Filler assembly for cable gland

Abstract

A dispenser apparatus for a curable liquid material is disclosed. The apparatus comprises a flexible bag defining a first compartment for accommodating a first component of a curable liquid material, and a second compartment for accommodating a second component of the curable liquid material and adapted to communicate with the first chamber to enable mixing of the first and second components to initiate curing of the curable liquid material. A first clamp temporarily prevents mixing of the first and second components, and an elongate nozzle communicates with the second compartment to dispense the mixed curable liquid material therefrom. A second clamp temporarily prevents passage of the curable liquid material from the second compartment to the nozzle.

Description

STATEMENT CONCERNING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

FIELD OF THE INVENTION

The present invention relates to a filler assembly for cable glands and relates particularly, but not exclusively, to such a filler assembly for filling cable glands for use in hazardous areas.

BACKGROUND OF THE INVENTION

Many cable glands for use in connecting a cable to an enclosure in hazardous areas need to be filled with a compound which provides a barrier against the effects of an explosion occurring within the enclosure to which the cable gland is attached. The barrier is typically formed from a two-part clay-filled epoxy compound. The two component parts of the compound need to be thoroughly mixed with each other prior to fitting into the gland, and the resulting putty like material needs to be packed between the individual conductors in the cable. Such an arrangement is disclosed in GB 2258350.

This known arrangement suffers from a number of drawbacks. Firstly, the cure time of the putty like material is chosen to be relatively long, in order to enable it to be manipulated into the spaces between the individual conductors before curing becomes advanced. As a result, the filled cable assembly must be left undisturbed for a significant period, usually several hours, especially if mixed at low temperatures. Also, the components of the filler material sometimes contain hazardous materials which become harmless when the filler material is mixed. Persons mixing the components of the putty like filler material may come into contact with these hazardous materials during mixing, and air can become trapped within the cable gland by the filler material which may cause the barrier formed by the filler material to fail in the event of an explosion. Filling of the cable gland is also relatively difficult, especially in the case of small cable glands.

GB 765082 discloses an arrangement for insulating a splice between two stranded connectors in which resinous material is introduced from a capsule having an elongate tip. However, this arrangement suffers from the drawback that it is not suitable for filling cable glands, since the introduction of a material which is sufficiently fluid to penetrate between the individual conductors of a cable would cause material to flow along the conductors along the interior of the cable, which would prevent the cable gland from being sufficiently filled to expel all of the air from the cable gland to avoid air voids.

Preferred embodiments of the present invention seek to overcome one or more of the above disadvantages of the prior art.

SUMMARY OF THE INVENTION

According to an aspect of the present invention, there is provided a filler assembly for filling a cable gland, having a plurality of cores of at least one cable extending therethrough, with curable liquid material, the assembly comprising:

(a) a dispenser apparatus for a curable liquid material, the apparatus comprising:

a body adapted to define at least one first chamber for accommodating a first component of a curable liquid material, and at least one second chamber for accommodating a second component of said curable liquid material, wherein mixing of said first and second components initiates curing of said curable liquid material; and

at least one elongate dispenser device adapted to dispense said mixed curable liquid material therefrom between a plurality of cores of at least one cable; and

(b) at least one flexible barrier member having at least one respective aperture therethrough and adapted to engage a plurality of cores of a cable to provide a barrier to passage of said curable liquid material along said cores.

As a result of the provision of at least one elongate dispenser device, dispensing of the curable liquid can be more carefully controlled, as a result of which less viscous and faster curing liquid material can be used than in the prior art. This therefore provides the advantage of enabling more rapid formation of a filled cable gland incorporating the material, while also allowing the liquid material to be introduced into the cable gland in such a way that the air is expelled from the cable gland to avoid air voids, which could lead to failure of the cable gland in the event of an explosion. In addition, with the present invention, the curable material can be dispensed into the assembled gland, i.e. the cable gland can be filled with the conductors of the cable in a connected state, as a result of which the electrical integrity of the joint can be ensured, whereas the putty like compound of the known arrangement must be molded around the conductors of the cable with the gland disassembled, as a result of which the cable cores can not be electrically connected. The provision of at least one barrier member for restricting the extent of penetration of said curable liquid material along the cable cores provides the advantage of enabling highly flowable curable liquid material to be used, while also enabling filling of the cable gland.

The body may be flexible.

This provides the advantage of making the apparatus easier and less expensive to manufacture.

The assembly may further comprise a first component of a curable liquid material in at least one said first chamber, and a second component of said curable liquid material in at least one said second chamber.

The curable liquid material may be adapted to change colour as a result of curing thereof.

This provides the advantage of providing a visual indicator to the user when the cable gland filling process is complete.

The assembly may further comprise a cover member for covering an external screw thread of a cable gland to prevent said curable liquid material coming into contact with said screw thread.

The cover member may be adapted to prevent curable liquid material from penetrating an end face of the cable gland.

At least one said barrier member may comprise a respective flexible member having at least one aperture therethrough for engaging at least one core of at least one cable.

At least one said barrier member may have a respective tapering portion.

According to another aspect of the present invention, there is provided a method of filling a cable gland with curable liquid material, the method comprising:

using a filler assembly that includes:

(a) a dispenser apparatus for a curable liquid material, the apparatus comprising:

a body adapted to define at least one first chamber for accommodating a first component of a curable liquid material, and at least one second chamber for accommodating a second component of said curable liquid material, wherein mixing of said first and second components initiates curing of said curable liquid material; and

at least one elongate dispenser device adapted to dispense said mixed curable liquid material therefrom between a plurality of cores of at least one cable; and

(b) at least one flexible barrier member for having at least one respective aperture therethrough and adapted to engage a plurality of cores of a cable to provide a barrier to passage of said curable liquid material along said cores;

locating at least one said barrier member in the cable gland; and

locating an outlet of at least one said dispenser device in said cable gland and dispensing curable liquid material therefrom so as to expel air from the cable gland.

The step of locating at least one said barrier member in the cable gland may comprise locating at least one said barrier member around at least one said core of at least one said cable.

The assembly may further comprise at least one barrier apparatus for temporarily preventing passage of the curable liquid material from the or each second chamber to at least one dispenser device. In addition, the barrier apparatus may comprise at least one releasable clamp.

According to another aspect of the invention, there is provided a cable gland for receiving a plurality of cores of at least one cable, the cable gland comprising:

(a) a body adapted to have a plurality of cores of at least one cable extend therethrough;

(b) a dispenser apparatus for a curable liquid material, the apparatus comprising:

a body adapted to define at least one first chamber for accommodating a first component of a curable liquid material, and at least one second chamber for accommodating a second component of said curable liquid material, wherein mixing of said first and second components initiates curing of said curable liquid material; and

at least one elongate dispenser device adapted to dispense said mixed curable liquid material therefrom between a plurality of cores of at least one cable; and

(c) at least one flexible barrier member having at least one respective aperture therethrough and adapted to engage a plurality of cores of a cable to provide a barrier to passage of said curable liquid material along said cores.

The elongate dispenser device may be sufficiently stiff to be inserted between the cores of the cable in the vicinity of the flexible barrier member.

BRIEF DESCRIPTION OF THE DRAWINGS

A preferred embodiment of the invention will now be described, by way of example only and not in any limitative sense, with reference to the accompanying drawings in which:

FIG. 1 is a perspective view of a dispensing apparatus embodying the present invention;

FIG. 2 is a partially cut away perspective view of a cable gland having a filler formed using the apparatus of FIG. 1; and

FIG. 3 is a cross sectional view of the filled cable gland of FIG. 2 with a thread protector in place.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

A preferred embodiment of the invention will now be described, by way of example only and not in any limitative sense, with reference to the accompanying drawings in which:

FIG. 1 is a perspective view of a dispensing apparatus embodying the present invention;

FIG. 2 is a partially cut away perspective view of a cable gland having a filler formed using the apparatus of FIG. 1; and

FIG. 3 is a cross sectional view of the filled cable gland of FIG. 2 with a thread protector in place.

Referring to FIG. 1, a dispenser apparatus 2 embodying the present invention and for use in filling a cable gland 4 (FIG. 2) with curable liquid material 6 comprises a body of suitable transparent flexible plastics material defining a flexible bag 8 having a first compartment 10 for accommodating a first component of a liquid curable material 6, and a second compartment 12 for accommodating a second component of the material 6. A first clamp 14 temporarily separates the first compartment 10 and second compartment 12 to thereby prevent mixing of the first and second components of the material 6. The first and second components are coloured differently (for example blue and yellow) so that thorough mixing of the first and second components produces a green liquid, thereby providing a visual indication when thorough mixing of the first and second components has occurred. Mixing of the first and second components together causes gelling of the material and initiates curing of the curable liquid material 6.

The dispenser apparatus 2 is also provided with an elongate hollow nozzle 16 extending from the second compartment 12 such that dispensing of the mixed curable liquid material can be carefully controlled. In particular, the nozzle 16 can be inserted a considerable distance into the cable gland 4 and between individual core conductors 20 of the core of a cable 22 attached to the cable gland 4 (FIG. 2) so that the liquid material 6 can be highly flowable and fast-curing, as a result of which the cable gland 4 can be rapidly filled and air entrapment by the liquid material 6 minimised. A second clamp 18 temporarily prevents material flowing from the second compartment 12 into the nozzle 16, so that dispensing of the material 6 can be prevented until thorough mixing together of the first and second components has occurred.

The flexible bag 8 is formed from two sheets of material welded together along all but one of their edges to form a bag having an open mouth, which is then mounted to the nozzle 16. The second clamp 18 is then mounted to the bag adjacent to the nozzle 16, and the second component of the material 6 is dispensed into the second compartment 12. The first clamp 14 is then mounted to the bag to seal the second component in the second compartment 12, and the first component is then dispensed into the first compartment 10. The open edge of the bag is then sealed to seal the first component in the first compartment 10.

Referring to FIGS. 2 and 3, the cable gland 4 to be filled by means of the dispenser apparatus 2 of FIG. 1 comprises a threaded outer connector 24 for threaded connection to an enclosure (not shown) and a compound tube 26 rotatably mounted within the outer connector 24. A cable connector 28 is mounted to the end of the cable 22 and is connected to the outer connector 24 by means of cooperating screw threads (not shown).

A ring 30 abuts the cable connector 28 and a flexible seal 32 is located around the core conductors 20 of the cable 22 and compressed between the compound tube 26 and ring 30 for limiting the extent of penetration of curable material 6 into the cable gland 4 before curing of the curable material 6. The flexible seal 32 comprises a generally frusto-conical body of elastomeric material having an aperture (not shown) therethrough for engaging the core conductors 20 of the cable 22. The aperture in the seal 32 is sized such that it stretches to pass around the core conductors 20 to tightly engage the core conductors 20 to form a reasonably effective barrier to passage of the material 6 along the space defined between the core conductors 20 and the compound tube 26.

Referring to FIG. 3, a thread protector 34 formed of elastomeric material such as rubber is located over the external screw thread of the outer connector 24 of the cable gland 4 prior to filling of the cable gland with curable material 6. The thread protector 34 has a hollow rim 36 for catching excess curable material 6 which may flow out of end 40 of the cable gland 4 during the filling procedure, and an inner circular rim 38 which prevents penetration of curable material 6 into the gap between the outer connector 24 and the compound tube 26. This ensures that the compound tube 26 complete with cable connectors 28 can be removed from the outer connector 24 after curing of the material 6.

The process of filling the cable gland 4 of FIGS. 2 and 3 by means of the dispenser apparatus 2 of FIG. 1 will now be described.

In order to fill the core of the cable gland 4 with curable material, the flexible seal 32 initially placed over the core conductors 20 of the cable 22 so that the seal 32 tightly grips the core conductors 20. The outer connector 24 with compound tube 26 are then mounted to the ring 30 and cable connector 28 to compress the seal 32 between the ring 30 and compound tube 26. As a result, the flexible seal 32 acts as a barrier to penetration of the curable liquid material 6 into the interior of the cable gland 4.

The first clamp 14 is then removed from the dispenser apparatus 2 and the second clamp 18 left in place, to enable thorough mixing of the first and second components of the curable liquid material 6. The first and second components are coloured blue and yellow respectively, a result of which the curable liquid material 6 is bright green when it is thoroughly mixed. The second clamp 18 is then removed, and the outlet of the nozzle 16 is placed at a location near the seal 32. The liquid material 6 is then dispensed through the nozzle 16 into the space between the core conductors 20 of the cable 22 and into the space around the core conductors 20 inside the compound tube 26 of the cable gland 4, where its movement along the axis of the cable gland 4 is restricted by the flexible seal 32. The location of the outlet of the nozzle 16 near the seal 32 causes air to be expelled from the cable gland when the curable liquid material 6 is dispensed from the nozzle 16. The seal 32 provides a sufficient barrier to penetration of the material 6 to hold back the curable material until it begins to get and support itself. At the same time, the thread protector 34 protects the external thread of the outer connector 24 from excess curable material and prevents penetration of the liquid curable material between the outer connector 24 and the compound tube 26. The material 6 is arranged to change colour to dark green when it is cured, so that a visual indication is provided when the curing process is completed.

It will be appreciated by persons skilled in the art that the above embodiment has been described by way of example only, and not in any limitative sense, and that various alterations and modifications are possible without departure from the scope of the invention as defined by the appended claims.

Claims

1. A filler assembly for filling a cable gland with curable liquid material, the assembly comprising: (a) a two-chamber dispenser apparatus for a curable liquid resin compound for creating a barrier to an explosion, the apparatus comprising:a body defining at least one first chamber accommodating a first component of a curable liquid resin compound, and at least one second chamber accommodating a second component of said curable liquid resin compound, wherein mixing of said first and second components initiates curing of said curable liquid resin compound; andat least one dispenser device adapted to dispense said mixed curable liquid material therefrom between a plurality of said cores of said cable; and(b) at least one elastomeric flexible barrier member capable of having at least one respective aperture therethrough configured to be adapted to stretch to engage a plurality of cores of a cable while in use to provide a barrier to passage of said curable liquid resin compound along said cores to create the barrier to an explosion.

2. An assembly according to claim 1, wherein said body is sufficiently flexible to enable manipulation of said curable liquid material through said body.

3. An assembly according to claim 1, further comprising at least one first barrier apparatus for temporarily preventing mixing of said first and second components, and one second barrier apparatus for temporarily preventing passage of the curable liquid resin compound to at least said one dispenser device.

4. An assembly according to claim 1, wherein the flexible barrier is formed of a rubber elastomeric material to form a seal that tightly grips the plurality of cores.

5. An assembly according to claim 1, wherein the curable liquid material is adapted to change color as a result of curing thereof.

6. An assembly according to claim 1, further comprising a cover member for covering an external screw thread of a cable gland to prevent said curable liquid material coming into contact with said screw thread.

7. An assembly according to claim 6, wherein the cover member is adapted to prevent curable liquid material from penetrating an end face of the cable gland.

8. An assembly according to claim 1, wherein at least one said barrier member has a respective tapering portion.

9. An assembly according to claim 1, further comprising at least one second barrier apparatus for temporarily preventing passage of said curable liquid resin compound from said second chamber to at least one said dispenser device.

10. An assembly according to claim 9, wherein at least one said second barrier apparatus comprises at least one releasable clamp.

11. A method of using a filler assembly for filling a cable gland, having a plurality of cores of a cable extending therethrough, with curable liquid material, the method comprising: a) mixing a first component of a curable liquid resin compound in a first chamber of the filler assembly with a second component of said curable liquid resin compound located in a second chamber of the filler assembly, wherein mixing of said first and second components initiates curing of the curable liquid resin compound in a dispensing apparatus; b) introducing plurality of cores of cable through at least one flexible barrier member to form an aperture therethrough adapted to stretch to engage the plurality of said cores of said cable while in use to provide a barrier to passage of said curable liquid resin compound along said cores; c) locating an outlet of said dispenser device in said cable gland; d) locating at least one said barrier member in the cable gland; and e) dispensing the mixed curable liquid resin compound from the dispensing apparatus between a plurality of said cores of said cable so as to expel air from the cable gland; f) allowing the curable liquid resin compound to cure forming a barrier to an explosion.

12. A method according to claim 11, wherein the step of locating at least one said barrier member in the cable gland comprises locating said barrier member around a plurality of said cores of said cable.

13. The method according to claim 11, further comprising the step of breaking a seal between the first chamber and the second chamber and a seal between the second chamber and the outlet of said dispenser.

14. A cable gland assembly comprising: a) a body, including a threaded outer connecter adapted for threaded connection to an enclosure;b) a dispenser apparatus for a curable liquid material, the apparatus comprising: a body defining at least one first chamber accommodating a first component of a curable liquid material, and at least one second chamber accommodating a second component of said curable liquid material, wherein mixing of said first and second components initiates curing of said curable liquid material; andat least one dispenser device adapted to dispense said mixed curable liquid material therefrom between a plurality of cores of a cable; andc) at least one flexible barrier member having capable of having at least one respective aperture therethrough and adapted to stretch to engage a plurality of said cores of said cable to provide a barrier to passage of said curable liquid material along said cores.

15. An assembly according to claim 14, wherein the one flexible barrier member tightly grips said plurality of said cores of said cable.

16. A filler assembly according to claim 14, wherein the barrier member is sufficiently flexible and the curable liquid material is sufficiently liquid that the barrier member is adapted to stretch to engage a plurality of cores of a cable to provide a barrier to passage of said curable liquid material along and between said cores beyond the barrier member.