AU636222B2

AU636222B2 - Pre-treatment tank

Info

Publication number: AU636222B2
Application number: AU76238/91A
Authority: AU
Inventors: Clifford Wallace McMaster
Original assignee: C-MAC INDUSTRIES (AUST) Pty Ltd
Current assignee: C-MAC INDUSTRIES (AUST) Pty Ltd
Priority date: 1990-07-30
Filing date: 1991-04-29
Publication date: 1993-04-22
Anticipated expiration: 2011-04-29
Also published as: AU7623891A

Description

/636oo22/o Form PATENTS ACT 1952 COMPLETE SPECIFICATION

(ORIGINAL)

FOR OFFICE USE Short Title: Int. CI: Application Number: Lodged: Complete Specification-Lodged: Accepted: Lapsed: Published: Po'rity: Related Art: %ame of Applicant: Address of Applicant: Actual Inventor: Address for Service: TO BE COMPLETED BY APPLICANT C-MAC INDUSTRIES (AUST) PTY LIMITED 72 Mandoon Road, Girraween NSW 2145 CLIFFORD WALLACE McMASTER PETER MAXWELL ASSOCIATES Blaxland House, Ross Street, NORTH PARRAMATTA NSW 2151 Complete Specification for the invention entitled: PRE-TREATMENT TANK The following statement is a full description of this invention, including the best method of performing it known to me:-* 'Note: The description is to be typed in double spacing, pica type face, in an area not exceeding 250 mm in depth and 160 mm in width, on tough white paper of good quality and it is to be inserted inside this form.

14599/78-L Printed by C. J. THOMPSON, Commonwealth Government Printer, Canberra The present invention relates to a pre-treatment tank for rain water collected from roofs and the like.

It is known in the art to provide for pre-treatment of rain water between its collection point and its storage point.

In some cases the pre-treatment step can be as simple as the provision of a diverter system which diverts the initial flow of rain water away from the collection point.

0* This approach is described in Australian patent 581,211.

10 Another approach is to provide a simple sump arrangement which receives the initial flow of rain water and passes only overflow from the sump to the point of storage.

The problems with these approaches is that it is not unknown to receive rain water with flushed solids in it throughout the entire time during which rain is falling upon the collection point.

0:48 The present application seeks to disclose a modified sump arrangement which is designed to trap polluting solids at all times.

o0008, 20 Accordingly, in one broad form of the invention, there is provided a pre-treatment tank for removing solids from a flow of rain water comprising a tank which includes inflow means and outflow means placed so as to cause a vortex to be generated in rain water in said pre-treatment tank whereby said vortex traps solids for retention within said pretreatment tank.

-3- Preferably, the outflow means takes overflow rain water from at or near the surface of rain water in the pretreatment tank. It is also preferred that the outflow means takes the overflow rain water from a point on the tank generally opposite the inflow means.

In a preferred form of the invention, the pre-treatment tank includes vortex breaker means placed so as to mini:ise the effect of the vortex at or near said outflow means.

Of 6* The vortex breaker means may comprise a curved wall t0 placed in the line of flow of the vorte; at the surface of the rain water in said tank and extending below said surface a predetermined distance and may be removable from said tank.

The walls of the pre-treament tank may nip inwardly immediately below the line of the bottom of said curved wall and a mesh panel may cover the point of exit of water from the tank into the outflow means.

A drain tap may be provided near the base of the preoo treatment tank to allow water to be drained from the pretreatment tank down to a predetermined level.

20 In order that the invention may be more readily understood and put into practical effect, reference will now be made to the accompanying drawings in which:- Fig. 1 is a top plan view of a pre-treatment tank according to one embodiment of the invention, Fig. 2 is a section through line AA of Fig. 1, and Fig. 3 is a side view in the direction of arrow B of Fig. 1.

Fig. 1 shows the top section of a pre-treatment tank (with cover removed) in plan view. An inlet pipe 11 directs rain water through inlet aperture 12 into the tank Outlet pipe 13 draws overflow water from the surface of water 15 through outlet aperture 14.

The top section of the tank 10 comprises a vortex body 16 (as best seen in Figs. 2 and 9 JJ-pr" whose bottom edges are nipp.'d into a narrow waist 17 to the bottom of which is attached main settlement tank 18.

10 The main settlement tank 18 comprises a generally cylindrical tank which is in liquid communication with the vortex body 16 by way of waist 17.

The settlement tank 18 has a drain tap 19 located near but not at the bottom 20 of the settlement tank 18.

The bottom 20 of the settlement tank 18 comprises a circular plate clamped to the bottom flange of the settlement tank 18 using an 0-ring seal 21 to provide a liquid tight seal.

The inlet pipe 11 and the outlet pipe 13 are located o tangentially on opposite sides of the vortex body 16. This 00 arrangement causes rain water channelled in through inlet pipe 11 to swirl into a vortex having its centre generally in line with the centre of the vortex body 16 and tank 18.

A vortex breaker wall 22 comprises an arcuate panel adapted to intersect the water surface under operational conditions. The panel is attached at points 23 and 24.

Points 23 and 24 are located on opposite sides of a diameter 1_ of the vortex body 16.

-j The lower edge 25 of the vortex breaker wall 22 extends below the lowest portion of the outlet aperture 14, but not so low as to foul or intersect with the walls of the vortex body 16.

As best seen in Fig. 1, the outlet 13 draws overflow rain water from under the vortex breaker wall 22 and in a reverse direction to the general flow of the vortex at the point of draw off. It has been found that this arrangement ensures that there is a very low likelihood of any solids

C

10 carried in through inlet 11 passing out through outlet 13.

In this embodiment of the invention, the main ;o .o settlement tank 18 holds approximately 54 litres and the drain tap 19 is placed approximately 75 millimetres from the bottom 20 of the settlement tank. The diameter of the inlet 90.45 and outlet pipes 11, 13 is approximately 90 millimetres. The diameter of the vortex body 16 is approximately 16 inches J across the top with a straight wall height of approximately 6 inches. The main settlement tank 18 has a height of approximately 4 feet and a diameter of approximately 7 to 8 20 inches.

The outlet aperture 14 can include a mesh panel 27 across it for the purpose of catching relatively large, light solids which may have escaped the vortex action.

Normally a cover 28 which is removable for inspection purposes covers the top of the vortex body 16.

The main settlement tank 18 can include a ball 26 shown in dotted outline in Fig. 2 which is of sufficient diameter L, c; sol fthat it seals the 4se\17 as and when the water level in the vy 3

"-A

main settlement tank 18 rises too close to thejAt=ee 17.

In use, the pre-treatment tank 10 is placed below the level of the rain catchment area (usually the roof of a house or the like), but with its outlet 13 at a level above the top of a main rain water storage tank (not shown).

At the commencement of rain fall onto the catchment area, the initial surge of caught rain water will contain many pollutants both solid and chemical in nature. The first .o 54 litres or so flows through inlet 11 and directly into main 10 settlement tank 18. This first surge of water is stored for S* later draining through drain tap 19.

•As additional rain water is collected, it flows through inlet pipe 11 into the vortex body 16 (which is now sealed by wa-el 26 from the main settlement tank 18) and swirls around the inside of the vortex body 16 in a generally clockwise direction as viewed in the plan view of Fig. 1 whereby a :vortex is formed which tends to drag suspended solids towards the centre of the vortex. Predominantly solid-free water flows generally in the direction of the arrow C in Fig. 2 O beneath the vortex breaker wall 22 and out through outlet pipe 13 and on into the main rain water storage tank (not shown). The direction of draw off of water is generally in the opposite direction to the flow of the vortex at the point of draw off.

The above describes only one embodiment of the present invention and modifications obvious to those skilled in the art can be made thereto without departing from the scope and 41. spirit of the present invention.

Claims

1. A pre-treatment tank for removing solids from a flow of rain water, said pretreatment tank including inflow means and outflow means placed so as to cause a vortex to be generated in rain water in said pre-treatment tank whereby said vortex traps solids for retention within said pre-treatment tank.

2. The pre-treatment tank of claim 1 wherein said outflow means takes overflow rain water from at or near the surface of rain water in said pre-treatment tank.

3. The pre-treatment tank of claim 1 or claim 2 wherein said outflow means takes said overflow rain water from a point on said tank generally opposite said inflow means.

4. The pre-treatment tank of any preceding claim wherein said pre-treatment tank includes vortex breaker means placed so as to minimise the effect of the vortex at or near said outflow means.

5. The pre-treatment tank of claim 4 wherein said vortex breaker means comprises a curved wall placed in the line of .flow of the vortex at the surface of the rain water in said tank and extending below said surface a predetermined distance.

6. The pre-treatment tank of claim 5 wherein the walls of said pre-treatment tank nip inwardly immediately below the line of the bottom of said curved wall.

7. The pre-treatment tank of any one of claims 4 to 6 wherein said vortex breaker means is removable from said tank.

8. The pre-treatment tank of any preceding claim wherein a mesh panel covers the point of exit of water from said tank into said outflow means.

9. The pre-treatment tank of any preceding claim wherein said pre-treatment tank includes a drain tap near its base which allows water to be drained from said pre-treatment tank down to a predetermined level. A pre-treatment tank as hereinbefore particularly described with reference to what is shown in the accompanying drawings. Dated this 5th day of February, 1993. e C-MAC INDUS2RIES (AUST) PTY LIMITED by their Patent Attorneys, PETER MAXWELL ASSOCIATES.