
for the water storage system shown in FIG. 4;
[0053] FIG. 6 shows a cross-section of the joining of the liner to
the top of the tank;
[0054] FIG. 7 shows an example flange for the joining shown in FIG.
6; and
[0055] FIG. 8 shows a cross-section of a liner extension.
DETAILED DESCRIPTION OF THE PREFERRED FORMS
[0056] Referring to FIG. 1, the water storage system of the
invention is shown generally as 10. The system 10 includes a
flexible liner 12 and a rigid tank 14. The figure shows an
exemplary form of the tank and liner that is cylindrical in shape
with a circular cross-section. Those skilled in the art will
appreciate that this specific form is not essential, and numerous
variations can be employed. For instance, a spherical or
frustoconical liner/tank as taught in New Zealand Patent No. 244107
may be employed instead.
[0057] Although the tank 14 is rigid, it need not be an integral or
one-piece rigid construction. As taught in New Zealand Patent No.
244107, the tank 14 may be made of a number of smaller construction
units that are bound and/or attached together to form the rigid
tank 14.
[0058] The specific shape of the liner and tank is chosen such that
the tank walls are able to support the flexible liner walls when
the liner contains a volume of water. As shown in FIG. 1, the size
of the liner 12 is comparable to the size of the tank 14. This is
preferred because, as the liner expands when water is stored in the
liner, the expansion is substantially immediately supported by the
rigid tank walls.
[0059] In view of the above, the internal shape of the tank in
relation of the shape of the flexible liner is of importance. For
instance, if a cylindrical flexible liner is to be optimally
supported, the tank inner walls should be cylindrical in shape and
have a diameter only slightly larger than the liner. This is shown
in FIG. 1.
[0060] It is also envisaged that aesthetically-pleasing outer tank
walls may be employed. For example, a designed and/or textured
outer tank surface may be used. This adaptability of the outer wall
tank allows the water storage system to be blended in with its
environment, or conversely, to be a focal point.
[0061] In the arrangement shown in FIG. 1, the liner 12 is
installed into the tank 14 by inserting the liner 12 through the
top of the tank 14. As such the base of the liner, shown as 16, is
inserted into the tank 14 so as to abut the base of the tank, shown
as 18.
[0062] To ensure the liner 12 is correctly installed, the liner
base 16 includes a substantially rigid extension 20. In the
preferred form, the substantially rigid extension 20 may allow
fluid communication into and/or out of the liner 12. Most
preferably, the substantially rigid extension 20 placed in the
liner base 16 functions as a water outlet for the liner 12. For
this purpose, the substantially rigid extension 20 may be a plastic
tubing or pipe that is located so as to extend outwardly of the
liner base 16 at one end, and to extend inwardly into the liner 12
at the other end.
[0063] The substantially rigid extension 20 is preferably joined to
the flexible liner base by virtue of water-proof welding. As the
liner 12 is installed inside the tank 14, the substantially rigid
extension 20 is received in a key-in-lock relationship in an
aperture 22 that is provided on the tank base 18. By designing the
location and form of the extension/aperture as will be described
below, the mating of the extension and the aperture substantially
ensures the correct placement of the liner 12 in the tank 14.
[0064] The correct placement of the liner 12 inside the tank 14 may
be dependent on the shapes chosen for the liner 12 and tank 14. As
described, the placement must secure the liner 12 such that when it
contains a volume of water, the walls of the liner 12 are
adequately supported by the walls of the tank 14.
[0065] In the simplest form where both liner 12 and tank 14 share
the same shape, the location of the substantially rigid extension
20 with respect to the liner base 16 will be the same as the
location of the aperture 22 with respect to the tank base 18. This
is shown in FIGS. 1 and 2, where both liner and tank have a
cylindrical shape. Here, the substantially rigid extension 20 and
aperture 22 are best located in the centre of the liner base 16 and
tank base 18 respectively. Once the liner 12 is located inside the
tank 14 and the substantially rigid extension 20 is placed through
the aperture 22, the liner 12 will be correctly installed, as shown
in FIG. 2. Although not shown, the tank 14 is then preferably
covered using a lid that is joined to the liner 12 so as to seal
the liner 12 within the tank 14.
[0066] Preferably where only one extension/aperture is designed for
the water storage system, the extension and aperture are located in
the centre of the liner base and tank base respectively. If the
central location is not possible, it is preferable that two or more
extension/aperture arrangements are provided.
[0067] However there may be configurations in which a central
extension/aperture is not optimal, for instance where the tank and
liner have a substantially square or rectangular cross-section. If
one central extension/aperture is used here, the square
cross-section liner may be installed with the edges of the liner
pressed against the faces of the tank walls (that is the liner
forms a diamond-shape within the square tank). When filled with
water, the faces of the liner may not be adequately supported. In
such an arrangement, the optimal layout may be to locate a number
of extensions/apertures distributed close to the edges of the
square cross-section.
[0068] FIGS. 3A-3F show alternative forms of the aperture layout
with respect to the tank base 18. It will be appreciated that the
liner 12 will have a similar shape to the tank and thus the layout
of the substantially rigid extensions from the liner base will
mirror the aperture layout shown in FIGS. 3A-3F. Of course the
forms shown in these figures are only exemplary and are not
restrictive. For instance, although all apertures are depicted as
circles having the same diameter, this is not necessary. The
aperture size/shape may be varied, particularly to suit the
application of the extension that will be passing through the
aperture. Persons skilled in the art will no doubt be able to
precisely arrange the aperture/rigid extensions in a multitude of
layouts.
[0069] In FIG. 3A, two apertures 22 distanced from one another are
provided on the circular tank base 18. FIG. 3B shows a similar
aperture layout, but on a tank base 18 having a square
cross-section. The exact distance and angled locations of the
apertures are of course not essential to the working of the
invention.
[0070] FIG. 3C shows a circular tank base 18 having three apertures
22 laid out in a triangular arrangement. A similar triangular
arrangement is shown in FIG. 3D for the square cross-section tank.
Again the layout shown is not essential--the three apertures may be
located in an L-arrangement if desired.
[0071] FIG. 3E shows a circular tank base 18 having four apertures
22 arranged in a square arrangement, and FIG. 3F shows a square
tank base 18 having four squarely arranged apertures 22.
[0072] FIGS. 4 and 5 show an alternative embodiment of the water
storage system. The liner 12 and tank 14 are structurally and
functionally equivalent to the embodiment described with reference
to FIGS. 1 and 2. Thus the construction, variants and modifications
previously described with reference to FIGS. 1 and 2 are also
applicable to the embodiment shown in FIGS. 4 and 5.
[0073] Referring to FIG. 4, the extension 20 of the liner is no
longer provided on the base of the liner, but is instead located on
the wall of the liner. In the preferred form shown, the extension
20 extends outwardly of the liner wall at about the middle of the
liner height. This position can of course be varied, depending on
the outcome to be achieved, as will be described below. To receive
the extension 20, an aperture 22 is provided on the wall of the
tank 14.
[0074] By placing the extension 20 on the liner wall, the
positioning benefits similar to the embodiment of FIGS. 1 and 2 are
realised. That is, once the liner 12 is inserted into the tank 14,
and extension 20 is mated with aperture 22, the liner 12 will be
correctly installed in the tank. However the additional benefit of
locating the extension/aperture on the wall of the liner/tank is in
terms of vertical support.
[0075] As is visible in FIG. 5, flexible liner 12 is held up in its
erect position by locating the extension 20 through aperture 22.
The vertical support afforded by this arrangement may avoid the
liner 12 from folding or collapsing onto itself, for instance if
the liner ages and sags. More importantly, where a heating element
is provided within the liner 12 to heat the stored water, the
support afforded by the extension/aperture mating may avoid the
liner walls from collapsing and coming into contact with the
heating element.
[0076] In view of the above, the extension 20 may be provided
higher up the liner wall to provide optimum vertical support for
the liner 12. In this case, the extension 20 is most preferably a
water inlet into the liner 12. The extension 20 may alternatively
be provided on the wall at a locating closer to the base. Although
the amount of vertical support may be reduced in this arrangement,
the extension 20 could be more optimally used as a water outlet for
the liner 12. As before, two or more extensions/apertures may be
employed.
[0077] FIG. 6 shows a cross-section of the joining of the liner 12
to the tank 14, in particular to the tank lid 26. The liner 12
includes a flange 24 that provides the liner 12 with a
substantially rigid attachment point. The flange is preferable
attached to the liner 12 by virtue of water-proof welding. The lid
26 may be made of polystyrene in favour of its light-weight and
heat-insulation properties.
[0078] As is known from New Zealand Patent No. 244107, various
devices may be located in the liner 12 to monitor and/or control
the storage of water. For instance the liner 12 may be provided
with heating element(s) and a thermostat to controllably heat the
volume of water stored. Alternatively or additionally, level
sensors may be provided. To provide a stable point of connection
and support for such devices, a plate 28 may be provided on the lid
26. This would avoid having the devices resting directly on the
preferred polystyrene lid 26.
[0079] The flange 24 will now be described with reference to both
FIGS. 6 and 7. The flange acts as a rigid connector and includes a
shoulder portion 30 and a neck portion 32. The shoulder portion 30
is welded to the liner 12 such that an opening through the flange
24 into the liner 12 is established. The welding must also be
water-proof so as to prevent stored water from leaking out of the
liner. The neck portion 32 is then located through the tank lid 26
so as to allow the liner 12 to be securely attached to the tank lid
26.
[0080] As indicated earlier, the substantially rigid extension 20
may allow for fluid communication into and/or out of the liner 12.
Although not shown for the embodiment in the figures, the water
inlet for the liner 12 is located about the lid 26, in particular
through flange 24. The substantially rigid extension 20 thus
functions as the water outlet. In this form, the substantially
rigid extension 20 serves to both indicate/ensure a correct
installation of liner 12, and to direct the flow of stored water
out of the liner 12.
[0081] Referring to FIG. 8, a cross-sectional view of an example
liner extension is shown. A fitting 20a is attached to the liner
base, for instance by water-proof welding, to detachably receive an
extension 20b. The fitting 20a and the extension 20b may be
provided with screw threads, clips or the like to releasably secure
the extension 20b to the fitting 20a. To afford substantial
rigidity to the liner extension as a whole, both the fitting 20a
and the extension 20b may be substantially rigid. Alternatively,
either the fitting 20a or the extension 20b may be substantially
rigid.
[0082] Preferably the fitting 20a includes one or more aligning
means to receive the extension 20b. In the example shown in FIG. 8,
the fitting 20a is provided with a frustoconical section to receive
a cone-shaped head on the extension 20b. Other shapes of aligning
means, such as pyramids or hemispheres, can be employed in the
alternative.
[0083] The foregoing describes the invention including preferred
forms thereof. Alterations and modifications as will be obvious to
those skilled in the art are intended to be incorporated within the
scope hereof, as defined by the accompanying claims.
* * * * *