IMPROVEMENTS IN RELATION TO DRAINAGE OF CONTAINMENT TANKS

Description

TECHNICAL FIELD

THIS INVENTION relates to containment tanks or ponds of the type having a flexible liner and more particularly to drain inlet assembly that may be used in an under tank drainage system.

BACKGROUND

Containment tanks or ponds usually are temporary and pond drainage is employed to empty the tanks. These drainage arrangements can involve pipes entering over the top of the side walls of the tank or under the tank or through the tank wall. The tank is usually formed by metal segments clamped together into a cylindrical open above ground form which holds and supports a flexible liner. To empty the pond a pump is used to pump the pond through an outlet. Under pond drains have the advantage that there is less requirement for pump capacity since the pump does not have to lift the water over the wall. The following listed patents provide general background as well as examples of various pond drains and outlet arrangements. The disclosure of these is incorporated by cross-reference. The disclosure herein does not comprise any form of admission that any of the material in the patent specifications is common general knowledge or the material described in relation to FIG. 1 is common general knowledge which has typically been used on private property and may not be publicly known at the priority date.

The listed patents as follows:

• • a) U.S. Pat No. 1,618,720A;
  • b) U.S. Pat No. 2,094,437A;
  • c) U.S. Pat No. 9,238,525B2;
  • d) U.S. Pat No. 10,239,687,B1;
  • e) US2016153161A1;
  • f) US2017088346A1;
  • g) USRE49933E.

These were revealed in a post-invention search based on a priori knowledge of the Applicant's invention. Of particular note is Patent No. U.S. Pat. No. 10,239,687,B1 and its Reissue Patent USRE49933E which describes an under pond drain and sump which bridges the pond wall underneath and has the liner clamped around a hole formed in the liner. FIG. 1 herein also shows an under pond drain and sump of a type known to the Applicant. Both these employ a gasket or gaskets to seal the drain around a hole in the liner by clamping and sandwiching the liner.

Plumbing, pipes, drains and seals are extraordinarily common. It should be very clear that the art is a very mature one.

The Applicant's invention should be viewed through the lens of a crowded art and it would be prima facie wrong to suggest that there was, or is, apart from the very general problem of sealing the hole in the liner, that there was any a particular problem or motivation extant at the filing date of the present application that would give rise to the non-inventive notional person coming up with the present invention and its improvements either in idea, concept or practical form. Thus the recognition and the present conception should be considered as whole or part of the Applicant's inventive step.

With this and the other background factors, including as set out above, in mind, it should be clearly appreciated to the reader, that it is elementary that exercise of the inventive faculty in all the circumstances, in such a crowded art, is likely to be present in small variations. This is a background observation in hindsight only and is not to say that any of Applicant's new features whether individually or in combination are in any way slight or small. All that is required is a “scintilla”of invention.

Even though the art has become crowded, the later offerings have not been widely accepted. Consequently, there is a requirement for a fresh look at the general problems, and to look “outside the box”, through new eyes in an effort to provide an alternative to the efforts made over the last many years. It would be desirable to have something that is simple and easy to assemble and use, yet effective.

The present invention concerns methods and apparatus for containment tank drainage. In terms of apparatus it concerns a containment tank drain inlet assembly and in a preferred form, application of that assembly to an under pond drain assembly that provides the industry with a useful alternative to the prior gasket type. In a preferred form the invention also provides a method employing a leak test to check leakage before filling the pond. The present invention also enables tests to be performed to check on the leakage over time and if needed to aid identifying the need to replace seals. In terms of apparatus, when it is desirable to replace seals the seals may be easily replaced.

SUMMARY OF THE INVENTION

In one aspect there is provided a method for managing the integrity of a seal in a containment tank seal around a hole in a flexible liner comprising the step of pressure testing the seal before filling the tank. The method preferably comprises the step of forming the seal with at least one pressure test chamber and subsequently pressurising the chamber(s) to test the seal.

It follows that, in a preferred form, there is provided a method for managing the integrity of a seal in a containment tank around a hole in a flexible liner, comprising the step of pressure testing the seal before filling the tank. The method includes the step of forming the seal with at least one pressure test chamber and subsequently pressurising the chamber to test the seal. The test is preferably performed on a drain inlet assembly positioned inside a tank or pond, the inlet assembly comprising an opening in the flexible pond liner providing a flow path through the assembly and a seal adapted to adopt a fluid-type seal with the liner. The seal includes at least one pressure test envelope or chamber to enable the seal to be pressurised before the pond is filled, thereby simulating hydraulic pressure. The inlet assembly is typically located at one end of a drain assembly having an outlet positioned outside the pond.

Typically, the pressure test chamber is supplied with pressurised air—up to a predetermined pressure—and checks for leakage are made by observing a pressure drop on a gauge or by applying a detergent or similar liquid to detect bubbles. In a preferred form, two chambers are provided, one above and one below the liner, each chamber having a corresponding test valve for independent pressurisation.

In this example, the method is implemented using a drain assembly having an inlet assembly located within the pond, with the pressure test chambers arranged on opposite sides of a liner margin sandwiched between respective clamping sections of the drain inlet assembly. The clamping sections comprise first and second companion clamps including a manually operable clamping mechanism that clamps the liner so as to surround the flow path through the assembly.

Preferably, the seal is formed by the companion clamping parts acting on the liner, with a connecting means between the parts. The connecting means may comprise a connecting rod, and the companion parts are moved axially along the rod under clamping pressure to sandwich the liner. The clamping parts include respective flanges extending around the liner—preferably annular flanges—that carry spaced-apart O-rings. These O-rings define the pressure test chambers, which are located between the O-rings and the liner and enclosed by the clamping parts of the inlet assembly.

It further follows that in another form there is provided a method for managing the integrity of a seal in a containment tank or pond, the seal being around a hole in a flexible liner, the method comprising forming the seal with at least one pressure test chamber; and pressure testing the seal before filling the tank, and further wherein the test is performed on a drain inlet assembly positioned inside a containment tank or pond, the assembly comprising:

• • a. an opening in the flexible pond liner providing a flow path through the assembly; and
  • b. a seal adapted to adopt a fluid-tight seal with the flexible pond liner, the seal including the at least one pressure test chamber adapted to be pressurised to simulate a corresponding hydraulic pressure prior to filling the pond, the inlet assembly being positioned at one end of a drain assembly having an outlet located outside the pond.

Typically, the pressure test chamber is supplied with pressurised air up to a predetermined pressure, and the integrity of the seal is tested by observing a pressure drop on a gauge or by applying a liquid capable of revealing gas leakage by bubbling. Preferably, the seal comprises two chambers and each chamber has a corresponding test valve adapted to enable pressurisation of its respective chamber. Typically, one chamber is positioned above the liner and the other chamber is positioned below the liner.

In another aspect, there is provided a drain inlet assembly comprising an opening in a flexible pond liner providing a flow path through the assembly, and a seal adapted to adopt a fluid-tight seal with the flexible pond liner, the seal including at least one pressure test chamber adapted to be pressurised before filling the pond to simulate the corresponding hydraulic pressure. In a preferred form, the drain inlet assembly is located at one end of a drain assembly having an outlet positioned outside the pond.

During implementation of the method, the pressure test envelope or chamber is supplied with pressurised air, usually from a manual pump, up to a predetermined pressure, typically 10 psi, and then checks are made for leakage, this may be by observing a pressure drop on a gauge or by applying a detergent or other similar liquid to detect bubbles arising from a leak. Remedial action may then be taken and the seal tested again.

Preferably, the seal includes both an upper and a lower test chamber, with the upper chamber located above a portion of the liner and the lower chamber located below a corresponding portion of the liner. These respective liner portions are sandwiched between opposing clamping components of the drain inlet assembly, forming a sealed interface above and below the liner.

Preferably, a test chamber is provided above a portion of the liner sandwiched between respective clamping sections of the drain inlet assembly and a second test chamber is provided below the liner sandwiched between respective parts of the drain inlet assembly. The clamping components preferably comprise a first and second clamp ring joined by a manually operable clamping means. In one example, a threaded connecting rod permits axial movement of the rings toward one another under clamping pressure, thereby drawing the companion rings together to securely sandwich the liner between them.

The clamping parts may comprise first and second clamps and include a manually operable clamping means so that the liner is clamped between companion clamping parts so as to surround the flow path through the assembly. Typically there is a connecting means between the clamping parts, typically the connecting means is a connecting rod and there is relative movement in an axial direction along the rod under the influence of a clamping pressure to move the companion parts toward each other to sandwich the liner between the clamping parts. Each clamp ring preferably includes an annular flange extending around the liner opening. The annular flanges carry spaced seals, typically O-rings, arranged to define the pressure test chambers between the respective O-rings, the liner, and the clamping components of the inlet assembly.

Preferably the clamping parts comprise respective flanges extending around the liner, the flanges may be in any form but are typically annular flanges and these flanges carry spaced apart seals, typically spaced O-rings defining the pressure test chambers between the O-rings and the liner and the clamping parts of the inlet assembly. The clamping rings may also incorporate a central connecting means such as a threaded rod secured to one ring and passed through the opposing ring. Relative axial displacement under tightening force compresses the seals against the liner. Preferably, the connecting rod includes a protective sleeve to shield its threads, and the upper ring is advanced using a winged nut to apply the clamping force manually.

It follows for the above that in a variation there is provided a drain assembly comprising:

• • a drain inlet assembly positioned inside a containment pond or tank and comprising an opening in a flexible pond liner providing a flow path through the assembly;
  • a seal adapted to adopt a fluid-tight seal with the flexible pond liner, the seal including at least one pressure test chamber configured to be pressurised prior to filling the pond to simulate hydraulic pressure,
  • wherein the drain inlet assembly is positioned at one end of a drain assembly having an outlet located outside the pond.

In another form the seal comprises a first pressure test chamber located above a portion of the liner and a second pressure test chamber located below the liner, the respective portions of the liner being sandwiched between clamping sections of the drain inlet assembly. In this case the clamping sections comprise first and second companion clamps and include a manually operable clamping means adapted to clamp the liner between the clamping sections so as to surround the flow path through the assembly. In another form the seal comprises companion clamping parts configured to clamp the liner, and a connecting means between the clamping parts, the connecting means comprising a connecting rod, and wherein relative movement in an axial direction along the rod under a clamping pressure urges the clamping parts toward each other to sandwich the liner therebetween. In a narrow version the clamping parts comprise respective annular flanges extending around the liner, and wherein each flange carries spaced apart O-rings such that the pressure test chambers are defined between the O-rings, the liner, and the clamping parts of the inlet assembly. As described above the pressure test chamber is fluidly connected to a test valve via a porting pathway, the pathway including at least one internal conduit formed in a spoke of a clamping component of the assembly. Typically, the porting pathway comprises a first conduit leading from a lower chamber below the liner to a test valve positioned above the drain inlet assembly. In addition, there may be a second porting pathway which connects an upper chamber above the liner to a corresponding test valve positioned above the drain inlet assembly.

Typically, the clamping parts and associated seals form a removable subassembly adapted for replacement, servicing, or inspection.

Typically, the annular flanges are each formed with a plurality of spokes extending radially from a central hub.

Typically, at least one of the spokes includes an internal conduit forming part of the porting pathway between the pressure test chamber and a test valve.

Typically, the connecting rod includes a protective sleeve to shield the threads of the rod during use and operation.

Typically, the upper clamping ring includes a manually operable winged nut for advancing the clamp along the rod to apply axial clamping force.

Typically, the lower clamping ring is permanently affixed or welded to a drain housing.

Typically, the annular flanges are profiled in a conical configuration converging toward the central flow axis when assembled.

Typically, the drain inlet assembly includes a pair of spaced-apart test valves located above the pond floor, accessible for pressure testing during and after installation.

BRIEF DESCRIPTION OF THE DRAWINGS

In order that the present improvements may be more readily understood and put into practical effect reference will now be made to the accompanying drawings which illustrate preferred embodiments of the invention and wherein:

FIG. 1 is a drawing illustrating an under pond drainage assembly known to the applicant to have been in use before the filing date;

FIG. 2 is a drawing illustrating application of the present invention to a containment pond;

FIG. 3 is a drawing illustrating a drain assembly including a drain inlet assembly according to the present invention;

FIG. 4 is an exploded view of a typical clamp assembly utilised in a drain inlet assembly according to the present invention;

FIG. 5 is a cutaway view illustrating the flow of liquid during an emptying procedure;

FIG. 6 is a part cutaway view of a drain in that assembly showing the test valves and test chambers.

METHOD OF PERFORMANCE

Referring to the drawings and initially to FIG. 1 there is illustrated the basic principle of hollow drawing box 10 located in a trench 11 with its top surface 12 at the level of levelled ground 12 over which is placed a flexible liner shown in part at 14.

There is a drainage opening 15 through the liner 14 into the box 10. The box 10 communicates with outlets 16 and 17 which are controlled with butterfly valves 18 and 19 in the usual way via a manifold 20. The box 10 bridges underneath a vertical wall at 21 (not shown in detail-see FIG. 2), the base of the wall is on ground level, presented by line 22 and this wall supports the liner vertically at 23 right around the above ground wall. The liner tracks the wall draping over it and down along the ground.

The principle of an under pond drain is that it may be installed before the pond is built and there are no concerns with liner damage by over-wall drainage pipes and pumping capacity may be reduced since there is no requirement to pump over the wall. The main comparative disadvantage is that there has to be a penetration through the liner for the under pond drain.

In the case of the drain of box 10 of FIG. 1 there is an inlet opening in the box at 15 overlaid by the opening 24 in the liner, the edges 25 of the liner opening being inboard of a clamping flange 26. The box 10 has a companion flange directly below flange 26.

The section of liner 14 between these flanges 15 is located between upper and lower gaskets, the upper gasket 27 being visible in FIG. 1. The flange 26 is secured to its companion using multiple bolts 28. Thus the hole is sealed by clamping its margin and using gaskets.

Referring now to FIG. 2, this illustrates in overview a pond and a drain assembly 30 according to the present invention. In principle it is located in a trench 11 in the same way as in FIG. 1 (like numerals illustrate like features). The above ground pond 29 has an inlet at 31.

The main difference between the drain of FIG. 1 is the drain inlet assembly 31. The inlet assembly 31 is illustrated operatively positioned in FIG. 2 and exploded view in FIG. 3. It is shown clamping a marginal section 32 of liner 14 hole 33. A lower annular ring 34 is welded to a corresponding opening in box 10. This ring has concentric O-ring slots 35 and 36 carrying O-rings 37 and 38. A top clamp ring 39, companion to ring 34 has O-ring slots 40 and 41 carrying O-rings 42 and 43. Each ring 34, 39 has three evenly spaced radial spokes 44, 45, 46, 47, 48, 49.

Each ring has a central hub 50, 51 and a threaded rod in the form of stud 52 is secured in hub 50 via sleeve 53 and pin 54. The stud has a thread protective sleeve at 55, which acts to shield the threads from environmental exposure or mechanical damage during installation and operation. The pin 54 passes through holes 56 and 57. A hex nut 58 with wings 59 and 60 is provided for manual winding, so that hub 51 may slide up or down as a clamping force is applied to ring 39. Thus, the O-ring seals are clamped onto the liner marginal section 32. The spokes of the ring 39 form a general cone configuration with hub 51, such that the assembled upper and lower flanges define a conical profile converging toward the central flow axis. The clamping components including the rings, seals and connecting rod may be preassembled and configured as a removable subassembly to facilitate installation and later replacement or servicing.

It will be appreciated that the liner marginal section 32 between the respective sets of O-ring seals creates tiny annular chambers 61 and 62 above and below the liner between the seals.

Porting pathways, in the form of internal conduits formed within the spokes of the rings, are provided for testing. The chamber 61 below the liner 15 is connected to a test valve 66 via an internal conduit formed in spoke 46. That conduit includes a vertical leg 63 and a horizontal leg 64, collectively forming a porting pathway leading to the test valve. The upper chamber 62 is connected via a second internal conduit 67 in another spoke to a second test valve 68. The conduits may be formed as blind-drilled or cast bores within the radial spokes, ensuring compact integration of the test connections. The chambers may be pressurised to test the seals for leakage at set-up and to check ongoing integrity at service intervals or each time the pond is emptied.

Referring to FIG. 5, there is illustrated the flow through the drain assembly with the invention at the inlet and showing an internal brace below the tank wall, while FIG. 6 shows the complete drain assembly showing the ease of access to the test valves 66 and 67 positioned above the pond floor and accessible during service or inspection.

Whilst the above has been given by way of illustrative example many variations and modifications will be apparent to those skilled in the art without departing from the broad ambit and scope of the invention as herein set forth. For example the inlet assembly is illustrated and used in an under pond drain assembly but it will be appreciated that the method includes application to any flow passage through a liner penetration set out in the appended claims.