Improvements in or relating to flap valves

Abstract

Flap valve 1 comprising a valve body 10 having a flow opening 20, a flap 30 attached to an upper portion of the body by a hinge, and a seal 100 which fits in the flow opening and comprises a tubular b

Description

Technical Field of the Invention The present invention relates to improvement in or relating to flap valves. In particular, the present invention relates to improved sealing and / or improved construction of flap valves. Background to the Invention Flap valves are one-way valves, generally installed at an end of a fluid conduit such as a pipe or culvert. The flap valve allows fluid to exit the pipe or culvert, whilst preventing rising external fluid water levels flooding back into the pipe or culvert. Flap valves comprise a valve body adapted to be mounted on a support structure, which may be the conduit itself, an adjacent wall or other support structure. The valve body has a flow opening corresponding to the end of the conduit. In use, the valve body is mounted such the flow opening is aligned with the end of the conduit so fluid can flow from the end of the conduit through the flow opening. A flap member is attached to an upper portion of the valve body by a hinge mechanism. The weight of the flap member causes the flap member to hang in a closed position covering the flow opening and thereby blocking the exit of fluid from the conduit. A flow of fluid from the conduit urges the flap member away from the flow opening allowing the fluid to exit the conduit. External fluid, in contrast, acts against the flap member moving away from the flow opening. Flap valves incorporate a seal between valve body and the flap member, the seal surrounding the opening and usually spaced apart from the edges of the flow opening. Typically, this comprises a seal projecting from the valve body, such as a lip seal. Optionally, a similar seal may instead be provided on the flap member or indeed interacting seals may be provided on both valve body and flap member. Such seals are typically integrated into the valve body / flap member or are secured in position by use of adhesive. In many instances an additional seal is also provided on the rear of the valve member or on sections of the valve member adapted to fit on to the conduit itself, an adjacent wall or other support surface. Whilst these options can provide effective sealing, if the seal becomes damaged or fails, repair can be difficult if not impossible. Consequently, the whole valve may be replaced when a seal fails. Similarly, it may be impractical for a seal to be fitted to a valve on site, limiting the options for unskilled assembly or assembly from a kit. In existing flap valves, the hinge mechanism is constructed by welding or bolting hinge mounts into slots provided on the valve body. This is time consuming and cumbersome for the assembler. It also limits the potential for supply of the valve as a kit assembly on site and / or the attractiveness of facilitating repair of a damaged hinge mechanism. Accordingly, damage to the hinge mechanism can result in replacement of the whole valve. In many flap valves, the flap member further comprises a biasing weight. This helps ensure that mass of the flap member is sufficient to urge it into a closed position. Typically, as with the hinge mounts, the biasing weight is attached by welding or bolting hinge mounts into slots provided on the flap member. Similarly to the hinge mounts, this is time consuming and cumbersome for the assembler whilst limiting the potential for supply of the valve as a kit assembly on site and / or the attractiveness of facilitating repair of a damaged hinge mechanism. It is therefore an object of the present invention to provide a flap valve that at least partially overcomes or alleviates some of the above problems. Summary of the Invention According to a first aspect of the present invention, there is provided a flap valve comprising: a valve body having a flow opening; a flap member attached to an upper portion of the valve body by a hinge mechanism so as to be movable between an open position and a closed position where the flap member covers the flow opening; and a seal adapted to fit within the flow opening, the seal comprising a tubular body with a flap end and conduit end, the flap end having an externally projecting flap end flange and the conduit end each having an externally projecting conduit end flange. In the present invention, the respective flap end flange and conduit end flanges can hold the seal securely in position within the flow opening, whilst the tubular body provides an internal flow passage within the flow opening. Furthermore, the flap end flange can provide a seal between the valve body and the flap member when the flap member is in the closed position. Similarly, the conduit end seal can provide a seal between the valve body and the adjacent wall or support structure, when the valve member is mounted in position. Beneficially, both seals are close to the edges of the flow opening. Additionally, fitting the seal (or replacing a damaged seal) is very straightforward even without specialised equipment. This has the further benefit, of facilitating supply of the valve in kit form. This has the benefit of increasing repair options by reducing the need for the replacement of whole valves and thus providing an environmental benefit for the present invention. The flap end flange may have a thickness of the same order as the seal body. In some embodiments, the flap end flange may be thinner than or thicker than the seal body. The flap end flange may project externally for a distance greater than the thickness of the flap end flange. In some embodiments, the flap end flange may project externally for a distance in the region of 3-15 or 2-10 or 3-5 times the flap end flange thickness. The flap end flange may be provided with one or more enhanced sealing formations. The enhanced sealing formations may be provided on a flap member side of the flap end flange. The enhanced sealing formations may form a complete loop on the flap member side of the flap end flange. In this manner, the enhanced sealing formations may surround the inner passage of the tubular body. The enhanced sealing formations may comprise one or more flexible lips. Each said lip may project away from the flap side of the flap end flange radially and / or axially relative to the tubular body. In one embodiment, there may be two lips projecting in different directions. In such embodiments, the two lips may define a channel therebetween. The conduit end flange may have a thickness of the same order as the seal body. In some embodiments, the conduit end flange may be thinner than or thicker than the seal body. The conduit end flange may project externally for a distance greater than the thickness of the conduit end flange. In some embodiments, the conduit end flange may project externally for a distance in the region of 1-15, or 2-10 or 3-5 times the conduit end flange thickness. The conduit end flange may be provided with one or more gripping formations. The gripping formations may be provided on a conduit side of the conduit end flange. The gripping formations may form a complete loop on the conduit side of the of the conduit end flange. In this manner, the gripping formations may surround the inner passage of the tubular body. The gripping formations may comprise a series of ridges and / or grooves. In one embodiment, the gripping formations may comprise a series of ridges defining grooves therebetween. Each said ridge may have substantially the same cross-section. In particular embodiments, each said ridge may have a semicircular or semi oval crosssection. The exterior of the tubular body may be adapted to closely fit against the flow opening. To facilitate this, the tubular body may have an external cross-section substantially matching the cross-section of the flow opening. In many embodiments, the flow opening may have a substantially circular cross-section and thus the tubular body may have a substantially circular cross section. In other embodiments other crosssections such as oval, square, rectangular, trapezoid or variations upon shapes may be substituted. The tubular body may have an axial length corresponding to the thickness of the valve body. In this manner, the respective flap end and conduit end flanges closely fit against the flap side and conduit sides of the valve body when the seal is installed. The tubular body may have a substantially constant thickness along its axial extent. In this manner, the interior of the tubular body may define a flow passage within the flow opening, when the seal is installed. The seal formed from any suitable material. In particular, the seal may be formed from an elastomeric material. Suitable seal materials include but are not limited to EPDM (ethylene propylene diene monomer); PVC (polyvinyl chloride), Silicone, Rubber; Styrene-Butadiene Rubber (SBR); Nitrile Rubber; Neoprene; or the like. The seal may be formed from a single material. The seal material may vary in hardness between different parts of the seal. In one such embodiment, the tubular body and the flap end flange may be formed from a harder material and the conduit end flange may be formed from a softer material. This beneficially allows greater compression of the conduit end flange than the other parts of the seal. This helps maintain an effective seal between the valve body and a support surface without compromising the structural integrity of the rest of the seal. In such embodiments, the harder material and softer material may be different formulations of the same material. In one example, the softer material may be a foam or partially foamed formulation of the harder material. In one example the harder material may be EPDM and the softer material may be EPDM foam. In some embodiments, the harder material may have a hardness in the region of 50-80, or 55-65 or around 60 as measured on the IRHD (international rubber hardness degree) scale. In some such embodiments, the softer material may have a hardness in the region of 30-50, or 35-45 or around 40 as measured on the IRHD scale. The valve body may be provided with fixing means to enable the valve to be mounted in relation to a conduit. The fixing means may comprise one or more fixing holes adapted to receive corresponding fixing elements. The fixing elements may comprise screws, bolts or the like. Where appropriate, the fixing element may additionally comprise cooperating elements such as nuts, washers or the like. The fixing elements may enable the valve body to be mounted to a wall or other support surface surrounding the end of the conduit. In embodiments where the conduit is a pipe end, the valve may be provided with an adaptor mount. In such embodiments, the adaptor mount may comprise a pipe section having a mounting flange at one end. The mounting flange thereby provides a support surface onto which the valve body can be mounted. The pipe section may be connected to the pipe end by way of a suitable pipe coupling. Alternatively, the pipe section may be received within the pipe end. In such cases, a circumferential seal may be provided around the exterior of the pipe section. In these manners, a similar security of seal can be achieved for pipe mounts of the valve of the present invention as for wall mounts. The valve body may comprise a handle. This can aid a user in transporting the valve to an installation location. The handle may also aid manoeuvring the valve into position and / or holding the valve in position during construction or installation. The handle may be defined by a handle opening provided in the valve body. The flap member may comprise a core portion for covering the flow opening when in the closed position. The hinge mechanism may comprise one or more hinge arms of the flap member, each hinge arm adapted to engage with one or more hinge mounts provided on the valve body. Each hinge arm may be provided with one or more pivot connectors for rotatably engaging with the hinge mounts. In one embodiment, each pivot connector comprises a shaft provided within and projecting from a through bore within the hinge arm. In another embodiment, each pivot connector comprises a lug projecting from the hinge arm. The hinge mounts may comprise a pair of tabs projecting from a base. Each tab may be provided with a pivot hole adapted to receive a pivot connector. The pivot holes on each tab may be aligned with each other. The pivot holes may comprise through bores. In such embodiment, the pivot connectors each may additionally be provided with an end cap. The provision of an end cap can prevent the pivot connector being removed from the pivot hole in which it is received. The end cap may be a removable end cap. In such embodiments, the end cap may be attached to the end of a pivot connector by snap fitting and or by interlocking threads. Each hinge mount may be fitted to an upper portion of the valve body. Each hinge mount may be adapted to fit into a corresponding hinge receiving slot provided on the valve body. The hinge mounts may be adapted to be received into the hinge receiving slots from a conduit side of the valve body. The hinge receiving slots may have a wider section toward the conduit side of the valve body and a narrower section toward the flap side of the valve body. The wider section may be adapted to correspond to the size of the base of the hinge mounts. In particular embodiments, this can enable the base of the hinge mount to be received completely within the hinge receiving slot. The narrower section of the hinge receiving slot may be smaller than the hinge base. As such, this can block excessive insertion of the hinge mount into the hinge receiving slot. The size of the narrower section of the hinge receiving slot may substantially correspond to the size and spacing of the tabs of the hinge mounts. In particular, the slot may have side walls which correspond to the separation of the outer sides of the tabs of the hinge mount. In some embodiments, the hinge mounts may be adapted to be welded into hinge receiving slots on the valve body and / or secured in hinge receiving slots on the valve body by use of an adhesive. In other embodiments, the hinge mounts may be adapted to snap fit into the hinge receiving slots. In such embodiments, the hinge mounts may comprise hinge snap fitting elements. The hinge snap fitting elements may engage with the hinge receiving slots to prevent or inhibit removal of the hinge mount from the hinge receiving slot after insertion. This provides for simple and secure mounting of the hinge mounts, even by unskilled personnel. This has the further benefits of facilitating supply of the valve in kit form and increasing repair options by reducing the need for the replacement of whole valves and thus providing an environmental benefit for the present invention. The hinge snap fitting elements may comprise a wedge projection having a sloped surface facing away from the base and an engaging surface facing the base. The wedge projections may be provided on the outer side of each tab at a position such that the wedge projection is on the flap side of the valve body when the hinge mount is fully inserted into the hinge receiving slot. The sloped surface of the wedge projection thereby permits the hinge mount to be fully inserted into the hinge receiving slot, and the engaging surface of the wedge projection may engage with the flap side of the valve body to prevent or inhibit subsequent removal. In some embodiments, the flap member is provided with a biasing weight. The biasing weight increases the weight of the flap member. This helps to hold the flap member in a closed position. The biasing weight may be fitted to the flap side of the flap member. The flap side would be the side of the flap member distal from the flow opening. This helps keep the weight from providing a snagging hazard to exit flow from the flow opening. The biasing weight may be fitted towards the lower portion of the flap member. This improves the effectiveness of the biasing weight in urging the flap member to the closed position. The flap member may comprise one or more eight receiving slots for the biasing weight. In some embodiments, the biasing weight may be adapted to be welded into weight receiving slots on the flap member and / or secured in weight receiving slots on the flap member by use of an adhesive. In other embodiments, the biasing weight may be adapted to snap fit into the weight receiving slots. In such embodiments, the biasing weight may comprise weight snap fitting elements. The weight snap fitting elements may be adapted to engage with the weight receiving slots to prevent or inhibit removal of the biasing weight from the weight receiving slot after insertion. This provides for simple and secure mounting of the biasing weight, even by unskilled personnel. This has the further benefits of facilitating supply of the valve in kit form and increasing repair options by reducing the need for the replacement of whole valves and thus providing an environmental benefit for the present invention. The weight snap fitting elements may comprise one or more rods having a wedge profile rim at a distal end. The wedge profile rim may have with a sloped surface facing the rod end and an engaging surface facing away from the rod end. The rods may be split rods or partially split rods. The split or partial split may extend along an axis of the rod from the distal end. The rods may correspond in length to the thickness of the flap member. In this way, the wedge rim may be provided on the conduit side of the flap member when the rod is fully inserted into the weight receiving slot. The sloped surface of the wedge rim thereby permits the rod to be fully inserted into the hinge receiving slot, and the engaging surface of the wedge rim may engage with the flap side of the flap member to prevent or inhibit subsequent removal. According to a second aspect of the present invention there is provided a seal adapted to fit within the flow opening of a flap valve, the seal comprising a tubular body with a flap end and conduit end, the flap end having an externally projecting flap end flange and the conduit end each having an externally projecting conduit end flange. The seal of the second aspect of the present invention may incorporate any or all aspects of the flap valve of the first aspect of the present invention, as required or as desired. According to a third aspect of the present invention there is provided a flap valve comprising: a valve body having an opening; a flap member attached to an upper portion of the valve body by a hinge mechanism; and a seal provided between the valve body and valve member wherein the hinge mechanism comprises hinge mounts adapted to snap fit into hinge receiving slots on the valve body. The flap valve of the third aspect of the present invention may incorporate any or all aspects of the flap valve of the first aspect of the present invention or the seal of the second aspect of the present invention, as required or as desired. According to a fourth aspect of the present invention there is provided a flap valve comprising: a valve body having an opening; a flap member attached to an upper portion of the valve body by a hinge mechanism; and a seal provided between the valve body and valve member wherein the flap member is provided with a biasing weight adapted to snap fit into one ore more weight receiving slots in the flap member. The flap valve of the fourth aspect of the present invention may incorporate any or all aspects of the flap valves of the first and third aspects of the present invention or the seal of the second aspect of the present invention, as required or as desired. Detailed Description of the Invention In order that the invention may be more clearly understood one or more embodiments thereof will now be described, by way of example only, with reference to the accompanying drawings, of which: Figure I shows a flap valve according to the present invention in (a) a closed position and (b) an open position; Figure 2 shows the flap valve according to the present invention in (a) a crosssection of a closed position and (b) a front perspective view of a crosssection of a closed position (c) a rear perspective view of a closed position and (d) a cross-section of an open position; Figure 3 shows a seal for a flap valve according to the present invention in (a) perspective view, (b) cross-section of the full seal, and (c) expanded cross-section of the seal profile; 5 Figure 4 is a cross-section view of a flap valve according to the present invention mounted to a wall at the end of a pipe or conduit; Figure 5 is (a) a cross-sectional and (b) a perspective view of a flap valve according to the present invention mounted to a pipe end via a mounting plate and a coupling; 10 Figure 6 is a cross-sectional view of a flap valve according to the present invention mounted to a pipe end via a mounting plate and pipe section fitting within the pipe end; 15 Figure 7 shows (a) a cross-section of a hinge mount for a flap valve according to the present invention, (b) a front perspective view of a receiving slot for a hinge mount in a valve body of a flap valve according to the present invention, and (c) a front perspective view of the hinge mount positioned for insertion into the receiving slot; Figure 8 shows (a) a perspective view of and (b) a cross-sectional view of the hinge mount of figure 4 partially received into the receiving slot of figure 4; 20 Figure 9 shows (a) a front perspective view of, (b) a rear perspective view of and (c) a cross-sectional view of the hinge mount of figure 4 fully received into the receiving slot of figure 4; and 25 Figure 10 shows (a) perspective view of a flap member of a flap valve according to the present invention, (b) an expanded scale view of a biasing weight for attachment to the flap member. Turing now to figures 1 to 6, this shows a flap valve 1 suitable for being installed at an end of a fluid conduit 2 such as a pipe or pipe or culvert (conduit shown in figures 4 to 6 below). The flap valve 1 allows fluid to exit the conduit 2, whilst preventing fluid external to the conduit from flooding back into the conduit 2. The flap valve 1 comprises a valve body 10 adapted to be mounted on a support structure, which may be the conduit 2 or an adjacent wall 80 (figure 4) or any other convenient structure. In cases where the conduit 2 is the exposed end of the pipe 85, an adaptor mount 90 (shown in figures 5 and 6) comprising a pipe section 91 having a mounting flange 92 provided at one end. The mounting flange 92 thereby provides a support surface onto which the valve body 10 can be mounted. The pipe section 91 can be coupled to the exposed end of the pipe 85 using a pipe coupling 95. In the example shown in figure 5, this can be a pipe coupling 95 of the type comprising an elastomeric sleeve 98 adapted to receive internally the ends of the pipe 85 and pipe section 91 and one or more circumferential clamping bands 96 provided externally at each end of the sleeve. As illustrated in figure 5, the coupling 95 may also comprise a shear support band 97 between the clamping bands 96. As a further alternative, as illustrated in figure 6, the pipe section 91 may fit within the pipe 85. A circumferential seal 93 can be provided around the pipe section 91 to provide a seal between the end of pipe 85 and the pipes section 91. The valve body is secured to the support structure using fixing bolts 60, which can project through fixing holes 61 in the valve body and can be secured using fixing nuts 62. The valve body 10 may also have a handle opening 70 defining a handle 71. This can help a user to carry the valve 1 or hold it in position during installation. The valve body 10 has a flow opening 20 typically corresponding in size / shape to the end of the conduit 2. In use, the valve body 10 is mounted such the flow opening 20 is aligned with the end of the conduit 2 so fluid can flow from the end of the conduit 2 through the flow opening 20. A flap member 30 has a core portion 31 and upwardly extending hinge arms 32 attached to an upper portion of the valve body 20 by a hinge mechanism 40. This permits the flap member 30 to move between a closed position (figure la, figures 2a-c) where the flap member 30 blocks the flow opening 20 and a fully open position (figure lb, figure 2d) where the flap member 30 does not block the flow opening 20. The hinge mechanism 40 comprises hinge mounts 41 which fit into hinge receiving slots II provided on the valve body 10. Each hinge mount 41 comprises a base 42 and a pair of projecting tabs 43. Each tab 43 has a pivot hole 44 adapted to receive a pivot connector 34 of the hinge arm 31, such that the pivot connector 34 can rotate within the pivot hole 44. A removable end cap 33 can be fitted to prevent the pivot connector 34 being removed from the pivot hole 44 in which it is received. The weight of the flap member 30 causes the flap member to hang in a closed position covering the flow opening 20 thereby blocking the exit of fluid from the conduit 2. A flow of fluid from the conduit 2 urges the flap member 20 away from the flow opening allowing the fluid to exit the conduit 2. External fluid, in contrast, acts against the flap member 30 moving away from the flow opening to a partially open position. As illustrated, in this example, the flap member 30 is also provided with a biasing weight 50 which helps ensure that mass of the flap member 30 is sufficient to urge it into the closed position. An elastomeric seal 100 is provided, the seal 100 adapted to fit within the flow opening 20, the seal 100 being shown in more detail in figure 3. As can be seen from the drawing, the seal 100 comprises a tubular body 110 defining an inner passage 111 with a flap end 120 and a conduit end 130. The flap end 120 has an externally projecting flap end flange 121. The conduit end 120 has an externally projecting conduit end flange 131. The tubular body 110 has a cross-section that corresponds to the flow opening 20, so that it can fit closely within the flow opening. The axial extent of the tubular body 110 corresponds to the thickness of the valve body 10. Accordingly, when the seal 100 is inserted into the flow opening, the flap end flange 121 abuts the flap side 12 of the valve body 10. Similarly, the conduit end flange 131 abuts the conduit side 13 of the valve body 10. The flap end flange 121 and conduit end flange 131 thereby hold the seal 100 securely in position within the flow opening 20. When in position, the tubular body 110 defines an internal flow passage 111 within the flow opening. When mounted to a support surface, the conduit end flange 131 is pressed between conduit side 13 of the valve body 10 and the support surface 80, 91. The conduit end flange 131 thereby forms a seal between the valve body 10 and the support surface 80, 91, preventing the escape of any fluid flowing out of the conduit 2. When the flap member 30 is in the closed position, the flap end flange 121 is pressed between the flap side 12 of the valve body 10 and the flap member 30. The flap end flange 121 thereby forms a seal between the valve body 10 and the flap member 30, preventing the ingress of any fluid from outside the conduit 2, when the flap member 30 is in the closed position. As the seal 100 is elastomeric, it can be readily fitted into the flow opening 20 by folding, inserting and unfolding. This is much similar than known flap valves where separate flaps seals and support seals are provided and where each is typically preattached or requires the use of adhesive to attach. Accordingly, this facilitates providing the flap valve 1 in kit form. It also allows a worn or damaged seal to be readily removed and replaced without specialist equipment. As shown in the example of figure 3, the tubular body 110 has a substantially cylindrical form having a substantially constant wall thickness. The skilled person will appreciate that the cross-section of the tubular body 110 may be varied to adapt to different flow openings, as desired or required. As shown in the example of figure 3, the flap end flange 121 is provided with enhanced sealing formations 122, in the form of a pair of projecting flexible lips 123. The pair of lips 123 define a channel 124. The lips 123 each extend to form a complete loop on the flap member side 125 of the flap end flange 121. When the flap member 30 moves to the closed position, it presses against the lips 123 to form a seal. By providing two projecting lips 123, contact is initiated and maintained even if the flap member 30 vibrates slightly. Additionally, air can be forced out of the channel 124 as the flap member 30 moves to the closed position. This can create a suction effect acting against movement of the flap member 20 to a partially open position, helping to hold the flap member 20 in a closed position until a threshold flow ox- force is applied. As shown in the example of figure 3, the conduit end flange 131 is provided with gripping formations 132 comprising a series of ridges 133 defining grooves 134 therebetween. The gripping formations 132 form a complete loop on the conduit side 135 of the of the conduit end flange 131. The gripping formations help form a seal against the support surface even if the support surface is uneven. In the illustrated example, the seal 100 is formed from an extruded profile of a material such as EPDM. Of course, the skilled person will appreciate that other suitable elastomeric materials may be substituted, if desired or required. As indicated in the cross-sectional views of figures 3b and 3c, the conduit end flange 131 can be formed from a softer material than the tubular body 110 and the flap end flange 121. This helps maintain an effective seal between the valve body 10 and a support surface without compromising the structural integrity of the rest of the seal 100. The softer material of the conduit end flange 131 can be a different material to harder material of the tubular body 110 and the flap end flange 121 or can be a different formulation or treatment of a common base material. In a particular example, the softer material is a foamed or partially foamed EPDM and the harder material is normal EPDM. In such an example, the softer material forming the conduit end flange 131 has hardness in the region of 40 as measured on the IRHD scale whereas the harder material forming the tubular body 110 and the flap end flange 121 has hardness in the region of 60 as measured on the IRHD scale. Turning now to figures 7-9, the hinge mechanism 40 and especially the installation of the hinge mechanism 40 is illustrated in more detail. In this example, the hinge mounts 41 snap fit into the hinge receiving slots 11 from a conduit side 13 of the valve body 10. This permits the hinge mechanism 40 to be installed readily by a relatively unskilled end user, facilitating supply of the valve 1 in kit form. Furthermore, since the hinge mounts 41 are not welded into place or secured by adhesive, they can be readily removed and replaced if worn or damaged. Each hinge receiving slot 11 comprises a wider section 14 toward the conduit side 13 of the valve body 10 and a narrower section 15 toward the flap side 12 of the valve body 10. The wider section 14 is adapted to correspond to the size of the base 42 of the hinge mounts 41 whilst the narrower section 15 is narrower than the base 42. In particular, as illustrated, the narrower section 15 can correspond to the size and spacing of the tabs 43 of the hinge mounts 41. Each hinge tab 43 is provided with a wedge projection 45 having a sloped surface 46 facing away from the base 42 and an engaging surface 47 facing the base 42. During installation, the hinge mount 41 is provided on the conduit side 13 of the valve body 10 with the tabs 43 aligned with and projecting toward the hinge receiving slot 11, as shown most clearly in figures 4b and 4c. Subsequently, as illustrated in figures 5a and 5b, the hinge mount 41 is inserted tabs 43 first into the hinge receiving slot 11. As insertion continues, engagement between the sides of receiving slot 11 and the sloped surface 46 of wedge projections 45 gradually and resiliently deflects the tabs 43 inward. Insertion is completed when the base 42 is received completely within the hinge receiving slot 11 as illustrated in figures 6a-6c. At this point, the wedge projections 45 have passed through the hinge receiving slot 11 and emerged on the flap side 12. The engaging surface 47 then abuts the flap surface 12 of the valve body 10 and thereby resists or inhibits subsequent removal of the hinge mount 11. This may be overcome if a sufficient inward compression is applied to both tabs 43. This would typically not occur during use due to the presence of the hinge arms 32, but could be applied if these are removed, thereby allowing user replacement of the hinge mounts 41. Turing now to figure 10, the biasing weight 50 is fitted to the flap side 35 of the flap member 30. This helps keep the biasing weight 50 from providing a snagging hazard to exit flow from the flow opening 20. As shown in figure 7, the biasing weight is fitted toward the lower edge of the flap member 30, which improves the effectiveness of the biasing weight 50 in urging the flap member 30 to the closed position. It can also potentially provide a convenient handle for manual movement of the flap member 30. As illustrated in the present invention, the biasing weight 50 is adapted to snap fit into weight receiving slots 36 provided in flap member 30. This permits the biasing weight 50 to be installed readily by a relatively unskilled end user, facilitating supply of the valve 1 in kit form. Furthermore, since the biasing weight 50 is not welded into place or secured by adhesive, it can be readily removed and replaced if worn or damaged. More specifically, the biasing weight 50 comprises a weight bar 51 mounted between a pair of bar ends 52. Each bar end is provided with a rod 53 adapted to snap fit with into one of the weight receiving slots 36. To enable snap fitting, rods 53 each have a wedge profile rim 54 at a distal end 55. The wedge profile rim 54 has a sloped surface 56 facing the rod end 55 and an engaging surface 57 facing away from the rod end 55. The rods 53 each also comprise an axial split 58. The rods 53 each correspond in length to the thickness of the flap member 30. In use, the rods 53 are inserted into the weight receiving slots 36. During insertion, engagement between the sides of the weight receiving slot 36 and the sloped surface 56 of wedge rim 54 gradually and resiliently deflects the portion of the rod 53 either side of split 58 inward. When fully inserted (as shown best in figure 2c and figure 2d), the wedge rims 54 have passed through the weight receiving slots 36 and emerged on the conduit side 37 of the flap member 30. The engaging surface 57 the abuts the conduit surface 37 of the flap member 30. This thereby resists or inhibits subsequent removal of the weight 50. This may be overcome if a sufficient inward compression is applied to the wedge rims 54. This would typically not occur during use, but could be applied by a user, thereby allowing user replacement of the biasing weight 50. The one or more embodiments are described above by way of example only. Many variations are possible without departing from the scope of protection afforded by the appended claims.

Claims

1. A flap valve comprising: a valve body having a flow opening; a flap member attached to an upper portion of the valve body by a hinge mechanism so as to be movable between an open position and a closed position where the flap member covers the flow opening; and a seal adapted to fit within the flow opening, the seal comprising a tubular body with a flap end and conduit end, the flap end having an externally projecting flap end flange and the conduit end each having an externally projecting conduit end flange.

2. A flap valve as claimed in claim 1, wherein the flap end flange is provided with one or more enhanced sealing formations on a flap member side of the flap end flange.

3. A flap valve as claimed in claim 2, wherein the enhanced sealing formations form a complete loop on the flap member side of the flap end flange.

4. A flap valve as claimed in claim 2 or claim 3, wherein the enhanced sealing formations comprise two flexible lips, each said lip projecting away from the flap side of the flap end flange radially and / or axially relative to the tubular body so as to define a channel therebetween.

5. A flap valve as claimed in any preceding claim, wherein the conduit end flange is provided with one or more gripping formations on a conduit side of the conduit end flange.

6. A flap valve as claimed in claim 5, wherein the gripping formations form a complete loop on the conduit side of the of the conduit end flange.

7. A flap valve as claimed in claim 5 or claim 6, wherein the gripping formations comprise a series of ridges defining grooves therebetween.

8. A flap valve as claimed in any preceding claim, wherein the tubular body has an external cross-section substantially matching the cross-section of the flow opening and an axial length corresponding to the thickness of the valve body.

9. A flap valve as claimed in any preceding claim, wherein the tubular body and the flap end flange are formed from a harder material and the conduit end flange are formed from a softer material.

10. A flap valve as claimed in any preceding claim, wherein the valve body is provided with fixing means to enable the valve to be mounted in relation to a conduit, the fixing means may comprise one or more fixing holes adapted to receive corresponding fixing elements such as screws or bolts.

11. A flap valve as claimed in claim 10, wherein if the conduit is a pipe end, the valve is provided with an adaptor mount comprising a pipe section having a mounting flange at one end, the pipe section connected to the pipe end by way of a pipe coupling or wherein the pipe section is received within the pipe end.

12. A flap valve as claimed in any preceding claim, wherein the hinge mechanism comprises one or more hinge arms of the flap member, each hinge arm adapted to engage with one or more hinge mounts provided on the valve body.

13. A flap valve as claimed in claim 12, wherein each hinge arm is provided with one or more pivot connectors for rotatably engaging with the hinge mounts.

14. A flap valve as claimed in claim 13, wherein each hinge mount comprises a pair of tabs projecting from a base, each tab provided with a pivot hole adapted to receive a pivot connector.

15. A flap valve as claimed in any one of claims 12 to 14 wherein each hinge mount is adapted to fit into a corresponding hinge receiving slot provided on the valve body from a conduit side of the valve body.

16. A flap valve as claimed in claim 15, wherein each hinge receiving slot has a wider section toward the conduit side of the valve body and a narrower section toward the flap side of the valve body, the wider section adapted to correspond to the size of the base of the hinge mounts and the narrower section of the hinge receiving slot being smaller than the hinge base.

17. A flap valve as claimed in claim 15 or claim 16, wherein the hinge mounts comprise hinge snap fitting elements which engage with the hinge receivingslots to prevent or inhibit removal of the hinge mount from the hinge receiving slot after insertion.

18. A flap valve as claimed in claim 17, wherein the hinge snap fitting elements comprise a wedge projection having a sloped surface facing away from the base and an engaging surface facing the base, the wedge projections provided on the outer side of each tab at a position such that the wedge projection is on the flap side of the valve body when the hinge mount is fully inserted into the hinge receiving slot.

19. A flap valve as claimed in any preceding claim, wherein the flap member is provided with a biasing weight fitted towards the lower portion of the flap side of the flap member.

20. A flap valve as claimed in claim 19, wherein the biasing weight comprised weight snap fitting elements adapted to engage with weight receiving slots on the flap member to prevent or inhibit removal of the biasing weight from the weight receiving slot after insertion.

21. A flap valve as claimed in claim 20, wherein the weight snap fitting elements comprise one or more split or partially split rods having a wedge profile rim at a distal end, the wedge profile rim having with a sloped surface facing the rod end and an engaging surface facing away from the rod end, such that the wedge rim is provided on the conduit side of the flap member when the rod is fully inserted into the weight receiving slot.

22. A seal adapted to fit within the flow opening of a flap valve, the seal comprising a tubular body with a flap end and conduit end, the flap end having an externally projecting flap end flange and the conduit end each having an externally projecting conduit end flange.

23. A seal as claimed in claim 22, wherein the flap end flange is provided with one or more enhanced sealing formations on a flap member side of the flap end flange and / or wherein the conduit end flange is provided with one or more gripping formations on a conduit side of the conduit end flange.

24. A seal as claimed in claim 22 or claim 23. wherein the tubular body and the flap end flange are formed from a harder material and the conduit end flange are formed from a softer material.

25. A flap valve comprising: a valve body having an opening; a flap member attached to an upper portion of the valve body by a hinge mechanism; and a seal provided between the valve body and valve member wherein the hinge mechanism comprises hinge mounts adapted to snap fit into hinge receiving slots on the valve body.

26. A flap valve as claimed in claim 25, wherein the hinge mounts have hinge snap fitting elements comprising a wedge projection having a sloped surface facing away from the base and an engaging surface facing the base, the wedge projections provided on the outer side of each tab at a position such that the wedge projection is on the flap side of the valve body when the hinge mount is fully inserted into the hinge receiving slot.

27. A flap valve comprising: a valve body having an opening; a flap member attached to an upper portion of the valve body by a hinge mechanism; and a seal provided between the valve body and valve member wherein the flap member is provided with a biasing weight adapted to snap fit into one ore more weight receiving slots in the flap member.

28. A flap valve as claimed in claim 26, wherein the biasing weight has weight snap fitting elements comprising one or more split or partially split rods having a wedge profile rim at a distal end, the wedge profile rim having with a sloped surface facing the rod end and an engaging surface facing away from the rod end, such that the wedge rim is provided on the conduit side of the flap member when the rod is fully inserted into the weight receiving slot.Application No: GB2405461.1Claims searched: 1-9, 22-24Examiner: Contract Unit ExaminerDate of search: 22 November 2024Patents Act 1977: Search Report under Section 17Documents considered to be relevant:Category Relevant to claims Identity of document and passage or figure of particular relevance X 1-9, 22-24 CN205331518 U (UNIV HEFEI TECHNOLOGY; LAN SHI whole document EN GROUP CORP) the X 1-9, 22-24 CN103453183 A (WU RUIXIA) the whole document X 1-3, 5-9, 22-24 CN102635713 A (DINGHONG LI) the whole document A - CN104110514 B (WUHAN SHENG YU DRAINAGE SYSTEMS CO LTD) figures 1, 2, 5 A - KR20090010776 A (PARK MIN HYE) figures 1, 5Categories:X Document indicating lack of novelty or inventive step A Document indicating technological background and / or state of the art. Y Document indicating lack of inventive step if P Document published on or after the declared priority date but combined with one or more other documents of before the filing date of this invention. same category. & Member of the same patent family E Patent document published on or after, but with priority date earlier than, the filing date of this application.Field of Search:Search of GB, EP. WO &US patent documents classified in the following areas of the UKCX :Worldwide search of patent documents classified in the following areas of the IPC____________E03F; F16J; F16K___________________________________________________The following online and other databases have been used in the preparation of this search reportInternational Classification:Subclass Subgroup Valid From F16K 0001 / 20 01 / 01 / 2006 F16K 0015 / 03 01 / 01 / 2006

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