Field of the invention

The present invention is concerned with an inspection chamber base or manhole base, an inspection chamber or manhole, a plug for an inspection chamber base or a manhole base.

Background

Inspection chamber bases are the bases on which an inspection chamber is disposed. Inspection chambers are used in sewage and rainwater drainage systems. In sewage and rainwater drainage systems a series of pipes are connected to one another. Sometimes it is necessary for the flow of sewage/rain to change direction. Sometimes, it is further necessary to be able to access the sewage/rainwater drainage systems for maintenance or trouble shooting reasons.

A manhole is a type of inspection chamber. Typically, as the name suggests, a manhole in an inspection chamber is sufficiently large to allow a person to access the drainage system. A manhole, as with an inspection chamber has a base, a manhole base. The manhole base has the same function as the inspection chamber base. A disadvantage of the known bases is that a large variety thereof is used which requires wide-ranging production equipment and space for storing different variants to solve varying needs.

Branched bases serve to merge different flows from a number of pipes into a single flow, and have inside a main channel and a number of branch channels entering into the main channel. For these, it is known, for example, from WO 2008/153403 (Pipelife Norge AS) and GB 1577987 (Wavin B.V.), to provide a junction for a sewage system in an inspection chamber.

From GB 1 577987 (Wavin B.V.), it is known to provide a straight main channel and a group of branch channels where one or more pipes are connected to to form a branched arrangement. The main channel has an inlet and an outlet. The branch channels are arranged to direct flow into the main channel in the direction of the flowthrough the main channel. Each of the branch channels has an inlet and extends from the inlet to a respective side of the main channel To selectively block undesired entry of solids into unused branch channels, the base is provided with a plastic obturating member which is constructed to fit over a group of branch channels.

From WO 2008/153403 (Pipelife Norge), it known that for a configuration of a main channel and two or more branch channels is possible to cover an inlet of a branch channel by providing a cover device, also referred to as a fill-in element, over the inlet from the inner side of the inspection chamber before installation. The fill-in element has a plate formed cover part which in contour is adapted to the inlet opening. This fill-in element has in general an elliptic contour and it is curved in the height direction in accordance with the curl of the end of the inlet pipe socket which it shall lie near to and cover.

The branched arrangements of WO 2008/153403 (Pipelife Norge AS) and GB 1 577 987 (Wavin B.V.) reduce the number of variants required for bases with branched flow channels. However, the flow possibilities remain limited to the arrangement of a straight main channel, with a selected number of branches, the number ranging from 0 to allthe branches available. It has been found by the inventors of the present invention that for other flow possibilities these known arrangement are not suitable, and in particular that these known solutions are not suitable to form in the base a bend with a selected angle.

The inventors of the present invention have further found that in conventional inspection chambers (and manholes), the angle range of the curve achievable in a junction in an inspection chamber base/manhole base is limited and smooth (laminar) flow of the fluid in the junction is not maintained.

SUMMARY

An object of the present invention is to address at least some of the drawbacks of known inspection chamber bases and manhole bases. In particular, it is an object of the present invention to provide an inspection chamber base or manhole base, which has at least one of: improved versatility and performance in terms of the flow provided and improved ease and versatility in terms of how it is deployed.

It is a further object of the present invention to transport the contents of the system smoothly.

It is a yet further object of the present invention to increase the range of angles through which a change of direction of flow in the base is possible whilst maintaining a smooth (laminar) flow of fluid in the system.

In accordance with one aspect of the invention, there is provided: an inspection chamber base or manhole base, comprising: a plurality of flow channels, each channel having a respective port located at an inlet/outlet region of the base from which the plurality of flow channels extend, the ports being circumferentially distributed around the base at unequal distances from each other, wherein the plurality of flow channels are selectively closeable to form a single bent flow channel having a selected bend angle.

In this way, the range of angles through which a change of direction of flow in the base can be achieved, is increased whilst maintaining a smooth (laminar) flow of fluid in the system. According to a further aspect of the invention, there is provided: an inspection chamber or manhole comprising: the inspection chamber base or manhole base according to the present invention, and a shaft protruding from the base.

According to a yet further aspect of the invention, there is provided: a plug for insertion into the inspection chamber base or manhole base according to the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention, and various embodiments thereof, will further be explained on the basis of examples, with reference made to the drawings, in which:

Fig. 1 shows a plan view (top view; bird ^' s eye view) of an inspection chamber base or manhole base according to an embodiment of the invention;

Fig. 2 shows a view of an inspection chamber or a manhole according to an embodiment of the invention;

Fig. 3 shows an embodiment of the present invention having a single flow channel with a bend of 90 degrees, in particular,

Fig. 3a shows a plug according to an embodiment of the present invention,

Fig. 3a i) shows a plan view (top view; bird ^' s eye view) of a plug,

Fig. 3a ii) shows a side view of the plug shown in Fig. 3a i),

Fig. 3b shows a plan view (top view; bird ^' s eye view) of an inspection chamber base or manhole base according to an embodiment of the invention, in which the plug of Fig. 3a is shown in place to form a single flow channel having a bend of 90 degrees,

Fig. 3c shows a side view of the inspection chamber base or manhole base of Fig. 3b in which a plug is in place;

Fig. 4 shows an embodiment of the present invention having a single flow channel with a bend of 120 degrees, in particular,

Fig. 4a shows a plug according to an embodiment of the present invention,

Fig. 4a i) shows a plan view (top view; bird ^' s eye view) of a plug,

Fig. 4a ii) shows a side view of the plug shown in Fig. 4a i),

Fig. 4b shows a plan view (top view; bird ^' s eye view) of an inspection chamber base or manhole base according to an embodiment of the invention, in which the plug of Fig. 4a is shown in place to form a single flow channel having a bend of 120 degrees,

Fig. 4c shows a side view of the inspection chamber base or manhole base of Fig. 4b in which a plug is in place; Fig. 5 shows an embodiment of the present invention having a single flow channel with a bend of 150 degrees, in particular,

Fig. 5a shows a plug according to an embodiment of the present invention,

Fig. 5a i) shows a plan view (top view; bird ^' s eye view) of a plug,

Fig. 5a ii) shows a side view of the plug shown in Fig. 5a i),

Fig. 5b shows a plan view (top view; bird ^' s eye view) of an inspection chamber base or manhole base according to an embodiment of the invention, in which the plug of Fig. 5a is shown in place to form a single flow channel having a bend of 150 degrees,

Fig. 5c shows a side view of the inspection chamber base or manhole base of Fig. 5b in which a plug is in place;

Fig. 6 shows a plan view (top view; bird ^' s eye view) of an inspection chamber base or manhole base according to a further embodiment of the invention;

Fig. 7 shows a further embodiment of the present invention having a single flow channel with a bend of 90 degrees;

Fig. 8 shows a further embodiment of the present invention having a single flow channel with a bend of 120 degrees;

Fig. 9 shows a further embodiment of the present invention having a single flow channel with a bend of 105 degrees;

Fig. 10 shows a further embodiment of the present invention having a single flow channel with a bend of 135 degrees;

Fig. 11 shows a further embodiment of the present invention having a single flow channel with a bend of 150 degrees;

Fig. 12a shows a plan view (top view; bird ^' s eye view) of an inspection chamber base or manhole base according to a yet further embodiment of the invention;

Fig. 12b shows a side view of the inspection chamber base or manhole base of Fig. 12a;

Fig. 13 shows a yet further embodiment of the present invention having a single flow channel with a bend of 90 degrees, in particular,

Fig. 13a shows a plug according to a yet further embodiment of the present invention, Fig. 13a i) shows a plan view (top view; bird ^' s eye view) of a plug,

Fig. 13a ii) shows a side view of the plug shown in Fig. 3a i),

Fig. 13b shows a plan view (top view; bird ^' s eye view) of an inspection chamber base or manhole base according to a yet further embodiment of the invention, in which the plug of Fig. 13a is shown in place to form a single flow channel having a bend of 90 degrees, Fig. 13c shows a side view of the inspection chamber base or manhole base of Fig. 13b in which a plug is in place.

DETAILED DESCRIPTION OF EMBODIMENTS

In the drawings and in the detailed description hereinbelow, like reference signs denote like features. The invention is exemplified in the embodiments described below. The invention is not limited to these embodiments, which are schematically shown.

Fig. 1 shows a plan view (top view; bird ^' s eye view) of an inspection chamber base or manhole base according to an embodiment of the invention. Fig. 2 shows a view of an inspection chamber or a manhole according to an embodiment of the invention.

An inspection chamber has an inspection chamber base 2 and a shaft 4 protruding from the base 2. Likewise, a manhole has a manhole base 2 and a shaft 4. The shaft 4 may also be referred to as a riser. The shaft 4 extends upwards from the manhole base 2. As shown, the manhole shaft 4 extends from the base 2 up to the top of the inspection chamber or the manhole. In this example, the top is open and a (not shown) suitable cover or grating can be provided at the top to close-off the top. When placed below ground, the shaft 4 provides an above ground (or at ground level) entrance to the base 2 underground, e.g. for visual inspection from outside the inspection chamber or manhole, or, depending on the specific dimensions, for inspection and/or maintenance equipment or a human to enter the manhole. The base 2 comprises a bottom and a circumferential wall extending upwards from the bottom. The shaft 4 is fixated to the circumferential wall of the base 2. In this example, the shaft 4 is a separate part removably fixated to the wall, but alternatively, the manhole shaft may be an integral part extending upwards from the wall. As show, the base 2, optionally together with the shaft 4, forms a chamber which is to be buried into the ground and accessible from the surface to inspect the water transport system of which the manhole 1 is part.

Whether a chamber is referred to as an inspection chamber or a manhole typically depends on the dimensions of the chamber. Inspection chambers typically have smaller dimensions, in particular, the diameter d of the base and/or shaft (in the x-y plane) determines whether the chamber is an inspection chamber or a manhole. An inspection chamber allows inspection equipment, such as cameras to be introduced typically via a shaft 4 for the purposes of inspecting the water treatment/sewage system. Typical diameters d of inspection chambers are 250mm, 300mm, 400mm, 600mm and 800mm. A manhole typically refers, as the name suggests, to an inspection chamber which is so dimensioned to allow a person to access the water treatment/sewage system. The sizes of manholes are standardized. A typical diameter d of a manhole (in the xy plane) is 800mm, 1000mm and 1250mm. The present invention is not limited with regard to any particular diameter d of base or shaft.

The inventors of the present invention have found that for larger conventional inspection chambers and manholes, for example, an inspection chamber having a diameter d of 600mm, the more expensive it becomes in terms of tooling to produce a base having a specific bend (change of direction). The present invention further addresses this problem.

In the embodiments described below and shown in the figures, the bases 2 and shafts 4 are those of either inspection chambers and manholes. All the embodiments herein described and shown are equally applicable to both applications (inspection chambers and manholes).

In embodiments of the present invention, for example, as shown in Fig. 2, the base 2 is formed as a stand-alone product. However, the invention is not limited in this respect. In alternative embodiments, the base 2 may be an inlayer arranged to be positioned in a substrate structure (not shown). The inspection chamber base/manhole base may be made of plastic. Further, the inlay may be made of plastic. In those embodiments having a substrate, the substrate structure may be made of plastic or concrete.

According to an embodiment of the present invention, the inspection chamber base 2 or manhole base 2 comprises a plurality of flow channels 6a, 6b, 6c. A flow channel is a channel through which a fluid flows. The flow channel has a starting point and an end point. The flow channels are dimensioned so that the fluid flowing in the channel has a flow profile. The flow profile describes the flow in the channel. Preferably, the flow profile is smooth (laminar). Preferably, the flow profile has low turbulence. In one embodiment, the flow channels have a circular cross section. One function of the inspection chamber base/manhole base is to change the direction of flow in the system. The inventors have found that in accordance with the present invention, the direction of flow through various angles can be achieved whilst maintaining a smooth (laminar) flow profile in the flow channel.

The base may further comprise an inlet port 8 and an outlet port 8, wherein a single, bent flow channel, described in detail below, extends from the inlet port 8 to the outlet port 8. As explained, the bent flow channel is obtained by selectively closing one or more of the flow channels to obtain a bent with a selected bent angle. In this respect, the bent angle is the angle between the direction of the flow at the inlet port, into the bent, and the direction of the flow at the outlet port, out of the bent. Each channel 6 has a respective port 8 located at an inlet/outlet region 10 of the base 2 from which the plurality of flow channels 6 extend. The port, for example, may be a cylindrical part. The ports 8 enable the flow channels to be open or closed, respectively.

According to an embodiment, the inspection chamber base/manhole base is manufactured so that the ports 8 are all closed in the first instance. When the inspection chamber base/manhole base is deployed, the ports 8 can be opened or remain closed in accordance with the particular application. Typically, therefore, the user opens or keeps the ports 8 closed depending on the situation of the deployment and the nature of the change in direction, the bend, required at the point of deployment.

According to an embodiment, the ports 8 are circumferentially distributed around the base 2 at unequal distances from each other. In the shown embodiments, the distance is different for each port and the successive port, or in a more mathematical manner for each pair of a port and the, in the circumferential direction, next port, the distance between the ports in the pair is different from those between the ports in the other pairs. In this example, the ports are located in the circumferential wall of the base, and the flow channels 6a, 6b, 6c extend from the respective port in the circumferential wall into the interior space of the base 2, defined by the circumferential wall. In this example, the flow channels extend inside the base 2, radially inwards from the respective port 8 in the wall. In this example the flow channels are parallel to the radial direction from the respective port to the centre of the base, and accordingly the flow channels 6 are at unequal angles with respect to each other. That is, for a given flow channel, the angle between that channel and another one of the channels is not the same for any of the other channels. In an alternative embodiment, the flow channels may be non-parallel to this radial direction, and e.g. converge in a point at a distance from the centre of the base 2. When the base is posited correctly, that is with the wall upright and extending vertically, the channels extend horizontally, but alternatively they may be slightly sloped, to facilitate gravity induced fluid flow in the respective channels.

Via the ports, the flow channels 6 inside the base 2 can be connected to pipes of the sewage and rainwater drainage system located, outside the inspection chamber or manhole. The inlet/outlet regions 10 are those regions where fluid enters or leaves the base, respectively. Each of the inlet/outlet regions 10 can function either as an inlet region or an outlet region depending on the flow and how the base 2 is connected in the system.

Further, the plurality of flow channels 6 are selectively closeable to form a single bent flow channel having a selected bend angle, as described in further detail herein below. ln embodiments, the inspection chamber base 2 or manhole base comprises a convergence region 12 at which the plurality of channels 6 converge. The inspection chamber base or manhole base may extend in a plane, for example, the xy plane shown in the Figs. However, the invention is not limited in this respect. It is not necessary for the base to be planar. In embodiments, the inlet/outlet region 10 is located at a periphery of the base 2.

Further, as shown in the embodiments, the convergence region 12 may be located in a central region of the base 2. In this example, the convergence region 12 is located inside the interior of the base, at a distance from the circumferential wall of the base. The flow channels 6a, 6b, 6c extend from the respective port in the circumferential wall into the interior space of the base 2 up to the convergence region 12. The channels extend in this example all radially inwards. The channels 6a, 6b, 6c form a spoke-like configuration, with the convergence region 12 forming the hub where the channels 6a, 6b, 6c are connected to each other to be in liquid communication. In one embodiment, the inlet/outlet region 10 and the convergence region 12 are located in or in the vicinity of the plane in which the base 2 extends. More specifically, in the shown examples the inlet/outlet region 10 and the convergence region 12 are at the same height from the bottom of the base 2. They are located seen in the vertical direction between the bottom of the base 2 and the top of the base, more specifically between the exterior bottom side of the base and the interior bottom of the inspection chamber or manhole (which is formed in this example by a bottom plate inside the base as explained below). However, the invention is not limited in this respect. Other arrangements wherein the inlet/outlet region 10 and / or the convergence region 12 are not located in or in the vicinity of the plane in which the base 2 extends and/or at different heights are also possible.

In embodiments, one or more or all of the plurality of flow channels 6 are upwardly open. In particular, the plurality of flow channels 6 may be open in a direction opposite to the direction of gravity. Thus, the upper side of the upwards open flow channel 6 is accessible from the top of the inspection chamber or manhole. In the shown example, when in operation, liquid flows in the bottom part of the upwards open channel, and the liquid level is below the upper edge of the channel. The liquid flow is thus confined to the channels, and the parts of the interior bottom of base outside the channels are not submerged in the liquid. As shown, each of the flow channels 6 is in this example formed by a recess in a bottom plate inside the base 2. As shown, the bottom plate is located at some height above the outside bottom of the base but forms and forms the bottom of the inside of the base 2. Said differently the bottom plate defines the bottom of the chamber which is at a distance from the outside bottom of the manhole 2, . With reference in particular, to Figs. 1 and 3 to 5, 12 and 13, the plurality of flow channels 6, 60 comprises a first flow channel 6a, 60a, a second flow channel 6b, 60b and a third flow channel 6c, 60c. An angle between the flow channels is determined by the angle between a radial direction from the port 8a, 80a of the first flow channel 6a, 60a to a centre of the base 2, 20, and a radial direction from the port of the respective second or third flow channel 6b, 60b, 6c, 60c and the centre.

Hereinbelow, where reference is made to an angle between flow channels, the angle is defined in a clockwise direction. For example, with reference to Fig. 6, there is a 135 degree angle between the fourth flow channel 160d and the second flow channel 160b in a clockwise direction. The angle in the anti-clockwise direction is 360 degrees minus the angle in the clockwise direction.

In further detail, Fig. 3 shows an embodiment of the present invention having a single flow channel 6a to 6b with a bend of 90 degrees. For example, with reference to Figs. 1 and 3, a single bent flow channel having a selected bend angle of 90 degrees is achieved by closing a flow channel 6c. The single bent flow channel extends from a first flow channel 6a to a second flow channel 6b (Fig. 3).

A single bent flow channel having a selected bend angle of 120 degrees is achieved by closing the first flow channel 6a. The single bent flow channel extends from the second flow channel 6b to a third flow channel 6c (Fig. 4).

A single, bent flow channel having a selected bend angle of 150 degrees is achieved by closing the second flow channel 6b. The single bent flow channel extends from the first flow channel 6a to the third flow channel 6c (Fig. 5).

The single bent flow channels 6a to 6b, 6b to 6c and 6a to 6c respectively, shown in Figs. 3 to 5 may also be described as curved. In embodiments, they are non-linear, that is they do not extend in a straight line. In other words, the fluid flowing in the single bend flow channels is subject to a change of direction.

In the embodiment shown in Figs. 1, 3 to 5, 12 and 13, an angle between the first flow channel 6a, 60a and the second flow channel 6b, 60b is substantially 90 degrees. Further, in this embodiment, the angle between the second flow channel 6b, 60b and the third flow channel 6c, 60c is substantially 120 degrees.

Further, in this embodiment, the angle between the third flow channel 6c, 60c and the first flow channel 6a, 60a is substantially 150 degrees.

In embodiments, the plurality of flow channels 6, 60 each have substantially the same width as each other in at least one of the inlet/outlet region 10 and the convergence region 12. Preferably, in some embodiments, between the respective port 8 and the convergence region 12, each flow channel is a straight channel. Also preferred is that each flow channel has a constant width from the inlet/outlet region 10 to the convergence region. In the embodiments of FIGs.3-5 for example, the width of the flow channels narrows from the respective port 8 to the opposite side of the inlet/outlet region, and then remains constant over an intermediate section which extends from the inlet/outlet region up to the convergence region. However, the invention is not limited in this respect. For example, in the embodiments shown in Figs. 12 and 13, preferably, in further embodiments, between the respective port 80 and the convergence region 120, each flow channel 60 is a curved channel.

As described above, the angle of the bend of the single flow channel may be one of 90 degrees, 120 degrees, 150 degrees. In a further embodiment described hereinbelow with reference to Figs. 6 to 11, the angle of the bend of the single flow channel may be one of 90 degrees, 120 degrees, 105 degrees, 135 degrees or 150 degrees.

The single bent flow channel may be continuous.

Fig. 3a shows a plug 14 according to an embodiment of the present invention. In embodiments, the inspection chamber base or manhole base 2 further comprises at least one plug 14 for closing at least one of the plurality of flow channels 6. Preferably, the plug 14 can be inserted via the top of the inspection chamber or manhole, which allows to configure the bend in-situ, after installation of the base in the ground and connection to the pipes. In the shown example, for instance, the plug can be placed in the selected flow channels from the open top side of the flow channels, and has a shape which fills and seals-off the respective channel

Preferably, the plug 14 comprises a first portion 14a which is configured to fit inside a third one of the plurality of flow channels 6 and a second portion 14b having a surface which is configured to face towards the convergence region 12. The surface 14b serves to join a first one of the plurality of flow channels with a second one of the plurality of flow channels. For example, in the embodiment shown in Fig. 3, the surface 14b is configured to join the first flow channel 6a with the second flow channel 6b. The plug 14 is configured to plug (close) the third flow channel 6c. The surface 14b provides a smooth transition between the second and first flow channel. More specifically, the surface 14b is shaped such that when the plug is placed inside the flow channel, it bridges the gap between the walls of the second and first flow channel, which gap is formedby the opening of the third flow channel. The surface 14b thus forms a smooth continuation of the walls of the second and first flow channel, and forms the wall of the bend flow channel in the gap between these walls. When the plug 14 is placed, the first and second flow channel are joined in the convergence region to form a single, bend flow channel with a smooth, stepless, interior wall, - li as can e.g. be seen in FIG. 3 c). The other flow channels 6a and 6b can also be closed with appropriately configured plugs as shown and described with respect to Figs. 4 and 5.

Fig. 3a i) shows a plan view (top view; bird ^' s eye view) of a plug, Fig. 3a ii) shows a side view of the plug shown in Fig. 3a i), Fig. 3b shows a plan view (top view; bird ^' s eye view) of an inspection chamber base or manhole base according to an embodiment of the invention, in which the plug 14 of Fig. 3a is shown in place to form a single flow channel having a bend of 90 degrees. Fig. 3c shows a side view of the inspection chamber base or manhole base of Fig. 3b in which a plug is in place.

The plug 14 may be made of a plastic material or other material suitable to close at least one of the plurality of flow channels 6. Depending on the bend angle of the single, bent flow channel, the dimensions of the plug will vary, as will the form of the surface to join the respective flow channels.

For example, Fig. 4 shows an embodiment of the present invention having a single flow channel 6b to 6c with a bend of 120 degrees. In particular, Fig. 4a shows a plug 16 according to an embodiment of the present invention. Fig. 4a i) shows a plan view (top view; bird ^' s eye view) of the plug 16, Fig. 4a ii) shows a side view of the plug 16 shown in Fig. 4a i). In particular, the plug 16 has a first portion 16a and a surface 16b. Fig. 4b shows a plan view (top view; bird ^' s eye view) of an inspection chamber base or manhole base according to an embodiment of the invention, in which the plug 16 of Fig. 4a is shown in place to form a single flow channel having a bend of 120 degrees. Fig. 4c shows a side view of the inspection chamber base or manhole base of Fig. 4b in which a plug is in place.

Fig. 5 shows an embodiment of the present invention having a single flow channel with a bend of 150 degrees. In particular, Fig. 5a shows a plug 18 according to an embodiment of the present invention. Fig. 5a i) shows a plan view (top view; bird ^' s eye view) of the plug 18. Fig. 5a ii) shows a side view of the plug 18 shown in Fig. 5a i). In particular, the plug 18 has a first portion 18a and a surface 18b. Fig. 5b shows a plan view (top view; bird ^' s eye view) of an inspection chamber base or manhole base according to an embodiment of the invention, in which the plug 18 of Fig. 5a is shown in place to form a single flow channel having a bend of 150 degrees. Fig. 5c shows a side view of the inspection chamber base or manhole base of Fig. 5b in which the plug 18 is in place.

In the embodiments shown and described with reference to Figs. 1, 3 to 5, 12 and 13, the inspection chamber base/manhole base 2 has three flow channels 6a, 6b, 6c, 60a, 60b, 60c. The present invention is not limited in this respect and may include any plurality of flow channels. For example, as shown and described with reference to Figs. 6 to 11, the inspection chamber base/manhole base 200 may have four flow channels 160 a, b, c, d. The inspection chamber base/manhole base 200 shown and described with reference to Figs. 6 to 11 is the same as that described with reference to Figs. 1 and 3 to 5, and differs in that rather than having three flow channels, the inspection chamber base/manhole base 200 has four flow channels. In as far as the inspection chamber base/manhole base 200 of the embodiment shown in Figs. 6 to 11 is the same as that shown in Figs. 1 and 3 to 5, the description with regard to Figs. 1 and 3 to 5 is referred to.

In particular, Fig. 6 shows a plan view (top view; bird ^' s eye view) of an inspection chamber base or manhole base 200 according to a further embodiment of the invention having four flow channels 160 a, b, c, d. In this embodiment, there is provided a first flow channel 160a, a second flow channel 160b, a third flow channel 160c and a fourth flow channel 160d. The four flow channels 160 converge in a convergence region 1200. The centre of the base 200 is located at the centre of the convergence region 1200. The angle between the first flow channel 160a and the second flow channel 160b is 90 degrees. The angle between the second flow channel 160b and the third flow channel is 120 degrees. The angle between the third flow channel 160c and the fourth flow channel 160d is 105 degrees. The angle between the second flow channel 160b and the first flow channel 160a is 150 degrees. The angle between the third and the second flow channel is 135 degrees. According to the embodiment of the invention shown in Fig. 6, two of the flow channels are closeable, for example, with an appropriately configured plug 140, 150, 170 (Figs. 7, 8 and 9) or two appropriately formed plugs 180, 190, 210, 220 (Figs. 10 and 11) to form a single, bent flow channel having a selected bend angle. In particular, Fig. 7 shows a further embodiment of the present invention having a single flow channel with a bend of 90 degrees. The plug 140 is a single plug. Fig. 8 shows a further embodiment of the present invention having a single flow channel with a bend of 120 degree. The plug 150 is a single plug. Fig. 9 shows a further embodiment of the present invention having a single flow channel with a bend of 105 degrees. The plug 170 is a single plug.

In the embodiments shown in Figs. 10 and 11, two flow channels are closeable with two separate plugs. In particular, Fig. 10 shows a further embodiment of the present invention having a single flow channel with a bend of 135 degrees. The two flow channels are closeable with two separate plugs 180, 190, respectively. Fig. 11 shows a further embodiment of the present invention having a single flow channel with a bend of 150 degrees. In Fig. 11, the two flow channels are closeable with two separate plugs 210, 220, respectively.

The plugs 140, 150, 170, 180, 190, 210, 220 of the embodiments shown in Figs. 6 to 11 are configured with the same considerations in mind as those plugs shown and described with reference to Figs. 3 to 5. In particular, they have a respective first portion disposable in a flow channel and a surface configured to face towards the convergence region 1200 and which serves to join two flow channels. In the embodiments, where only one plug is necessary, the one plug 140, 150, 170 provides this function. In the embodiments where two plugs are necessary to close the two respective flow channels, the combined effect of the two plugs is to provide a surface to join the two remaining flow channels.

In the embodiments described with reference to all figures, it is envisaged that a further flow channel may be needed depending on the deployment. For example, a period of time after installation of the base 2, the sewage and rainwater drainage system may be modified to connect a third pipe to the inspection chamber or manhole. In such a case, two ports are joined to form a single bent flow channel, also referred to as a mainstream channel, that is the channels extending from those ports are opened, or kept open, to converge in the convergence region and form the mainstream channel. The base may then be installed to connect these two ports to respective main pipes of the sewage and rainwater drainage system. To form the further flow channel, a third port is opened and the plug is removed. In the case where a single plug closes two flow channels, in such a situation, the single plug is replaced with one separate plug that closes of a single one of said two flow channels. To the third port, another pipe may be connected.

In a yet further embodiment of the present invention, an inspection chamber base/manhole base is provided, wherein between the respective port and the convergence region, each flow channel is a curved channel.

The inspection chamber b/manhole base 20 shown and described with reference to Figs. 12 and 13 is the same as that described with reference to Figs. 1 and 3 to 11, and differs in that rather than having straight (linear) flow channels, the inspection chamber base/manhole base 20 has curved flow channels. In as far as the inspection chamber base/manhole base 20 of the embodiment shown in Figs. 12 and 13 is the same as that shown in Figs. 1 and 3 to 11, the description with regard to Figs. 1 and 3 to 11 is referred to.

In particular, Fig. 12a shows a plan view (top view; bird ^' s eye view) of an inspection chamber base or manhole base 20 according to a yet further embodiment of the invention. According to this yet further embodiment, the inspection chamber base/manhole base 20 comprises a first curved flow channel 60a, a second curved flow channel 60b and a third curved flow channel 60c. The flow channels converge in a convergence region 120. The base 20 comprises inlet/outlet regions 100a, 100b, 100c corresponding to the first, second and third flow channels 60a, 60b and 60c, respectively. Similarly, the base 20 comprises respective ports 80a, 80b, 80c corresponding to the first, second and third flow channels 60a, 60b, 60c, respectively. Fig. 12b shows a side view of the inspection chamber base or manhole base of Fig. 12a.

As shown, each of the first, second and third flow channels 60a, 60b and 60c has curved side walls. The curvature of the side walls differs, such that one side wall of each flow channel is has a different bend than the other side wall. The flow channels widen from the respective port towards the centre of the base 2. In this example, the convergence region extends from the ports in the circumferential wall inwards to the centre of the base, and the channels do not have an intermediate section with constant width. As shown, the curvature of the side walls is such that pairs of the flow channels share a continuous side wall without sharp corners, with the total number of side walls the same as the number of channels. For instance, the first flow channel 6a and the third flow channel 6c share an arc-shaped side wall, the first flow channel 6a and the second flow channel 6b share an arc-shaped side wall, and the second flow channel 6b and the third flow channel 6c share an arc-shaped side wall.

Fig. 13 shows the inspection chamber base/manhole base 20 of Fig. 12 according to the yet further embodiment of the present invention. In particular, Fig. 13a shows a plug 230 according to a yet further embodiment of the present invention. Fig. 13a i) shows a plan view (top view; bird ^' s eye view) of a plug 230. As with the plugs of other embodiments, the plug 230 comprises a first portion 230a and a surface 230b. The first portion 230a and surface 230b are configured with the other embodiments. Fig. 13a ii) shows a side view of the plug 230 shown in Fig. 3a i). Fig. 13b shows a plan view (top view; bird ^' s eye view) of an inspection chamber base or manhole base 20 according to the yet further embodiment of the invention, in which the plug of Fig. 13a is shown in place to form a single flow channel having a bend of 90 degrees. Fig. 13c shows a side view of the inspection chamber base or manhole base of Fig. 13b in which a plug is in place. In Fig. 13b, the plug 230 is disposed in the third curved flow channel 60c. The single bent flow channel extends from the first flow channel 60a to the second flow channel 60b.

In Fig. 13 the arrangement is shown where the single flow channel has a bend of 90 degrees. It will be understood that, as described with reference to Figs. 3 to 5, it is possible to provide the same angled single bent flow channels as in Figs. 3 to 5 by adapting the plug and closing, rather than the third flow channel 60c (Fig 13b), the first or second channel 60a, 60b.

Further with regard to the plugs described above and shown in the Figures, in the embodiments shown, the dimensions of the plug are chosen in such a way as to fit in the entire flow channel. The invention is not limited in this respect, however. It is envisaged that the plug only closes the flow channel on the side of the convergence region 12, 120. The dimensions of the plug in these embodiments are configured so that the plug has the form of a partition or wall facing the convergence regionl2, 120. In this case, the partition or wall has a surface serving the same function as the plugs described above. In such further embodiments, the flow channel is still open as seen from above and closed on both sides by the partition or wall facing the convergence region 12, 120 and by a closed port at the end of the flow channel. With regard to all embodiments described above with respect to Figs. 1 to 13, preferably, at least one, and preferably all, ports are provided with an angle adapter (not shown), the angle adapter comprising a pivot joint between the base and a connector for a pipe. Preferably, the pivot joint has an angular pivot range of at least 10 degrees, or at least 15 degrees, or at least 30 degrees. The pivot joint may for example be implemented as described in Dutch application 2026033, filed 9 July 2020 in the name of Wavin B.V., the contents of which are herein incorporated by reference or as described in European patent application publication EP 1 141495, the contents of which are herein incorporated by reference. The angular adapter adapter provides a wider range of choice for the angle of the bend, and allows an angle which lies in an interval around the angle between the selected channels

Further, preferably, the bend angle of the single, bend flow channel is selectable in a continuous range between 0 and 180 degrees, or between 60 and 180 degrees. For example, with three channels each with a 15 degree (or more) angle adapter and the respective angles between the channels 6 being 90,120 and 150 degrees, the base 2 can be configured as a bend with a bend angle having any value in the range from 60 to 180 degrees. For example, with four channels each with a 22.5 (or more) degree angle adapter and the respective angles between the channels 6 being 45, 90,120 and 150 degrees, the base 2 can be configured as a bend with a bend angle having any value in the range from 0 to 180 degrees.

Further in the embodiments described above, with reference to Figs. 1 to 13, the plug is arranged to be insertable in the convergence region 12, 120. Preferably, the inspection chamber base/manhole base 2, 20, 200 further comprises: an inlet port 8, 80, an outlet port 8 and a pipe connection socket (not shown), wherein the pipe connection socket is connected to at least one of the inlet port 8, 80 and the outlet port 8, 80, wherein one of the plurality of flow channels 6, 60, 160 extends from the inlet port 8, 80 and the outlet port 8, 80, respectively, at an angle. Further preferably, the pipe connection socket comprises a pivot joint to connect a pipe into the socket, so that the pipe is pivotably connected to the at least one inlet port 8, 80 and the at least one outlet port 8, 80.

Further, in embodiments, for at least two pairs of, in circumferential direction, successive ports 8, 80 the distances differ, and wherein preferably each pair of successive ports 8, 80 has a different distance. Further, preferably, the single bent flow channel has an inlet channel 6, 60, 160 and an outlet channel 6, 60, 160, wherein the inlet and outlet channels 6, 60, 160 are a first one and a second one of the plurality of flow channels 6, 60, 160, respectively.

The invention is not limited to the embodiments shown and described above.