Portable liquid storage tank

A collapsible portable tank for storing liquids has a liquid impervious liner. The side walls of the liner are supported by a collapsible frame. A plurality of hand grips in a zigzag pattern on the floor panel of the liner facilitates manipulation of the liner to collapse the liner with the frame. The liner floor panel is of heavier material than the side walls and is heat sealed along its entire perimeter to the liner side walls, affording a more durable floor while eliminating clumsy excess liner material at the corners of the tank. Another hand grip on the floor panel opposite a drain in the liner side walls facilitates evacuation of stored liquid from the tank prior to collapsing the tank.

BACKGROUND OF THE INVENTION

This invention relates generally to storage tanks and more particularly concerns collapsible portable tanks for storing liquids.

Collapsible portable tanks for storing liquids are well known and have changed very little over the years. They are, for example, often used by firefighters as a water reservoir at the scene of a fire. It is desirable that they can be quickly opened, emptied and collapsed by one or two workers, that they be lightweight but durable and that they be inexpensive.

Modern tanks have liners which include side walls and a floor panel which are made from a single sheet of material. The side walls are supported by a frame while the floor panel rests on the ground. Since the floor panel incurs the most significant abuse, the entire liner is made of material of sufficient weight to meet the requirements for the floor panel. This needlessly increases the total cost of the entire liner. Furthermore, since the sheet of material is folded to form the side walls and floor panel of the liner, excess pleats of material are created in each corner of the tank. The excess material adds unnecessarily to the weight of the liner and to the bulk of material that must be gathered in the collapsing process. The excess material is usually tri-folded and sewn, making the finished product neater and somewhat easier to handle but not reducing the weight of the liner at all. Sometimes the excess material is cut away in an effort to reduce this weight and bulkiness, but this compromises the integrity of the sheet and each of the corners must be separately sealed.

To empty a modern tank of its remaining contents before collapsing the tank, one or more workers must manually grip handfuls of the wet floor panel on one side of the tank and lift the liner to force the remaining liquid toward a drain on the opposite side of the tank. They are often wearing gloves and working in cold conditions. The floor panel, as it is pulled, creates a vacuum with the ground and resists the process. This is a clumsy, difficult task and often results in damage to the liner.

To collapse a modern tank, the workers must perform a similar task as described with respect to emptying the tank, further complicated by the need to simultaneously cause the tank frame to collapse while gripping and pulling on the wet floor panel. This is even more clumsy and difficult and further imperils the liner.

It is, therefore, an object of this invention to provide a portable liquid storage tank which can be quickly opened, emptied and collapsed by one or two workers. Another object of this invention is to provide a portable liquid storage tank which is lightweight. A further object of this invention is to provide a portable liquid storage tank which is durable. Yet another object of this invention is to provide a portable liquid storage tank which is inexpensive. It is also an object of this invention to provide a portable liquid storage tank which has side walls and a floor panel not formed from one sheet of material. Still another object of this invention is to provide a portable liquid storage tank which does not have excess pleats of materials in its corners. An additional object of this invention is to provide a portable liquid storage tank which has less bulk of material to be gathered during the collapsing process. Another object of this invention is to provide a portable liquid storage tank which does not have corners compromised by cutting away excess material. A further object of this invention is to provide a portable liquid storage tank which does not require separate sealing of each of its corners. Yet another object of this invention is to provide a portable liquid storage tank which does not require gripping of handfuls of wet floor panel in order to empty or collapse the liner.

SUMMARY OF THE INVENTION

In accordance with the invention, a collapsible portable tank is provided for storing liquids. A liner of material impervious to the liquid to be stored has side walls and a floor panel. The side walls of the liner are supported by a collapsible frame.

One feature of the tank is the inclusion of a plurality of hand grips in the floor panel to facilitate manipulation of the liner to collapse the liner with the frame. Preferably, the collapse of the frame is enabled by hinges at its corners and hinges approximate the mid-points of two of its opposite sides. Most preferably, the hand grips are arranged in a zigzag pattern in relation to a vertical plane extending through the opposite side hinges with the first hand grips on each side of the floor being on opposite sides of the plane. This enables workmen on opposite sides of the tank to move the opposite side wall hinges inwardly while lifting successive hand grips with one hand and then the other so as to simultaneously collapse the frame and the liner as they move toward each other. The use of the hand grips significantly reduces the time of the collapsing process. A formerly 30 minute task, for example, can now be accomplished in 15 minutes.

Another feature of the tank is that its liner floor is a separate panel of heavier material than its liner side walls. The floor panel preferably is heat sealed along its entire perimeter to the side walls of the liner. This affords the benefits of a durable floor without increasing the weight and cost of the side walls while also eliminating either a clumsy excess of liner material at the corners of the tank or the labor involved in cutting the excess material away and separately sealing the corners.

A further feature of the tank is inclusion of a hand grip in the floor panel proximate the center of the side of the liner which is opposite a drain in the liner side walls. This facilitates evacuation of stored liquid from the tank prior to collapsing the tank.

While the invention will be described in connection with a preferred embodiment thereof, it will be understood that it is not intended to limit the invention to that embodiment or to the details of the construction or arrangement of parts illustrated in the accompanying drawings.

DETAILED DESCRIPTION

Turning toFIGS. 1-3, a preferred embodiment of the collapsible portable tank10for storing liquids is illustrated. Such tanks10are typically, though not necessarily, square. They are usually about 30″ high, from 6′ to 18′ on each side and hold from 500 to 5,000 gallons of water.

The tank liner20is preferably made using PVC vinyl, but any material impervious to the liquid to be stored can be used. The liner20has side walls21,23,25,27and a floor panel29. The floor panel29, which will be subjected to greater stress and abuse, is made of material heavier than the material of the side walls21,23,25,27. For example, for water storage tanks the floor panel29may be of 28 oz to 40 oz PVC vinyl while the side walls21,23,25,27can be of significantly lighter material. As best seen inFIG. 6, it is preferred that the floor panel perimeter31overlap the lower edge33of the side walls21,23,25,27and that the floor panel29and side walls21,23,25,27be heat sealed along the entire perimeter31of the floor panel29.

Looking atFIGS. 1 and 2, the side walls21,23,25,27of the liner20are supported by a collapsible frame40. As shown, the frame40consists of top41,43,45,47and bottom51,53,55,57rails spaced apart by vertical struts59. Hinges61,63,65,67at each of the corners connect the rails of the frame40and hinges71,73approximately at the midpoints of the rails41,51,45,55of two of the opposite sides allow those sides to fold in half. The midpoint hinges71,73define a vertical plane75, indicated inFIG. 3, approximately bisecting the tank10. As best seen inFIG. 2, the hinges61,63,65,67,71,73are oriented to rotate so that, as the midpoint hinges71,73are moved toward each other along the vertical plane75, the hinged rails41,51,45,55fold and the other rails43,53,47,57are drawn in parallel toward the vertical plane75. The frame40be constructed, for example, using 1″×1″⅛″ square aluminum tube or ⅞″ by 14 gage round steel pipe, MIG welded as necessary, for the rails and struts. Tanks having frames of such components can be folded to a thickness of approximately 7″.

Continuing to look atFIG. 2, the upper perimeter of the side walls of the liner is doubled over77and sewn for strength and fitted with grommets79. A cord81is laced around the upper rails41,43,45,47and through the grommets79so that the side walls21,23,25,27of the liner20are supported by the upper rails41,43,45,47of the frame40. For example, #4 solid brass grommets on 6″ centers have been found to work satisfactorily.

Turning toFIG. 3, hand grips83,85,93,95are provided on the floor panel29to facilitate manipulation of the liner. Preferably, the hand grips83,85,93,95are arranged in a zigzag pattern in relation to the vertical plane75. The first hand grips83,93on each side of the floor panel29are on opposite sides of the vertical plane75. This arrangement enables workmen on opposite sides of the tank10to move the opposite side wall hinges71,73inwardly while lifting successive hand grips83and85,93and95so as to simultaneously collapse the frame40and the liner20as they move toward each other. The grips83,85,93,95, as seen inFIGS. 4 and 5, may be approximately 6″×8″× 3/32″ oblong plates87supporting a handle91in a trowel-like configuration. The grips83,85,93,95are preferably made of PVC and radio-frequency welded to the top surface of the floor panel40. For most tanks, two grips83and85,93and95are provided for each worker, as shown the first grip83or93for the worker's right hand and the second grip85or95for the left hand. In larger tanks, a third grip (not shown) for the right hand may be located on each side of the tank. By way of example, it has been found to be satisfactory to locate the grips of a 10′×10′ tank approximately 18″ on either side of the vertical plane75with the first and second grips83and85,93and95on each side being approximately 20″ and 48″, respectively, away from their side walls21and25.

Continuing to look atFIG. 3, a drain97is provided in one side27of the tank liner20for emptying the tank10. The drain97may, as shown, be a 10″ PVC tube99which is heat sealed to the liner side wall27. The drain tube99is preferably closed by use of a D-ring (not shown) on the tube99which can be raised and engaged on a J-hook (not shown) on the top rail47so that the tube opening89is above the liquid level in the tank10.

To facilitate emptying the tank10, a grip35similar to those above described is located on the top surface of the floor panel40approximately on the center line37of the tank10which is perpendicular to the vertical plane25and approximately 12″ from the side wall23of the liner20opposite the drain tube99. This hand grip35can thus be lifted to raise the portion of the floor panel40proximate the grip35and cause the liquid to flow toward the drain97.

Thus, it is apparent that there has been provided, in accordance with the invention, a portable liquid storage tank that fully satisfies the objects, aims and advantages set forth above. While the invention has been described in conjunction with a specific embodiment thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art and in light of the foregoing description. Accordingly, it is intended to embrace all such alternatives, modifications and variations as fall within the spirit of the appended claims.