AU684170B2 - Tank roof structure - Google Patents

Description

'd 44115 GEH:PFB P/00/009 Regulation 3.2

AUSTRALIA

Patents Act 1990

ORIGINAL

o r* r e r ~r r o o COMPLETE SPECIFICATION FOR AN INVENTION

ENTITLED

Invention Title: TAN ROOF STRUCTURE Name of Applicant: A H BRISTER HOLDINGS PTY LTD Address for Service: COLLISON CO. 117 King William Street, Adelaide, S.A. 5000 The invention is described in the following statement This invention relates to a tank roof structure, more particularly to a roof structure whereby the rainwater falling on the roof is collected and does not pass to waste.

BACKGROUND OF THE INVENTION.

Water tanks, particularly rainwater tanks are a virtual necessity in many areas of Australia, particularly where there is no reticulated water supply. While underground water is often available, this water can be heavily laden with salts and other minerals and even may not be suitable for the watering of plants and gardens. Even in some areas where there is a reticulated supply, 1 0 the water supplied is sometimes not palatable to many people.

Thus in these areas, the rainwater tanks have to be of large capacity, the rainwater being collected from most available roofs so that the maximum of the available water is collected in the tank or tanks. The tanks for these remote areas are transported from the manufacturing site, but their size is limited by S 1 5 transport regulations relating to the maximum width and height of loads on transport vehicles. The on site construction of galvanised iron tanks of such large size is not practicable due to the construction techniques involved.

Patent Application AU 49037/93 discloses a prefabricated tank which is available in kit form and which can be easily erected on site, the tank having a 2 0 sheet metal wall and is erected on a base comprising preformed base elements which are position to support the tank wall as disclosed in copending application No 13502/95.

It is virtually necessary for the tanks in these areas to be provided with a roof, not only to prevent the entry of vermin and other animals, even birds 2 5 attempting to obtain a drink, but also to minimise evaporation particularly during periods of high temperatures and/or high winds.

Thus it is common practice for the tank to be provided with a roof, and these metal roofs usually extend over the edge of the tank wall to shed the water outside the tank to waste. These roofs of large t anks are thus of considerable 3 0 weight and require substantial support to also resist the high wind loadingi which can occur during strong winds It is an object of this invention to provide a tank roof which overcomes one or more of the problems of existing tank roofs.

It is a further object of the invention to provide a roof for a tank which is of light weight.

It is a further object of this invention to provide a roof for a tank which can easily and quickly be assembled on a tank, even tanks of larger diameter.

It is a still further object of the invention to provide a roof for a tank which has provision for passing the rainwater falling onto the roof directly into the tank itself, thus increasing the effective catchment area for the tank.

BRIEF STATEMENT OF THE INVENTION There is provided according to this invention a roof structure for a tank having I 0 a wall, a flexible membrane forming the roof of the tank, attaching means for attaching the membrane to the wall, support means supporting the membrane in the interior of the tank so that the membrane slopes towards the wall of the tank, and drainage means to allow the water collected on the membrane to enter the tank.

1 5 Preferably the membrane is attached to the wall of the tank so that a depression is formed into which the water flows, there being at least one aperture in the membrane to allow water to drain there through into the tank.

Preferably also the support means comprises a pole positioned in the tank and resting on the tank base, the pole being adjustable in length to support 2 0 the central portion of the membrane at a higher level than the portion of the membrane adjacent the tank wall BRIEF DESCRIPTION OF THE DRAWINGS.

In order to more fully describe the invention reference will now be made to the accompanying drawings in which:- 2 5 Figure 1 is a cross sectional view of a tank with a roof according to the invention, and Figure 2 is an enlarged view of the portion circled in Figure 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT.

The tank 1 has a wall 2 which is supported on a concrete perimeter footing 3.

3 0 The bottom of the tank is preferably a sand fill 4 covered by a waterproof membrane 5 anchored at 6 to the bottom of the wall and the footing. In a preferred form of the invention the tank can be a prefabricated metal tank as described in the above mentioned AU49037/93, while the base of the tank can be as described in above mentioned AU13502/95. However it is to be realised that the present invention can be applied to other metal tanks such as corrugated iron tanks, and also tanks other than circular.

The roof comprises a flexible membrane, preferably a PVC coated fabric 7 which is supported in the centre by a pole 8 which is adjustable in length to tension the fabric as later described. The bottom of the pole is positioned in a 1 0 recess 9 in a pole support 10 on the floor of the tank The edge of the fabric 7 is provided with a bead or rope hem 11 which is positioned over the edge of the wall 2. Around the top edge of the tank wall 2 there is provided a stiffening ring 12 having a cylindrical ring 13 extending downwardly inside the tank wall 2 and a horizontal flange 14 extending 1 5 inwardly of the tank. The upper edge of the cylindrical ring has a turned over hook portion 15 which snugly engages the upper edge of the wall 2. This stiffening ring is positioned on the wall edge after the fabric 7 has been S°positioned so that the stiffening ring 12 ciarnps the fabric in position with the rope hem 11 engaged against the end 16 of the turned over portion. Thus the 0 stiffening ring which not only stiffens and provides structural strength to the top of the tank wall, also anchors the edge of the fabric roof of the tank.

order to securely clamp the stiffening ring 12 and the roof fabric to the wall, o the wall and the stiffening ring have aligned holes 17 and 18 for the provision of a clamping bolt 19 and nut 20. Drainage holes 21 are provided spaced 25 around the stiffening ring 12 for the passage of water there through, and after the roof fabric has been positioned, holes can be cut through the fabric corresponding to the drainage holes 21 to allow the water to drain into the tank.

During the construction of the tank, the roof fabric is positioned and clamped 3 0 by the stiffening ring. The roof fabric is preferably provided with a closable access open to allow entry into the tank, the entry being closable by a flap which can be closed by a zipper, or other fastening devices such as studs, buttons, VelcroTM or the like.

The centre pole is then installed and its length adjusted so that its upper end 3 5 engages the fabric through a pressure spreading member 22 and so tensions L the fabric into a conical shape. Preferably the roof has a slope of 6-10 degrees to provide drainage of the water. In this way the centre of the roof does not extend above the tank wall to any great extent thus providing a degree of protection against strong winds.

While it has been found that most leaves and wind blown debris will be blown off the roof, if desired filters can be fitted to each opening to prevent the entry of rubbish into the tank. Also small mesh screens can be fitted to prevent the entry of mosquitoes thus preventing the breeding of mosquitoes and the presence of larvae in the tank.

1 0 Preferably the roofing material is a fabric impervious to light and water and also is UV resistant, has great tensile strength and resistance to tearing. The rope hem around the edge provides an anchor when assembled with the tank wall stiffening ring.

Thus there is provided a light weight durable roof for a tank which can be 1 5 easily and readily erected on site, the roof not being restricted by the dimensions of the tank. Thus there is no need to provide additional structural support for the roof. The items required for the erection of the prefabricated tank, the roofing fabric can be folded and the adjustable pole collapsed into its shorter length thus occupy very little volume for transport.

2 0 While the roof is of light weight construction, the roof also provides a simple means for the collection of the rainwater which is caught by the roof, this in large diameter tanks increasing the collection area available for collecting rainwater. In areas where there is minimum rainfall, if there is 20 mm of rain, then this 20 mm is added to the volume of water in the tank.

2 5 In a further form of the invention the membrane is attached to the wall of the tank, the central portion of the membrane being anchored to be at a lower level than the perimeter of the membrane, and an aperture at the lower portion to allow water to drain there through.

Although one form of the invention has been described in some detail, it is to 3 0 be realised that the invention is not to be limited thereto, but can include variations and modifications falling within the spirit and scope of the invention.

Claims (11)

1. A roof structure for a tank having a wall, a flexible membrane forming the roof of the tank, attaching means for attaching the membrane to the wall, support means supporting the membrane in the interior of the tank so that the membrane slopes towards a lower area of the membrane, and drainage means to allow the water collected on the membrane to enter the tank.

2. A roof structure as defined in claim 1 wherein the membrane is attached to the wall of the tank so that an annular depression is formed into which the water flows, there being at least one aperture in the membrane to 1 0 allow water to drain there through into the tank.

3. A roof structure as defined in claim 1 or claim 2 wherein the support means comprises a pole positioned in the tank and resting on the tank base, the pole being adjustable in length to support the central portion of the membrane at a higher level than the portion of the membrane adjacent the 00o. 15 tank wall. o

4. A roof structure as defined in any one of the preceding claims wherein the attaching means for attaching the membrane to the wall of the tank comprise a peripheral stiffening ring extending around the upper edge of the tank, said membrane being clamped between the stiffening ring and the tank wall.

5. A roof structure as defined in claim 4 wherein the stiffening ring has a hooked portion to fit over the wall edge, a depending annular ring and a flange extending inwardly of the annular ring, said membrane being clamped between the hooked portion and the annular ring.

6. A roof structure as defined in claim 5 wherein the membrane has a bead on its peripheral edge, which bead engages the end of the hooked portion to securely locate the membrane.

7. A roof structure as defined in any one of the preceding claims wherein spaced apetures are provided through the flange and the membrane 3 0 to allow water to pass there through. I

8. A roof structure as defined in any one of claims 4 to 6 wherein the stiffening ring is bolted to the wall.

9. A roof structure substantially as herein before described with reference to and as illustrated in the accompanying drawings. Dated this 7th day of July 1995 A H BRISTER HOLDINGS PTY LTD By his Patent Attorneys,

1 0 COLLISON CO. 8 SQ** *o

11 ABSTRACT A roof structure for a rainwater tank, the roof structure being a flexible membrane stretched across the top of the tank. The membrane is clamped to the top of the tank wall, and is supported centrally of the tank by a post tensioning the membrane. Apertures are formed in the membrane near the perimeter of the tank to allow rainwater collected on the roof to pass directly into the tank. e *4* *6* O.i s ee o &0-o0 o 04 *o .4 a 0 0e *f bo ,oaB 00 ft °e P OaaO rs