GB2194861A

GB2194861A - Cable sealing device

Info

Publication number: GB2194861A
Application number: GB08621618A
Authority: GB
Inventors: Raws Shariff Bin B Moh Shariff
Original assignee: Individual
Current assignee: Individual
Priority date: 1986-09-08
Filing date: 1986-09-08
Publication date: 1988-03-16
Anticipated expiration: 2006-09-08
Also published as: MY100871A; GB2194861B; GB8621618D0

Abstract

A cable sealing device for, for example, an underground open duct telephone cable system, comprising two hollow sealing ring (1,1') made of resiliently compressible material, each sealing ring having a generally cylindrical outer surface (1b,1'b) and a tapered internal bore (1a,1'a), and first and second coupling plate means (2a,2'a) for axially compressing the sealing rings when the sealing rings are placed end-to- end with their internal bores in axial alignment. Each coupling plate means comprises four arcuate coupling plates, and the sealing rings are drawn together by bolts 3. <IMAGE>

Description

SPECIFICATION Cable sealing device This invention relates to a cable sealing device, and in particular, to a device for sealing the mouth of a duct containing a cable.

An underground open duct system is used to route telephone cables from an exchange, the system being constituted by banks of ducts (or pipes) made of, for example, polyvinyl chloride. Each bank of ducts is laid section-by-section in a trench. Manholes are constructed at regular intervals (say 30 metres) along such a trench. The ducts associated with a given manhole terminate at the inner vertical wall of that manhole, and the cables are exposed inside the manhole. The main purpose of the manholes is to enable cable "leaders" to be pulled through the ducts when new cables are installed. This minimises the length of cable that need replacement in the event of cable faults, and provides means for effecting cable junctions in both the original direction of cable routing, and also at right-angles to this route.

The main disadvantage of this type of system is that the joints between the ducts and the manholes are not water-proof or gas-tight.

This results in rainwater (or water from a broken water mains) finding its way into the ducts and flooding the ducts and the manholes. Similarly, gas can seep through the ground and get into both ducts and manholes.

The aim of the invention is to provide a cable sealing device which does not suffer from these disadvantages.

The present invention provides a cable sealing device comprising two hollow sealing rings made of resiliently compressible material, each sealing ring having a generally cylindrical outer surface and a tapered internal bore, and means for axially compressing the sealing rings when the sealing rings are placed endto-end with their internal bores in axial alignment.

In use, the sealing rings are positioned around a cable within a duct, and are then compressed so that their outer surfaces seal aginst the duct and their internal bores seal against the cable. The tapering of the internal bores permits the device to be used with cables having different diameters.

Advantageously, the outer cylindrical surface of each sealing ring is provided with a plurality of circumferential ribs. These ribs enhance the sealing effect between the sealing rings and the duct.

In a preferred embodiment, each sealing ring is formed with a longitudinal cut extending from its outer cylindrical surface to its internal bore. The cuts permit the sealing rings to be opened up, thereby facilitating the positioning of the sealing rings over a cable (or over the leader of a cable). preferably, the cuts are of castellated form.

Advantageously, the compressing means is constituted by first and second coupling plate means and by means for drawing the coupling plate means together, the first and second coupling plate means being positioned at opposite axial ends of the device. Preferably, each coupling plate means is constituted by four arcuate coupling plates, and four bolts constitute the means for drawing the coupling plates together, the coupling plates of one coupling plate means having threaded bores to match the threads of the bolts, and the coupling plates of the other coupling plate means having unthreaded bores through which the shanks of the bolts can pass freely.

Preferably, the sealing rings are made of rubber, and the coupling plates and bolts are made of stainless steel.

A cable sealing device constructed in accordance with the invention will now be described in detail, by way of example, with reference to the accompanying drawings, in which: Fig. 1 is a side elevation of the device; Fig. 2 is an end elevation of the device; and Fig. 3 is a schematic representation of the device positioned in sealing relationship with a cable and its duct.

Referring to the drawings, Fig. 1 shows the cable sealing device prior to being positioned on a cable C (see Fig. 3). The device is constituted by two sealing rings 1 and 1', two sets of coupling plates 2 and 2', and four bolts 3 (only one of which is shown). Each of the sealing rings 1 and 1' is a generally cylindrical hollow member made of rubber. Each sealing ring 1, 1' has an internal bore 1a, 1'a which tapers from a diameter of 80 mm to a diameter of 80 mm. Each sealing ring 1,1' is formed with a plurality of circumferential ribs 1b, 1'b on its cylindrical outer surface. A respective cut 1c, 1'c extends from the outer surface of each sealing ring 1,1' to its internal bore 1a, 1'a. As shown in Fig.1, each of the cuts 1c, 1'c is of castellated form.This permits the sealing rings 1,1' to be opened up to enable them to be positioned over the cable C, whilst forming a labyrinthtype seal against the cable. Four equispaced, axial bores 1d, 1'd (only one of each of which is shown in Fig. 1) are formed in each of the sealing rings 1,1'.

The coupling plates 2,2' are arcuate plates made of stainless steel. The plates 2 each have a central unthreaded bore 2a whose diameter is greater than that of the shanks of the bolts 3, and the plates 2' each have a central threaded bore 2'a which matches the threaded portions of the bolts.

In use, the sealing device is assembled over the cable C in the following manner. Firstly, the two sealing rings 1,1' are positioned over the cable leader (not shown). This is done by opening up the sealing rings 1,1' and forcing the leader into the bores 1a,1'a through the cuts 1c, 1'c. The sealing rings 1;1' are positioned, as shown in Fig. 1, so that their internal bores la, 1'a taper towards one another, and the bores 1d are in alignment with the bores 1'd. The sealing rings 1,1' are then held lightly together by the coupling plates 2,2' and the bolts 3.This is done by positioning each of the coupling plates 2 with its unthreaded bore 2a in alignment with a respective bore 1 d of the sealing ring 1, by positioning each of the coupling plates 2' with its threaded bore 2'a in alignment with a respective bore 1'd of the sealing ring 1', and by inserting the bolts 3 through the bore 2a, 1d and 1'd into threaded engagement with the bores 2'a. The bolts 3 must not be overtightened at this stage, as the sealing rings 1,1' must maintain a certain degree of free movement.

The entire device is then inserted into the duct D (see Fig. 3) housing the cable to be sealed. The bolts 3 are then tightened to compress the sealing rings 1,1'. This compression forces the ribbed outer cylindrical surfaces of the sealing rings 1,1' into sealing engagement with the internal cylindrical surface of the duct D, and anchors the entire device within the duct. The cable C is then pulled into the device using the leader. As this happens, the tapered internal bores la, 1'a of the sealing rings 1,1' seal against the outer cylindrical surface of the cable C. The device then forms an effective seal between the cable C and the duct D, thereby preventing any flow of water or gas. This position is shown in Fig. 3.

The tapered bores Ia, l'a of the sealing rings 1,1' enable the device to be used with cables having diameters in the range of from 50 mm to 80 mm. By modifying the size of the bores la, 1'a, the device can be used with cables having smaller or larger diameters. For example, by providing sealing rings with bores tapering from 50 mm to 20 mm, cables of a diameter range of from 50 mm to 15 mm can be accommodated.

It will be apparent that the sealing device described above could be modified. For example, the sealing rings could be made of resiliently-compressible materials (such as polyurethane) that can be injection moulded or press moulded.

Claims

1. A cable sealing device comprising two hollow sealing rings made of resiliently-compressible material, eqch sealing ring having a generally cylindrical outer surface and a tapered internal bore, and means for axially compressing the sealing rings when the sealing rings are placed end-to-end with their internal bores in axial alignment.

2. A sealing device as claimed in claim 1, wherein the outer cylindrical surface of each sealing ring is provided with a plurality of circumferential ribs.

3. A sealing device as claimed in claim 1 or claim 2, wherein each sealing ring is formed with a longitudinal cut extending from its outer cylindrical surface to its internal bore.

4. A sealing device as claimed in claim 3, wherein the cuts are of castellated form.

5. A sealing device as claimed in any one of claims 1 to 4, wherein the compressing means is constituted by first and second coupling plate means and by means for drawing the coupling plate means together, the first and second coupling plate means being positioned at opposite axial ends of the device.

6. A sealing device as claimed in claim 5, wherein each coupling plate means is constituted by four arcuate coupling plates, and four bolts constitute the means for drawing the coupling plates together, the coupling plates of one coupling plate means having threaded bores to match the threads of the bolts, and the coupling plates of the other coupling plate means having unthreaded bores through which the shanks of the bolts can pass freely.

7. A sealing device as claimed in any one of claims 1 to 6, wherein the sealing rings are made of rubber, and the coupling plates and bolts are made of stainless steel.

8. A cable sealing device substantially as hereinbefore described with reference to, and as illustrated by, the accompanying drawings.