IES20020157A2

IES20020157A2 - A method and apparatus for detecting and prevention of water in cable joint closures

Info

Publication number: IES20020157A2
Application number: IE20020157A
Authority: IE
Inventors: William Dominick Mary Horgan
Original assignee: Paltexa Ltd
Priority date: 2002-03-01
Filing date: 2002-03-01
Publication date: 2003-09-03
Also published as: GB0304781D0; WO2003074623A9; WO2003074623A1; GB2388373A; AU2003209962A1; GB2388373B; AU2003209962A8; IE20030151A1

Abstract

The method comprises a series of steps where the presence of water and/or leaks through which water can enter a cable joint closure are located using a pressure testing apparatus (1). The leaks are sealed using a polyurethane sealant which provides a water and gas impermeable barrier. The cable joint closure is retested on a regular basis ensuring there is no recurrance of leaks. <Figure 1>

Description

A METHOD AND APPARATUS FOR DETECTION AND PREVENTION OF WATER IN CABLE JOINT CLOSURES This present invention relates to a method and apparatus for detection and prevention of 5 water in cable joint closures and more particularly to telecommunication cable joint closures.

The most commonly used joint closure in telecommunication access network’s is the “31A joint”. The “31A joint” comprises a dome shaped cover which screws over a base unit.

A main telecommunication cable enters the joint through an opening within the base unit, the main telecommunication cable is connected to a number of individual cables. The individual cables exit the joint via other openings on the base unit and are used to connect places of residence, business and so forth to the telecommunication network. A high percentage of customer complaints about substandard lines detected by a buzzing noise or a crossed-line where another person’s conversation can be overheard can be linked to water leaking into the “31A joint”.

At present when “31A joints” are completed, the only method of testing whether the “31A joint” is completed to standard is a visual test. Most “31A joints” are stored in access junctions beneath the ground. It has been estimated that on average in any telecommunication access network 30% or greater of the “31A joints” are leaking. If the joints are used in a particularly wet environment, where the underground access junction could fill with water, water can enter the sealed joint by capillary action along the cabling.

A telecommunication access network that has a water leakage problem suffers the following problems; Joints with water in them Contacts and Earth_connection shorting.

Dis and inter Dis pairs (paired telephone lines, this is due to corrosion after long periods) Noisy Pairs (a buzzing noise is heard on the line when in use) ISTTCL_£ Changed Pairs (other people’s conversations can be heard in the background when using the phone) A large number of line faults are reported that may all stem from the same “31A joint” thus leading to a false recording of the level of faults within a network. Repairing the fault within a joint does not necessarily mean that the problem is solved or that a repeat fault on the same cable will not occur. Areas where upgrade work was completed and visually checked resulted in 30% of the “31A joints” leaking within a short period of time At present the methods of correcting this fault are either spraying the damaged leaking area with oxygen (O2) or sealing the area with an epoxy resin. The epoxy resin used at present does not form a strong bond with the materials used in the “31A joint”. It is also difficult to use as it must be hand-mixed before applying to the leaking area, once it is applied to the area it requires at least forty minutes to harden sufficiently.

It is the object of the present invention to seek to alleviate the aforementioned problems.

Accordingly, the present invention provides a method of detecting repairing leaking units, the method comprising the steps of: (a) using an air pressure testing apparatus to check for leakage points in or on a unit, (b) repairing the leakage points, (c) re-testing the unit to ensure that the leakage points are repaired.

The present invention also provides a pressure testing apparatus to test a cable joint comprising a hollow housing unit, which is adapted to fit over and seal with the base of a cable joint unit, and inlet valve, wherein a pump is attachable to the inlet valve. •Π ri Ideally, the inlet valve is attached to the hollow housing unit using a manifold where the manifold also has a pressure gauge attachment and a pressure release safety valve attachment.

Ideally, the exterior of the unit being tested is covered with a leak detection fluid.

Optionally the pump used is a foot pump. Ideally, the air from the pump is passed through a desiccator unit prior to entering the pressure testing apparatus.

As the pressure within the unit increases, air is forced out through the leaking points on the unit. It is preferable to use a leak detection fluid which bubbles as the air passes through it, giving a visual indication of the location of the leak. When the leakage point(s) are detected the pressure is released from the unit, The air pressure is released using the pressure release safety valve. Ideally once the pressure has been released, the pressure testing apparatus is detached from the unit being tested.

It is preferable to clean the unit prior to repairing the seal, in order to remove grease and dirt that may prevent a good seal forming.

Advantageously the present invention provides a two-part epoxy resin to repair the leaking cable joint. Ideally the epoxy resin comprises 4, -4Diphenylmethane-di-isocyanate hardener with water blown Polyalkylene Glycol. Advantageously the constituents are statically mixed using a gun with mixing nozzle. Ideally, once the constituents of the epoxy resin are mixed, a foaming two part polyurethane adhesive is formed.

Preferably, the foaming two part polyurethane adhesive is dispensed directly from the mixing nozzle into the leaking unit. Advantageously the foaming two part Polyurethane adhesive hardens rapidly and is cured within fifteen minutes to form a very strong hard resin with sealant properties. At temperatures below 5 °C the curing time may increase.

Advantageously, once the foaming two part polyurethane adhesive has formed the very strong hard seal, the cable joint is re-tested to ensure that the leaks have been repaired using the pressure testing apparatus as previously described.

The invention will now be described by way of example only and with reference to the accompanying drawings in which: Figure 1 is a front view of the pressure test apparatus of the invention; Figure 2 is a plan view of the pressure test apparatus of Figure 1; and Figure 3 is an exploded perspective view of the desiccation pump mechanism.

Referring to the drawings and initially to figure 1, there is shown a pressure test apparatus indicated generally by the reference numeral 1. The pressure test apparatus 1 has a hollow cylindrical body 5 to which a dome 5 a is attached enclosing one end of the hollow cylindrical body 5. The dome 5 a is defined as the top of the pressure test apparatus 1. Remote from the dome 5a is the base of pressure test apparatus 1.

The base of the pressure test apparatus 1 comprises a circular rim 5b. The inner surface of the circular rim 5b is flush with the inner surface of the hollow cylindrical body 5, the circular rim 5b extends outwardly from the inner surface beyond the circumference of the main cylindrical body 5 of the pressure test apparatus 1 and provides stability and support for the pressure test apparatus 1 in a standing position. The base 5b also provides a screw thread on the inner surface that enables the pressure test apparatus to be screwed onto a “31A joint” forming a pressure seal.

Positioned on the exterior surface of the hollow cylindrical body 5 is a pressure gauge 2, an inlet valve 3 and pressure release safety valve 4. In this example the pressure gauge 2, inlet valve 3 and pressure release safety valve 4 are positioned at an upper point on the hollow cylindrical body 2 near the dome 5a of pressure test apparatus 1. The pressure gauge 2 is not limited to this position on the pressure test apparatus 1, any convenient position determined by a person skilled in the art can be used.

Referring to Figure 2, the pressure gauge 2, inlet valve 3 and pressure release safety valve 4 are connected to the hollow cylindrical body 5 of the pressure test apparatus 1 using a manifold 7 with 6.3mm fittings. The manifold 7 has a four way output 7a - 7d. The pressure release safety valve 4 is attached at 7a, the pressure gauge 2 is attached at 7b and the inlet valve 3 is attached at 7c. Point 7d on the manifold 7 is inserted through a hole on the hollow cylindrical body 5 of the pressure test apparatus 1 and held securely in position by a nut 8.

The hole through which the manifold 7 is attached to the hollow cylindrical body is sealed to prevent any leakage of air when the pressure test apparatus 1 is in operation. The pressure release safety valve 4 is set at 34.5 kPa +/- 10%, thus when in operation if the pressure within the manifold hence the pressure test apparatus 1 exceeds the value, the valve opens releasing the pressure. The pressure gauge 2 measure pressure with a range of 0-15 psi, however the pressure that is produced is limited to 5psi.

In this example the pressure gauge 2 is attached to the manifold 7 at 7b using a back entry, however the pressure gauge 2 - manifold 7 connection point is not limited to this position, any suitable connection point can be used. The inlet valve 3 attached to the manifold 7 at 7c is a female connector (6.3mm x 6.3mm) with a 9.5mm quick release coupling for safety.

The pump mechanism comprising a foot pump (not shown) and desiccator cartridge system 100 of Figure 3 is attached to the pressure test apparatus 1 via the inlet valve 3 on the manifold 7 of Figure 2.

Figure 3 is an exploded perspective view of the desiccator cartridge system 100. A first hollow tube 23 is completely encircled by a second hollow tube 24. In this example the first hollow tube 23 is an acrylic tube whilst the second hollow tube 24 is formed from a suitable alloy material. A circular gasket 22 is positioned at each end of the hollow tubes 23 and 24. The diameter of the circular gaskets 22 are equivalent to the diameter of the !5o second hollow tube 24. Ideally, the circular gasket 22 is formed from silicon rubber, however any suitable sealant material known to a person skilled in the art can be used.

A baize filter 21 is attached to each of the circular gaskets 22 at each end of the hollow pipes 23 and 24. The baize filter 21 is not limited to baize any suitable material can be used. The hollow pipes 23 and 24, the circular gaskets 22 and the baize filters 21 are all held securely in position using plates 20. Where plates 20 are positioned beside each baize filter 21. Each plate 20a and 20b is rectangular in shape. Three threaded bars 11 pass through the plates 20 at points 12 located off centre on the face of plate 20. Each of the threaded bars 11 are secured using nyloc nuts 10 on the face of plates 20 that is remote the baize filter 21.

The nyloc nuts 10 are tightened such that all of the component parts, that is the hollow tubes 23 and 24, the circular gaskets 22 and the baize filters 21 intermediate the plates 20 are held tightly together preventing both air and water from entering or leaving the desiccator cartridge system 100.

The desiccator cartridge system 100 attaches to the pump (not shown) using plates 20 and pump legs 30. The plates 20 are secured to pump legs 30 using a nut and bolt mechanism 25. The bolts 25 pass through an opening 15 on the plates 20, the opening 15 is positioned remote from openings 12.

The air from the pump is transported to the desiccator cartridge system 100 using a flexible tube 35 fitted with two elbow connectors 31 and 54 respectively, the pump is the first elbow connector 31 is attached to the flexible tube 35 at the end remote from the second the flexible tube 35 attaches to this connector 54 and elbow connector 54. The second elbow connector 54 inserts into a t-junction 53, which connects to the desiccator cartridge system 100 via an opening 14 on plate 20a. The third connection point of t-junction 53 is fitted with a safety relief valve 52.

A further opening 14a on plate 20a is sealed with a plug 50. The further opening 14a enables a second pump to be attached if greater pressure is required. Alternatively it provides a second opening for a pump inlet should something happen the first opening. Advantageously the plug 50 acts as a further safety device should the pressure build up become too great.

The air from the pump exits the desiccator cartridge system 100 via opening 14b on plate 20b. An elbow connector 40 is attached to opening 14b on plate 20b, a piece of flexible tubing 41 fitted with a non-return valve 42 is attached to the elbow connector 40. The flexible tubing is fitted with a quick release plug 44 at the end of the tube remote the elbow connector 40. The quick release plug 44 fits into the inlet valve 3 of the pressure test apparatus 1 of Figures 1 and 2.

Once the foot pump and desiccator cartridge system 100 are connected to the pressure test apparatus 1, the equipment is ready for use in detecting the presence of water in cable joint closures. The pressure test apparatus Tis specifically shaped to mimic the cover of a 31A telecommunication joint closure, therefore the process of the invention will be explained in detail with reference to this type of joint closure. However the apparatus and process of the invention can be readily adapted to suit any type of joint closure.

The method of detecting and repairing the cable joints is a follows: 1. Initial testing The existing cover of the “31A joint” is removed. Any spilled or warm resin surrounding the cables within the joint or around the seal area is removed. The pressure test apparatus 1 is positioned over the joint and is subsequently screwed to the joint forming a seal. In effect the pressure test apparatus 1 mimics the cover of the “31A joint”. Leak detection fluid is placed around the seals of the “31A joint” including the seal between the “31A joint” and the pressure test apparatus 1.

Air is pumped into the sealed pressure test apparatus 1 and “31A joint” by a foot pump. The foot pump is connected to the desiccator cartridge system 100 (Figure 3) and the inlet valve 3 (Figures 1 and 2) as previously described. The pressure is monitored using pressure gauge 2 (Figures 1 and 2). The pressure is limited to 34.5kPa, the pressure release safety valve 4 (Figures 1 and 2) on the pressure test apparatus 1 are set to a safety pressure level of 34.5kPa+/- 10%. If there are leaks present in the “31A joint” the air is forced out through the seals, the leaks detection fluid bubbles as the air is forced through the seal. The air pressure is maintained at 34,5kPa during the test to ensure that all leaks are detected.

The pressure release safety valve 4 (Figures 1 and 2) is removed and the pressure released from the pressure test apparatus 1 and the “31A joint”. 2. Repair of Leak(s) A two part epoxy resin is used to bond to the cable and “31A joint” thus repairing the leaks. The main elements of the epoxy resin are 4, -4 Diphenylmethane-di-isocyanate hardener with water blown Polyakylene Glycol. When mixed the constituents give rise to a foaming two part Polyurethane adhesive with sealant properties. This epoxy resin is used to bond to a variety of surfaces including Polycarbonate, Perspex, uPVC, Nylon, High impact polystyrene (HIPS), Fibreglass with polystyrene (GRS) and Plastic (ABS). No deterioration of these materials has been detected with use of this epoxy resin.

Method of Use The cable and surrounding area within the “31A joint” is cleaned using a Isoparafin (PF) wipe. The PF wipe comprises a lint free cloth impregnated with PF solution. The areas cleaned by the PF wipe are then clean and degrased allowing for a clean bonding area. The “31A joint” is then filled with the two part epoxy resin. The two part epoxy resin is delivered using a known delivery gun and mixing nozzle. The constituents of the epoxy resin are individually contained within tubes. The gun is engineered to force the constituents out of their individual tubes and premix at a one to one ratio within the mixing nozzle.

The outer base of the “31A joint” is sealed with Amalgamating tape. If there are any spare chambers within the “31A joint”, i.e. areas that do not have cable, an article mimicking the presence of cable is inserted to ensure the epoxy resin does not spill into them. The epoxy resin forms a bond with the cable and the “31A joints” after a number of minutes. The epoxy resin has hardened within ten minutes. After fifteen minutes the epoxy resin has hardened into a very strong resin and a secure seal is firmly formed between the epoxy resin, the cables and the “31A joint”. 3. Retest The pressure test apparatus 1 (Figures 1 and 2) is then reapplied over the “31A joint” and sealed to the “31A joint”. The same procedure as therefore is followed to ensure that the leak(s) are sealed and no water can get into the “31A joint”, 4. Final Stage Once the pressure test apparatus 1 (Figures 1 and 2) is removed after testing, a signed an dated silica gel bag is placed in the joint. The silica gel absorbs any residual water/moisture that remains in the joint or around the cable. The O-ring which forms a seal between the “31A joint” and the cover is cleaned and the cover is replaced. If the Oring is damaged, it is replaced prior to replacing the “31A joint” cover.

A number of trials of both the apparatus and the process have been conducted.

TRIAL ONE Trial one took place on an “old” access network, Table 1 synopsises the results of the initial findings at this location Table 1 Total “31A joints” leak tested 21 Leaked at unused indentation in the base 1 Leaked due to insufficient resin used 1 Leaking at the base - not cleaned properly 6 Leaked due to a broken seal 1 Leaked at base due to resin not set properly 1 Total Leaking 10 “31A joints” Leaking “old” Access Network 50% 50% of “31A joints” in this sample of “old” access network were found to be leaking TRIAL TWO This trial took place on a newly built housing estate, Table 2 synopsises the results of the initial findings.

Table 2 Total “31A joints” leak tested 15 Leaked due to rubber seal damaged 1 Leaked due to No Resin I Leaking at the base (not abraded) 2 Total Leaking 4% “31A joints” Leaking on New Building 25% % of “31A joints” in this sample of new buildings were found to be leaking The leaking joints in the above trials were repaired and retested to ensure that water could no longer leak into the “31A joint” using the process of the invention. Silica gel bags were placed in each of the joints tested. Six weeks later a further re-test was carried out on all of the joints. The silica gel within the joints remained blue (a change to white/colourless/pink would indicate the presence of water). Testing with the pressure test apparatus 1 (Figures 1 and 2) indicated that no leaks were present.

TRIAL THREE A number of “31A joints” were tested on a third housing estate. Out of seven “31A joints” tested, two were found to be leaking, one was sound and four were previously upgraded and were structurally sound. The two leaking “31A joints” were repaired using the process of the invention described above. The estate was revisited and all “31A joints” were found to be sound with no water presence detected within the joint.

A number of other spot tests were conducted on joints at different location within a city environment, there were a mixture of “31A joints” and 32B joints. Of nine joints tested, three joints leaked. The joints were repaired and re-tested using the process of the invention. It was determined that all joints were successfully repaired.

It will of course be understood that the invention is not limited to the specific details as herein described, which are given by way of example only, and that various alterations and modifications may be made without departing from the scope of the invention.

Claims

CLAIMS:

1. A method of detecting and repairing a leaking telecommunication cable joint closure, the method comprising the steps of: (a) using an air pressure testing apparatus to check for leakage points in or on a cable joint closure; (b) repairing the leakage points; and (c) re-testing the closure to ensure that the leakage points are repaired; optionally cleaning the closure intermediate step (a) and step (b); optionally using a two-part polyurethane sealant to repair the leakage points on the closure at step (b); and optionally using the air-pressure testing apparatus to re-test the closure at step (c).

2. An apparatus for pressure testing a telecommunication cable joint closure comprising a hollow housing unit, which is adapted to fit over and seal with the base of the cable joint closure, and an inlet valve, wherein a pump is attachable to the inlet valve; optionally the inlet valve is attached to the hollow housing closure using a manifold; optionally the manifold includes a pressure gauge; optionally the manifold includes a pressure release safety valve; optionally the pump used is a mechanical pump; and optionally the air from the pump is passed through a desiccator closure prior to entering the pressure testing apparatus.

3. A sealant for a telecommunication cable joint closure comprising:a two-part polyurethane sealant, one part being an isocyanate and the second part being a polyol.

4. A sealant for a telecommunication cable joint closure as claimed in Claim 3, wherein the isocyanate is 4,-4Diphenylmethane-di-isocyanate and the polyol is polyalkylene glycol, and optionally the polyalkylene glycol is water-blown polyalkylene glycol.

5. A method for detecting and repairing a leaking telecommunication cable joint closure substantially as herein described with reference to the accompanying drawings.