AU2012203154A1

AU2012203154A1 - Barrier Cable Gland

Info

Publication number: AU2012203154A1
Application number: AU2012203154A
Authority: AU
Inventors: Nicholas Franz Edward Lackinger
Original assignee: CCG AUSTRALASIA Pty Ltd
Current assignee: CCG AUSTRALASIA Pty Ltd
Priority date: 2012-04-17
Filing date: 2012-05-29
Publication date: 2013-10-31
Anticipated expiration: 2032-05-29
Also published as: GB2501329A; GB201209560D0; GB2501329B; KR20130117321A; ZA201203710B; CN103378575B; KR101669070B1; CN103378575A; AU2012203154B2

Abstract

An embodiment of a method of installing a barrier cable gland is provided in which a compression seal seals onto the outer surface of an immediately surrounding cable sheath at a position between the ends of the cable gland. The cable gland is installed on a prepared cable end with the compression seal engaging the outer surface of the surrounding cable sheath with a terminal end of the cable sheath generally in the vicinity of the compression seal. With an open end of the inner tubular body is uppermost, a curable liquid two component resin mix is introduced into a cavity defined by an inwardly directed surface of the inner tubular body and the compression seal at a lower end thereof. The resin mix is introduced by way of a double syringe wherein each of the two liquid components of the resin is separately packaged in a syringe barrel and an elongated mixing nozzle is fitted to the double syringe to effect mixing as resin components are ejected into and through the mixing nozzle. III ________________12 Figure 1

Description

P/00/011 28/5/91 Regulation 3.2 AUSTRALIA Patents Act 1990 ORIGINAL COMPLETE SPECIFICATION STANDARD PATENT Name of Applicant: CCG Australasia Pty Ltd Actual Inventor Nicholas Franz Edward LACKINGER Address for service is: WRAYS Ground Floor, 56 Ord Street West Perth WA 6005 Attorney code: WR Invention Title: Barrier Cable Gland The following statement is a full description of this invention, including the best method of performing it known to me: 1 -2 BARRIER CABLE LAND TECHNICAL FIELD [0001] This invention relates to a barrier cable gland of a type that may be used in hazardous areas in which combustible or explosive gasses may be able to enter voids between a plurality of electrically insulated conductors within an electrically insulating sheath that encloses them. [0002] More particularly, but not exclusively, the invention relates to a barrier cable gland that is particularly, although not exclusively, adapted to be used in conjunction with armoured or shielded electrical cable wherein electrically conductive armour wires or shielding is sandwiched between an electrically insulating inner sheath and an electrically insulating outer sheath. [0003] The application of the invention thus extends to barrier termination cable glands for use in association with electrical cables having conventional more robust helically wound armour wires or less robust shielding in any one of a variety of different forms including copper or aluminium tape and woven or braided layers of electrically conductive wires, and even no armouring or shielding at all. BACKGROUND ART [0004] Each document, reference, patent application or patent cited in this text is expressly incorporated herein in their entirety by reference, which means that it should be read and considered by the reader as part of this text. That the document, reference, patent application or patent cited in this text is not repeated in this text is merely for reasons of conciseness. [0005] The following discussion of the background to the invention is intended to facilitate an understanding of the present invention only. It should be appreciated that the discussion is not an acknowledgement or admission that any of the material referred to was published, known or part of the common general knowledge of the person skilled in the art in any jurisdiction as at the priority date of the invention.

-3 [0006] The presence of a combustible or explosive gas mixture in any voids in an electrical cable may arise from gasses entering from either end of the cable and any such gasses may migrate along the length of the cable and possibly exit at the other end of the cable. Should this happen, the gasses may transfer an explosion from one end of the cable to the other. Also, the cable itself may be severely damaged between its ends in consequence of the rapid expansion of gasses within the cable. Explosive gases could also migrate from a hazardous gas area of a plant to a non-hazardous area of a plant down the interstices of an unfilled cable. [0007] Barrier cable glands are designed to address this issue by sealing off any entries to voids at the relevant end of a cable, and typically both ends, of such a cable. Of course, the efficacy of the sealing is of paramount importance as, if any voids are not properly sealed off, the problem envisaged above could persist nevertheless. [0008] A two part quick setting epoxy putty has been extensively used to fill these voids at a termination end of a cable. This system has found increasing acceptance, especially in instances in which the compound resin seal can be inspected by removal of the surrounding component of the cable gland. [0009] However, the placement of such epoxy putty becomes more difficult and risky with increasing numbers of conductors passing through a single electrically insulating sheath which necessarily means more access openings to more voids between the bunched individually insulated conductors. [0010] Accordingly, interest has shifted towards the use of more liquid two component resins that can flow into the openings communicating with the voids. One system that was introduced to the market some years ago provided a generally flat envelope divided into two parts by a transverse clip that was removed for the purpose of intimately mixing the two components and installing the curable liquid resin by way of an outlet at one end of the envelope. A substantially similar arrangement is currently being pursued by a different manufacturer. Published European patent applications EP2287084; EP2287986 and EP2294666 all relate to finer detail of such a system.

-4 [0011]Applicant believes that the massaging of a generally flat envelope in order to mix two components of an epoxy resin together is somewhat risky unless considerable physical mixing forces are applied to the outside of the envelope. Of course, the mixed resin has only a short shelf-life to permit its introduction into a gland and a compromise needs to be reached as regards mixing time and installation time. Should it turn out that mixing has not been adequately achieved, the entire integrity of the seal may be compromised. [0012] Furthermore, because the generally flat envelope is fairly large in size, squeezing it, typically by rolling up the envelope from its end opposite a discharge end, is difficult to achieve with one hand whilst, in most instances, the other hand needs to be used to hold the cable gland. The application of the liquid resin may become rather messy as a result. Indeed, one of the aforementioned published European patent applications relates particularly to a cover for covering the end of a cable gland during application of the curable liquid resin. [0013] There is a need for an improved method of installing a barrier cable gland utilizing curable liquid resin composed of two intimately mixed components and for a barrier cable gland installed using such a method. [0014] In this specification the term "cylindrical" is intended to include generally cylindrical surfaces that taper somewhat from one end to the other and are therefore of truncated conical shape of typically very small cone angle. SUMMARY OF THE INVENTION [0015] In accordance with a first aspect of this invention, there is provided a method of installing a barrier cable gland of the type that has an outer tubular body or union nut having a free end forming an entry end for a cable and an inner tubular body having an externally screw threaded portion in cooperating engagement with an internally screw threaded portion of the outer tubular body or union nut with the two bodies forming an internal cavity whereof a part is defined by a cylindrical inwardly directed surface of the inner tubular body that in the installed condition . surrounds a plurality of individually electrically insulated conductors extending out of an immediately surrounding cable sheath, wherein the cylindrical inwardly directed surface has a release layer or film applied thereto and the cable gland has a compression seal for sealing onto the outer surface of -5 said immediately surrounding cable sheath at a position between the ends of the cable gland and wherein the compression seal is brought under compression by screwing the inner tubular body into the outer tubular body or union nut, the method of the invention comprising installing the cable gland on a prepared cable end such that said compression seal engages the outer surface of the immediately surrounding cable sheath with a terminal end of the immediately surrounding cable sheath generally in the vicinity of the compression seal, orientating the cable gland so that an open end of the inner tubular body is uppermost, and introducing curable liquid two component resin mix into a cavity defined by the inwardly directed surface of the inner tubular body and the compression seal at a lower end thereof with the resin mix being introduced by way of a double syringe wherein each of the two liquid components of the resin is separately packaged in a syringe barrel and an elongated mixing nozzle is fitted to the double syringe to effect mixing as resin components are ejected into and through the mixing nozzle, the introduction of resin mix into said cavity being effected to substantially fill at least a part of the cavity immediately adjacent the inner seal and terminal end of the immediately surrounding cable sheath so as to substantially fill voids between individual conductors of the cable and the immediately surrounding cable sheath. [0016] Further features of embodiments of the invention provide for the inner part of the cable gland to have an open end remote from the compression seal; for the cavity to be filled with resin mix substantially to the open end thereof so as to form a solid plug of set resin extending from the compression seal to the formerly open end of the inner tubular body of the cable gland; for the resin mix and the double syringe dispenser to be a commercially available package of suitable quality epoxy resin components for producing an epoxy conforming with applicable standards; and for a smaller cross-sectioned tubular extension to be attached to the discharge end of the mixing nozzle to facilitate introducing the liquid resin mix in between the individual conductors. [0017] In one variation or embodiment of the invention, the cable gland may have an armour or shielding clamp assembly that may typically include an armor clamping cone held captive relative to the inner tubular body and a cooperating clamping ring that is held captive relative to the outer tubular body and that are -6 operatively urged into cooperating relationship by screwing the inner tubular body into the outer tubular body. In such an instance the entry into the cable gland may have an outer compression seal associated therewith for sealing onto an outer surface of an outer electrically insulating sheath of the electrical cable and the compression seal referred to above forms an inner compression seal for sealing onto the outer surface of the inner electrically insulating sheath of the cable. [0018] In another variation or embodiment of the invention the cable gland is devoid of any armour or shielding clamp assembly and the outer body part assumes the form of a union nut for urging a compression seal into contact with the outer surface of the electrically insulating sheath immediately surrounding the individually electrically insulated conductors. [0019] In accordance with a second aspect of the invention, there is provided an installed cable gland as is generally defined above (that is, having an outer tubular body or union nut having a free end forming an entry end for a cable and an inner tubular body having an externally screw threaded portion in cooperating engagement with an internally screw threaded portion of the outer tubular body or union nut with the two bodies forming an internal cavity whereof a part is defined by a cylindrical inwardly directed surface of the inner tubular body that surrounds a plurality of individually electrically insulated conductors extending out of an immediately surrounding cable sheath, wherein the cylindrical inwardly directed surface has a release layer or film applied thereto and the cable gland has a compression seal sealing onto the outer surface of said immediately surrounding cable sheath at a position between the ends of the cable gland) with or wherein a set plug of resin is located immediately adjacent said compression seal and occupying at least a part of the cavity defined by the inwardly directed surface of the inner tubular body of the cable gland. The set plug of resin is preferably clear so that inspection of the installed cable gland is facilitated and voids and air pockets within the resin plug can be observed. (0020] In accordance with a third aspect of the invention, there is provided a cable gland whenever supplied with instructions as to conducting the method defined above according to the first aspect of the invention.

-7 [0021] In accordance with a fourth aspect of the invention, there is provided a double syringe package of two component resin whenever sold in association with instructions as to conducting the method defined above according to the first aspect of the invention. [0022] In order that the above and other features of the invention may be more fully understood, one embodiment thereof will now be described with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS [0023] In the drawings: Figure 1 is a partly sectioned elevation of one variation of barrier cable gland installed on a cable showing the plug of set resin material partially in section and taken along line I - I in Figure 3; Figure 2 is a cross-section taken along the line Il - 11 in Figure 1; Figure 3 is a cross-section taken along the line Ill - Ill in Figure 1; Figure 4 is an elevation of a two component epoxy package suitable for use in carrying out the method of the invention; Figure 5 is a partly sectioned elevation of a second variation of barrier cable gland similar to Figure 1 and taken along the line V - V in Figure 6 with the cable gland being devoid of any armour or shielding clamp; and, Figure 6 is a cross-section taken a long line VI - VI in Figure 5. DETAILED DESCRIPTION OF EMBODIMENTS [0024] In the application of the invention the result of which is illustrated in Figures 1 to 3 of the accompanying drawings, a method of installing a barrier cable gland according to an embodiment of the invention is applied to a cable gland of the type illustrated in the drawings and described hereunder. [0025] Such a cable gland, that is generally indicated by numeral (1), is made for use on an armoured or screened (herein referred to as "armour" irrespective of its - 8 exact nature) electrical cable (2) having an armor clamp assembly that typically includes an armor clamping cone (4) preferably held captive relative to an inner tubular body (5) and a cooperating clamping ring (6) that is preferably held captive relative to an outer tubular body (7). The armour clamp assembly operatively urges the armour clamping cone into the cooperating clamping ring to firmly clamp armour wires (8) of the cable that pass between an outer electrically insulating sheath (9) and an inner electrically insulating sheath (10). This is achieved by screwing the inner tubular body that has an external screw-thread on its outer surface into the outer tubular body that has an internal cooperating screw-thread on an inner surface thereof. [0026] A series of individually insulated conductors (12) extend along the length of the cable within the inner electrically insulating sheath (10). [0027] The entry end of the cable gland has an outer compression seal (13) that is brought into operation by its own union style nut (14). [0028] Within the cable gland is an inner compression seal (15) that is positioned between an end of the armour clamping cone remote from the armour clamp assembly and a shoulder (16) within the inner tubular body. [0029] As shown most clearly in Figure 1, such a gland is installed by removing the outer insulating sheath for a distance from a free end of the cable so that the outer sheath is engaged by the outer compression seal in the installed condition. Similarly, the inner electrically insulating sheath is removed from a position that is approximately in line with the inner compression seal in the installed condition so that the plurality of individual conductors (12) of the cable project out of the open end (18) of the inner tubular body part of the cable gland. [0030] The inner tubular body and the outer tubular body form an internal cavity whereof a part is defined by a cylindrical inwardly directed surface (22) of the inner tubular body that, in the installed condition, surrounds the plurality of individually electrically insulated conductors that extend out of the inner cable sheath. [0031] The cylindrical inwardly directed surface has a release layer or film applied thereto so that unsecured resin that comes into contact with it will not bond to it, -9 the purpose of which is to enable the inner tubular body part to be removed after the resin has set in the event that inspection is required of the installation. [0032] The inwardly directed cylindrical surface and the inner compression seal that seals onto the outer surface of the inner cable sheath together form a generally cylindrical cavity through which the individually electrically insulated conductors pass. [0033] Preparatory to carrying out the method of the invention, the installed cable gland is orientated so that an open end of the inner tubular body is uppermost. [0034] Curable liquid two component resin mix is then introduced into the cylindrical cavity by way of a double syringe (25) wherein each of two liquid components, namely a resin and a hardener of the epoxy variety of resin, is separately packaged in a syringe barrel. The outlets from the syringe barrels are fitted with an elongated mixing nozzle (26) extending from a manifold (27) connecting the two outlets. The mixing nozzle serves the purpose of effecting intimate mixing of the two components as they pass tortuously through a series of spaced baffles projecting alternately into a restricted flow path from opposite sides of the flow path. It will be understood that operation of one of these double syringes can be carried out using one hand whilst the other hand can be used to support the cable gland and its associated cable. [0035] The double syringe dispenser is conveniently a commercially available package of epoxy resin components although it is envisaged that it may be advantageous to produce custom double syringe dispensers that would have a more appropriate total volume of resin for a particular size of cable gland. In order to facilitate the introduction of the resin mix into rather small spaces and voids between the individual insulated electrical conductors, a smaller cross-sectioned tubular extension (28) may be attached to the discharge end of the mixing nozzle. Such a smaller cross-sectioned tubular extension may thus be used to facilitate introducing the liquid resin mix in between the individual conductors by manipulating the double syringe dispenser appropriately. [0036] The resin mix is introduced into the cavity to substantially fill at least the part of the cavity immediately adjacent the inner compression seal and the terminal end of the inner cable sheath so as to substantially fill voids between - 10 individual conductors of the cable and the immediately surrounding cable sheath in the first place, and between the individual electrically insulated conductors and the inwardly directed cylindrical surface of the inner tubular body of the cable gland. The inner compression seal prevents the liquid resin from further flowing past the cable end and into the gland body. [0037] This cavity is preferably filled with resin mix substantially to the open end thereof so as to form a solid plug (31) of set resin extending from the inner compression seal to the formerly open end of the inner tubular body of the cable gland. The resin mix will also abut the cut off end of the inner cable sheath thereby, in effect, forming an extension to the inner cable sheath. [0038] It has been found that with a suitable layer of release agent applied to the relevant surface of the inner tubular body of the cable gland, it is possible to remove the inner tubular body for the purpose of inspecting the solid plug of set clear resin and ensuring that no deleterious air pockets or voids remain. [0039] It is, of course, within the scope of the invention that the inwardly directed cylindrical surface could flare outwardly slightly to facilitate removal of the inner tubular body for the purpose of inspection. [0040] As indicated above, and with reference to Figures 5 and 6, the invention can also be applied to cable glands that have no armour or shielding clamp associated with it. Such glands may simply have an inner tubular body (41) that cooperates directly with a union style of nut (42) in order to compress a compression seal (43) onto the outer surface of the sole electrically insulating sheath (44). The principles of the invention are exactly as described above and the inwardly directed surface (45) of the inner tubular body is treated with a suitable release layer to which the two component liquid resin does not bond. The result is a plug (46) of set resin extending from the formerly open end of the inner tubular body to the severed end of the compression seal and electrically insulating sheath in the manner described above such that the plug effectively forms an extension to the electrically insulating sheath. [0041] It will be understood that numerous variations may be made to the applications of the invention described above without departing from the scope - 11 hereof. In particular, the type of gland to which the invention is applied can vary widely. [0042] Modifications and variations such as would be apparent to a skilled addressee are deemed to be within the scope of the present invention. [0043] Throughout the specification, unless the context requires otherwise, the word "comprise" or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers. [0044] Furthermore, throughout the specification, unless the context requires otherwise, the word "include" or variations such as "includes" or "including", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

Claims

1. A method of installing a barrier cable gland of the type that has an outer tubular body or union nut having a free end forming an entry end for a cable and an inner tubular body having an externally screw threaded portion in cooperating engagement with an internally screw threaded portion of the outer tubular body or union nut with the two bodies forming an internal cavity whereof a part is defined by a cylindrical inwardly directed surface of the inner tubular body that in the installed condition surrounds a plurality of individually electrically insulated conductors extending out of an immediately surrounding cable sheath, wherein the cylindrical inwardly directed surface has a release layer or film applied thereto and the cable gland has a compression seal for sealing onto the outer surface of said immediately surrounding cable sheath at a position between the ends of the cable gland and wherein the compression seal is brought under compression by screwing the inner tubular body into the outer tubular body or union nut, the method of the invention comprising installing the cable gland on a prepared cable end such that said compression seal engages the outer surface of the immediately surrounding cable sheath with a terminal end of the immediately surrounding cable sheath generally in the vicinity of the compression seal, orientating the cable gland so that an open end of the inner tubular body is uppermost, and introducing curable liquid two component resin mix into a cavity defined by the inwardly directed surface of the inner tubular body and the compression seal at a lower end thereof with the resin mix being introduced by way of a double syringe wherein each of the two liquid components of the resin is separately packaged in a syringe barrel and an elongated mixing nozzle is fitted to the double syringe to effect mixing as resin components are ejected into and through the mixing nozzle, the introduction of resin mix into said cavity being effected to substantially fill at least a part of the cavity immediately adjacent the inner seal and terminal end of the immediately surrounding cable sheath so as to substantially fill voids between individual conductors of the cable and the immediately surrounding cable sheath.

2. A method as claimed in claim 1 in which the inner part of the cable gland has an open end remote from the compression seal. - 13

3. A method as claimed in either one of claims 1 or 2 in which the cavity is filled with resin mix substantially to the open end thereof so as to form a solid plug of set resin extending from the compression seal to the formerly open end of the inner tubular body of the cable gland.

4. A method as claimed in any one of the preceding claims in which the resin mix and the double syringe dispenser is a commercially available package of suitable quality epoxy resin components for producing an epoxy conforming with applicable standards.

5. A method as claimed in any one of the preceding claims in which a smaller cross-sectioned tubular extension is attached to the discharge end of the mixing nozzle to facilitate introducing the liquid resin mix in between the individual conductors.

6. A method as claimed in any one of the preceding claims in which the cable gland has an armour or shielding clamp assembly that includes a clamping cone held captive relative to the inner tubular body and a cooperating clamping ring that is held captive relative to the outer tubular body and that are operatively urged into cooperating relationship by screwing the inner tubular body into the outer tubular body.

7. A method as claimed in claim 6 in which the cable gland has an outer compression seal associated therewith for sealing onto an outer surface of an outer electrically insulating sheath of the electrical cable and the compression seal referred to in any one of claims 1 to 5 forms an inner compression seal for sealing onto the outer surface of the inner electrically insulating sheath of the cable.

8. A method as claimed in any one of the claims 1 to 5 in which the cable gland is devoid of any armour or shielding clamp assembly and the outer body part assumes the form of a union nut for urging a compression seal into contact with the outer surface of the electrically insulating sheath immediately surrounding the individually electrically insulated conductors.

9. An installed cable gland having an outer tubular body or union nut having a free end forming an entry end for a cable and an inner tubular body having an externally screw threaded portion in cooperating engagement with an internally - 14 screw threaded portion of the outer tubular body or union nut with the two bodies forming an internal cavity whereof a part is defined by a cylindrical inwardly directed surface of the inner tubular body that surrounds a plurality of individually electrically insulated conductors extending out of an immediately surrounding cable sheath, wherein the cylindrical inwardly directed surface has a release layer or film applied thereto and the cable gland has a compression seal sealing onto the outer surface of said immediately surrounding cable sheath at a position between the ends of the cable gland and wherein a set plug of resin is located immediately adjacent said compression seal and occupies at least a part of the cavity defined by the inwardly directed surface of the inner tubular body of the cable gland.

10. An installed cable gland as claimed in claim 9 in which the plug of resin is clear so that inspection of the installed cable gland is facilitated and voids and air pockets within the resin plug can be observed.

11. A cable gland whenever supplied in association with instructions as to conducting a method as claimed in any one of claims 1 to 8.

12. A double syringe package of two component resin whenever sold in association with instructions as to conducting a method as claimed in any one of claims 1 to 8.

13. A method of installing a barrier cable gland substantially as hereinbefore described with reference to the accompanying drawings.

14. An installed cable gland substantially as hereinbefore described with reference to the accompanying drawings.

15. A cable gland substantially as hereinbefore described with reference to the accompanying drawings.

16. A double syringe package substantially as hereinbefore described with reference to the accompanying drawings.