The present invention relates to an arrangement for verifying the impermeability of a sleeve body in a cable network or the like, in which a device is provided that introduces gas into the interior of the sleeve, and an indicating device is provided for indicating the pressure inside the sleeve.

In order to verify and maintain the impermeability of cable networks, for example telecommunications cable networks, and/or to prevent the ingress of moisture from the outside, it is known (e.g. from DE 1226183), to subject the interior of a cable network to an excess pressure. It is also known, at least for testing purposes, to provide compressed air nipples for the connection of a source of compressed air at one point in the cable network, and devices for indicating the prevailing pressure at another point of the cable network. Such known devices are used for placing the network under pressure and for verifying the pressure at a given time. However continuous monitoring of the internal pressure is not practicable with the known devices on account of the very great expenditure involved.

Cable networks typically comprise sleeve bodies, for example, sleeve bodies enclosing cable splices, cable branches or the like. An object of the present invention is to provide a means of testing the internal excess pressure (i.e. pressure over ambient) in a cable network in a simple manner since verification of the excess pressure is a verification of the sleeve impermeability.

Thus the present invention provides an arrangement for verifying the impermeability of a sleeve body in cable networks or the like, comprising:

a) a gas cartridge provided within the sleeve body for introducing gas into the interior of the sleeve; and

b) an indicating device for indicating the excess pressure in the sleeve.

By means of the invention, it is possible to indicate to the user the particular state of impermeability of the sleeve and the cable network in the vicinity of the sleeve using comparatively simple means.

An arrangement according to the invention is espedally useful when it is not possible to ensure suffiάent availability of gas sources to a network after the cable network has been completed. By providing every or several sleeve body with an individual gas reservoir, suffiάent availability of gas sources is established at the outset.

Preferably the gas cartridge can be operated either (i) as the sleeve is dosed or (ii) after the sleeve is dosed from the outside of the sleeve.

The gas cartridge is preferably a CO ₂ cartridge. However any gas or mixture of gasses, e.g. air, can be used.

The gas cartridge preferably floods the interior of the sleeve with a gas.

The gas cartridge can be released, for example, by a plunger that can be operated from the outside of the sleeve body. It may also be possible to arrange the gas cartridge in the interior of the sleeve in such a manner that a plunger activates the gas cartridge when the sleeve is finally dosed. This may be possible for example where the sleeve body comprises half shells, the plunger piercing the gas cartridge as the half shells are brought together.

The pressure-indicating device can be designed in various ways according to the invention. For example, it may be in the form of a spring-loaded indicating piston provided in the sleeve wall and optionally guided in a transparent casing. As another example, it may be in the form of a bellows diaphragm, the bulging of which towards the exterior of the sleeve can be used as a measure of the pressure prevailing on the inside. Pressure indication with the aid of a membrane is shown in DE-AS 2245577.

Embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings, wherein:

Fig 1 is a simplified three-dimensional view of the end face of a sleeve body in a cable network.

Fig 2 is a sectional view taken approximately along the line II - II of the sleeve of Fig 1, showing a first embodiment of pressure indicating device,

Fig 3 is a sectional view through a sleeve wall showing a different embodiment of indicating device,

Fig 4 is a sectional view through a portion of a half -shell sleeve body showing a gas reservoir in the region of the plane of partition of the sleeve halves, and

Fig 5 is a sectional view through a portion of a sleeve wall showing another way of accommodating a gas reservoir in a sleeve body.

Referring to Figures 1 and 2, a sleeve body 1 in a cable network is shown with a cable 2 entering. The sleeve is provided with an end face 3 in which the pressure indicating device generally indicated as 6 is located. The interior of the sleeve 1 can be filled, for example, with CO ₂ by means of a compressed air or gas source contained within the sleeve, and not visible in Figures 1 and 2. The pressure indicating device, generally designated 6, consists in the embodiment of Figure 2 of an indicator piston 8 loaded by a spring 7. This piston 8 sits in a recess 10 in the end face 3 of the sleeve body 1, and can be caused to move by increasing the internal pressure in the sleeve. The piston moves from the position shown by continuous lines in Fig 2 into the position shown by dot-dash lines. The inner wall 9 of the displacement recess 10 can be provided, for example, with scale markings which allow readings to be made relating to the prevailing internal pressure in the sleeve 1. The spring 7 acts to cause return of the piston towards its initial position (as shown by continuous lines), if the pressure is reduced.

Figure 3 shows a modified example of an indicating device 6' for use in end wall 3 of sleeve body 1. In this case, it is not a piston 8 that is displaced but a diaphragm 11. This diaphragm 11 can similarly be returned to the pressureless starting position by means of a spring 7a, and can be used to measure the pressure within the sleeve.

Figure 4 shows the interior of a sleeve body 1 comprising half shells 15 hinged at 16. A gas reservoir in the form of a gas cartridge 12, is positioned in the interior of sleeve la. In the solution shown in Figure 4, there is provided, in the plane of partition of the half shells 15, opposite the gas cartridge 12, a pressure plunger 13 which, upon dosure of the sleeve, is able to puncture the seal of the gas cartridge 12 in such a manner that the gas in the gas cartridge 12 is able to flow into the interior of the sleeve 1.

Figure 5 shows another possible method of opening the seal 14a of a gas cartridge (in this case indicated as 12a). In this case, a pressure plunger 13a that can be operated by action from the outside of the sleeve is provided. The plunger 13a can also be so mounted with respect to the wall of the sleeve that it can be operated in a different manner, for example by means of an articulated lever or the like.

The described iEustrative embodiments of the invention can, of course, be further modified in various respeds without departing from the basic concept. In particular, the pressure indicating device 6 or 6' may be in the form of a pre¬ fabricated element that can be integrated into the wall 3 of a sleeve 1, for example in the form of a blind cable entry, or the said device may alternatively be an integral part of the sleeve wall.

Also the piston 8 and the diaphragm 11 may be provided with electrical switch contacts or proximity switches which send an electrical switching pulse in a pre-determinable position when the pressure drops, so as to indicate the loss of pressure, in the network overall, or in an individual sleeve, with an indication of the corresponding location. Such electrical pulses may be transmitted to the user of the cable network via monitoring lines.