This patent relates to a pipe coupler, more particularly, a fire-stopping coupler for coupling a pipe system in a partition cavity and blocking the pipe system in the event of a fire. The invention also relates to a coupler for coupling and securing a pipe system in a partition cavity.

There are many instances where piping must pass through a partition such as a wall or floor. For instance, many buildings, particularly blocks of flats, have a vertical length of piping running from a ground level draining system to the top floor of the building that carries waste water. Such vertical plumbing arrangements are generally referred to as "soil stacks". In the event of a fire, the holes in the partitions through which these pipes pass can provide a means for fire to spread from one room or floor to another. This problem is particularly acute for floor/ceiling partitions,, due to the tendency of fire to spread upwards.

Throughout this specification, the expression "piping system" refers to a series of piping components defining a course for, for example, fluid to pass. Such a piping system may be substantially straight, or may take a winding path. Typical piping systems may have a number of branches. The expressions "axial", "radial", "circumferential", and their derivatives are to be taken with reference to the coupler or pipe overall and not with reference to any particular component. Therefore, where the terms are used in describing a component, they should be interpreted with reference to the component in situ within the coupler or upon the pipe, as appropriate.

A conventional soil stack 10 is shown in Figure 1. The soil stack 10 comprises lengths of pipe 1 provided with an integral socket 7. Each integral socket 7 is located in a hole in a concrete floor slab 2, which hole may be filled with mortar 8. The soil stack 10 may further comprises a branch fitting 5 on one or every floor. Each branch fitting 5 is shown to have a bottom connector that connects to the integral socket 7, a top connector that connects to a pipe 1 running vertically, and a lateral connector that connects to a plumbing components on the floor of the branch fitting 5 (for example, from a toilet).

The soil stack is fixed at every floor by means of a socket bracket 6 that is clipped around the respective branch fittings 5, and is secured to a suitable solid surface such as a wall.

A fire collar 9 is typically attached to the underside of each concrete floor slab 2 around the piping 1. A more detailed drawing of a conventional fire collar 9 is shown in Figure 2. The fire collar 9 comprises a metal case 13, which houses a ring of intumescent material 12. The fire collar 9 further comprises tabs 14 with fixing holes 15.

The term "intumescent material" refers to a class of materials that expands as a result of heat exposure.

In order to install the conventional fire collar 9, it must be clipped around the pipe 1 , and then be secured to the underside of the concrete floor slab 2 by means of the fixing holes 15 in the tabs 14.

In the event of a fire, heat causes the intumescent material 12 of the fire collar 9 to expand, so as to seal the piping system below the concrete floor slab 2 to stop the passage of fire through the hole in the concrete floor slab 2.

Such conventional fire collars 9 are associated with a number of problems. One such problem is that the fire collars 9 are difficult to install correctly. Depending on the relative dimensions of the hole in the concrete floor slab 2 and the tabs 14, the fixing holes 15 are either aligned with the underside of the concrete floor slab 2 or the underside of the mortar 8. In either case, the fixing surface for the fire collar 9 would often be uneven, for instance due to mortar or other building materials on this surface. It has been found in tests that if the fire collar 9 is not fixed entirely flush with the underside of the concrete floor slab, or more particularly if there is in excess of a 6 mm gap between the intumescent material 12 and the fixing surface, fire can pass through this gap without hindrance, thus destroying the collars' fire stopping capabilities. A further installation difficulty can arise if the fire collar 9 is to be secured to the mortar 8. Such mortar may often contain holes or voids, if not mixed properly. It may then be difficult to secure the fire collar 9, even with masonry anchor bolts.

Furthermore, soil stacks 10 are often located in relatively inaccessible parts of a building, such as in corners. Accordingly, there may be little space to work in order to fit such fire collars 9.

In addition, there is no guarantee that the installer will use an appropriate fixing for a fire collar 9. For example, an installer could use plastic rawlplugs. On a casual inspection the fire collar 9 would appear to be properly installed. However, in the event of a fire, plastic rawlplugs will melt causing the floor coupler 9 to fall from the underside of the concrete floor slab 2 long before the intumescent material 12 has had a chance to activate properly.

Hence, conventional fire collars 9 may be difficult to install properly and proper installation is very reliant on the skill and knowledge of the installer. As a result, the collars are often installed incorrectly, which may result in little or no fire protection.

In addition to the above issues relating to fire-stopping, conventional soil stacks 10 are associated with a number of other problems. One such problem is the need to fix the soil stack at set intervals (shown as on every floor in Figure 1).

Furthermore, when the soil stack 10 is installed, it is necessary to accommodate for thermal expansion in the system. Otherwise, different portions of the soil stack can expand at different rates, which can cause "creak", in which a loud noise emanates from the piping components as they expand at different rates. It can even cause damage to the components of the soil stack, which can lead to leaks from the piping system.

Typically, this thermal expansion is accommodated by withdrawing the lower connector of the branch fitting 5 by around 10 mm from the integral socket 7 and by fixing the branch fitting in this withdrawn position by means of a socket bracket 6. Whether such withdrawal is done correctly is entirely dependent on the skill of the installer. Conventional soil stacks are also associated with poor acoustic properties, as there may be structure-borne sound transfer from the concrete slab 2 to the pipes 1 and back again.

Although the above disadvantages have been discussed in relation to vertical soil stacks, it will be appreciated that many of these disadvantages apply just as equally to pipe running through holes in other partitions, such as walls. In particular, the need to fix the piping arrangement in place, prevent the spread of fire and reduce noise from one partition to the next is common to all such partitions between rooms or floors.

According to a first aspect of the invention, there is provided a fire-stopping coupler for joining two pipe portions in a pipe system, the coupler comprising: an inner body including a first socket for receiving a first pipe portion, the first socket comprising a first mouth and a first wall defining a first cylindrical bore, wherein in use a radially outer surface of the first pipe portion is adjacent the radially inner surface of the first wall, and a second socket for receiving a second pipe portion, the second socket comprising a second mouth and a second wall defining a second cylindrical bore; at least one layer of intumescent material arranged to extend at least partially around the radially outer surface of the first wall; wherein in the event of a predetermined temperature, the intumescent material is arranged to expand into the space previously defined by the first cylindrical bore so as to seal the pipe system.

The invention provides for a coupler featuring combined pipe joining and fire-stopping capabilities. Therefore, only one component is required to couple elements of a piping system and provide said system with fire-stopping properties. This facilitates installation and reduces the risk of errors. The coupler according to the invention can be secured in place during assembly of the pipe system. As a result, the fire-stopping properties will be guaranteed at the time of the construction of the pipe system, and are independent on the skill of installer. Moreover, no separate installer is required for installing a fire collar.

The intumescent material is arranged to overcome two layers of material during its expansion, namely that of the inner body and that of an inserted pipe portion. Thanks to such configuration the coupler can be of compact dimensions, especially its axial length. This may help to facilitate its installation. Furthermore, the intumescent material can be kept separate from the pipe-coupling components of the coupler. Depending on the material of the two layers (e.g. PVC or any other material) and the actual heat conditions during use, the expanding intumescent material may penetrate and flow through said layers and/or deform and collapse said layers.

To facilitate installation, the first and second socket can be of the push-fit type. The first or second pipe portion may be a spigot of a pipe fitting or a length of pipe.

In some embodiments, intumescent material can be provided around the cylindrical bores of both sockets. Accordingly, the fire blocking capacity of the coupler can be increased and prolonged, without substantially affecting the overall dimensions of the coupler, in particular its axial length.

A heat-retaining layer may be provided on an outer surface of the intumescent material. This heat-retaining layer can keep the intumescent material hot in the event of a fire, and therefore promote activation of the intumescent material.

The coupler may furthermore comprise a layer of acoustic foam, arranged to prevent direct contact between the inner body and the partition wall in which the coupler is mounted, in use. Accordingly, the acoustic foam can help to prevent structure-borne sound from propagating between the pipe system and the partition via the coupler. Alternatively, the intumescent material may act as acoustic layer.

In some embodiments, the coupler is arranged to constrain the expansion of intumescent material in the region of the second socket, so as to promote expansion of the intumescent material in the region of the first socket. This can help ensure an efficient breach of the cylindrical bore of the first socket and the first pipe portion.

In some embodiments, a ring seal is provided in one or both sockets for sealing the respective pipe portions.

In some embodiments, an expansion gasket is provided in one or both sockets for sealing the respective pipe portions. This provides the advantage that an installer does not have to take into account thermal expansion of the system. This simplifies installation, as it removes a further element from dependency on the skill of the installer. The expansion gasket may further help to constrain the abovementioned expansion of intumescent material in the region of said gasket. In some embodiments, the coupler may further comprise an outer casing. The outer casing may be arranged to fit in a hole in a partition through which the pipe system passes. The outer casing may comprise a plurality of flexible lugs adapted to be secured to a suitable fixing surface, such as the upper surface of a horizontal partition or any other adjacent wall. Accordingly, the lugs enable the coupler to function as an integral fixing bracket for the pipe system, removing the need for additional fixing means such as a socket bracket. This has the advantage that fewer components are needed, and that the bracketing of the pipe system becomes an automatic part of assembling the pipe system.

Furthermore, the outer casing may be secured to the remainder of the coupler by means of radially inwardly projecting teeth that contact acoustic foam and/or intumescent material.

According to a second aspect of the invention, there is provided a coupler arranged to secure a pipe system, the coupler comprising: an inner body including a first socket for receiving a first pipe portion and a second socket for receiving a second pipe portion, the first and second pipe portions forming at least part of said pipe system; an outer casing arranged to fit in a hole in a partition through which the pipe system passes, the outer casing including a plurality of flexible lugs adapted to be secured to a surface of the partition or another suitable surface so as to secure the pipe system in place.

In such embodiments, the coupler functions as an integral fixing bracket for the pipe system. Therefore, additional fixing means are not required.

According to a third aspect of the invention, there is provided a coupling system for joining two pipe portions in a pipe system that passes through a partition, the system comprising: a coupler according to any of the embodiments of the first or second aspects, wherein the coupler is arranged to fit in a hole in a partition through which the pipe system passes, the hole being located between first and second surfaces of the partition; a first plate arranged to be secured in the region of the first surface of the partition, the first plate including a hole through which the pipe system passes; and/or a second plate arranged to be secured in the region of the second surface of the partition, the second plate including a hole through which the pipe systems passes. The first and/ or second plate may be provided with a layer of intumescent material arranged to contact the partition when the plates are mounted.

The first and/or second plate may be arranged to be secured to the first, respectively second surface of the partition. Alternatively or in addition, the first and/or second plate may be secured to the coupler or a pipe portion. To that end, the plates may for instance be provided with flexible teeth arranged to establish an interference fit with the coupler or pipe portion. The coupler may be provided with a plurality of circumferential ridges that engage with hook portions provided on the flexible teeth. Additional fixing means may be provided to secure the teeth in place, for instance a surrounding band or ring.

The coupling system may be used in a horizontal partition, wherein the first surface of the partition is a lower surface and the second surface of the partition is an upper surface, and the second pipe portion in the pipe system is a lower pipe portion and the first pipe portion in the pipe system is an upper pipe portion. In such application, the upper plate can be provided with holes to allow the outer casing of the coupler to be attached thereto with its lugs. Accordingly, the partition itself does not need to be provided with holes for fixation of said lugs. Furthermore, the lower plate can serve to close off the gap between the hole in the partition and the coupler, eliminating the need to fill said gap with concrete or mortar.

Embodiments of the invention will now be described by way of example and with reference to the accompanying drawings in which:-

Figure 1 is a cross-sectional view of a known soil stack;

Figure 2 is a perspective view of a known fire collar;

Figure 3A is a cross-sectional view of a fire-stopping coupler in accordance with an embodiment of the invention;

Figure 3B is a perspective view of a fire-stopping coupler in accordance with an embodiment of the invention with a partially cut-away portion; Figure 4 is a cross-sectional view of a fire-stopping coupler in accordance with an embodiment of the invention showing the coupler used to join two pipe ends;

Figure 5 is a cross-sectional view of a fire-stopping coupler of Figure 4 showing how the expansion of intumescent material stops the spread of fire;

Figure 6 is a cross-sectional view of a soil stack using a fire-stopping coupler in accordance with an embodiment of the invention;

Figure 7 is a cross-sectional view of a fire-stopping coupler in accordance with an embodiment of the invention fixed in a joisted floor;

Figure 8 is a cross-sectional view of a fire-stopping coupler in accordance with an embodiment of the invention fixed in a stud wall;

Figure 9 is a cross-sectional view of a fire-stopping coupler in accordance with an embodiment of the invention fixed in a block wall;

Figure 1OA is a plan view of a fire-stopping top plate in accordance with an embodiment of the invention;

Figure 1OB is a side view of the fire-stopping top plate shown in Figure 10A;

Figure 11A is a plan view of a fire-stopping bottom plate in accordance with an embodiment of the invention;

Figure 11 B is a side view of the fire-stopping bottom plate shown in Figure 11 A;

Figure 12 is a cross-sectional view of a fire-stopping coupler in accordance with an embodiment of the invention used with a fire-stopping top plate and bottom plate in accordance with an embodiment of the invention; and

Figures 13-16 are partial cross-sectional views of alternative embodiments of a fire- stopping coupler according to the invention used with a fire-stopping top plate and bottom plate in accordance with the invention. A fire-stopping coupler 100 according to one embodiment of the present invention will now be described with reference to Figures 3-6. The coupler 100 comprises an outer casing 110. In this embodiment the casing 110 is made out of steel of 0.7 mm thickness. Of course, in other embodiments stainless steel or another suitable metal and/or other thicknesses could be used. The outer casing 110 is provided with flexible lugs 120, which each comprise at least one fixing hole 121 and 122. The flexible lugs 120 are shown in this embodiment as radially outwardly projecting flanges. The flexible lugs 120 can be bent so that the fixing holes 121 and 122 can be arranged to be adjacent a suitable fixing surface, as will be discussed in more detail below.

The coupler 100 comprises an inner body 130 which in this embodiment is made out of PVC-u. Other suitable material could be used. Suitable plastics materials include: PVC, polyurethane or high-density polyethylene.

The inner body 130 is provided with a first socket 131 for receiving a first pipe end 1a and a second socket 135 for receiving a second pipe end 1 b in the manner shown in Figure 4. The first socket 131 comprises a first mouth 132, a wall portion defining a first cylindrical bore 133, and a radially inwardly projecting abutment 134 defining the end of the cylindrical bore 133. The bore 133 in this embodiment has an inner diameter that is substantially equal to the outer diameter of the pipe end 1a. The first mouth 132 comprises a ring seal 170 for sealing the pipe end 1a in the first socket 131.

The second socket 135 comprises a second mouth 136, a wall portion defining a second cylindrical bore 137, and a stepped portion with two flanges 138 and 139 defining the opening of the second mouth 136. The second cylindrical bore 137 is provided with an expansion gasket 180, comprising a radially inwardly projecting abutment 181 for the pipe end 1b and a radially outwardly projecting abutment 182 that in use abuts against the flange 138 of the second socket 135. The expansion gasket 180 is dimensioned to provide a close fit with the pipe end 1 b to as to seal the second pipe end 1 b in the second socket 135. The expansion gasket 180 may for instance be made out of rubber so as to accommodate pipe expansion in the axial direction.

Between the inner body 130 and the outer casing 110, there may be provided a number of layers. In this embodiment, there is provided a layer of intumescent material 140, which in this embodiment extends circumferentially around the first and second socket 131 , 135. The intumescent material 140 may be formed as a single block or layer. Alternatively, the intumescent material 140 may comprise several layers, as illustrated in Figure 4, wherein a first most inner layer 141 extends circumferentially around the wall portion that defines the first cylindrical bore 133. The first layer 141 may have a thickness of for instance 2 mm. The first layer 141 may be surrounded by further layers of intumescent material, such as for instance a second, third and fourth layer 142, 143, 144 respectively, which each may have a thickness of for instance 4 mm.

The or each layer of intumescent material 140 may have the form of a flexible strip. The layer may be made from a carrier loaded with a suitable percentage of graphite particles, preferably treated exfoliating graphite. The carrier may for instance be a PVC, preferably a soft grade PVC. Other suitable carriers include polyurethane or hard grade PVC. Of course the carrier can also be composed of two or more of the aforementioned materials or any other suitable materials. The graphite loading may be chosen depending on the required expansion characteristics in combination with the given characteristics of the selected carrier material. The graphite loading can for example range from about 10%-50%. At graphite loadings of over 50%, the finished material may be too brittle, and at graphite loadings of under 10%, the material may not undergo sufficient expansion on activation. A particularly useful range of graphite loadings has been found to be 40-50%.

The intumescent material 140 is surrounded by a layer of aluminium foil 150. In the illustrated embodiment, a layer of 30 micron Aluminium foil is used. However, other thickness or more than one layer could be used. For example, in some embodiments, two 30 micron layers of Al foil could be used. Two layers of Al foil could be used in this way, because two layers of thin foil is more pliable than one layer of thicker foil. Alternatively, it will be appreciated that any suitable material could be used in place of the Al if a heat-retaining layer is used.

The layer of aluminium foil 150 is in turn surrounded by a layer of acoustic foam 160. This layer 160 extends around the flange 139 of the second mouth 136. In the illustrated embodiment the layer has a thickness of 2 mm. Of course, other thicknesses are possible. The layer 160 may for instance be made from polyethylene or any other suitable plastic foam. The outer casing 110 is provided with radially inwardly directed teeth 112 that contact the acoustic foam 160, and radially inwardly directed teeth 111 that contact the sides of the intumescent material 140 that are proximate the first mouth 132. The teeth 111 and 112 secure the inner body 130, the outer casing 110 and the various intermediate layers together. In this way, there is no direct contact between the outer casing 110 and the inner body 130.

In use, a coupler 100 according to the invention may be arranged in a soil stack as shown in Figure 6. Like in Figure 1 , the soil stack 20 comprises lengths of pipe 1 that pass through concrete floor slabs 2, and couplers 100 according to the invention, installed in respective holes in the concrete floor slabs 2. On each floor there may be a branch fitting 5, which can be a conventional branch fitting of the type discussed in relation to Figure 1.

To install a length of pipe in the coupler 100, the expansion gasket 180 is removed from the second socket 135 and placed over the end 1b of the pipe from the floor below. No chamfering of the pipe end 1 b is required, but it is desirable to remove any burrs that may be present before placing the expansion gasket 180 over the pipe.

The expansion gasket 180 is then pushed along the length of the pipe until the pipe end 1b abuts against the radially inwardly projecting abutment 181 of the expansion gasket 180.

Next the expansion gasket 180 with the pipe end 1b is inserted into the second socket 135 of the coupler 100 until the radially outwardly projecting abutment 182 of the expansion gasket 180 abuts against the flange 138 of the second socket 135. The installer does not need to bother about leaving appropriate expansion gaps, as this is taken into account automatically by the use of the expansion gasket 180. To facilitate insertion, lubricant may be applied between the gasket 180 and the second socket 135.

Next, a spigot of a branch fitting 5 or lower end 1a of a pipe length is inserted into the first socket 131 of the coupler 100, and the maximum insertion depth is reached when the spigot or pipe end 1a abuts against the radially inwardly projecting abutment 134 of the first socket 131. The first socket 131 and the second socket 135 of the inner body 130 therefore provide a push-fit coupler for the two pipe ends 1 a and 1 b.

The coupler 100 can be fixed in the hole by fixating the lugs 120 to the upper surface of the floor slab 2 by means of the holes 121, 122 and suitable fixing means. In contrast to conventional fire collars 9, a large range of fixing means can be used, for instance plastic rawl plugs, as these fixing means will not come into contact with fire from the floor below, Of course, it is not necessary to fix the coupler 100 using both fixing holes 121 and 122 on each lug 120.

Thanks to the fixing lugs 120 the coupler 100 can function as an integral fixing bracket, removing the need for additional fixings. Therefore, in contrast to the arrangement of Figure 1 , no additional socket brackets 6 are required.

As shown in Figure 6, mortar 8 can be used to fill the gap between the hole in the concrete floor slab 2 and the outer casing 110 of the coupler 100. The use of mortar 8 is not essential. For example, a fire-stopping foam or mineral rockwool could be used in place of the mortar 8. In some arrangements, the outer casing 110 may sit flush with the hole in the concrete floor slab 2, if for example the hole has been dimensioned accurately to match the dimensions of the outer casing.

As for conventional soil stacks, the lengths of pipe 1 between the couplers 100 may be covered with mineral rockwool 11. Preferably, a gap of about 50 mm is left between the rockwool 11 and the underside of the coupler 100, to allow heat to be transmitted to the fire-stopping coupler 100 to activate the intumescent material 140.

One problem associated with conventional fire couplers is that the intumescent material has a tendency to self-insulate from heat, because the expanding intumescent material will act as an insulating buffer preventing the heat from activating the remaining intumescent material. In a setup according to Fig. 6, where heat will spread upward, this would result in only a lower portion of the coupler being activated. It will be appreciated that this may result in poor fire stopping.

In a coupler according to the invention this problem is overcome or at least reduced by encouraging the intumescent material 140 to preferentially expand and flow towards the cylindrical bore 133 of the first socket 131. This is achieved in a number of ways. One way is to constrain expansion in the other directions. Expansion in axial direction is constrained by the flanges 138 and 139 at the lower end and teeth 111 of the casing 110 at the upper end. Expansion in radial outward direction is constrained by the aluminium foil 150, acoustic foam 160 and casing 110. Expansion in radial inward direction in the region of the second socket 135 is constrained by the gasket 180.

The flow towards the cylindrical bore 133 of the first socket 131 is furthermore enhanced by the first most inner intumescent layer 141 which is arranged to extend around the first socket 131 only.

Furthermore, the rubber gasket 180 helps to slow activation of the intumescent material that surrounds it, that is the intumescent material at the lower end of the coupler. The gasket 180 further helps to slow collapse of the second socket 135. When exposed to the heat from a fire, the inner body 130 and the gasket 180 will char and deform. However, the rubber expansion gasket 180 will char at a different rate than the PVC inner body 130. This will help to slow the charring and collapsing of the second socket 135.

The material of the first socket 131 and the pipe end 1a will char and deform and the radially inward expansion of the intumescent material will eventually cause the layer 141 to flow into the cylindrical bore 133 of the first socket 131 and past the material forming the radially outer surface of the pipe end 1a. The intumescent material continues to expand, eventually sealing the pipe system as shown in Figure 5. The mass of intumescent material then forms a complete fire seal, blocking the upwards passage of fire through the pipe system.

Hence, in the even of a fire, the intumescent material 140 flows past or through two layers of material to block the piping system. In contrast, conventional arrangements such as fire collars only have the intumescent material overcoming one layer of material, this layer being the pipe.

Furthermore, the intumescent material 140 may have a large PVC component. As the intumescent material 140 activates, it can mix with the charring PVC-u material of the inner body 130 and possibly with the material of the pipe as well. The aluminium foil layer 150 increases the heat on the outer edge of the fourth layer 144 of intumescent material, preventing the intumescent material from self-insulating itself and encouraging it to activate. Therefore, the intumescent material continues to exfoliate and char across the two layers of burning PVC materials of the pipe and the cylindrical bore 133 of the first socket 131.

As the intumescent material according to the invention can be controlled to flow through or past two layers of material, said material can be arranged around one or both sockets 131 , 135 of the coupler and the pipe ends 1a,b inserted therein. Thanks to such arrangement, the inner body 130 of the coupler 100 according to the invention can have sockets of the push-fit type. Furthermore, the coupler can be of compact dimensions, especially in axial direction. This may facilitate installation, because an installer will have more space to work with.

The acoustic foam layer 160 prevents direct contact between the metal outer casing 110 and the PVC-u inner body 130 and thus helps to prevent structure-borne sound from propagating between the concrete floor slab 2 and the pipes 1 via the coupler 100.

Figure 7 shows use of a coupler 100 according to the invention in an alternative type of floor 200. This floor 200 is a conventional plasterboard and timber floor in which the floor is supported by timber floor joists 210.

In this arrangement, the coupler 100 is placed in a hole in the plasterboard and timber floor 200 and is secured in place by means of the flexible lugs 120. Preferably, at least two flexible lugs are each secured to a timber floor joist of the floor 200 by means of a suitable fixing means through the fixing holes. The use of the flexible lugs 120 enables the coupler to be used with different joist spacings. As shown in Figure 7, the joists 210 and 211 are located at a set spacing and the flexible lugs are bent so that the fixing holes 121 are arranged so as to be flush with the top surface of two joists 210 and 211.

In Figure 7, the coupler 100 projects slightly below the lower surface of the hole in the floor 200 so as to enable the fixing holes 121 of two lugs to reach the top surface of the two joists 210 and 211. Should, however, the two joists 210 and 211 be located at different distances from each other, then by raising or lowering the coupler and bending the lugs 120, it can be assured that either the fixing holes 121 and/or the fixing holes 122 can be arranged flush with the top surface of the joists 210 and 211. Alternatively, the lugs 120 could be bent so that either or both of the fixing holes are arranged to be flush with the sides of a joist.

To fill the gap between the hole in the floor 200 and the casing 110, fire-stopping foam 80 is used in this embodiment. In other embodiments a fire stopping mastic may be used, mineral rockwool, or another suitable material.

It is noted that a coupler according to the invention does not require all of the features discussed above in relation to the Figures. For example, in some embodiments the acoustic foam 160 is not required, if for example, the acoustic properties of the system are secondary to, for example, the fire stopping. In some embodiments the layer of aluminium foil 150 may be omitted or its function may be taken over by the metal casing 110. In some embodiments, the ring seal and/or expansion gasket may be replaced by any known means for effecting a seal between the coupler and the pipe ends. For example, instead of an expansion gasket, a further ring seal could be used in the second socket. In some embodiments, the lugs 120 may be omitted.

Furthermore, some embodiments of the invention do not require an outer casing. An example of such an embodiment could include a coupler of push-fit type that is provided with a wrap of intumescent material around one or both socket(s) of the coupler. Such a coupler could be placed in a hole in a concrete floor slab, with mortar or fire-stopping foam used to fill any gaps between the hole and the wrap of intumescent material. Such an embodiment may be provided with or without aluminium layer and/or acoustic layer.

Such a coupler could be provided with a means for directing expansion of the intumescent material. For example, a rubber o-ring could be provided around the wrap of intumescent material in the region of the cylindrical bore of the second socket. In a similar way to the expansion gasket 180, such a rubber o-ring could constrain the expansion of the intumescent material in the region of the cylindrical bore of the second socket, causing preferential expansion in the region of the cylindrical bore of the first socket. Other means for causing the intumescent material to preferably expand in the region of the cylindrical bore of the first socket could be provided. The simplest implementation would simply be to only provide intumescent material around the cylindrical bore of the first socket, with mortar or fire-stopping foam surrounding the rest of the outer surface of the coupler.

In addition, some embodiments of the invention may be solely concerned with fixing the coupler in place, and not with fire stopping. An example of such an embodiment includes a coupler of the push-fit type that is similar to that shown in Figures 3A and 3B, but without the intumescent, aluminium and acoustic layers between the inner body and the outer casing. Such a coupler could be placed in a hole in a concrete floor slab or other suitable partition, with mortar, fire-stopping foam, or fire-stopping, mastic used to fill any gaps between the hole and the outer casing. The coupler could then be fixed to the surface of the concrete floor slab or another suitable surface by means of lugs on the casing in the way discussed above in relation to Figure 6.

In such embodiments, the coupler would provide an integral fixing bracket for the pipe system. Therefore, additional fixing means such as the socket brackets 6 shown in Figure 1 would not be required. If such an arrangement was used in conjunction with an expansion gasket for one of the sockets of the coupler, this would also mean that the installer would not need to take into account thermal expansion of the system, again easing installation.

It will be appreciated that while the present invention has been thus far described in relation to piping in a vertical soil stack, the present invention is applicable to any piping components that pass between a floor/ceiling partition in a building or vertical partitions between two rooms on the same floor.

Figure 8 is a cross-sectional view of a fire-stopping coupler in accordance with an embodiment of the invention fixed in a stud wall. The illustrated stud wall comprises 15 mm board 500 with a block 510, wooden studs 520 and metal stud noggins 530. A coupler 100 is shown joining two pipe lengths through a hole in the stud wall, with the coupler located between two studs. The lugs of the coupler 100 are fixed to an outer surface of the board 500. An intumescent sealant 512 is used to fill any space between the coupler and the hole in the wall partition. Other embodiments could use an alternative sealant.

Figure 9 is a cross-sectional view of a fire-stopping coupler in accordance with an embodiment of the invention fixed in a block wall 550. The block wall 550 is provided with a hole in which a coupler 100 is provided to join two pipe lengths 1. The lugs of the coupler 100 are fixed to an outer surface of the block wall 550. In this embodiment, a fire stopping foam 80 is used to fill any space between the coupler and the hole in the wall partition. Other embodiments could use an alternative sealant.

Figures 10A, 10B show a fire-stopping top plate 300, and Figures 11 A, 11 B show a fire-stopping bottom plate 350, which can be used in conjunction with a coupler according to any of the embodiments of the invention.

The top plate 300 is a generally annular disc with a central hole 301. The top plate can for instance be made from 0.7 mm steel. A series of radial slits 303 is provided that run radially outwardly from the hole 301. The radial slits 303 define teeth 302. A number of fixing holes 321 and 322 is provided between the slits 303 and the outer edge of the top plate 300. The under surface of the top plate 300 can be coated with intumescent material 341 and the opposite surface 305 may be free from intumescent material. The outer edge of the top plate 300 comprises a series of radial notches that help keep the metal flat during the forming of the top plate 300.

The bottom plate 350 is a generally annular disc with a central hole 351. The bottom plate may be made from 0.7 mm steel. A series of radial slits 353 is provided that run radially outward from the hole 351. The radial slits 353 define teeth 352. A number of fixing holes 361 is provided between the slits 353 and the outer edge of the bottom plate 350. One surface of the bottom plate 350 is coated with intumescent material 342 in this embodiment, and the opposite surface 355 is free from intumescent material.

Figure 12 shows schematically a coupler 100 according to an embodiment of the invention used with top and bottom plates of the type shown in Figures 10A, 10B, 11A and 11 B. The coupler is mounted in a hole in a concrete floor slab 2. The gap between the hole and the outer casing may be filled by fire-stopping foam 80. The coupler 100 is shown as joining a pipe 1 to a spigot of a boss manifold 51.

The top plate 300 is arranged to sit around the hole in the concrete floor slab 2. Its surface that comprises the intumescent material 341 is in contact with the upper surface of the concrete floor slab 2. The coupler 100 in Figure 12 is shown as comprising lugs 120 that project from its outer casing. The lugs 120 are bent so that they lie flush with the surface 305 of the top plate 300 that is not coated with intumescent material. In this embodiment, the fixing holes 121 , 122 of the lugs 120 of the coupler 100 are arranged so that they line up with the holes 321 and 321 in the top plate 300 when the top plate 300 is installed.

The bottom plate 350 is arranged to sit around the hole in the concrete floor slab 2, with its surface that comprises the intumescent material 342 being in contact with the under surface of the concrete floor slab 2. The bottom plate 350 can be secured to the under surface of the concrete floor slab 2, using suitable fixing means (such as masonry anchor bolts) via the fixing holes 361.

The teeth 352 of the bottom plate 350 are bent towards the coupler 100 and extend over the outer surface of the pipe in this embodiment. This helps close off any gap between the outer surface of the pipe and the lower opening of the hole in the partition. The teeth 352 grip the pipe and hold the bottom plate 350 in place during installation, before the bottom plate 350 is fixed in place.

The top plate 300 and bottom plate 350 may each provide a number of advantages. They can provide extra fire safety. Due to the intumescent material 341 , 342 the plates 300, 350 provide the overall system with greater fire-stopping capabilities. This is particularly useful to stop fire progressing around the outer side of the coupler 100 in the space between the coupler and the hole in the partition (i.e. bypassing any fire- stopping capabilities of the coupler). In such a situation, the intumescent material 341 , 342 will react, sealing off the hole. This may be particularly useful if a fire-stopping foam were used to fill any space between the coupler and the hole in the partition, as such fire-stopping foam may be less fire resistant than mortar. Furthermore, in some arrangements, the fire-stopping capabilities of the intumescent material 341 , 342 on the plates 300, 350 may be sufficient to enable the installer to omit any material between the coupler and the hole in the partition.

The intumescent material 341 , 342 also has acoustic dampening properties, which further helps to reduce noise from being transmitted from the floor to the piping system.

Furthermore, the intumescent material 341 , 342 is typically flexible. When the top plate 300 is fixed in place, this flexibility may help to accommodate for any unevenness in the floor's top surface. The top plate 300 can operate as a secure base for the lugs 120 of a coupler 100. This is particularly useful where the hole in concrete floor slab 2 or other floor type is uneven, for instance in case where a jackhammer has been used to create the hole.

The bottom plate 350 can aid the installation of the coupler 100 into holes that are filled with mortar or equivalent materials. The bottom plate 350 can act as framework, as a substitute to a timber frame, so that when mortar is poured into the hole, it is retained in the hole by the bottom plate 350.

It will be appreciated that numerous modifications to the top and bottom plates could be made. For example, the intumescent could be omitted or replaced by foam to accommodate an uneven upper surface of the floor slab and/or to provide acoustic dampening properties.

Furthermore, a bottom plate 350 can advantageously be used with conventional fire- stopping means (for example, a fire collar 9 of the type shown in Figure 2). The bottom plate 350 can provide a secure fixing point for the fire collar 9 rendering it significantly easier to install. Even if the bottom plate 350 were fixed imperfectly, for example with a gap greater than 6 mm, such a gap would be closed in the even of a fire by the activation of the intumescent material 342. Also, the flexibility of the intumescent material 342 may help to accommodate for any unevenness in the underside of the floor, thereby further reducing any problems with gaps.

Figure 13 illustrates the installation of a top plate 300 and bottom plate 350 as respectively shown in Figures 10A, 10B and Figures 11A, 11 B. The teeth 303 of the top plate 300 are bent towards the coupler 100 and extend over the outer casing of the coupler 100. This is beneficial, as it helps close off any gap between the outer casing of the coupler 100 and the hole 301 in the top plate 300.

Likewise, the teeth 352 of the bottom plate 350 can be bent towards the coupler 100 and extend over the outer casing of the coupler 100. In this embodiment, the bottom plate 350 would then be held in place as a result of an interference fit between the teeth 352 and the outer casing of the coupler 100. The teeth 352 may be provided with hook sections 354 near their ends, to help ease the attachment of the teeth 352 around the outer casing. They may obviate the need for fixing means such as anchor bolts for securing the bottom plate 350 to the under surface of the floor partition. Of course, as an option, fixing holes 321 and 322 (as shown in Figure 13) may be provided to enable the fixing of the bottom plate 350 to the under surface of the partition. In other embodiments, the hook sections 354 may be omitted.

Figure 14 shows an alternative attachment mechanism for the bottom plate 350. The outer casing of the coupler 100 is provided with a number of circumferential ridges 190, which provide locations for the hook section 354 of the teeth 352 to clip on to. This may render the fixation of the bottom plate 350 more secure than the arrangement shown in Figure 13.

Figure 15 shows another attachment mechanism for the bottom plate 350, wherein a metal band 600 is placed around the outer surface of the teeth 352, pressing the teeth against the outer surface of the coupler 100. The metal band 600 may be provided with a toggle fixing (not shown). Of course, other ways of fixing the metal band 600 around the teeth 352 could be used.

Figure 16 shows yet another attachment mechanism for the bottom plate 350. In this arrangement, a ring band 650 is placed around the outer surface of the teeth 352 once the bottom plate 350 is arranged around the outer surface of the coupler 100. The ring band 650 is provided with a bayonet fixing (not shown). Once in place the ring band 650 will compress each of the teeth 352 so as to keep the bottom plate 350 in place. Alternatively, other ways of fixing the ring band 650, for example a linking pin arrangement, could be used.

In case where the coupler 100 is arranged to be flush with the under surface of the partition wall, the bottom plate 350 may prevent an installer from plastering over the bottom of the coupler 100. Such plastering could insulate the intumescent material 140 in the coupler 100 from heat, thus preventing its proper activation in the event of a fire.

The top and bottom plates 300, 350 can be of similar design, so as to be interchangeable, thereby reducing the number of different components. Furthermore, only one plate could be used, either at the top or bottom.

Many further modifications and variations will suggest themselves to those versed in the art upon reference to the foregoing illustrative embodiments, which are given by way of example only and which are not intended to limit the scope of the invention, that being determined by the appended claims.