This invention relates to an assembly which may be used for making an access chamber, and to an access chamber manufactured from the assembly. The invention also relates to a method of making the chamber.

An access chamber is a chamber having an upwardly opening cover through which a person may enter the chamber to gain access to various fittings and connections therein. Above and below ground access chambers are extensively used in general infrastructure to house a wide range of equipment. Distribution networks for gas, water, electricity, telecom and cable networks all use below ground chambers to house various connections, monitoring equipment and transformers. Fuel distribution systems typically found on the petroleum forecourt locate chambers on top of the fuel storage tanks where the distribution manifold and various monitoring equipment are located.

Access chambers can be simply described as large boxes that are capable of housing equipment and have sufficient structural strength to support the surrounding earthworks whilst at the same time permitting access of pipes and cables through their walls. In a number of applications a chamber is required to be water tight and must be able to facilitate various types of seals that connect pipes/cables to the chamber walls.

Access chambers can be made of various materials such as concrete, steel, glass fibre composite and thermoplastics such as high density polyethylene. Irrespective of materials used or the manufacturing method employed to make the chamber, these chambers suffer from a common problem when transported from the point of manufacture, typically via a distributor, to the site of installation. These chambers are large volume relatively low value products. They therefore incur high transportation costs relative to the value of the chamber. Nesting chambers can reduce the transportation costs. However this is only a partial solution. Nesting of chambers is not efficient as it requires that particular features are incorporated into the chamber design which might not be acceptable within the overall design of the chamber. For example, only thin walled chambers can be nested and even these require the chamber wall to have a significant slope angle in order to achieve any reasonable degree of nesting.

According to a first aspect of the present invention an assembly for an access chamber comprises:

a base, the base including a lower channel defining a socket extending generally peripherally of the base;

a plurality of panels, each panel including a top edge, a bottom edge and flanges on two vertical sides;

a housing including an aperture configured to be connected to a frame for an access cover to close the chamber in use;

at least one connecting member comprising an elongate body, having two channels, each channel being adapted to engage an edge of panel so that the connecting member forms a permanent sealed engagement between two adjacent panels;

wherein one of the housing and panels includes an upper socket extending generally peripherally of the chamber and the other of the housing and panel including a flange configured to be received in the socket;

wherein the flanges when received into respective sockets or channels are engaged by an adhesive to form a permanently sealed engagement.

In preferred embodiments the assembly further comprises a multiplicity of retainers configured to be received in a channel, the channel including an abutment configured to prevent upward removal of the retainer from the channel.

Preferably the base includes an upwardly opening socket arranged to receive and engage a downwardly extending edge of each panel. The socket may be shaped to guide the panels into a correct orientation. The socket may open upwardly for example in a V-shaped cross section to facilitate correct alignment of the edge during insertion of the panels.

The or each panel may include an upwardly opening socket arranged to receive a downwardly extending flange or edge of the housing. Alternatively the housing may include one downwardly opening socket arranged to receive an upwardly extending edge of each panel.

In preferred embodiments the sockets and channels are configured with an inward dimension selected to securely receive a flange or edge and have a transverse dimension selected to provide a cavity on one or both sides of the panel to accommodate a quantity of settable adhesive composition to permanently seal the flange within the socket or channel.

Preferably retaining means are provided in each channel to securely hold a flange in the channel prior to curing of the adhesive.

The retaining means may comprise spring clips. Each clip may have a channel or recess dimensioned to receive an edge of a flange, the clip further comprising resilient retaining means, for example rearwardly extending barbs, arranged to be deformed by insertion of a flange into the channel but to engage the surface of the flange preventing withdrawal of the panel from the socket.

A preferred clip may be formed from laminar spring steel folded to form a rectangular channel with cut outs to form inwardly extending spikes on opposite sides of the channel, so that a flange inserted into the channel is engaged by the barbs and prevented from withdrawal.

The socket may have a constant depth around the periphery of the base or housing. The channels also have a constant depth.

The flanges of each panel may include a marker located at a predetermined distance from the edge of the flange, arranged to be aligned with the opening of the socket or channel when the flange is fully inserted into the socket or channel and correctly aligned with the base, or housing. A preferred marker comprises a rebate or slot cut into the surface of the panel. This arrangement has the advantage that a sealant may be deposited along the rebate or slot to seal the assembly. Preferably the flanges have a reduced thickness in comparison to the main body of the panel. This allows the connecting member to fit flush with the panel surface reducing the dimension of the chamber

The marker may comprise a shoulder, rebate or groove. Alternatively a visible marking may be applied to the surface of the flange.

Preferably the sockets are arranged to be upwardly opening. This facilitates retaining the adhesive in the socket during assembly prior to curing of the adhesive.

The housing may be connected to the access cover frame by means of a skirt or other tubular structure. The skirt may have an adjustable length to allow adjustment of the location of the cover relative to the chamber.

Use of the present invention confers several advantages. Transportation costs are significantly reduced by providing a chamber that can be packaged in an essentially flat or compact format and then assembled at the site of installation. The invention also may provide a chamber which is totally water tight when assembled at the place of installation.

Assembling equipment on site typically requires skilled labour equipped with appropriate tools. This can present problems that result in increased labour and equipment costs. The present invention provides a chamber that can be assembled without use of tools or specialised equipment. The component parts of the chamber may be supplied with adhesive and a suitable dispenser. No other equipment may be necessary.

According to a second aspect of the present invention an access chamber kit comprises a base, housing, cover, panels, connecting members, retaining means and an adhesive in accordance with the first aspect of this invention. The retaining means may comprise clips pre-inserted into the channels.

According to a third aspect of the present invention there is provided a method of assembly of an access chamber as described below. The invention may be exemplified by the type of chamber that would be installed on a fuel storage tank. These chambers are required to be watertight and involve the connection of a number of pipes which must pass through a chamber wall. It is a further advantage of the invention that the task of aligning the exit point of pipes through the chamber wall and subsequent task of cutting the appropriate hole is simplified.

A chamber typically consists of a base and side panels onto which a top housing is attached. The top housing serves to connect the chamber to an access cover of which there are many types and sizes. The chamber may be round, multi sided, polygonal, square or rectangular. The chamber described below is multi sided and in the case illustrated has twelve sides. The panels may be planar or curved in plan view. A chamber may comprise a plurality of similarly shaped panels. Alternatively, a combination of different panels may be employed. The invention applies to all configurations of chamber.

The chamber has a separate base and side panels or walls and for the purpose of this description the preferred material of construction is a glass fibre composite. The side panels or walls may consist of three sections each having four flat faces. The side panel sections fit into a socket formed by a groove located around the outer edge of the base into which they will ultimately be bonded.

The four sided chamber section may be supplied with a pre-assembled connecting member comprising an aluminium extruded section secured to a flange on one of the vertical edges. The section has two recesses of identical shape which receive the edge of the chamber side section. Prior to leaving the factory each recess may be equipped with steel clips. The number of clips may be dependent on the length of the connecting member. The clips may be inserted by sliding into place from an end of the aluminium section into a receiving groove provided by the channel created within the aluminium section. The clips are retained in their respective positions by a spot adhesive. A typical example is LOCTITE (RTM) 496 Instant Adhesive. One channel in the aluminium section connecting member then receives a continuous bead of polyurethane adhesive. A typical example is DETAFLEX (RTM) 4000. The aluminium section may be then pressed onto the edge of a chamber side section so that the edge becomes embedded into the body of adhesive. The clips located in the recess are equipped with barbs that allow the chamber side to enter the groove but prevent its removal. Hence the aluminium section is securely held in place on the edge of the chamber side. In this manner the adhesive can proceed to cure during which time the two parts are securely held without the need for any form of external clamping or use of tools.

The adhesive is preferably thixotropic. Fast curing resins such as the acrylic series that are used in assembly applications are expensive. However in the case of this jointing system a slow curing polyurethane adhesive can be used to afford a significant cost saving.

The chamber base and multi sided chamber panel sections nest together occupying minimal space and typically ten chambers may occupy the volume that one conventional solid bottom chamber occupies. The result is a significant reduction in transportation and shipping costs.

The chamber is assembled on site in the following manner. The method described is representative of what might be employed to assemble a chamber to a typical fuel storage tank supplied with a reverse up stand.

The tank may be supplied with a manifold prepared with the appropriate pipe connection fittings. A pipe fitter may commence to build up the pipe work and in doing so will establish the direction and position of all pipes and cables that will leave or enter the chamber. This work can be carried out unhindered by the chamber up to the point where it becomes necessary to take the pipes and cables through the chamber wall.

The chamber base may be provided with an aperture and associated bolt holes that match the up stand on the tank. The sizes and bolt configuration are normally specific to the tank manufacturer. The base together with appropriate seal may be then bolted to the tank up stand.

Each side section of the chamber may then be placed into its final position by locating it in the groove of the socket running around the edge of the base. For each panel for example, using a laser pointer, the exit position of each pipe that is to pass through that section of chamber wall can be found and marked. The section can then be removed to a suitable location and the appropriate hole configuration drilled to accommodate the pipe seals. The pipe seal can also be fitted at the same time if required. Undertaking the assembly work in this manner removes the need to a minimum for the pipe fitter to enter the chamber where available working space is limited.

On completion of all drilling the multi sided chamber panel can then be assembled as follows. In a preferred embodiment three panels are employed.

The three chamber panels have a continuous bead of adhesive placed into the open channel of the aluminium extrusion. They are then pressed together ensuring the upper and lower faces create a flat surface. The panel section flange is reduced in thickness at the point where it enters the aluminium section connecting member and provides a sighting line. This allows the person assembling the panels to establish if the components are correctly seated within the aluminium section.

A preferred adhesive is a rapid cure polyurethane system. A typical adhesive is PERMABOND (RTM) PT326, that cures within 30 minutes. The clip system located in the channels of the aluminium extrusions ensures that no clamping of the chamber sections is required and the chamber is ready for assembly to the chamber base. The groove socket in the outer edge of the chamber base then receives a continuous bead of polyurethane adhesive. A typical adhesive is DETAFLEX (RTM) 4000. The chamber is then correctly positioned relative to the pipe work and pressed down into the socket to contact the bead of adhesive. The socket locates and retains the chamber and the chamber weight forces the chamber into the groove displacing the adhesive around the edge of the chamber to create a water tight and strong adhesive bond. The aluminium extrusion connecting member is fully bonded to the edge of the chamber panel forming a continuous surface. The thickness of the flange and connecting members are selected so that a continuous outer surface of the chamber is provided to avoid a liability to snag on external objects during installation. The socket in the outer edge of the base section receives both the chamber edge and bonded connecting member, both of which are embedded into the bead of adhesive within the socket of the base section forming a watertight bonded joint.

Once the adhesive bonding the chamber to the base is cured the pipe work can be completed. This approach to the task of fitting the pipe and the cable work into the chamber reduces the requirement for the pipe fitter to enter the chamber to a minimum.

The chamber depth is typically 850mm. There may be a situation where the chamber depth exceeds the depth of a single chamber panel. To accommodate greater depths the chamber of the invention can be built up in multiples of 850mm with smaller height variations being accommodated by reducing the height of the chamber.

A water tight connection joint between chamber sections may be provided by an elastomeric extruded section, typically made of VITON(RTM). The extruded section may be formed into a continuous ring by cutting a precise length and bonding the ends to form a complete annular sealing ring. The extrusion is provided with two grooves situated diametrically opposite each other. The identical grooves are designed to accommodate either the upper or lower edge of the panel section including the joint created by the aluminium section.

The method of assembling a chamber to a second chamber is described as follows:

One groove in the elastomeric ring is provided with a continuous bead of polyurethane adhesive. A typical example is DETAFLEX (RTM) 4000. The ring is then pressed into position on the top edge of the assembled panels. A continuous bead of adhesive is then applied into the upper groove in the elastomeric ring. The second chamber can then be lowered down into the groove pressing firmly into place to ensure it is fully embedded into the adhesive. The assembly is allowed to fully cure and the process repeated if required.

To complete a chamber assembly a connection system may be provided at the top of the chamber. This may take a number of different forms depending on the type of installation. In the case of a fuel tank it is normal to fit a corbel unit. The outer edge of the corbel unit is provided with a groove that matches the shape of the multisided chamber and is similar to that of the groove in the base section. The groove is provided with a continuous bead of polyurethane adhesive and the corbel unit is then placed onto the chamber edge resulting in the edge being pressed into the bead of adhesive.

The invention will now be described by means of example but not in any limitative sense, with reference to the accompanying drawings, of which:

Figure 1 is a conventional access chamber;

Figure 2 is an isometric view of a base unit and three side panels of a chamber according to the invention;

Figure 3 is an isometric view of a chamber side element with a connecting member bonded to one edge;

Figure 4 is a cross sectional view of the connecting member;

Figure 5 is an isometric view of a steel clip;

Figure 6 is an end view of an aluminium connector section with steel clip housed in recess;

Figure 7 is an isometric view of a steel clip housed in the recess of a connecting member and retained in position by spot adhesive;

Figure 8 is a partial isometric view of a connecting member bonded to an edge of a panel;

Figure 9 is a partial view of the base showing the socket;

Figure 10 is a partial cross sectional view of the base with a panel bonded in place;

Figure 11 is a cross sectional view of an elastomeric extrusion;

Figure 12 is a partial cross sectional view of a chamber to chamber joint;

Figure 13 is a partial cross sectional view of a corbel bonded to the chamber; Figure 14 is an external isometric view of a chamber with a chamber extension and a corbel unit;

Figure 15 illustrates the space occupied by ten complete chambers in a flat pack arrangement prior to shipping; and

Figure 16 is an isometric view of an assembled chamber with a corbel.

Figure 1 shows a solid base conventional access chamber (1), chambers of this configuration occupy a large volume relative to their value and therefore have high transport costs. They are also difficult to handle due to their weight and size.

Figure 2 shows part of an assembly in accordance with this invention. A chamber base unit (2) and three side panel elements (3) are shown in an exploded view. Each side element has four sides.

A single panel element (3) is shown in Figure 3. This has a fitted connection member (4) bonded to one edge. The connection member comprises an aluminium extrusion and enables the panel member (3) to be bonded to an adjacent panel member (not shown) to make the essential body section in the chamber.

Figure 4 shows a cross-sectional view of the connection member (4). Two channels (6) extend outwardly from a central body portion (5). In the embodiment shown the channels are inclined at an angle of 30°. The two channels (6) are each able to receive a flange of a panel element (3). Recesses (7) within the channel (6) form an inwardly facing abutment dimensioned to receive a clip or other retaining means (8) as shown in Figures 5 and 6.

A steel clip (8) shown in Figure 5 has a base portion and two side portions to define a channel dimensioned to receive and engage a flange of a panel member. Inwardly facing barbs (9) are resiliently deflected outwardly when the flange or the panel is inserted providing permanent engagement of the flange within the channel. A number of clips (8) typically three, may be inserted into each recess (7) sliding them into place from the end of the aluminium extrusion and spaced apart as shown in Figure 7. The clips are retained in position in the channels by application of a small dot of adhesive. A suitable adhesive is Loctite (RTM) 496 Instant Adhesive. The connecting member (4) is then bonded to the chamber side panel (3) by applying a continuous bead of adhesive (11) into one recess (6) in the connecting member.

Figure 8 shows the aluminium extrusion (4) pressed onto the flange (12) of the side element (3) forcing adhesive to flow around the flange edge (12) creating a bonded joint (13).

As flange (12) enters the channel (6) in the connecting member (4) it engages with steel clip (8) and barbs (9). The flange is allowed to fully enter the recess (6) as shown in Figure 8. Once the flange (12) is fully located in the recess, this can be determined by comparing the witnessed line (14) to the outer edge (15) of the connecting member (4). The flange is retained in position by barbs (9). In the event that there is an attempt to separate the connecting member (4) from the panel (3), barbs (9) penetrate the surface of the flange (12) to resist movement. Adhesive (11) serves to complete the curing process without movement occurring between the panel

(3) and connecting member (4). In preferred embodiments a single aluminium extrusion connecting member (4) is assembled onto the panel (3) at the factory prior to shipment. This reduces the work required on site.

Figure 9 is a partial view of the base element (16) of the access chamber. The central part of the base element (16) may be adapted to the particular installation requiring the chamber assembly (17). The base element may be solid or have a section removed and bolt holes provided to facilitate connection to equipment such as a fuel storage tank.

On site assembly of the three chamber elements (3) to form the central section (17) of an access chamber involves providing a continuous bead of fast curing adhesive in the remaining channel (6) of the aluminium extrusion connecting member

(4) in each panel (3). Flange (12) of each of the side panels (3) is then pressed into the channel (6) of the adjacent panel and retained in position by the steel clips and their associated barbs. The completed central section (17) can then be assembled onto the base element (16). The outer edge of base element (16) is provided with a recess (18) as shown in Figure 9. To assembly the chamber central section to the base element the recess (18) provided with a continuous bead of adhesive (19). The chamber central section (17) is then pressed down into the recess (18) displacing the bead of adhesive (19) to form a bonded joint (20) as shown in Figure 10.

Figure 11 is a cross sectional view of an elastomeric extrusion (21) having two symmetrical channels (22). The function of the extrusion (21) is to facilitate the assembly of chamber central sections (17) to each other. The elastomeric extrusion (21) is formed into a continuous seal by bonding. To assemble chamber central sections together a continuous bead of adhesive is placed into one recess (22) of seal (23) which is then pressed onto the edge of the central section (17) already assembled to base element (16). A continuous bead of adhesive (24) is then applied to the remaining upper recess (22) of seal (23) and a second chamber central section (17) is inserted into the recess and pressed into place. This displaces adhesive (24) to form a bonded joint (25) as shown in Figure 12.

Methods of connection chambers to access covers and entrance points vary considerably. A single method using a corbel unit is described for clarity.

Corbel unit (26) is provided around its outer edge with a recess (27) as shown in Figure 13. The corbel unit (26) is assembled to the chamber central section (17) by applying a continuous bead of adhesive (28) into recess (27). The corbel unit (26) is then placed onto the chamber central section (17) and pressed down to displace the adhesive to form a bonded joint (29). A completed chamber unit including a second chamber extension is shown in Figure 14.

Figure 15 illustrates ten complete chamber units packaged in preparation for shipping.

Figure 16 is an illustration of a complete chamber fitted with a corbel and a mannequin shown to provide a concept of scale.