Abstract:
A collapsible tank comprises a flexible unitary container having an inner surface and an outer surface and a flexible partial container having an inner surface and an outer surface. The inner surface of the unitary container defines a first compartment for storing a first fluid. The partial container is mounted to the unitary container to divide the unitary container into a first portion and a second portion and to form a second compartment between the inner surface of the partial container and the outer surface of the second portion of the unitary container to store a second fluid. The second portion of the unitary container is flexible and movable relative to the first portion of the unitary container and the partial container to reciprocally change the relative volumes of the first and the second compartments.

Description:
FIELD OF THE INVENTION  
       [0001]     The invention relates to a collapsible tank for storing fluid. In one aspect, the invention relates to a collapsible multi-compartment tank for storing diverse fluids. In another aspect, the invention relates to a collapsible tank having expandable and collapsible compartments for storing different or the same fluids.  
       DESCRIPTION OF THE RELATED ART  
       [0002]     When fuel-powered machinery and equipment operate in remote locations or locations that are distant from a fuel source, supplying fuel to the machinery and equipment can be problematical. Either the machinery and equipment must be transported to the source of fuel, or the fuel has to be delivered to the remote location. In the latter case, fuel can be stored at the remote location in a collapsible tank that can be easily compacted and stowed for transportation to another location, if desired.  
         [0003]     A similar problem arises with respect to the supply of water and other fluids in remote locations. As with fuel, the water can be stored in a collapsible tank, but the tanks for fuel, water, and other fluids are typically single purpose tanks because the material used in the tank construction must be compatible with the specific fluid stored therein. The base material for these tanks is commonly made from a woven nylon that is coated with a flexible thermoplastic polymer to render the material impermeable to the specific fluid. For example, the tank comprises a woven nylon material coated with a polyether polymer when the tanks are to be used to store water and with a polyester polymer when the tanks are used for fuel storage. As a result, a tank inventory must include multiple types of tanks corresponding to the different fluids compatible with each tank.  
       SUMMARY OF THE INVENTION  
       [0004]     According to the invention, a collapsible multi-compartment tank comprises a unitary container formed of a first contiguous wall having an inner surface and an outer surface, the inner surface of the first contiguous wall defining a first compartment for storing a first fluid and a flexible partial container formed of a second contiguous wall having an inner surface, an outer surface and an open end. The open end of the second contiguous wall is mounted to the first contiguous wall to divide the first contiguous wall into a first portion and a second portion and to form a second compartment between the inner surface of the second contiguous wall and the outer surface of the second portion of the first contiguous wall for storing a second fluid.  
         [0005]     The relative sizes of the first contiguous wall and second contiguous wall can vary over a wide range depending on the intended uses of the tank. In an illustrative embodiment of the invention, the second contiguous wall is about half of the size of the first contiguous wall and the first and the second compartments have comparable maximum capacities.  
         [0006]     The second portion of the first contiguous wall is flexible and is movable relative to the first portion of the first contiguous wall and relative to the second contiguous wall to change the relative potential volumes of the first and the second compartments. Thus, an increase in the maximum volume of one of the first and the second compartments corresponds to a decrease in the maximum volume of the other of the first and the second compartments. In a preferred illustrative embodiment of the invention, the maximum volumetric increase and decrease of the first and the second compartments are of substantially equal magnitude.  
         [0007]     Typically, a fill/discharge assembly, a vent, and a drain are mounted to each of the first contiguous wall and the second contiguous wall for filling and dispensing the liquid in each of the compartments.  
         [0008]     The first contiguous wall preferably comprises a fluid barrier to prevent fluid in one of the compartments from leaching into another compartment. In one illustrative embodiment, the fluid barrier comprises an inner surface fluid barrier on the inner and outer surfaces of the first contiguous wall. In one illustrative embodiment, the inner surface fluid barrier and the outer surface fluid barrier comprise a polymer coating. In another illustrative embodiment, one of the inner surface fluid barrier and the outer surface fluid barrier comprises a polyester coating and the other of the inner surface fluid barrier and the outer surface fluid barrier comprises a polyether coating. Further, the second contiguous wall comprises an inner surface fluid barrier on the inner surface thereof. Preferably, the inner surface fluid barrier of the second contiguous wall comprises the same material as the outer surface fluid barrier of the first contiguous wall. In one embodiment, the inner surface fluid barrier of the second contiguous wall and the outer surface fluid barrier of the first contiguous wall comprises one of a polyester and a polyether coating.  
         [0009]     The first and second contiguous walls are joined together in a secure joint, preferably with a lap joint at a junction between the first contiguous wall and the second contiguous wall. In one illustrative embodiment, the lap joint is thermowelded.  
         [0010]     The two or more compartments that are formed by the tank according to the invention can be filled with a wide variety of fluids. Typically, the compartments may be filled different fluids, conceivable remarkably different fluids such as aqueous fluids, such as water, and organic fluids, such as fuel oil. The coatings on the inside surfaces of the compartments will be selected to provide a barrier to the fluids for which the tanks are adapted.  
         [0011]     Further according to the invention, a collapsible tank comprises a flexible container having an interior surface that defines a maximum volumetric capacity and a flexible partition secured at its edges at the interior surface of the container to divide the interior of the tank into a first compartment with a first volume for storing a first fluid and a second compartment with a second volume for storing a second fluid. The partition is of a size and pliability that it is movable within the container to reciprocally change the first and second volumes within the tank.  
         [0012]     In a preferred embodiment of the invention, the partition is sized so that first and second compartments each have a maximum capacity comparable to the maximum volumetric capacity of the container. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]      FIG. 1  is a side view of a collapsible tank according to the invention.  
         [0014]      FIG. 2  is a schematic top view of the container of  FIG. 1 .  
         [0015]      FIG. 3  is a sectional view taken along line  3 - 3  of  FIG. 1  showing a first compartment filled to its maximum capacity.  
         [0016]      FIG. 4  is a sectional view similar to  FIG. 3  with a second compartment filled to its maximum capacity.  
         [0017]      FIG. 5  is a sectional view similar to  FIG. 3  with each of the first and the second compartments partially filled.  
         [0018]      FIG. 6  is an enlarged view of the region labeled VI in  FIG. 3 .  
         [0019]      FIG. 7  is an enlarged view of the region labeled VII in  FIG. 4 . 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0020]     Referring now to the figures and particularly to  FIGS. 1-5 , a multi-compartment collapsible tank  10  according to the invention can be used to store a single fluid, such as fuel or water, or two dissimilar fluids, such as water and fuel. The tank  10  comprises a unitary container  12  having an inner surface  14  and an outer surface  16  and defining a first compartment  18  with a corresponding first volume. The container  12  is formed from one or more pliable fabric panels that are thermowelded at the seams thereof to form a water tight compartment  18 . The tank  10  further comprises a partial container  22  formed from flexible panels that are thermowelded together at their seams to form inner and outer surfaces  24 ,  26  and an open end. The open end of the partial container  22  is attached to the unitary container  12  at a central region of the container  12  through a continuous lap seam  50  to thereby form a second compartment  28  with a second volume with the outside surface  16  of that section of the unitary container  12  within the lap seam  50 . The wall of the partial container  22  is about half the size of the wall of the unitary container  12 . That part of the wall of the container  12  that forms the second compartment  28  with partial container  22  is designated portion  12 B whereas the other part of the wall of container  12  is designated portion  12 A.  
         [0021]     The unitary container  12  and the partial container  22  are made of a flexible material so that they can collapse onto themselves to form a compact configuration. For example, the unitary container  12  and the partial container  22  can be formed of woven nylon panels coated with a fluid barrier, such as a polymer, to render the nylon impervious to a first fluid stored in the first compartment  18  and to a second fluid stored in the second compartment  28 . The particular type of fluid barrier is selected based upon the types of fluids stored in the first and the second compartments  18 ,  28 . For example, when the first fluid is water, the inner surface  14  of the unitary container  12  is preferably coated with a polyether polymer, and when the second fluid is fuel, the outer surface  16  of the unitary container  12  and the inner surface  24  of the partial container  22  are coated with a polyester polymer. When either of the compartments  18 ,  28  are filled with a food-grade substance, the corresponding surfaces of the unitary container  12  and the partial container  22  are preferably coated to comply with requirements set by the United States Food and Drug Administration (FDA). The fluid barrier prevents leakage of the first and the second fluids from the tank  10  and also prevents cross contamination between the first and the second fluids.  
         [0022]     Referring particularly to  FIGS. 3-5 , the second portion  12 B essentially functions as a flexible partition between the first portion  12 A of the unitary container  12  and the partial container  22 . In other words, the second portion  12 B can be viewed as a flexible partition within a collapsible tank formed by the first portion  12 A of the unitary container  12  and the partial container  22 . When the tank if filled to capacity, the volumes of the first and second compartments  18 ,  28  are reciprocal and vary depending on the position of the second portion  12 B relative to the first portion  12 A and to the partial container  22 . Because the partial container  22  and the second portion  12 B are of substantially equal size, the maximum volume of the first and the second compartments  18 ,  28  is equal, as shown in  FIGS. 3 and 5 . The maximum volume of the first compartment  18  is achieved when the first compartment  18  is filled and the second compartment is empty so that the second portion  12 B of the container  12  abuts or nearly abuts the inner surface  24  of the unitary container  22 , as viewed in  FIG. 3 , and this condition corresponds to a minimum volume of the second compartment  28 . Likewise, the maximum volume of the second compartment  18  is achieved when the second compartment  28  is filled and the first compartment  18  is empty so that the second portion  12 B of the unitary container  12  abuts or nearly abuts the inner surface  14  of the first portion  12 A, as viewed in  FIG. 4 , and this condition corresponds to a minimum volume of the first compartment  18 . As the second portion  12 B of the container  12  moves between these two extreme positions, as shown in  FIG. 5 , an increase in the volume of one of the first and the second compartments  18 ,  28  corresponds to a decreased of the same magnitude in the maximum volume of the other of the first and the second compartments  18 ,  28 . The maximum volumes of the first and the second compartments  18 ,  28  are reciprocal or compensatory such that the sum of the maximum volume of the first and the second compartments  18 ,  28  is substantially equal to the maximum volume of one of the individual compartments  18 ,  28 .  
         [0023]     As shown in  FIGS. 1-5 , the tank  10  further comprises a pair of fill/discharge assemblies  30 ,  32 , a pair of vents  34 ,  36 , and a pair of drains  38 ,  40 , wherein one member of each pair corresponds to one of the first and the second compartments  18 ,  28 . In particular, the fill/discharge assembly  30 , the vent  34 , and the drain  38  are attached to the first portion  12 A of the unitary container  12  and correspond to the first compartment  18 . Similarly, the fill/discharge assembly  32 , the vent  36 , and the drain  40  are attached to the partial container  22  and correspond to the second compartment  28 . Preferably, the fill/discharge assemblies  30 ,  32  are color coded or otherwise labeled or marked so that a user can distinguish between the first and the second compartment  18 ,  28  and thereby correctly match the first fluid with the first compartment  18  and the second fluid with the second compartment  28 . Further, the fill/discharge assemblies  30 ,  32 , the vents  34 ,  36 , and the drains  38 ,  40  are industry standard components so that the tank  10  can be utilized with other fluid storage systems.  
         [0024]     Referring now to  FIGS. 6 and 7 , the partial container  22  is joined to the unitary container  12  at the lap joint  50 , and the unitary container  12  is formed of multiple panels connected at lap joint seams (not shown). All of the lap joints are formed during a suitable joining process, such as thermowelding. The lap joint  50  joining the partial container  22  to the unitary container  12  is constructed such that forces generated as a result of filling the second compartment  28  are directed in a shear vector as opposed to a peel vector. This construction produces a joint that has a breaking strength equal to that of the lap joint seams of the unitary container  12 . When the first compartment  18  is filled, the tank  10  is under normal stresses associated with a conventional single compartment tank.  
         [0025]     The tank  10  can be constructed to have any desired capacity, and, preferably, the capacity of the tank  10  ranges from 100 to 50,000 gallons. In such a construction, the lap joints are preferably about two inches wide so that the tank  10  is suitably strong to support such a large volume of fluid. Additionally, all of the lap joint seams are barrier-coated over the inner and outer surfaces to prevent fluid from wicking through the nylon.  
         [0026]     An exemplary description of the operation of the tank  10  follows. It will be apparent to one of ordinary skill that the operation can carried out in any logical order and is not limited to the sequence presented below. The following description is for illustrative purposes only and is not intended to limit the invention in any manner.  
         [0027]     The tank  10  is pliable so that it can be collapsed and folded into a compact mass for shipment and storage. To fill the tank  10 , the user unfolds or unrolls the collapsed tank  10  onto a surface with the fill/discharge assemblies  30 ,  32  facing away from the surface. If the user desires to fill the tank with only the first fluid, then the user closes the drain  38 , opens the vent  34 , and attaches a hose to the fill/discharge assembly  30  and fills the first compartment  18  with a desired volume of the first fluid. Optionally, the user can fill the unitary container  12  to its maximum capacity, as illustrated in  FIG. 3 . On the other hand, if the user desires to fill the tank with only the second fluid, then the user closes the drain  40 , opens the vent  36 , and attaches a hose to the fill/discharge assembly  32  and fills the second compartment  28  with a desired volume of the second fluid.  FIG. 4  illustrates the tank  10  when the partial container  22  is filled to its maximum capacity. If the user desires to fill the tank  10  with both the first and the second fluids, then the user conducts both of the steps described previously in this paragraph, in any order or simultaneously, such that both the unitary container  12  and the partial container  22  are partially filled, as shown, for example, in  FIG. 5 . When the filled tank  10  is not in use, the fill/discharge assemblies  30 ,  32 , the vents  34 ,  36 , and the drains  38 ,  40  are all in a closed condition.  
         [0028]     To discharge fluid from the tank  10 , the user can apply pressure to the tank  10  so that the tank  10  collapses and thereby forces the fluid to flow out of the first and the second compartments  18 ,  28 , or, alternatively, the user can fill one of the first and the second compartments  18 ,  28  to displace the second portion  12 B and thereby force the fluid to flow out of the other of the first and the second compartments  18 ,  28 . For example, if the tank  10  solely contains the first fluid, then the user can open the fill/discharge assembly  30 , attach a hose to the fill/discharge assembly  30 , and apply pressure to the tank  10  to force the first fluid from the first compartment  18  and through the hose. Alternatively, the user can open both the fill/discharge assemblies  30 ,  32 , attach hoses to both the fill/discharge assemblies  30 ,  32 , and fill the second compartment  28  with the second fluid. As the second compartment  28  fills, the second portion  12 B of the unitary container  12  moves towards the first portion  12 A of the unitary container  12  to thereby reduce the volume of the first chamber  18  and force the first fluid through the hose attached to the fill/discharge assembly  30 . Thus, while the second compartment  28  is in a fill mode, the first compartment  18  is in a discharge mode. The situation is reversed for discharging the second fluid from the second container  28 . If the tank  10  contains both the first and the second fluids, then the user can optionally discharge both fluids at the same time through the fill/discharge assemblies  30 ,  32 .  
         [0029]     The tank  10  can also be used to circulate fluids from one of the first and the second compartments  18 ,  28  to the other of the first and the second compartments  18 ,  28 . For example, fresh water can be stored in one of the compartments, discharged from the compartment, used, and then stored in the other compartment as waste water. Similarly, fresh petroleum product can be stored in one of the compartments, discharged from the compartment, used, and then stored in the other compartment as waste petroleum product.  
         [0030]     The tank  10  according to the invention is a dual-compartment, multi-purpose, portable collapsible container for static storage of fluids. The unique design of the tank  10  enables multiple means of circulation and/or storage of dissimilar and flowable petroleum, water, water-based fluid products, and other fluid products. The tank  10  can be deployed multiple times in various locations to store the petroleum, water, water-based fluid products, or other fluid products. Further, because one tank  10  can be used to store more than one type of fluid and effectively replaces two types of tanks with one, the cost of inventorying collapsible containers is decreased.  
         [0031]     While the invention has been specifically described in connection with certain specific embodiments thereof, it is to be understood that this is by way of illustration and not of limitation. For example, the relative sizes of the unitary tank  12  and the partial tank  22  can vary over a wide range to accommodate prospective uses of the multi-compartment tank. Further, whereas the invention has been described with respect to tank with two compartments, the invention contemplates three or more compartments by the addition of one of more additional partial containers  22  to the unitary tank  12  and/or to the partial container  22  or other added partial tanks. Reasonable variation and combination are possible with the scope of the foregoing disclosure without departing from the spirit of the invention, which is defined in the appended claims.