Conduit seal and method of application

Abstract

This application relates to an apparatus and method for creating a primary seal around a cable. In particular, the primary seal is a one-piece seal, and the cable is one which cannot be cut, or accessed at the ends of the cable. The seal may be used in an overblow junction box, which is for overblowing fibreoptic cables through a conduit. The present invention also relates to the seal itself, and the frustoconical ring shaped primary seal mould. The seal creating arrangement may also be used on any other application where a one-piece seal is required.

Description

[0001] CONDUIT SEAL AND METHOD OF APPLICATION

[0002] FIELD OF THE INVENTION

[0003] The present invention relates to an apparatus and method for creating a primary seal around a cable. In particular, the primary seal is a one-piece seal, and the cable is one which cannot be cut, or accessed at the ends of the cable. The seal may be used in an overblow junction box, which is for overblowing fibreoptic cables through a conduit. The present invention also relates to the seal itself, and the frustoconical ring shaped primary seal mould. The seal creating arrangement may also be used on any other application where a one-piece seal is required.

[0004] BACKGROUND OF THE INVENTION

[0005] Fibre optic cables are a reliable, versatile, and widely used way of transferring information via pulses of light. These pulses of light travel along one or more transparent plastic or glass pipes, with each pipe being surrounded by cladding. A sheath is normally made up of several layers of insulated casing, and is wrapped around the cladded fibres. The whole bundle is usually inside a buffer tube, followed by a final outer jacket which is designed to protect the entire cable. Multiple cables are then fed into a sub-duct or conduit, which is effectively a larger, hollow, cylindrical tube. These conduits may comprise two or more cables which contain fibre optics.

[0006] Fibre optic cables are used for various applications such as: the internet, phonelines, networks, and any form of telecommunication. They are typically smaller than traditional cabling, and so take up less space underground where space is at a premium.

[0007] Fibre optic cables are required to provide 'Fibre Broadband’, which is becoming increasingly popular throughout the world. This network of fibre optic cables is what is used to connect various homes and businesses to the internet. Cables may be connected directly to homes, or connected to a cabinet which the street will share.

[0008] The sub-ducts or conduits which carry the cables need to be dug into the ground, which is a highly disruptive process, as it takes a lot of time and labour. Furthermore, it can be costly. Once these conduits are in the ground, cabling can be pulled or blown through the under-ground conduit with ease. The conduits provide protection from the elements underground, ensuring the fragile fibreoptic cables are kept safe.

[0009] Optical cables are usually placed inside a 25-40mm inside diameter conduit or subduct. These subducts may be located inside a larger diameter communication conduit. Fibre cables can be blown underground of distances up to a few kilometres. After these conduits or subducts are laid underground, they are usually left for many years without interference. Manholes are located along the length of the conduits, to enable access to the cables for maintenance purposes and to allow further cables to be inserted into the existing conduits.

[0010] A problem arises when a further cable is required to be added into the conduits, after the conduit has been buried underground. For example, there may be a conduit which has space for three cables, but is only occupied by two cables. The conduit may carry cables from location A to location C, via manhole B located between A and C. If a service provider wants to feed a new cable from location B to location C, they will need to ‘hijack’ the existing conduit at location B, and blow the new cable from location B to location C.

[0011] To do this, an overblow junction box is used. This is a junction box which allows the installation of a new cable, into an existing underground conduit or subduct. The existing conduit is cut, a short length or section is removed, leaving the cables exposed. The junction box is then lowered into the manhole and orientated and firmly attached to one end of the cut conduit, allowing the existing cable to pass through the junction box, whilst providing a Y-junction to introduce a new cable.

[0012] The junction box is then pressurised with air, and the new cable is ‘blown in’ to the existing conduit. The pneumatic flow inside the junction box reduces the friction of the cable passing down the conduit, by creating a barrier between the cable and whatever it comes into contact with. Friction is greatly reduced when using compressed air to aid the insertion of the cable.

[0013] For effective overblowing, the junction box needs to be correctly sealed, otherwise the high pressure air will leak out and reduce the advantageous effects previously mentioned. Sealing around the cut conduit is easily done by using collets and annular seals which can be slid over the cut conduit. This is also true of sealing around the new cable to be blown in. Using one-piece seals over the end of a conduit or cable is an easy task, as the one-piece seal can easily be slid over the end.

[0014] A more difficult scenario is when trying to seal around the existing cable(s). An annular seal cannot easily be slid over one end, as the cable is continuous, and runs from location A to C. The current solution in the art is to use a two-piece seal, which forms an annular seal around the cable. One piece is placed under the cable, and the other piece is placed on top of the cable. Alternatively, a seal with a cut in it may be used, which is then twisted over the cable, resulting in a seal which has one discontinuity present. The main disadvantage with this is that the seal is not as effective as a one-piece seal, due to the presence of the gap(s) in the seal. Another issue with the seals in the prior art is that they are generic split-seals, which are made to standardised sizes. These standardised sizes are often not well suited to each cable to be sealed, since each cable differs slightly. Furthermore, if the cable has an irregular profile or an uneven surface such as ridges along the outer diameter of the cable, the seal cannot tightly contact the entire outer diameter surface of the cable, resulting in leaks. This problem may also arise if the cable is not perfectly round.

[0015] For the above reasons, there remains a need to address or mitigate at least one or more of the aforementioned problems.

[0016] It is therefore an object of the present invention to provide an improved seal, which allows less air to leak than seals according to the prior art.

[0017] It is a further object of the present invention to provide a method to make an improved seal according to the present invention.

[0018] It is a further object of the present invention to provide an apparatus for forming a seal according to the present invention.

[0019] It is a further object to solve any of the problems associated with the issues in the prior art.

[0020] SUMMARY OF THE INVENTION

[0021] According to a first aspect of the present invention, there is provided an apparatus for creating a primary seal around a cable, the apparatus comprising: an outer forming jacket comprising an upper part and a lower part to allow the outer forming jacket to encircle the cable, wherein the outer forming jacket further comprises: a first jacket injection port connected to a first seal annulus, and a second jacket injection port connected to a primary seal mould and a primary seal cavity; a piston comprising a piston upper and a piston lower to allow the piston to encircle the cable, wherein the piston further comprises: a first piston injection port connected to a second seal annulus; wherein the primary seal mould is located between the first seal annulus and the second seal annulus, wherein the piston is slidably engageable with the outer forming jacket inside the primary seal cavity; and wherein in use, the outer forming jacket and the piston are assembled over a cable to be sealed: the first seal annulus, the second seal annulus, the primary seal cavity and the primary seal mould are filled with a sealant material, before the piston is inserted into the outer forming jacket to form a primary seal within the primary seal mould.

[0022] The sealant material may be any type of rubber and / or plastics material which is capable of being injected. The sealant material may be injected as a liquid, and it may set as a solid. The sealant material may be stored as two separate materials, the two materials only being mixed when they are injected into the apparatus.

[0023] The sealant material, when set, may create a high precision of the mould and cable which it sets in. This may result in a very good seal between the mould and the cable. The sealant material may be a polymer material, which when sets (or polymerises) does not shrink. The sealant material may therefore be capable of, wherever the sealant material is set.

[0024] The sealant material may set more quickly if higher temperatures are used.

[0025] The apparatus may be around 2-5 kgs in weight, and may be used in situ. For example, the apparatus may be used to make a primary seal around a cable down a manhole. The whole process of making a primary seal may take around 10-20 mins. The apparatus according to the invention may allow for a one-piece seal to be made around a cable, where the ends of the cable are inaccessible, making it impossible for a one-piece seal to be inserted over the cable.

[0026] The outer jacket or sheath of the cable may be a ridged, and the cable may have an irregular shape or profile. The ridges may allow the cable to be more easily inserted inside a conduit. The cable may be a fibre optic cable.

[0027] The process and apparatus discussed allows for bespoke primary seals to be formed around the cable to be sealed. For example, if a ridged cable is used, then the primary seal will form ridges to perfectly match the outer diameter ridge profile of the cable. This results in a primary seal which is much more efficient than the primary seals in the prior art, since there is more contact area with the cable to be sealed.

[0028] Furthermore, if the cable to be sealed has a manufacturing defect or is marginally smaller than it should be, a split seal according to the prior art would not seal the cable correctly.

[0029] The piston may further comprise a second piston injection port connected to a third seal annulus. This may provide an extra seal for efficiency purposes. Furthermore, having a third seal annulus on the piston can provide a second temporary seal on the piston. This can aid the pistons movement in and out of the outer jacket, as it can prevent the piston from yawing inside the jacket, and therefore snagging. If more seals are required, for example if the system has extremely high pressures, then more seal annulus’ can be added. More seals may also be added to the outer jacket.

[0030] The primary seal mould may be generally frustoconical shaped. The primary seal which is made within the primary seal mould may be frustoconical shaped. The primary seal mould may be angled around 45 degrees. Alternatively, the primary seal mould may be angled around 30-50 degrees. The angle of the seal may be suited for an overblow junction box manifold. In use, the seal may be compressed against a mating surface, which is matched to the angle of the seal.

[0031] Alternatively, the primary seal mould may be a standard O-ring shape. This may result in a ringshaped seal, which may have a generally circular cross sectional area. The primary seal mould may also be any other suitable shape, for example with a rectangular shaped cross section.

[0032] The outer forming jacket may further comprise an overflow aperture connected to the primary seal mould. The overflow aperture may be located on the upper part or lower part of the outer forming jacket. The overflow aperture may be located such that when the piston is fully inserted into the outer forming jacket, the overflow aperture is closed off- resulting in an increase in pressure experienced by the primary seal.

[0033] To form the primary seal, the piston may compress the sealant material inside the primary seal mould. The sealant material may be kept within the primary seal mould by the temporary seals created inside the seal annulus.

[0034] The piston may be fastened to the outer forming jacket via a plurality of end fasteners. The end fasteners may be bolts. The end fasteners may be any type of fastener which allows for positional control of the piston relative to the outer forming jacket. The end fasteners may be used to move the piston in and out of the outer jacket. The piston may be used to compress the sealant material.

[0035] The distance the piston is inserted inside the outer forming jacket may be controlled via an adjustment screw. The adjustment screw may be inserted in and out of the end of the piston, which can set the depth the piston can be inserted into the outer forming jacket.

[0036] The injection ports may be connectable to a sealant material. The injection ports may be suitable for being connected to an adaptor which injects sealant material. The primary seal mould may be generally frustoconical shaped.

[0037] The apparatus may have a longitudinal axis, and wherein the cable to be sealed lies on the longitudinal axis. The longitudinal axis may run through the centre of the apparatus, and may generally lie on the centre of the axis of symmetry. The longitudinal axis may run along the longest length of the apparatus.

[0038] The apparatus may be portable. The apparatus may be used to make multiple primary seals in a short period of time. The apparatus may be used to make a plurality of primary seals which are for use inside or outside of an overblow cable junction box.

[0039] According to another aspect of the invention, there is provided a method of making a primary seal around a cable, the method comprising the steps of: providing an apparatus which can encircle the cable, wherein the apparatus comprises an outer jacket and a piston, the piston being slidably engageable within the outer jacket, and the outer jacket having a primary seal mould; creating a first temporary seal around the cable, the first temporary seal being created within the outer jacket; creating a second temporary seal around the cable, the second temporary seal being created within the piston; creating the primary seal around the cable, the primary seal being created between the first and second temporary seals, wherein the primary seal is created within the outer jacket, and wherein the piston is used to create a pressure force on the primary seal mould to form the primary seal.

[0040] The sealant material may be the same material which is injected to the seal annulus’ and the primary seal mould, or the sealant material may be different for each seal made.

[0041] The sealant material may take around 5-10 minutes to set and harden, after it is been injected into the apparatus. The compressive forces exerted by the piston may increase the quality of the primary seal by removing any gasses or impurities.

[0042] A third temporary seal may be created around the cable, and the third temporary seal may be created within the piston.

[0043] The apparatus may be split into upper and lower parts, thus allowing the apparatus to encircle a cable which cannot be fed through an aperture. The upper and lower parts may be in halves, i.e. each half encompassing 180 degrees of the cable to be sealed. Alternatively, the upper and lower parts may be a non-equal combination, i.e. the upper may be 200 degrees, and the lower may be 160 degrees.

[0044] The temporary seals may be formed via annulus shaped moulds within the apparatus, wherein the annulus shaped moulds may encircle the cable. The temporary seals may be formed before the primary seal. The temporary seals may be made purely to assist in the making of the primary seals.

[0045] After the primary seal has been made around the cable, the temporary seals may be removed, prior to the primary seal being used. The primary seal may be kept on the cable for future usage, or may be used to assist the sealing of any wrap around enclosure or casing used to provide a final seal to the conduit whenever the work is complete, or the primary seal may be removed.

[0046] The primary seal may be formed by filling the primary seal mould with a sealant material, and then compressing the sealant material to remove any gas or impurities.

[0047] The piston may be moved relative to the outer jacket via a plurality of end fasteners. The end fasteners may be wound in with simple hand tools, or they may be wound in with power tools.

[0048] The sealant material may be injected into the apparatus by a user.

[0049] The sealant material may comprise an activator ingredient, which sets the sealant material. The activator may be mixed with the sealant material as the sealant material is injected into the apparatus.

[0050] According to another aspect of the present invention, there is provided a primary seal formed by the method as according to a previous embodiment of the present invention.

[0051] The seal may be a frustoconical ring shaped seal.

[0052] The seal may be suitable for a cable overblowing junction box.

[0053] According to another aspect of the present invention, there is provided a method of making a singlepiece primary seal around a cable, the method comprising the steps of: providing an apparatus which can be split, the split allowing the apparatus to encircle the cable, the apparatus comprising a primary seal mould which encircles the cable when in use; injecting a sealant material into the primary seal mould, thereby creating a single-piece primary seal around the cable. The cable may be a fibre optic cable.

[0054] The apparatus may be a junction box manifold.

[0055] The method and apparatus may use any steps or features which are comprised in any of the methods and apparatus’ described above.

[0056] The present invention should also be construed to cover embodiments where a single-piece seal is made around a fibre optic cable in-situ. This is a fundamental element of the invention, with the benefits of a single-piece seal over a split seal as described above. For example, the idea to create a single-piece seal may also be used in combination with a modified version of an existing junction box manifold. An existing junction box manifold, or any similar type of device, may be modified to make it capable of making a single-piece seal, as previously described.

[0057] A single-piece seal may be formed by injecting a sealant material into an existing junction box manifold head, or any device which is used to join cables or house cables. The devices may be used inside a manhole. Any existing apparatus may have a retro-fitted injection port bored into it, thus allowing sealant material to be injected inside. An injection port may be bored into an existing cavity where a split mould would be located. A sealant material may then be injected into the existing cavity, thus creating a single-piece mould.

[0058] According to another aspect of the present invention, there is provided an apparatus for creating a seal around a cable, wherein the apparatus is comprised of components which are split along a longitudinal axis, enabling them to encircle the cable. The split allows the seal to be created to be a one-piece seal. The apparatus may be according to any previously described apparatus.

[0059] According to another aspect of the present invention, there is provided a method for making a seal around a fibre optic cable, wherein the seal is made in-situ around the fibre optic cable, thus creating a single-piece seal. This seal may be made by using equipment according to the present invention, or may be made by using a modified version of an existing junction box manifold.

[0060] According to another aspect of the present invention, there is provided an apparatus for making a seal around a fibre optic cable, wherein the apparatus splits to enable the apparatus to encircle the fibre optic cable, thus allowing a sealant material to be injected around the circumference of the fibre optic cable, thus creating a one-piece seal. The apparatus may be according to a previously described apparatus. The apparatus may be a modified apparatus according to the prior art. According to another aspect of the present invention, there is provided a method for making a seal around a cable, the method comprising splitting an apparatus to encircle the cable. The method further comprises injecting a sealant material into the apparatus to form temporary seals; the method then comprising injecting a sealant material to form the main seal. The method may include the steps as previously described in other methods.

[0061] BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Embodiments of the present invention will now be described, by way of example only, with reference to the following figures:

[0063] Figure 1 is an example according to the prior art, of a cable overblowing junction box;

[0064] Figure 2 is a seal according to an embodiment of the present invention, located over a cable with longitudinal grooves;

[0065] Figures 3 and 4 show examples of a seal according to the present invention in use, in a cable overblowing junction box;

[0066] Figure 5 shows an example of an outer forming jacket according to the present invention, showing an injection adaptor attached, for creating a seal according to the present invention;

[0067] Figure 6 shows a cross section of the forming jacket shown in Figure 5;

[0068] Figure 7 shows an example of a piston according to an embodiment of the present invention, showing two injection adaptors attached;

[0069] Figure 8 is a cross section of the piston upper shown in Figure 7, showing two injection adaptors attached;

[0070] Figure 9 shows an example of an outer forming jacket according to the present invention, with the piston inserted to a first injecting position;

[0071] Figure 10 is a cross section of the outer forming jacket shown in Figure 9;

[0072] Figure 11 is a perspective view of the assembly according to the present invention, where the piston is fully inserted into the outer forming jacket; Figure 12 is a cross section of the assembly shown in Figure 11 , showing the piston in the fully inserted position ;

[0073] Figure 13 shows a cross section view of the end of the piston, looking down the longitudinal axis of the piston;

[0074] Figure 14 shows an end elevation of the assembly according to the present invention;

[0075] Figure 15 shows an elevation of an assembly according to the present invention, along with the adjustment screw removed;

[0076] Figure 16 shows an image of an injection gun, which may be used in combination with the present invention; and

[0077] Figure 17 shows an example of a feed tube, which may be used in combination with the present invention.

[0078] DETAILED DESCRIPTION

[0079] Generally speaking, the present invention relates to an apparatus for forming a single-piece seal around an existing cable. The existing cable may be located within a conduit or subduct. The cable may be a fibre optic cable.

[0080] Figure 1 is an example according to the prior art, of a cable overblowing junction box 100. As described previously, this device is used to introduce a new cable 112 into an existing conduit 1 14. The existing conduit 114 may already contain an existing cable 116 which passes through the junction box 100. The new cable 112 is introduced from right to left, and is inserted into the slave conduit 118, which is a disposable piece of conduit which is only used as a temporary connecting link between the cable blowing machine and the overblow junction box, allowing easier insertion of the new cable 112. The slave conduit 118 provides a suitable insertion path for the new cable 112, and also matches the geometry of the existing conduit 114 which was cut. The slave conduit 118 can be of any suitable diameter required. Once the new cable 112 has been fully blown, the slave conduit 118 is disposed of.

[0081] The standard junction box is made up of a lower section 102 and an upper section 104. These sections are secured together, with each section encircling the conduits or cables. There is an existing conduit seal 106, a slave conduit seal 108, and a existing cable seal 110. These three seals encircle the cables and conduits, in effort to create an airtight seal inside the junction box 100. The seals shown are recessed O-ring cords set into the main body.

[0082] As has been previously described, the one-piece seals which are created around the conduits can easily be slid over the ends. This results in high quality one-piece seals being used , and result in little air leakage.

[0083] The difficulty presented in this application concerns the existing cable seal 110. This cable has no cuts or breaks in it, and so it is impossible for a one-piece seal to be inserted onto the existing cable 116. This is because the existing cable 116 would pass through the inspection pit from one side of the hole down the manhole to the other. There is no possibility to slide a ring shaped seal over this continuous cable 116.

[0084] The solution in the prior art is to use some form of split seal 110, which has a break in it, to allow the seal to encircle the existing cable 116. The break in the seal 100 will allow the seal to be twisted over the cable. The downside of using such a seal is that the break or discontinuity in the seal lets air leak out when the device is in use. . This results in a far less efficient cable blowing process, as high air pressures are unobtainable. This results in the cable blowing process being slow and the distance or range that the cable can be installed greatly restricted and very limited and sometimes impossible.

[0085] In use, after the junction box 100 is set up as shown, the upper section 104 is attached onto the lower section 102, and the system is pressurised. Air is inserted down the slave conduit 118, where it forms a flow of air into the junction box 100, and down the existing conduit 114. Sometimes there will be a high volume / pressure independent air source connected to the junction box through a separate quick release air connection fitted to the junction box to supply high velocity, high volume of pressurised air where required dependant on operational requirements. This air creates a barrier around the new cable 112, which reduces the friction of the new cable 112 as it is inserted inside the existing conduit 114. It also reduces friction between the pre-existing cable and assists in the installation of the cable through the principles of viscous drag. This allows the new cable 112 to be inserted, with low friction, up to hundreds of meters through the existing conduit 1 14.

[0086] After the blowing process is complete, the upper section 104 is removed from the lower section 102, the slave conduit 118 is discarded, and a short, new piece of overlapping close out enclosure or waterproof protective housing or conduit is placed is placed between the cuts in the original conduit. This is typically a 300mm piece of conduit, which easily fits inside a manhole. The new cable 112 is then placed alongside the existing cable 116, inside the existing conduit 114 and the new close out housing piece. This would then be tapped up and sealed, to keep the cables inside safe from external threats. Finally, at the end of the job the manhole cover would then be replaced.

[0087] Figure 2 is a cable seal 210 according to an embodiment of the present invention, located over a cable 216 with longitudinal grooves 218. The cable 216 is similar to the one shown in Figure 1 , however this cable 216 has longitudinal grooves 218 which extend along the whole length of the cable 216. These grooves 218 may vary in height / depth, and the number of grooves may depend on the diameter of the cable 216.

[0088] The grooves 218 are a new feature on fibre optic cables 216, and they are to improve the airflow around the cable 216 when the cable is being blown into the conduit. The grooves 218 also reduce friction and surface area contact between the new cable and the legacy cable and sub duct / conduit when the cable is being blown into the conduit. A difficulty presented by the grooves 218 is that when a standard seal is used, a series of small gaps exists around the circumference of the cable 216 and the lip or sealing area of a conventional seal that is typically used in such an application. This results in an inefficient and ineffective seal.

[0089] The seal 210 shown in Figure 2 is a seal 210 according to the present invention. As the seal 210 is created around the cable 216 which it is to intended be used on (in-situ), the profile of the outer circumference of the cable is transferred to the inner circumference of the seal 210. This means the seal 210 cross section matches the cable 216 cross section perfectly, resulting in a very efficient seal.

[0090] The seal 210 may be made from any type of material. The material may be a rubber and / or plastics material.

[0091] The seal 210 material may be injected as a liquid, and it may set as a solid. The seal 210 material may be stored as two separate materials, the two materials only being mixed when they are injected into the apparatus.

[0092] The seal 210 material, when set, may create a of the mould and cable which it sets in. This may result in a very good seal between the mould and the cable. The sea 210 material may be a polymer material, which when sets (or polymerises) does not shrink. The seal 210 material may therefore be capable of very, wherever the seal 210 material is set.

[0093] The seal 210 material as described above may be the same as any other seal described in this application. The seal 210 is generally shaped as a frustoconical ring. This shape is advantageous for use with an overblowing junction box, as is shown in Figure 1. This will be discussed in more detail with reference to future Figures. The seal 210 may be shaped as a standard ‘O-ring’. The seal may be any suitable shape for the application in hand.

[0094] For example, the seal 210 may be for a stationary existing cable which is being sealed inside a junction box, or the seal may be for a new cable being introduced into an existing conduit.

[0095] Figures 3 and 4 show examples of a seal 210 according to the present invention in use, in a cable overblowing junction box 200. This apparatus is generally similar to the junction box 100 shown in Figure 1. The upper section of the junction box is not shown for clarity purposes. This device is used to overblow a new cable (not shown) into an existing conduit (not shown). The existing conduit port 214 is shown: this is where for example, an existing conduit would be located and secured via a collet arrangement. There would also be various seals, ensuring the existing conduit is sealed to the junction box 200.

[0096] An existing cable 216, which would be located inside the existing conduit inside the manhole is shown. Figures 3 and 4 show an example where there is one existing cable 216. There may be more than one existing cable 216. The existing cable 216 is the most problematic for the purposes of sealing, since there are no discontinuities in it. This means a one-piece ring-shaped seal cannot be slid over the cable 216. Contrary to the prior art, which uses split seals to overcome this issue, the seal 210 shown is a one-piece ring, which is made in situ.

[0097] The seal 210 is made around cable 216. This means the seal 210 is well suited and conforms to the profile of the cable 216. This may be important if the cable has an irregular cross section, or if the cable is ribbed / grooved for example.

[0098] The seal 210 is shown sitting inside the middle port 204. Since the middle port 204 is always used for existing cables 216, the port is a fixed diameter to suit the cables. The port 204 has a matching frustoconical seal seat 220, which is where seal 210 is located when the device is in use.

[0099] Two other ports can be seen, upper port 206 and lower port 208. These ports are used for either introducing more cables into the junction box, or alternatively can be used for clamping and sealing existing cables The seal 210 is shown to be a frustoconical ring. The seal seat 220 is manufactured to suit the shape of the seal 210. The seal seat 220 may be at the same angle as the seal 210. When the system is pressurised, a force acts upon the seal 210 to push it to the right (when looking at the page). When an O-ring or a standard ring shaped seal is used, this often results in the seal deforming and potentially leaking. Furthermore, split seals which are used in the prior art will often leak, due to the discontinuity.

[0100] The design of the frustoconical ring seal 210 means that as the pressure is increased, the seal 210 forms more pressure against the seal seat 220. The seal 210 moves towards the right, which effectively squeezes the seal 210 into the seat 220 forcing the seal to constrict tighter around the surface of the cable that requires to be sealed. This results in an increase in surface contact, which creates a tighter seal, which leaks less pressure. The junction box 200 therefore is more efficient when seals 220 according to the present invention are used, as there is far less air leakage.

[0101] The seal 210 and seat 220 is only shown in one of the ports, however the combination of seals and seats may be used in any or all of the other ports also and can be facing in any direction so that if an external mechanical device, sleeve or fastener was used to apply an external force to the frustoconical seal it could force it further into the junction box and achieve a greater sealing force around the cable.

[0102] As has been illustrated, the difficulty to be overcome by the present invention is ‘how to create an improved seal, over a cable which you cannot inserted a one-piece seal over’? This problem is overcome by the following apparatus and methods.

[0103] Figures 5 to 15 show embodiments of the apparatus according to the present invention, which is used to make seals according to the present invention. These Figures are generally arranged in the order of use, however the order presented should not be construed to be limiting. The overarching idea is that there are various set up steps to perform, which are all in view of making the final ‘in-situ’ frustoconical seal according to the present invention.

[0104] Figure 5 shows an example of an outer forming jacket 300 according to the present invention, showing an injection adaptor 310 attached to an injection port 312, for creating a seal according to the present invention. Figure 6 shows a cross section of the outer forming jacket 300 shown in Figure 5.

[0105] The forming jacket 300 is comprised of an upper part 302 and a lower part 304. These parts form half of the circumference of the forming jacket 300, to completely encircle the cable 316 which is to be sealed. Although the upper and lower parts are shown to be two 180 degree parts, the invention should not be limited to this set up.

[0106] Figure 6 shows the cable 316 which is to be sealed. The cable 316 would extend from one side of the manhole to the other, and would not be cut. To create a seal around the cable 316, the forming jacket 300 is separated, with the upper part 302 and the lower part 304 placed around the cable 316.

[0107] The outer forming jacket 300 may be made from any suitable material such as steel, aluminium, or a metal.

[0108] After the jacket 300 has been split, and is placed over the cable 316, the upper part 302 and lower part 304 are located together, and then fastened together via circumferential fasteners, which are located in the circumferential fastener slots 318. For example, robust cable ties may be used as suitable circumferential fasteners. These can be quickly installed, allowing the device to be used, and then quickly removed, allowing the device to be disassembled.

[0109] After the jacket 300 is fastened together, an injection adaptor 310 is inserted into the first jacket injection port 312a. The first jacket injection port 312a can be located anywhere ‘upstream’ of the primary seal mould 320 (i.e. closer to the outside of the device, or to the right, when looking at the page). The primary seal mould 320 is used to form the main or primary seal of the invention, whereas the other seals formed are all merely for the manufacture of the primary seal. The shape of the primary seal mould 320 will determine the shape of the primary seal which is made.

[0110] The primary seal mould 320 may have a taper angle of around 45 degrees. The primary seal mould 320 may comprise a taper which is between around 20-70 degrees, or 10-80 degrees.

[0111] The first jacket injection port 312a is connected to a first seal annulus 322. The first seal annulus 322 extends around the circumference of the cable 316, and is shaped with a rectangular cross section. The cross section should not be construed to be limiting, nor should the size of the annulus. The first seal annulus 322 is generally the first one to be made, however it should not be limited to being the first one to be made.

[0112] In use, the injection adaptor 310 is connected to a supply of sealant material (see Figures 16 and 17 for more information). The sealant material is then injected into the first seal annulus 322, where it fills the cavity around the cable 316. This process forms a ring seal around the cable 316. The outer diameter of the cable 316 determines the inner diameter of the seal, and the outer diameter of the first seal annulus 322 determines the outer diameter of the seal.

[0113] Once this first seal has set, and the annular ring seal has been formed, the jacket 300 is left in place, with the new first seal formed. This new first seal, which is inside the first seal annulus 322 provides the first resistance / stop for the primary seal to be formed.

[0114] Figure 7 shows an example of a piston 400 according to an embodiment of the present invention, showing two injection adaptors 410 attached. The piston 400, like the jacket 300, is split into a piston upper 402 and a piston lower 404. This is for the same reason as the jacket 300, i.e. so the piston 400 can be wrapped around the cable 316 to be sealed.

[0115] The piston 400 may be made from any suitable material such as steel, aluminium, or a metal.

[0116] Figure 8 is a cross section of the piston upper 402 shown in Figure 7, showing two injection adaptors 410 attached, via the first piston injection port 412a and the second piston injection port 412b. These injection ports are connected to their corresponding seal annulus’, the second seal annulus 422a and the third seal annulus 422b. Also shown in Figure 7 is an adjustment screw 406. This adjustment screw 406 is used to set the depth that the piston 400 goes inside the jacket 300.

[0117] Continuing with the order of use, whilst the first seal is setting inside of the first seal annulus 322 on the outer forming jacket 300, the piston 400 is split and is placed over the cable 316 in order to make the second and third seals. The piston 400 is placed to the left of the jacket 300, when looking at the page. These seals act as a safety barrier, and will provide the necessary seal to form the internal chamber to make the primary seal.

[0118] With the piston 400 in place, with the piston upper 402 and the piston lower 404 mated together, and held together by mechanical fasteners or screws and aligned by dowel pins the injection adaptors 410 are inserted into the first piston injection port 412a and the second piston injection port 412b. The piston upper 402 and piston lower 404 are kept in alignment via alignment pins or dowels located in the larger diameter end.

[0119] With the piston 400 secured, the sealant material is then injected into the second seal annulus 422a and the third seal annulus 422b. Just as with the first seal annulus 322, the sealant material forms a ring around the perimeter of the cable 316. These rings will generally conform to the outside diameter of the cable 316, and will create an air tight seal. Unlike the first seal which is made inside the first seal annulus 322, the second and third seals need to slide along the cable 316 for a short distance. This is because the piston 400 will be inserted into the outer forming jacket 300, and the jacket 300 is fixed in relation to the cable 316, due to the first seal.

[0120] After the sealant has been inserted and given sufficient time to cure (10-15 mins), the injection adapters are then removed, before the piston 400 is semi inserted into the jacket 300, as depicted in Figures 9 and 10.

[0121] Figure 9 shows the outer forming jacket 300 according to the present invention, with the piston 400 inserted to a first injecting position. Figure 10 is a cross section of the outer forming jacket 300 shown in Figure 9, with the piston 400 inserted part-way. The cable 316 has also been added for clarity purposes.

[0122] At this stage in the process, seals have been formed in the first seal annulus 322 located in the outer forming jacket 300, the second seal annulus 422a and the third seal annulus 422b located in the piston 400.

[0123] The adjustment / setting screw 406 is set to a certain depth to limit the insertion distance and travel of the piston so that the piston will assume the correct position and alignment to facilitate the loading or charging of the final chamber. The piston 400 is then inserted into the jacket 300. The end fasteners 408 are then screwed into the jacket 300, securing the piston 400 to the jacket 300. This then forms the final chamber to be filled by the sealant material, adjacent to the primary seal mould 320.

[0124] An overflow aperture 314 is provided, which is adjacent to the primary seal mould 320. This is to let excess sealant material escape. In use, the overflow aperture 314 would be located on top of the assembly, to allow any air bubbles to escape.

[0125] Continuing with the process, sealant material is injected through the injection adaptor 310 into the primary seal cavity and the primary seal mould 320, via the second jacket injection port 312b. The sealant material is injected into the primary seal cavity 324 until it fills the cavity 324 and fills the primary seal mould 320. The sealant material can only escape out of this region via the overflow aperture 314, due to the presence of the three seals created earlier in the annulus’ 322, 422a, 422b.

[0126] Once the sealant material starts to exit the overflow aperture 314, the user knows that the cavity has been filled. The apparatus is then ready for the next stage. Figure 11 is a perspective view of the assembly according to the present invention, where the setting screw 406 is fully retracted to allow the piston 400 to be fully inserted and located into the outer forming jacket 300 by the tightening of the fasteners 408.

[0127] Figure 12 is a cross section of the assembly shown in Figure 11 , showing the piston 400 in the fully inserted position.

[0128] The perspective view in Figure 11 shows the assembly, with the end fasteners 408 fully fastened into the jacket 300. The adjustment screw 406 is fully wound out, or removed from the assembly at this stage.

[0129] Carrying on from Figures 9 and 10, the cavity is now full of sealant material. Before the sealant material sets, the piston 400 is fully inserted into the jacket 300 by adjusting the end fasteners 408. This effectively squeezes the now full cavity, and ensures that the sealant material has completely filled up the primary seal mould 320. The piston 400 exerts a high pressure to the primary seal mould 320, ensuring that there are no air gaps or bubbles present. Any excess sealant material which escapes from the primary seal mould 320 will be stopped by the seals which are in the first seal annulus 322, the second seal annulus 422a and the third seal annulus 422b. Any excess pressure may also leak out of the overflow aperture 314.

[0130] The overflow aperture 314 may be located such that when the piston 400 is fully inserted into the jacket 300, the overflow aperture 314 is no longer in communication with the primary seal mould 320. This may serve to create an airtight chamber for the last stages of compression.

[0131] The compression forces exerted by the piston 400 may aid the setting of the sealant material.

[0132] Finally, after the device has been left in the position depicted in Figure 12 for some time, the primary seal will have set. The primary seal will have taken up the outer profile of the primary seal mould, and taken up the inner profile of the cable. In this example shown, a frustoconical ring shaped seal will have been made, as is shown in Figures 2-4. The piston 400 is then removed from the jacket 300, before both the piston 400 and the jacket 300 are separated- leaving the three initial seals and the primary seal remaining. The initial seals are removed, leaving just the primary seal. This is then suitable for use with an overblowing machine, as is shown in Figures 3 and 4 for example.

[0133] Figure 13 shows a cross section view of the end of the piston 400, looking down the longitudinal axis of the piston. Both the piston upper 402 and the piston lower 404 are shown. The piston upper 402 may be attached in any manner to the piston lower 404. In this example, piston fixing screws 418 are shown. These prevent any lateral movement between the piston upper 402 and the piston lower 404.

[0134] Furthermore, a locating pin 416 may be used as shown to aid the locating process. There may also be locating pins 416 on the outer jacket 300- which serve the same purpose.

[0135] Figure 14 shows an end elevation of the assembly according to the present invention. The piston 400 and the jacket 300 should be construed as being mere examples, and specific geometries or limitations should not be added to them. The principle behind the invention is a novel way of creating an air-tight seal around a cable, by using a split jacket and split piston assembly.

[0136] Figure 15 shows an elevation of an assembly according to the present invention, along with the adjustment screw 406 removed. The end fasteners 408 are shown fastening the piston 400 and the jacket 300 together.

[0137] Figure 16 shows an image of an injection gun 500, which may be used in combination with the present invention. This example injection gun 500 comprises a handle 502 and a trigger 504. The gun 500 also comprises a ratcheting mechanism 506, which is activated when the user squeezes the trigger 504. This prevents any of the sealant material from inadvertently retracting back into the gun 500 after the user has stopped squeezing the trigger 504. The sealant material is stored inside the chambers 508, before being ejected out of the gun.

[0138] Figure 17 shows an example of a feed tube 510, which may be used in combination with the present invention. The feed tube 510 would be attached to the injection gun 500. The sealant material may travel out of the gun 500 and into the feed tube 510, before going through the injection adaptor 310.

[0139] The feed tube 510 may contain baffles which enables the sealant material to mix before being ejected out. This may be beneficial if a two-part sealant material (a base material and an activator for example) is to be used.

[0140] Whilst specific embodiments of the present invention have been described above, it will be appreciated that departures from the described embodiments may still fall within the scope of the present invention.

Claims

CLAIMS1 . An apparatus for creating a primary seal around a cable, the apparatus comprising: an outer forming jacket comprising an upper part and a lower part to allow the outer forming jacket to encircle the cable, wherein the outer forming jacket further comprises: a first jacket injection port connected to a first seal annulus, and a second jacket injection port connected to a primary seal mould and a primary seal cavity; a piston comprising a piston upper and a piston lower to allow the piston to encircle the cable, wherein the piston further comprises: a first piston injection port connected to a second seal annulus; wherein the primary seal mould is located between the first seal annulus and the second seal annulus, wherein the piston is slidably engageable with the outer forming jacket inside the primary seal cavity; and wherein in use, the outer forming jacket and the piston are assembled over a cable to be sealed, the first seal annulus, the second seal annulus, the primary seal cavity and the primary seal mould are filled with a sealant material, before the piston is inserted into the outer forming jacket to form a primary seal within the primary seal mould.

2. An apparatus according to claim 1 , wherein the cable is a ridged cable.

3. An apparatus according to claims 1 or 2, wherein the cable is a fibre optic cable.

4. An apparatus according to claims 1 or 2, wherein the piston further comprises a second piston injection port connected to a third seal annulus.

5. An apparatus according to any preceding claim, wherein the primary seal mould is generally frustoconical shaped.

6. An apparatus according to any preceding claim, wherein the outer forming jacket further comprises an overflow aperture connected to the primary seal mould.

7. An apparatus according to any preceding claim, wherein to form the primary seal, the piston compresses the sealant material inside the primary seal mould.

8. An apparatus according to any preceding claim, wherein the piston is fastened to the outer forming jacket via a plurality of end fasteners.

9. A apparatus according to any preceding claim, wherein the distance the piston is inserted inside the outer forming jacket is controlled via an adjustment screw.

10. An apparatus according to any preceding claim, wherein the injection ports are connectable to a sealant material.

11. An apparatus according to any preceding claim, wherein the primary seal mould is generally frustoconical shaped.

12. An apparatus according to any preceding claim, wherein the apparatus has a longitudinal axis, and wherein the cable to be sealed lies on the longitudinal axis.

13. An apparatus according to any preceding claim, wherein the apparatus is portable.

14. A method of making a primary seal around a cable, the method comprising the steps of: providing an apparatus which can encircle the cable, wherein the apparatus comprises an outer jacket and a piston, the piston being slidably engageable within the outer jacket, and the outer jacket having a primary seal mould; creating a first temporary seal around the cable, the first temporary seal being created within the outer jacket; creating a second temporary seal around the cable, the second temporary seal being created within the piston; creating the primary seal around the cable, the primary seal being created between the first and second temporary seals, wherein the primary seal is created within the outer jacket, and wherein the piston is used to create a pressure force on the primary seal mould to form the primary seal.

15. A method according to claim 14, wherein a third temporary seal is created around the cable, the third temporary seal being created within the piston.

16. A method according to any of claims 14-15, wherein the apparatus can be split into upper and lower parts, thus allowing the apparatus to encircle a cable which cannot be fed through an aperture.

17. A method according to any of claims 14-16, wherein the temporary seals are formed via annulus shaped moulds within the apparatus, wherein the annulus shaped moulds encircle the cable.

18. A method according to any of claims 14-17, wherein the primary seal is formed by filling the primary seal mould with a sealant material, and then compressing the sealant material to remove any gas or impurities.

19. A method according to any of claims 14-18, wherein the piston is moved relative to the outer jacket via a plurality of end fasteners.

20. A method according to any of claims 14-19, wherein the sealant material is injected into the apparatus by a user.

21. A method according to any of claims 14-20, wherein the sealant material comprises an activator ingredient, which sets the sealant material.

22. A primary seal formed by the method of any of claims 14-21.

23. A primary seal according to claim 22 wherein the seal is a frustoconical ring shaped seal.

24. A primary seal according to either claim 22 or 23, wherein the seal is suitable for a cable overblowing junction box.

25. A method of making a single-piece primary seal around a cable, the method comprising the steps of: providing an apparatus which can be split, the split allowing the apparatus to encircle the cable, the apparatus comprising a primary seal mould which encircles the cable when in use; injecting a sealant material into the primary seal mould, thereby creating a singlepiece primary seal around the cable.

26. A method according to claim 25, wherein the cable is a fibre optic cable.

27. A method according to claim 25 or claim 26, wherein the apparatus is a junction box manifold.

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