GB2302265A - Cleaning tank - Google Patents

Abstract

A tank 1 for removing dirt and debris from objects in a perforated basket 22, and especially from material excavated at places of archaeological interest, includes a manifold 6 connected through a non-return valve (12 figure 3) and inlet pipe 8 to a pressurised source of cleansing fluid, such as mains water. The manifold is formed with a plurality of apertures 11 through which cleansing fluid can be directed onto the contents of the basket. An overflow is provided through which excess cleansing fluid can leave the tank, and closable opening 19 is formed in or towards the base of the tank for emptying the tank of cleansing fluid and other debris. The cleansing fluid may be water or water with added solvent. The manifold may extend across the tank in a horizontal plane. The overflow may comprise one or more lips 3 projecting from the upper rim of the tank or apertures formed within the tank below its upper surface. The base 18 of the tank may be conical. The tank may be placed on a stand 2.

Description

Imorovesents in and relating to Flotation Tanks This invention relates to flotation tanks. More especially, but not exclusively, the invention relates to portable flotation tanks for use on site when carrying out excavations at, for example, places of archaeological interest.

When seeking to recover objects of archaeological interest such as pottery, jewellery and the like at an excavation site, it is known to immerse quantities of soil and other debris which may include such objects in water contained in metal drums and/or to direct water jets onto soil quantities in an attempt to separate objects of interest from the soil. The use of such basic equipment is time consuming and, in many cases, not productive. Also, unless carefully controlled the water jets themselves can cause damage to delicate objects hidden in soil samples.

The present invention sets out to provide a portable ready-made flotation tank which overcomes or at least alleviates the disadvantages referred to above.

According to the present invention in one aspect there is provided a flotation tank for removing dirt and other debris from objects present in a perforated basket, the tank including a manifold connectable through a non-return valve to a pressurised source of cleansing fluid and formed with a plurality of apertures through which cleansing fluid can be directed onto the contents of the basket, overflow means by which excess cleansing fluid can leave the tank, and a closable opening formed in or towards the base of the tank for emptying the tank of cleansing fluid and other debris.

The cleansing fluid may be water to which a solvent may be added. The water may be at mains pressure and the tank may include means for coupling an inlet pipe or port of the tank to a source of mains water. The manifold may comprise a pipe assembly which is connected to the inlet pipe or port of the tank and extends generally across the width of the tank at a position close to the perforated basket. The manifold may lie in a generally horizontal plane and may be positioned either below, above or to one or more sides of the basket. The manifold may take the form of a cruciform, a ring, a square or any other suitable shape.

In an alternative arrangement, the manifold comprises a solid plate like structure which is formed in its surface with a plurality of apertures.

Where an annular basket is employed (or an annular array of such baskets), the manifold may be shaped to protrude at least partially into the centre of such basket or array.

The basket may be produced from wire mesh or may be produced from sheet material in which is formed a plurality of holes.

The overflow means may comprise one or more lips which project outwardly from the upper rim of the tank. These lips may be inclined and may be shaped to include side pieces which define a converging flow pattern.

Alternatively, the overflow means may comprise apertures formed within the tank at positions below its upper surface.

The base of the tank may be generally conical with the closeable opening positioned at its centre. The tank may comprise an open-topped chamber supported on a separable or integral stand. The tank may be produced from mild steel which may be galvanised. Other materials having similar properties may however be employed.

The invention will now be described by way of example with reference to the accompanying diagrammatic drawings in which Figure 1 is a side view in section of a flotation tank in accordance with the invention; Figure 2 is a side view in section of the tank illustrated in Figure 1 taken in the direction of arrow "A" of Figure 1; and Figure 3 is a plan view from above of the tank illustrated in Figures 1 and 2.

The flotation tank illustrated is produced from mild steel or other suitable material and comprises an opentopped upper chamber 1 of generally circular cross-section supported on a stand 2. The chamber 1 is formed at its upper end with a protruding overflow lip 3 whose upstanding sides 4 define a converging flow pattern. The floOR 5 of the lip may lie in a generally horizontal plane or be downwardly inclined. A manifold 6 is positioned within the chamber 1 and comprises a generally vertical section 7 connected to an inlet pipe 8 through a coupling 9, and a generally horizontal section 10 of cruciform shape in which are positioned a plurality of apertures 11. The apertures may be evenly spaced and have identical or similar dimensions.Alternatively the spacing between neighbouring apertures and/or their dimensions may vary to ensure that the flow through each aperture is approximately the same.

The outlet pipe is connected through a non-return valve 12, flow valve 14 and hose union 15 to a hose 16 connected to a source of mains water (not shown).

The height of the horizontal section 10 of the manifold is adjustable. Other shapes and constructions of manifold can be adopted.

A relief valve 17 is provided within the side of the chamber remote from the inlet pipe 8.

The base 18 of the chamber is conical and includes an outlet 19 whose opening is controlled by a valve 20.

Handles 21 are provided on the sides of the chamber for ease of lifting and movement.

In use a quantity of soil and other debris possibly containing items of archaeological interest is placed in a perforated basket 22 provided with hooks 23 which locate over the rim of the chamber 1 with the basket contents immersed in water already present in the chamber. The nonreturn valve 12 is then opened to admit mains water to the manifold, this water being directed by the apertures onto the basket contents to cause dirt and other debris either to float to the water surface for removal via the overflow lip 3 or to sink into the conical base of the chamber for later removal by opening of the valve 20. Items of archaeological interest are thereby revealed by the cleansing operation and can simply be removed from the basket when it in turn has been removed from the tank.

Water and debris leaving the tank via the overflow or the valve can be collected for subsequent inspection. For reasons of economy, the water may be filtered and recycled to the tank via the inlet pipe. A solvent or cleansing solution may be added to the water admitted to the tank.

It will be appreciated that the foregoing is merely exemplary of flotation tanks in accordance with the invention and that modifications can readily be made thereto without departing from the true scope of the invention. It will also be appreciated that flotation tanks in accordance with the invention can be used for purposes other than that described above. One such purpose is cleaning birds and other objects polluted by oil spills at sea. In this case, the basket may be provided with straps or the like to retain an oil-covered bird while water jets including a cleansing medium are directed onto the bird through the manifold apertures.

Claims (17)

1. A flotation tank for removing dirt wid older debris from objects present in a perforated basket, the tank including a manifold connectable through a non-return valve to a pressurised source of cleansing fluid and formed with a plurality of apertures through which cleansing fluid can be directed onto the contents of the basket, overflow means by which excess cleansing fluid can leave the tank, and a closable opening formed in or towards the base of thc tank for emptying the tank of cleansing fluid and other debris.

2. A flotation tank as claimed in Claim 1 wherein the cleansng fluid is water.

3. A flotation tank as claimed in Claim 2 wherein a solvent is added to the water.

4. A flotation tank as claimed in Claim 2 wherein the water is at mains pressure and the telk includes means for coupling an inlet pipe or port of the tank to a source of mains water.

5. A flotation tank as claimed in any one of the preceding Claims wherein the manifold comprises a pipe assembly which is connected to the inlet pipe or port of the tank and extends generally across the width of the tank at a position close to the perforated basket.

6. A flotation tank as claimed in any one of the preceding Claims wherein the manifold lies in a generally horizontal plane.

7. A flotation tank as claimed in Claim 6 wherein the manifold is positioned either below, above or to one or more sides of the basket.

8. A flotation tank as claimed in any one of the preceding Claims wherein the manifold takes the form of a cruciform.

9. A flotation tank as claimed in any one of Claims 1 to 7 wherein the manifold comprises a solid plate-like structure which is formed in its surface with a plurality of apertures.

10. A flotation tank as claimed in any one of the preceding Claims wherein the overflow means comprises one or more lips which project outwardly from the upper rim of the tank.

11. A flotation tank as claimed in Claim 10 wherein the lips are inclined and are shaped to include side pieces which define a converging flow pattern.

12. A flotation tank as claimed in any one of Claims 1 to 9 wherein the overflow means comprises apertures formed within the tank at positions below its upper surface.

13. A flotation tank as claimed in any one of the preceding Claims wherein the base of the tank is generally conical with the closeable opening positioned at its centre.

14. A flotation tank as claimed in any one of the preceding Claims which comprises an open-topped chamber supported on a separable or integral stand.

15. A flotation tank as claimed in any one of the preceding Claims which is produced from mild steel.

16. A flotation tank as claimed in Claim 15 which is galvanised.

17. A flotation tank substantially as herein described and as herein described with reference to Figures 1 to 3 of the accompanying drawings.