U.S. patent application number 10/849733 was filed with the patent office on 2004-10-28 for relocatable storage tanks for liquids and granular materials.
Invention is credited to Hunt, Rowland D..
Application Number | 20040211783 10/849733 |
Document ID | / |
Family ID | 26937357 |
Filed Date | 2004-10-28 |
United States Patent
Application |
20040211783 |
Kind Code |
A1 |
Hunt, Rowland D. |
October 28, 2004 |
Relocatable storage tanks for liquids and granular materials
Abstract
A relocatable storage tank for flowable materials such as
liquids and granular materials comprises a bag of flexible material
and has a generally square, rectangular, or circular shape, resting
on a solid surface, together with at least one central post which
supports the upper portion of the bag, wherein the post aids in
carrying the weight of the flowable materials to the ground,
thereby reducing the associated mechanical tensions in the fabric
of the flexible material.
Inventors: |
Hunt, Rowland D.; (Santa
Barbara, CA) |
Correspondence
Address: |
FREDERICK W. GIBB, III
MCGINN & GIBB, PLLC
2568-A RIVA ROAD
SUITE 304
ANNAPOLIS
MD
21401
US
|
Family ID: |
26937357 |
Appl. No.: |
10/849733 |
Filed: |
May 20, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10849733 |
May 20, 2004 |
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10245631 |
Sep 17, 2002 |
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6758361 |
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60325461 |
Sep 28, 2001 |
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Current U.S.
Class: |
220/565 |
Current CPC
Class: |
B65D 90/205 20130101;
B65D 88/16 20130101 |
Class at
Publication: |
220/565 |
International
Class: |
B65D 090/02 |
Claims
1-20 (Cancelled).
21. A flexible container comprising: a base portion for engaging a
supporting surface; a side portion extending upwardly from said
base portion; a non-buckling supporting post system mounted over a
substantially central portion of said base portion and supported by
said supporting surface; and a sloped upper portion opposite said
base portion, and extending upwardly from said side portion to
engage said supporting post system; wherein said supporting post
system being confined within said base portion and said side
portion, and wherein a vertical load carried by said supporting
post system is a compression load.
22. The flexible container of claim 21, further comprising an upper
cap positioned on said sloped upper portion.
23. The flexible container of claim 21, further comprising support
cables attaching said supporting post system to said supporting
surface.
24. The flexible container of claim 21, wherein said supporting
post system is hollow.
25. The flexible container of claim 21, further comprising an
entry/exit opening in said sloped upper portion.
26. The flexible container of claim 21, further comprising an outer
support fabric over said side portion and said sloped upper
portion.
27. The flexible container of claim 21, further comprising a
covering sheet over said side portion and said sloped upper
portion.
28. A partially-closed flexible container comprising: a base
portion for engaging a supporting surface; a side portion extending
upwardly from said base portion; a support rim positioned over said
base portion; a sloped upper portion extending upwardly from said
side portion and attached to said support rim; and a non-buckling
support post system mounted over a substantially central portion of
said base portion and supported by said supporting surface, wherein
said support post system being confined within said base portion
and said side portion, and wherein a vertical load carried by said
support post system is a compression load.
29. The flexible container of claim 28, further comprising a
plurality of cables attaching said support rim to said support post
system.
30. The flexible container of claim 28, wherein said support post
system comprises a hollow post.
31. The flexible container of claim 28, further comprising an
entry/exit opening in said sloped upper portion.
32. The flexible container of claim 28, further comprising an outer
support fabric over said side portion and said sloped upper
portion.
33. The flexible container of claim 28, further comprising a
covering sheet over said side portion and said sloped upper
portion.
34. A partially-open flexible bag comprising: a side portion; a
sloped upper portion extending upwardly from said side portion; and
a non-buckling support post structure confined within said side
portion and said sloped upper portion, and positioned below a
substantially central portion of said upper portion, wherein a
vertical load carried by said support post structure is a
compression load. wherein said flexible bag is secured to a
supporting surface opposite said upper portion, and wherein said
support post structure is secured to said supporting surface.
35. The flexible bag of claim 34, wherein said flexible bag extends
upwardly from said supporting surface, and is secured to one of a
support rim and said support post structure, wherein said support
rim is positioned below said sloped upper portion of said flexible
bag.
36. The flexible bag of claim 34, further comprising a plurality of
cables attaching said support rim to said support post
structure.
37. The flexible bag of claim 34, wherein said support post
structure comprises a hollow post.
38. The flexible bag of claim 34, further comprising an entry/exit
opening in any of said sloped upper portion and said support post
structure.
39. The flexible bag of claim 34, further comprising an outer
support fabric over said side portion and said sloped upper
portion.
40. The flexible bag of claim 34, further comprising a covering
sheet over said side portion and said sloped upper portion.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims the benefit of U.S. Provisional
Patent Application No. 60/325,461 filed Sep. 28, 2001.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention generally relates to flexible storage
tanks, and more particularly to a flexible relocatable storage tank
for flowable materials such as liquids and granular material.
[0004] 2. Description of the Related Art
[0005] Conventional structures for relocatable and collapsible
tanks utilize designs such as a pillow or bladder tank, available
from Aero Tec Laboratories, Inc., NJ, USA and others, which
consists of a bag made in the shape of a pillowcase using flexible
material. When empty, the bag folds flat and may be rolled or
folded for storage and shipment. The filling/discharge flange is
integrated into the top panel of the material, and the storage
volume is sealed at all times with a negligible air or vapor
pocket. This conventional design is a formless package when folded
for transport with no real strong confluence points to allow for
lifting to load onto a transport. In larger sizes, it must be
loaded onto a single stiff pallet to allow for lifting by a
forklift or crane. One of the other drawbacks of this conventional
design is that the pillow tank does not tolerate high site slopes,
and requires relatively high site areas because the average depth
of the stored liquid inside of the tank is low. Moreover, such
tanks appear to be relatively expensive, and do not lend themselves
to the storage of granular materials. Also, liquids stored in the
pillow tanks, which are exposed to bright sunlight, get extremely
hot. This is undesirable for fuels or potable water. In order to
ameliorate this effect, a cover needs to protect the tank from the
sun, which requires a considerable structure to span the overall
exposed surface of the tank.
[0006] Another conventional design uses rigid tanks, which are
built with rigid panels forming the sides, and often a rigid metal
support frame. The loads imposed by the stored liquid or grain are
carried directly by these panels. These tanks may have a plastic
membrane liner; however, this is not structural, rather it is
provided more for sealing purposes only. Such tanks usually require
prepared unsloped sites.
[0007] Other conventional designs consist of flexible bags with an
external frame, such as the type disclosed in U.S. Pat. No.
D334,238 and issued to Spedini, further illustrated in FIG. 1
herein. These designs are used especially for above-ground swimming
pools, and consist of a tank using a bag of strong flexible
material supported by an external metal frame consisting of a rim
in the horizontal plane, supported off the ground by a series of
inclined metal posts. As shown in FIG. 1, the flexible bag is a
structural member which carries the loads imposed by the weight of
the peripheral liquid or grain to the rim of the tank, and hence to
the ground via the supporting posts. The weight of the liquid/grain
in the central area of the tank, where the fabric is in contact
with the ground, is supported directly by the ground. This
conventional design offers a highly portable, low weight tank,
which can be quickly and easily installed and dismantled. However
it suffers from the following disadvantages.
[0008] First, the external structure of the conventional fabric
tank must be considerably over-designed for the chosen depth of the
associated liquid/grain because for depths differing from the
design depth, the rim and external posts of the tank are subjected
to extra bending loads, as depicted in the illustration of the
conventional design used in practice shown in FIG. 2. This is
particularly critical for the posts, which are subjected to
significant compression forces, because the applied bending
significantly increases the tendency for the posts to buckle. A
second disadvantage of the conventional design shown in FIGS. 1 and
2 is that for similar reasons related to the varying depths of the
associated liquid/grain, the problem is exacerbated if the tank is
to be used in an emergency or unprepared, sloping, or undulating
ground. Typically, these conventional tanks are severely limited to
a few degrees of slope. Thus, such designs with external frames are
used primarily for aboveground swimming pools, where the water is
typically at or close to design depth, and such designs have found
no functional application in storage tanks, which of course, must
accommodate a large range of depths.
[0009] Moreover, the conventional fabric tank designs use
relatively light fabrics for the bag and several light rigid
components for the external frame. However, it is really only
suitable for applications which can accept an open liquid surface,
thereby limiting its use to non-potable water. Moreover, these
conventional designs do not easily accept other granular materials,
nor do they tolerate more than minimal slopes, and the frame must
be stiffened appreciably to cope with partially filled
conditions.
[0010] Therefore, there is a need for a relocatable storage tank
for flowable materials such as liquids and granular materials
comprising a bag of flexible material and having a generally
square, rectangular, or circular shape, resting on a solid surface,
together with at least one central post which supports the upper
portion of the bag, wherein the post aids in carrying the weight of
the flowable materials to the ground, thereby reducing the
associated mechanical tensions in the fabric of the flexible
material. Moreover, there is a need for a larger flexible
relocatable storage tank for flowable materials such as liquids and
granular materials which can improve the ease of relocation of the
stored materials, and which allows for the use of the storage tank
in confined and sloping sites, especially for temporary and/or
emergency situations.
SUMMARY OF THE INVENTION
[0011] In view of the foregoing and other problems, disadvantages,
and drawbacks of the conventional storage tanks the present
invention has been devised, and it is an object of the present
invention to provide a structure for a relocatable storage tank for
liquids and granular materials. It is another object of the present
invention to provide a structure for a relocatable storage tank for
liquids and granular materials which improves the ease of
relocation of the tank, and to allow use of the tank in confined
and on sloping sites, especially for temporary and emergency
conditions. It is a further object of the present invention to
allow for larger depths of storage for the stored liquids in the
storage tank. Still another object of the present invention is to
allow for filling, storage, and discharge of granular materials
from the storage tank. Yet another object of the present invention
is to collect and carry the peripheral liquid/granular loads in
tension, in at least one internal support system.
[0012] In order to attain the objects suggested above, there is
provided, according to one aspect of the invention, a storage tank
for flowable material such as liquids and granular material,
wherein the storage tank comprises a container of flexible
material, wherein the flexible material comprises a base portion
for engaging a supporting surface, and at least one supporting post
system mounted over the base portion and supported by the
supporting surface, wherein the flexible material extending
upwardly from the base portion forms a side portion and an upper
portion of the storage tank, and is secured to the supporting post
system. Furthermore, the storage tank of the present invention is
provided in multi-geometrical embodiments including generally
square, rectangle, circular, and polygonal shapes. In an
alternative embodiment, the storage tank comprises an upper cap
positioned on the upper portion of the storage tank. In another
alternative embodiment, the storage tank further comprises support
cables attaching the supporting post system to the supporting
surface.
[0013] Additionally, the supporting post is generally rigid. Also,
in an alternative embodiment, the supporting post is generally
solid. Alternatively, the supporting post is generally hollow. In
another embodiment, the at least one supporting post system
comprises a plurality of supporting posts interconnected by a
linking element. Still alternatively, the storage tank comprises an
outer support fabric over the flexible material.
[0014] In an alternative embodiment, a storage tank for flowable
material such as liquids and granular material comprises a
container of flexible material, wherein the flexible material
comprises a base portion for engaging a supporting surface, and at
least one support system positioned over the base portion, wherein
the flexible material extends upwardly from the base portion to
form a side portion and an upper portion of the storage tank, and
is secured to one of a support rim and the support system. The
support system comprises one of a post and a float. Moreover, the
post may be either solid or hollow. In an alternative embodiment,
the storage tank further comprises a plurality of cables attaching
the support rim to the support system. Furthermore, in another
embodiment, the at least one support system comprises a plurality
of supports interconnected by a linking element. Alternatively, the
storage tank comprises an outer support fabric over the flexible
material.
[0015] In another alternative embodiment, the present invention
provides a storage tank for flowable material such as liquids and
granular material, wherein the storage tank comprises a flexible
bag having a side portion and an upper portion. The storage tank
further comprises at least one support structure contained within
the flexible bag, whereby the support structure is positioned below
the upper portion of the flexible bag, wherein the flexible bag is
secured to a supporting surface, and wherein the support structure
is secured to the supporting surface. Alternatively, the storage
tank further comprises a plurality of cables attaching the support
rim to the support structure. The support structure may be embodied
as a post, which may be hollow or solid, or the support structure
may be embodied as a float. Still alternatively, the at least one
support structure comprises a plurality of supports interconnected
by a linking element. In another embodiment, the storage tank
further comprises an outer support fabric over the flexible
material.
[0016] The present invention overcomes the several disadvantages of
the conventional designs. For example, the present invention
provides for an essentially vertical storage of the tank when it is
not in use (i.e., stored footprint is very small), without
requiring accessory equipment. Also, the present invention is
easily loadable and carried to site by a forklift, crane, etc.,
without requiring accessory lifting gear such as pallets or a
carrying case. The present invention tolerates installation and
filling on sloping sites. Moreover, on steep slopes (approximately
10 degree grade), the present invention can easily be made stable
by utilizing simple guy ropes/cables attached to the central post
and anchored to the high side of the site. Additionally, the
present invention's central post provides a support for a fly sheet
for solar heating and UV protection at a low cost. In fact, it is
feasible to use this fly sheet to create some shrapnel protection
for military use.
[0017] Other advantages of the present invention are that the
present design allows for larger depths of stored liquids than
conventional flexible tanks, and hence smaller footprint areas for
a given capacity, which is ideal at congested or restricted sites.
Furthermore, the present design accommodates for filling, storage,
and discharge of granular materials at lower production costs
compared to traditional designs.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] The foregoing and other objects, aspects and advantages will
be better understood from the following detailed description of the
preferred embodiments of the invention with reference to the
drawings, in which:
[0019] FIG. 1 is a schematic diagram of a conventional fabric tank
design;
[0020] FIG. 2 is a schematic diagram of a conventional fabric tank
design;
[0021] FIG. 3A is a schematic diagram of a storage tank according
to the present invention;
[0022] FIG. 3B is a schematic diagram of the storage tank of FIG.
3A on a sloped surface according to the present invention;
[0023] FIG. 3C is a schematic diagram of the storage tank of FIG.
3A on a sloped surface according to the present invention;
[0024] FIG. 4A is a schematic diagram of an alternative embodiment
of a storage tank according to the present invention;
[0025] FIG. 4B is a schematic diagram of an alternative embodiment
of the storage tank of FIG. 4A according to the present
invention;
[0026] FIG. 4C is a schematic diagram of an alternative embodiment
of the storage tank of FIG. 4A according to the present
invention;
[0027] FIG. 4D is a schematic diagram of an alternative embodiment
of the storage tank of FIG. 4A according to the present
invention;
[0028] FIG. 5A is a top view of a storage tank configuration
according to the present invention;
[0029] FIG. 5B is a top view of an alternative storage tank
configuration according to the present invention;
[0030] FIG. 5C is a top view of an alternative storage tank
configuration according to the present invention;
[0031] FIG. 5D is a top view of an alternative storage tank
configuration according to the present invention;
[0032] FIG. 5E is a top view of an alternative storage tank
configuration according to the present invention;
[0033] FIG. 5F is a top view of an alternative storage tank
configuration according to the present invention;
[0034] FIG. 5G is a top view of an alternative storage tank
configuration according to the present invention;
[0035] FIG. 5H is a top view of an alternative storage tank
configuration according to the present invention;
[0036] FIG. 51 is a top view of an alternative storage tank
configuration according to the present invention;
[0037] FIG. 5J is a top view of an alternative storage tank
configuration according to the present invention;
[0038] FIG. 5K is a top view of an alternative storage tank
configuration according to the present invention;
[0039] FIG. 6 is a schematic diagram of an alternative embodiment
of a storage tank according to the present invention;
[0040] FIG. 7 is a schematic diagram of an alternative embodiment
of a storage tank according to the present invention;
[0041] FIG. 8 is a schematic diagram of an alternative embodiment
of a storage tank according to the present invention;
[0042] FIG. 9A is a schematic diagram of an alternative embodiment
of a storage tank according to the present invention; and
[0043] FIG. 9B is a schematic diagram of an alternative embodiment
of a storage tank according to the present invention.
[0044] FIG. 9C is a schematic diagram of an alternative embodiment
of a storage tank according to the present invention.
[0045] FIG. 10A is a schematic diagram of an alternative embodiment
of a storage tank according to the present invention;
[0046] FIG. 10B is a schematic diagram of an alternative embodiment
of a storage tank according to the present invention; and
[0047] FIG. 10C is a schematic diagram of an alternative embodiment
of a storage tank according to the present invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION
[0048] As previously mentioned, there is a need for a novel
relocatable storage tank for liquids and granular materials. The
present invention provides a relocatable storage tank, which may be
easily stored, transported, and assembled if necessary, on
unprepared and/or sloping sites. The present invention provides a
flexible storage tank capable of taking some of the weight of the
stored liquid or grain down to the ground through a support system,
embodied as vertical post(s), thereby relieving the flexible bag of
some of the weight, which in turn, allows for reduced mechanical
tensions in the bag.
[0049] Referring now to the drawings, and more particularly to
FIGS. 3 through 10, there are shown preferred embodiments of the
structures according to the present invention. Specifically, FIG.
3A illustrates a storage tank 1 positioned on a level planar
supporting surface 2. The storage tank 1 comprises a container 3 of
flexible material 4 for storing internal contents such as liquids
and granular materials 19 at varying design depths 9. The container
3 further comprises a base portion 5 for engaging the supporting
surface 2. Moreover, the container 3 further comprises at least one
supporting system (support structure) 6 preferably embodied as a
post 6 mounted over the base portion 5 and is supported by the
supporting surface 2. The flexible material 4 extends upwardly from
the base portion 5 to form the sides 8 and the upper portion 17 of
the tank 1, and is secured to the supporting post 1 at the upper
portion 17 of the container 3.
[0050] The internal frame support system 11 of the tank 1 comprises
the at least one column or post 6, placed inside the suitably
shaped flexible bag 4. In this design, all of the peripheral
liquid/granular loads are carried up the fabric sides 8 to the top
7 of the central post 6. FIG. 3A shows the storage tank 1 on a zero
degree grade flat site 2, whereby all of the horizontal components
of the loads are balanced, and the only load to be carried by the
post 6 is a vertical compression load, which the generally
large-diameter single post 6 can easily withstand without
buckling.
[0051] The angle of the top or "roof" 17 (the angle of the roof is
that portion above the waterline 9 to the top 7 of the post 6) of
the tank 1 may be selected, preferably at any angle less than
approximately 80 degrees, but for acceptable post heights, it is
best selected no greater than approximately 45 degrees from the
horizontal. The shape of the curved side 8 of the fabric bag 4 is
best calculated for the chosen roof angle at the design depth 9,
when the fabric tensions are highest. For two dimensional balance,
the curve 8 is established by making the local radius of curvature
of the bag 3 at each liquid (or granular material) depth 9
according to the formula R=K(T/H), where R is the local radius of
curvature, T is the fabric tension, H is the local depth of the
stored material, and K is a constant and depends on the density of
the stored material.
[0052] From the design level 9 to the top 7 of the post(s) 6, the
bag 3 is generally straight. The bag 3 may distort somewhat from
this datum shape on sloping sites, and when the tank is less than
full, but this is accommodated by the flexible fabric 4, and the
tensions do not increase significantly beyond the design datum.
[0053] If the site 2 is sloping or undulating, as indicated by the
five degree slope in FIG. 3B, the horizontal loads will not be
completely in balance, resulting in an overturning and bending
moment M in the central post 6. For effective site slopes up to
approximately 10 degrees, as indicated in FIG. 3C, this overturning
and bending moment M can easily be carried by the generally short,
large diameter column 6 without overturning or buckling.
Furthermore, for such steep site slopes, a smaller diameter central
column 6 may be used and be relieved of some or all of this
overturning and bending moment M by attaching support cables 10,
such as guy wires/cables 10 to the support post system 6, and
preferably at the top 7 of the column 6, and anchoring the wires 10
to the ground 2 on the upper sides(s) 111 of the site 2.
[0054] This present design with an internal frame 11 makes it
feasible to use existing fabrics 4 for water depths 9 up to
approximately 10 feet, and grain depths 9 up to approximately 20
feet, with adequate factors of safety on fabric strength, for a
large variety of square, rectangular, polygonal, and circular tank
shapes.
[0055] The entry/exit locations 12 for the stored material 9 may be
within the post(s) 6 themselves, or in the fabric bag 4. The
concept allows for virtually any shape/configuration of the tank 1.
For example, FIG. 4A shows the geometry for a "square" tank 1 with
a liquid depth 9 one-third of the overall length L of the tank 1,
and a sloped top or roof 17 to shed rain and snow. The length L is
the overall length of the tank 1 when filled. This is within a few
% of the length of the tank 1 when empty. The length L of this
configuration may be increased without increasing the liquid depth
9, as shown in FIG. 4B. If eventually the central post 6 becomes
unacceptably high, then multiple posts 6 can be used, and
interconnected together with a linking element 13, as shown in FIG.
4C. Alternatively, the slope of the roof 17 may be
increased/decreased as shown in FIG. 4D, depending on the rate of
rain and snow to be shed, or the granular material to be stored.
Preferably, for granular material storage, the design is best
arranged with a roof angle steeper than its angle of repose.
[0056] In an identical fashion, the width of the tank may also be
increased, giving rise to multiple configurations shown in FIGS. 5A
through 5K. It should be appreciated by those skilled in the art,
that other configurations not specifically illustrated herein, may
be used within the context of this invention.
[0057] For non-emergency situations, where it is feasible and
economical to create a depression 14 in the ground 2 below the tank
100, the fabric bag 4 can be shaped whereby the base portion 5 of
the storage tank 100 fits into this depression 14, as is depicted
in FIG. 6. This allows practically all of the stored liquid to be
drawn off, and all of the stored granular material 19 to be stored
as long as the depression angle is greater than the angle of
repose. Alternatively, an inverted conical or pyramidal depression
may be formed by an elevated rigid platform 52, to allow for
unloading of the container by gravity as seen in FIG. 10B.
[0058] Next, as illustrated in FIG. 7, if necessary, to reduce the
non-divisible weight for installation or transportation, or to
carry higher tensions from increases in stored depth 9, the fabric
bag 4 can comprise a load-carrying outer support fabric 44 and an
inside non-load-carrying plastic liner 15 for sealing the liquids
or grains 19. The outer support fabric 44, which is positioned over
the flexible material 4, may comprise, for example, a polymer
coating on a woven base or scrim cloth. The inner plastic liner 15
may comprise, for example, a single film of polymer, which could
expand with the water depth 9. This solution may be particularly
useful for military purposes, where the tank 1 could be shipped
with several different plastic liners 15, to be chosen or rotated
at the site to allow for storage of fuel, potable water, etc. It
could also be useful to form a completely sealed storage volume
117, which needs no venting.
[0059] In all or most of the configurations described above, the
required vertical loads could alternatively be provided by
pressurized buoyancy bag(s) 16 floating on the liquid/grains 19
acting as the support system, as shown in FIG. 8, instead of by
rigid post(s). FIG. 9A shows the geometry for a storage tank 1 with
a fixed bottom cap 20 and a removable top cap 37. The upper cap 37
is positioned on the upper portion 17 of the storage tank 1. The
fabric 4 may be constructed using, for example, a 22 oz/sq.yd. high
strength PVC/polyester fabric. It may be folded and placed inside
the hollow supporting post system (cylinder) 6 for transportation
and storage. The diameter of cylinder 6 is sufficient to stabilize
the tank 1 when fully or partially filled 9, even on site slopes of
8 to 10 degrees. The fabric bag 4 of the container 3 can either be
carried all the way to the central post 6, as indicated in FIG. 9A,
or may be terminated just above the waterline 9 in a metal rim 21,
as shown in FIG. 9B, while straps or cables 22 carry the fabric
loads to the central post 6.
[0060] The present invention may be practiced in several
alternative embodiments depending on the application of use. For
example, the traditional use is to utilize a square planform tank 1
with a single vertical post 6, as illustrated in FIG. 4A. In
emergency fire fighting or fish farming use, the open tank 101
design of the present invention is most suitable, which requires
taking the fabric loads to a still metal support rim 21, and
carrying those loads to the support system (post) 6 by cables or
straps 22 as shown in FIG. 9B. For potable water uses, the top 17
of the storage tank 1 should be sealed, which is best performed by
continuing the fabric 4 directly to the support system (post) 6,
either in a stronger fabric 4 at the top 7 or by reinforcing straps
(not shown) welded to the fabric.
[0061] The preferred post configuration for non-potable water is to
make the post 6 as a hollow canister (cylinder) large enough to
contain the fabric bag 4 when it is folded. This means that the bag
4 can itself be stored in the rigid canister 6 when the tank 1 is
not in use, protected from UV and dust, and storage and handling
damage. The footprint of the canister 6 is generally small which is
important for storage and shipment in readiness for emergency
applications. For potable water tanks 201, as shown in FIG. 9C, the
post 60 is made with a generally small diameter (with a generally
wider base 131 and top 132), and the fabric bag 40 is folded up on
the outside of the narrow post 60. An upper cap 30 may also be
provided. This configuration does not provide the tank storage
protection, which the canister design provides. However, it avoids
any possible contamination, which might otherwise be caused by
inserting the canister 6 into the bag 4 on site.
[0062] Some of the alternative embodiments of the present invention
include using multi-shaped tanks with multiple posts, such as those
described in FIGS. 5A through 5K. Other embodiments include having
the bags 4 shaped to fit a level, conical, or V-shaped site 2, or
to be mounted on the surface of a raised platform 52 with a rigid
surface providing the bottom to the tank 301, 401, 501 as shown in
FIGS. 10A through 10C, respectively. Alternatively, a substitute
buoyant sphere 16 for generally square-shaped tanks 1, as seen in
FIG. 8, or a buoyant tube 25 positioned along the centerline of a
generally rectangular tank 1, may be used instead of the post(s) 6,
as shown in FIG. 5J. Still alternatively, for generally larger
tanks, use of a structural outer bag 14, which may be a woven mesh
or net to carry the loads and a thinner non-porous liner 15 to seal
the liquid may be incorporated. Moreover, the loads generally
increase near the support posts 6. In order to carry increased
tensions, several alternatives exist. First, heavier fabrics 4 may
be used near the upper portion 17 of the storage tank 1. Second,
welded on webbing straps 10, 22 may be used. Third, rods 125 may be
used to collect the loads and distribute them to the top 7 of the
posts 6 by cables or straps 122 (see FIG. 5K). Fourth, catenary
cables (not shown) may be used.
[0063] In the alternative embodiments described above, and as
illustrated in FIGS. 10A through 10C, the fabric bag 4 and support
structure 6 are attached directly to the supporting surface (ground
2 as seen in FIGS. 10A and 10C, or a raised platform 52, such as
the bed of a transportation vehicle as seen in FIG. 10B) thereby
avoiding the necessity of having a fabric base portion 5 as
required by the embodiments illustrated in FIG. 3A and FIG. 6. In
FIG. 10A, the storage tank 1 comprises a flexible bag 4 having a
side portion 8 and an upper portion 17; and at least one support
structure 6 contained within the flexible bag 4, wherein the
support structure 6 is positioned below the upper portion 17 of the
flexible bag 4, wherein the flexible bag 4 is secured to a
supporting surface 2, and wherein the support structure 6 is
secured to supporting surface 2.
[0064] The present invention overcomes the several disadvantages of
the conventional designs. For example, the present invention
provides for an essentially vertical storage of the tank when it is
not in use, without requiring accessory equipment (i.e., stored
footprint is very small). Also, the present invention is easily
loadable and carried to site by a forklift, crane, etc., without
requiring accessory lifting gear such as pallets or a carrying
case. The present invention tolerates installation and filling on
sloping sites. Moreover, on steep slopes (approximately 10 degree
grade), the present invention can easily be made stable by
utilizing simple guy ropes/cables 10 attached to the central post 6
and anchored to the high side 11 of the site 2. Additionally, the
present invention's central post 6 provides a support for a fly
sheet for solar heating and UV protection at a low cost. In fact,
it is feasible to use this fly sheet to create some shrapnel
protection for military use.
[0065] Other advantages of the present invention are that the
present design allows for larger depths of stored liquids than
conventional flexible tanks, and hence smaller footprint areas for
a given capacity, which is ideal at congested or restricted sites.
Furthermore, the present designs accommodate for filling, storage,
and discharge of granular materials at lower production costs
compared to traditional designs.
[0066] While the invention has been described in terms of preferred
embodiments, those skilled in the art will recognize that the
invention can be practiced with modification within the spirit and
scope of the appended claims.
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