Classifications

• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02G—INSTALLATION OF ELECTRIC CABLES OR LINES, OR OF COMBINED OPTICAL AND ELECTRIC CABLES OR LINES
  • H02G15/00—Cable fittings
  • H02G15/08—Cable junctions
  • H02G15/18—Cable junctions protected by sleeves, e.g. for communication cable
  • H02G15/1806—Heat shrinkable sleeves
  • H02G15/1813—Wraparound or slotted sleeves
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02G—INSTALLATION OF ELECTRIC CABLES OR LINES, OR OF COMBINED OPTICAL AND ELECTRIC CABLES OR LINES
  • H02G15/00—Cable fittings
  • H02G15/013—Sealing means for cable inlets

Definitions

• This invention relates to a method of making a seal with a heat-recoverable sleeve, particularly around an elongate article such as a cable, wire or pipe.
• the invention can overcome a problem of insufficient adhesive flow during installation of the sleeve, and thereby around the formation of leak paths.
• Heat-recoverable articles are now widely used in many areas where insulation, sealing and encapsulation are required. Usually these articles recover, on heating, towards an original shape from which they have previously been deformed, but the term "heat-recoverable”, as used herein, also includes an article which, on heating, adopts a new configuration, even if it has not been previously deformed.
• such articles comprise a heat- shrinkable sleeve made from a polymeric material exhibiting the property of elastic or plastic memory as described, for example, in U.S. Patents 2,027,962: 3,086,242 and 3,597,372.
• the original dimensionally heat- stable form may be a transient form in a continuous process in which, for example, an exiruded tube is expanded, whilst hot, to a dimensionally heat-unstable form but, in other applications, a preformed dimensionally heat stable article is deformed to a dimensionally heat unstable form in a separate stage.
• Heat-shrinkable sleeves find many applications, especially in the connection and the termination of wires, cables and pipes. However, there are other applications where it is desirable to provide a connecting, insulating or protective heat-recoverable member for elongate objects such as cables and pipes where the ends are not accessible or, if they are accessible, where it is undesirable to disconnect or otherwise displace them. For such applications so- called "wrap-around" sleeves have been developed. Basically these are heat-recoverable sheets which can be wrapped round the 94/23471
• substrate to form a generally tubular shape and which, in general are provided with fastening means for holding them in the wrapped up configuration during recovery.
• Heat-recoverable sleeves have been successfully employed in many fields of application.
• problems may arise when two or more substrates such as supply lines, for example cables or pipes, have to be sealed at one position.
• This problem which is known as "branch-off, may occur, for example, at the outlet of a heat- recoverable part.
• branch-off may occur, for example, at the outlet of a heat- recoverable part.
• outlets of the splice cases described and claimed in British Patent 1 ,431,167 may especially be mentioned the outlets of the splice cases described and claimed in British Patent 1 ,431,167.
• mastic tape to seal the gap between the supply lines so that, on recovery, a proper encapsulation is formed at the end of the heat- recoverable part.
• the use of such tape requires skill on the part of the installer and the method is not applicable to large parts.
• the mastic may degrade the overall performance of products which are provided with an inner lining or coating of a hot- melt adhesive.
• a method of forming a seal between a heat-shrinkable sleeve and an elongate substrate wherein at least a portion of the elongate substrate is surrounded by or otherwise provided with a sealing material, preferably a layer of hot-melt or other adhesive adjacent, and preferably enclosed within, a discontinuous spacer, and heat is applied to the sleeve to cause shrinking of the sleeve and flow of the sealing material into interstitial spaces in the discontinuous spacer and to form the desired seal.
• a sealing material preferably a layer of hot-melt or other adhesive adjacent, and preferably enclosed within, a discontinuous spacer
• the discontinuous spacer provides room for sufficient but not excessive sealing material flow. Surprisingly, the provision of voids around the substrate results in a reduction in the likelihood of leak paths after installation.
• the spacer may also act to reinforce the sealing material and/or other components of the overall structure.
• the discontinuous spacer comprises a polymer material fabric or net, preferably a polyolefin such as polyethylene. It may however comprise a plurality of rings or other structures spaced along the sealing material and/or elongate substrate. It may be heat-shrinkable, preferably shrinking during installation of the sleeve and flow of the sealing material. The material is preferably cross-linked such that it can soften and adapt its shape as necessary during installation without melting.
• an elongate substrate having an electrically insulating outer sheath at least a portion of which is surrounded by a sealing material adjacent, and preferably enclosed within, a discontinuous support.
• kit for making a seal between an elongate substrate and a heat-shrinkable sleeve which comprises a sleeve of sealing material for sliding onto the substrate, and a discontinuous support member for placing around the sealing material sleeve.
• Figure 1 is an isometric projection of a cable splice closure sealed by a method according to the present invention.
• Figure 2 is a cross-section through a branch-off seal taken on the line II-II of Figure 1 ;
• Figure 3 is a longitudinal section illustrating the end portion of a cable and sleeve assembly taken on the line III-III of figure 2.
• a cable 12 which may be a telecommunications cable, such as a multicore copper cable, a coaxial cable or a fibre optics cable, the individual conductors of which are joined to individual conductors of another cable in a splice closure 13.
• a single cable may be looped with the head of the loop held in the closure 13 and two cable portions 12A and 12B passing in and out of the closure.
• the closure 13 is shown as a butt splice closure known as a FOSC 100B (TM) closure sold by Raychem Limited but other types of closure could be used such as in-line closures and branch closures.
• FOSC 100B TM
• the closure 13 comprises a butt end plate 14 and a dome- shaped housing 15 secured to the end plate 14 by any suitable means such as a circular clamp, or as illustrated a heat-shrinkable sleeve 16.
• the heat shrinkable sleeve 16 may be electrically heated via power input 17, or it may be heated with a torch etc.
• the cable 12 passes into and out of the housing through an oval port 18 in the butt end plate 14, and the take off conductors to subscribers (not shown for simplicity) leave the housing 15 through hollow spigots 19 in the butt end plate 14.
• the splice be electrically earthed through at least one ground wire 21 which may also be colour coded to identify various cables in the splice.
• the two cable portions 12 A, 12B and ground wire 21 are sealed to the oval port 18 by a heat shrinkable sleeve 22 having a power input 23 for heating the sleeve 22.
• the two cable portions 12A and 12B are sealed within the heat shrinkable sleeve 22 by a clip 24 having two legs 25 external of the sleeve, and third central leg 26 having hot-melt adhesive thereon within the sleeve.
• a clip 24 having two legs 25 external of the sleeve, and third central leg 26 having hot-melt adhesive thereon within the sleeve.
• the adhesive on the clip and any adhesive coating on the sleeve melt and flow to fill any gaps left by shrinking the sleeve. All this is disclosed in detail in GB 1604981.
• a potential problem associated with sealing cables 12A, 12B and ground wire(s) 21 within one sleeve 22 can be that low adhesive melt temperatures are required. This can result in excessive adhesive flow as it is squeezed out of the shrinking sleeve, thereby causing leaks. Further the disparity in sizes between the ground wire and the cable 12 can cause gaps, since close conformance of the sleeve with a wire or cable of very smail radius can be difficult to achieve.
• ground wire 21 within the sleeve 22 having a tubular sleeve of sealing material 25 thereon surrounded by a discontinuous spacer 26 which can act during heat- installation as a restrainer or support for the flowing sealing material.
• the sealant is preferably a hot-melt adhesive based on polyamide or EVA materials
• the spacer 26 is preferably a polymeric material net, preferably a cross-linked polyethylene net 26.
• the adhesive material tubing and polyethylene net are placed over the insulating sleeve of the ground wire 21.
• Tests have been carried out to compare the integrity of splice closure in which the ground wire is sealed to the sleeve according to the present invention, with splice closures in which the ground wire is merely covered in an adhesive layer prior to heat shrinking of the sleeve.

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• Cable Accessories (AREA)

Priority Applications (1)

Applications Claiming Priority (2)

Publications (1)

Family

ID=10733052

Family Applications (1)

Country Status (4)

Cited By (3)

Citations (2)

• 1993
  • 1993-03-31 GB GB939306677A patent/GB9306677D0/en active Pending
• 1994
  • 1994-03-23 AU AU62628/94A patent/AU6262894A/en not_active Abandoned
  • 1994-03-23 WO PCT/GB1994/000593 patent/WO1994023471A1/en not_active Ceased
  • 1994-03-30 TW TW83102737A patent/TW253080B/zh active

Patent Citations (2)

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