AU2010200687A1

AU2010200687A1 - Composite Water Tank

Info

Publication number: AU2010200687A1
Application number: AU2010200687A
Authority: AU
Inventors: Given Not
Original assignee: Amari Tanks Pty Ltd
Current assignee: Amari Tanks Pty Ltd
Priority date: 2009-02-19
Filing date: 2010-02-19
Publication date: 2010-09-02

Description

P/00/0011 Regulation 3.2 AUSTRALIA Patents Act 1990 ORIGINAL COMPLETE SPECIFICATION STANDARD PATENT Invention Title: COMPOSITE WATER TANK Applicant: AMARI TANKS PTY LTD The following statement is a full description of this invention, including the best method of performing it, known to me: 2 COMPOSITE WATER TANK Related Applications This patent application claims priority from Australian provisional patent application 2009900707, the specification of which is hereby incorporated by 5 reference Field of the Invention The present invention relates to a water tank, and in particular to a composite water tank formed from two or more different primary materials. Background of the Invention 10 There has in recent times been a revival of interest in the collection, storage and use of rainwater, essentially for domestic purposes. Even in urban areas where a mains water service is available, rainwater tanks help conserve valuable drinking water and reduce runoff. Rainwater tanks reduce the physical impact of stormwater on drainage 15 infrastructure, roads, urban streams and beaches, and mitigate flooding. They also contribute to reducing contaminants in our waterways. This can be achieved through detention, which holds stormwater temporarily in tanks, but allows it to slowly flow to the drainage system. Alternatively, it can involve retention, which holds rainwater for reuse on site. 20 Retention of rainwater allows for its reuse for outdoor use such as gardening and washing cars. When integrated with household plumbing and by using a pump, a rainwater tank can also supply water for other uses. Reusing rainwater conserves drinking water thereby cutting costs for households, and commercial users, while reducing demand for potable water.

3 To this end many householders now seek to install rainwater tanks on their properties. To meet this need a large variety of tanks have been proposed, which tend to fall into two groups based on the primary material from which they are made, being either metal or plastic. 5 Rainwater tanks made from metal have a number of desirable qualities that stem generally from the qualities of the metal itself. Modern galvanized metal, painted or unpainted, is strong, durable and attractive. Metal rainwater tanks are however, not without their disadvantages. Firstly, metal tanks are subject to corrosion and, more particularly, external 10 corrosion. This corrosion occurs most severely on the base due to condensation forming underneath the tank when differential temperatures occur between the ground and the water in the tank. Such condensation causes accelerated corrosion on the underneath of the tank. Also, galvanised steel tanks can contaminate water with metals and rust over 15 time, a problem that has given rise to the use by manufacturers of, for example, an internal coating of a food grade polymer. Indeed, the use of such a coating has also extended to some of the exterior portions of a galvanised steel tank, particularly the underside of the base of such a tank where corrosion problems are common due to the regular formation of condensation 20 thereon. However, given the ease of damaging such a coating, difficulties are still regularly encountered even with this solution, particularly with the high likelihood of the underside of the base of a tank being scratched or scraped during manufacture, transport or installation. Secondly, metal tanks require skilled labour to assemble. Where a corrugated 25 tank wall is connected to both a planar base and a lid, multiple sheets of steel have to be handled and joined. In particular, the upper and lower edges of a tank wall will normally be mechanically folded and crimped to form upper and lower rims, with the peripheries of the base and lid having their edges flattened at 90 degrees. The connections between the base and the wall and the lid and 4 the wall are then crushed flat to form a lock joint which is then ultimately sealed with silicon or soldered to form a watertight join. The construction of the tank is therefore very labour intensive and costly. It reduces the production capacity of a facility and requires skilled sheet metal labour. It also generally requires a 5 tank to be fully assembled prior to being transported to the end site, introducing obvious transporting inefficiencies. Plastic rainwater tanks avoid the corrosion issues associate with metal but have their own problems. Plastic tanks are typically manufactured using food grade plastic in a rotational moulding process, which is necessary primarily due 10 to the walled configuration of the tanks. The process involves introducing plastic into a hollow mould which is rotated in two axes whilst being heated. The rotational moulding process is thus capital intensive and time consuming. In addition to the above limitations, and as with the metal tanks mentioned above, roto-moulded plastic tanks are also manufactured in one piece, again 15 making them very bulky and therefore costly to transport. Plastic tank manufacturers therefore also cannot easily take advantage of the lower labour costs in areas that are some distance from the location where the tank will be sold as the transport cost negates any benefit that arises from labour cost differentials. 20 The present invention has been conceived with the above factors in mind and an alternative to presently available water tanks is proposed. Before turning to a description of the present invention, it is useful to provide an explanation of some of the terms that will be used to define the spatial relationship of various parts thereof. In this respect, spatial references 25 throughout this specification will generally be based upon a water tank standing generally upright on a surface or stand, able to receive (or having received) therewithin water such as rainwater. With this environment as the basis, some parts may then be defined with reference to the "horizontal" and the "vertical", allowing further references to "upper" or "upwardly" and "lower" or 5 "downwardly". Further, it will be understood that a water tank always has an interior, and thus some parts may be defined with directional reference to "inner" or "inwardly" and "outer" or "outwardly" with respect to the interior of the water tank. 5 Summary of the Invention The present invention provides a water tank having a plastic base, a metal perimetric wall with an upper edge and a lower edge, and a plastic lid, wherein the base includes an upstanding peripheral lip having an engaging portion shaped to complement a correspondingly shaped engaging portion of the lower 10 edge of the wall, the connection of the engaging portion of the base with the engaging portion of the wall being water-tight and permanent. Preferably, the engaging portion of the upstanding peripheral lip of the base is non-straight, as would be the case if the wall was corrugated and the engaging portion included a curved portion having a curve of the same configuration as a 15 curve of a corrugation of the wall. In this respect, it will be appreciated that such a curved portion could be substituted by another non-straight portion, such as by a portion including a channel or a groove, or by a portion with a triangular or rectangular cross-sectional configuration. The base and its lip are preferably sized and shaped to fit tightly within the 20 lower edge of the wall, although it will be appreciated that the base and its lip could be sized and shaped to fit tightly outside the lower edge of the wall. In a preferred form, the lid includes a downstanding peripheral lip having an engaging portion shaped to complement a correspondingly shaped engaging portion of the upper edge of the wall, the connection of the engaging portion of 25 the lid with the engaging portion of the wall ideally being such that the lid is removable and replaceable. Preferably, the engaging portion of the downstanding peripheral lip of the lid is non-straight, as would be the case if the wall was corrugated and the engaging 6 portion included a curved portion having a curve of the same configuration as a curve of a corrugation of the wall. In this respect, it will again be appreciated that such a curved portion could be substituted by another non-straight portion, such as by a portion including a channel or a groove, or by a portion with a 5 triangular or rectangular cross-sectional configuration. The lid and its lip are preferably sized and shaped to fit tightly outside the upper edge of the wall, although configurations are envisaged where the lid and its lip are sized and shaped to tightly fit inside the upper edge of the wall, and still allow the lid to function as a removable and replaceable lid. 10 In relation to the connection of engaging portions, both of the lid with the wall and the wall with the base, the size and shape of the engaging portions will ideally be such as to provide an overlapping region of sufficient size and tightness to permit connection of an appropriate type. For example, the size and shape of the downstanding lip of the lid will ideally be such that the 15 overlapping region provides a simple friction fit, of a strength that provides the lid with its required usability in terms of removability. In some forms, the resilience of the lip, present due to the lid being formed from plastic, will assist in providing a suitable connection. Indeed, this resilience may assist in providing a snap-lock connection of the lid to the wall, 20 either with or without additional locking elements being provided. Having said that, the provision of locking elements is envisaged, being formed integrally with the engaging portions of either the downstanding lip or the upper edge of the wall, such as the provision of tongue and groove type locking elements formed into those engaging portions. 25 In relation to the connection formed by the overlapping region of the engaging portions of the upstanding lip of the base and the lower edge of the wall, the permanence and the need for this connection to be water-tight will typically place different requirements on the manner in which the connection is formed. It is envisaged that the overlapping region will be of a size that permits a series 7 of rivets, screws or bolts to be arranged about the periphery of the connection to secure the connection. Alternatively, a suitable metal/plastic adhesive could be utilised to secure the connection, or an externally located strap (possibly a removable strap) could be used to mechanically clamp the wall to the base (or 5 indeed the lid). Ideally, a gasket will be placed between the lip and the wall within the overlapping region to provide the water-tight seal, the gasket either being formed in situ or placed therebetween during assembly. The seal may alternatively simply be provided by a lining of silicon sealant or the like. In a preferred form, both the upstanding lip of the base and the downstanding 10 lip of the lid are non-straight, and include a curved portion that provides the engaging portion thereof. The preferred configuration of the perimetric wall of the water tank of the present invention is for it to be corrugated, namely for it to include a series of smoothly alternating concave and convex curves (with respect to the interior of the tank), normally of the same radius. In this form, 15 the portions of the wall that have been referred to above as the upper edge and the lower edge will ideally be at least half of one complete curve (either a concave or a convex curve). Thus, the preferred curved portions of the upstanding lip of the base and of the downstanding lip of the lid will also be at least half of one complete curve (again, either a concave or convex curve), of 20 the same radius to ensure the desired close fit. Preferably, the base also includes a floor area that incorporates a plurality of transverse strengthening rib members integrally formed therein. While these (or an equivalent) may not be necessary if the tank is to stand directly on the ground, they may be useful and desirable for adding strength and rigidity where 25 the tank is to be located on a stand. Description of Drawings The above and other objects, features, and advantages of the present invention will be apparent from the following detailed description of a preferred embodiment in conjunction with the accompanying drawings. In the drawings: 8 Figure 1 shows a partial perspective view of a first embodiment of a composite water tank in accordance with the present invention; Figure 2 shows a partial section of the engaging portions of the tank shown in Figure 1; 5 Figures 3a and 3b show perspective views of the lid (Figure 3a) and the base (Figure 3b) for the tank shown in Figure 1; Figures 4a, 4b and 4c show a perspective view of a second embodiment of a composite water tank in accordance with the present invention (Figure 4a), a perspective view (Figure 4b) of the base for the tank 10 shown in Figure 4a, and a partial section (Figure 4c) of the engaging portions of the tank shown in Figure 4a. Description of Preferred Embodiment The following detailed description of the invention refers to the accompanying drawings. Although the description includes exemplary embodiments, other 15 embodiments are possible, and changes may be made to the embodiments described without departing from the spirit and scope of the invention. Wherever possible, the same reference numbers will be used throughout the drawings and the following description to refer to the same and like parts. Illustrated in Figures 1, 2, 3a and 3b is a first preferred embodiment of a 20 composite water tank 10 in accordance with the present invention. In these Figures, the tank 10 is of slimline construction being adapted to fit into a narrow passageway or similar. It should, however, be appreciated that the invention is not to be limited to the specific geometry and that tanks of any variety of shapes and sizes may be constructed in accordance with the present 25 invention. Indeed, another example of a different shape of composite water tank (circular) in accordance with the present invention is illustrated in Figures 4a, 4b and 4c, where similar reference numerals have been used to describe similar parts and aspects.

9 The tank 10 includes a wall 12, a base 14, and a lid 16, and the tank 10 may be positioned on a suitable stand (not shown). It will be appreciated that a stand is optional and does not form a part of the tank 10 per se. The primary material of the tank wall 12 in this embodiment is a lightweight 5 corrugated steel, although it will be appreciated that other metals (such as stainless steel) could also be used. Indeed, in alternative embodiments, it is possible to use steel sheet. However, corrugated steel is both strong due to its form and aesthetically pleasing, and is therefore a generally useful material. The outer surface of the tank wall 12 has either a galvanized finish or is 10 painted. In either case, the external surface of the tank wall will preferably be durable, attractive and corrosion and UV resistant. The internal surface of the tank wall 12 preferably has a food grade polymer film bonded to the surface of the metal, such that water stored in the tank may be confidently used for drinking without being subject to contamination from the material of the tank 15 wall 12. Located towards the upper edge 18 of the tank wall 12 may be an overflow outlet (not shown) that serves to allow any excess water to drain from the tank 10. It will of course be appreciated that more than one overflow outlet may be provided if desired. A lowermost water outlet (also not shown) may also be 20 included in the tank wall 12. The base 14 includes a floor area 26 and an upstanding peripheral lip 28. The floor area 26 incorporates a plurality of transverse strengthening rib members 30 therein. The lip 28 has an engaging portion (represented by the region A-A) shaped to 25 complement a correspondingly shaped engaging portion 31 of the lower edge 20 of the wall 12, the connection of the engaging portion A-A of the base 14 with the engaging portion A-A of the wall 12 in this embodiment being permanent and water-tight (permanent in the sense of not being removable and replaceable in the same manner as the lid).

10 The base 14 and its lip 28 are sized and shaped to fit tightly within the lower edge 20 of the wall 12, although it will be appreciated that the base 14 and its lip 28 could be sized and shaped to fit tightly outside the lower edge 20 of the wall 12. 5 The lid 16 includes a downstanding peripheral lip 29 (shown in Figure 3a) having an engaging portion B-B (also shown in Figure 3a) shaped to complement a correspondingly shaped engaging portion B-B of the upper edge 18 of the wall 12, the connection of the engaging portion B-B of the lid 16 with the engaging portion B-B of the wall 12 ideally being such that the lid 16 is 10 removable and replaceable. The engaging portions A-A and B-B of the lips 28 and 29 are shown as non straight portions due to the wall 12 being corrugated. The engaging portions A A and B-B thus are curved portions having a curve of the same configuration as the curve of a corrugation of the wall 12. 15 The lid 16 and its lip 29 are sized and shaped to fit tightly outside the upper edge 18 of the wall 12, although configurations are envisaged where the lid 16 and its lip 29 are sized and shaped to tightly fit inside the upper edge18 of the wall 12, and still allow the lid to function as a removable and replaceable lid. The base 14 is a close fit within the lip 28. However, to further secure the base 20 14 to the wall 12, screws or rivets may be used passing through both the wall 12 and the base 14 where they overlap. To create a watertight seal, a flexible silicone sealing bead is run around the interior joining edge. Alternatively, a rubber membrane or a foamed seal may be used. The primary material of the base 14 is plastic and is preferably a food grade 25 polymer, for example food grade polyethylene, or food grade ABS, bringing to the final product many of the benefits of this material. In particular, plastic material is corrosion resistant in a way in which metal tanks are not. The present applicant has identified that corrosion problems associated with water tanks are particularly acute at the base 14 of the tank 12. In this area, corrosion 11 of a metal surface occurs from the outside in. The use of a plastic base 14 thus avoids this problem. The combination of a metal tank wall 12 and a plastic base 14 produces a composite water tank10 that is simply constructed with only minimal use of 5 skilled labour. The wall 12 can be formed of sheet metal cut to an appropriate size. The sheet can be curved and dropped over the base 14. The curved wall 12 can then be held in position with a band tightened to the required amount by any suitable means, for example by a ratchet. Whilst the wall 12 is held in position, the edges of the tank 10 can be secured in the general manner 10 described above and the base 14 can be secured to the wall 12. The tank 10 is then completed by the lid 16. As with the base 14, the primary material of the lid 16 is plastic. The lid 16 may be generally domed upwardly to avoid the formation of a depression in which water, leaves and dirt could collect, or may be provided with another suitable configuration such as that 15 shown in the Figures. In addition, it will be appreciated by a skilled addressee that the lid 16 could of course include any number and type of suitable water inlets (not shown) for water collection and inspection, possibly being covered with a strainer or similar device. Indeed, it is envisaged that the normal range of additions, parts and accessories for traditional water tanks would also be 20 usable with the composite water tank 10 of the present invention. The use of plastic material allows for the manufacture of a base 14 and of a lid 16 of varying shape. For example, a water inlet may easily be positioned either centrally or peripherally on the lid 16, and in construction the position of a water inlet and an overflow (also not shown) relative to one another may be easily 25 varied. Alternatively, the tank 10 may easily be provided with a plurality of openings to collect water from more than one inflow. In the case of tanks moulded entirely (including the tank wall) from plastics material, achieving such variability generally requires the construction of a large number of different moulds, or requires the production of a single multi- 12 purpose mould that provisions for every tank to include a wide range of accessories that may be unused. For example, traditional one-piece plastic tanks tend to be formed with a plurality of overflow options around the periphery of the tank, with a view to only one being mechanically removed by 5 an installer as necessary. This tends to lead to such a tank being regarded as being visually unattractive. Furthermore, in the case of a composite water tank constructed in accordance with the present invention, it can be seen that the manner in which the tank is constructed means that the tank may be easily transported in a flat state after 10 manufacture of the principal components, for assembly either at that location or at a separate location (such as on-site when being installed). Thus, the composite water tank of the present invention not only has the benefits of the known characteristic of plastic and metal, but also has benefits beyond those, making it a product attractive to a manufacturer. 15 Further advantages and improvements may very well be made to the present invention without deviating from its scope. Although the invention has been shown and described in what is conceived to be the most practical and preferred embodiment, it is recognized that departures may be made therefrom within the scope and spirit of the invention, which is not to be limited to the 20 details disclosed herein but is to be accorded the full scope of the claims so as to embrace any and all equivalent devices and apparatus.

Claims

1. A composite water tank having a plastic base, a metal perimetric wall with an upper edge and a lower edge, and a plastic lid, wherein the base includes an upstanding peripheral lip having an engaging portion 5 shaped to complement a correspondingly shaped engaging portion of the lower edge of the wall, the connection of the engaging portion of the base with the engaging portion of the wall being water-tight and permanent.

2. A composite water tank according to claim 1, wherein the engaging 10 portion of the upstanding peripheral lip of the base is non-straight.

3. A composite water tank according to claim 2, wherein the wall is corrugated and the engaging portion of the lip includes a curved portion having a curve of the same configuration as a curve of a corrugation of the wall. 15

4. A composite water tank according to any one of claims 1 to 3, wherein the lid includes a downstanding peripheral lip having an engaging portion shaped to complement a correspondingly shaped engaging portion of the upper edge of the wall, the connection of the engaging portion of the lid with the engaging portion of the wall being such that the 20 lid is removable and replaceable.

5. A composite water tank according to claim 4, wherein the engaging portion of the downstanding peripheral lip of the base is non-straight.

6. A composite water tank according to claim 5, wherein the wall is corrugated and the engaging portion of the lip includes a curved portion 25 having a curve of the same configuration as a curve of a corrugation of the wall. 14

7. A composite water tank according to any one of claims 1 to 6, wherein the base and its lip are sized and shaped to fit tightly within the lower edge of the wall.

8. A composite water tank according to any one of claims 1 to 6, wherein 5 the base and its lip are sized and shaped to fit tightly outside the lower edge of the wall.

9. A composite water tank according to any one of claims 1 to 8, wherein, in relation to the connection of engaging portions, both of the lid with the wall and the wall with the base, the size and shape of the engaging 10 portions is such as to provide an overlapping region of sufficient size and tightness to permit connection of the engaging poritions.

10. A composite water tank according to claim 9, wherein the size and shape of the downstanding lip of the lid will be such that the overlapping region provides a friction fit. 15

11. A composite water tank according to any one of claims 1 to 10, wherein resilience of the lid provides a snap-lock connection of the lid to the wall.

12. A composite water tank according to any one of claims 1 to 10, wherein locking elements are provided, being formed integrally with the engaging portions of either the downstanding lip or the upper edge of the wall. 20

13. A composite water tank according to claim 1, substantially as herein described in relation to the accompanying drawings.