Optical waveguides – Accessories – Bushing structure
Patent
1991-05-07
1992-08-11
Gonzalez, Frank
Optical waveguides
Accessories
Bushing structure
G02B 636
Patent
active
051386917
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a sealing arrangement for a duct, and in particular to a seal for incorporation in a duct along which an optical fibre package is installed by fibre blowing.
A duct along which a transmission line (e.g. optical fibre) package is installed provides a continuous path along which fluid can travel. Unless such a duct is provided with seals to inhibit fluid flow, hazards can arise. For example, gas leaks may result in the introduction of toxic or explosive gases at secondary locations, or water may leak across otherwise watertight bulkheads. Therefore, to comply with safety requirements, after a blown optical fibre installation is completed, seals or blockages are provided at intervals by perforating the duct and injecting a resin. The disadvantage of this technique is that the resin forms a permanent blockage in the duct, and prevents further installation of fibre packages, or the replacement of an installed package without first removing the resined section of the duct. Removal of the resined section is time-consuming, and requires cutting of the optical fibre package, requiring subsequent replacement of a complete duct section, or the introduction of additional splices.
The aim of the invention is to provide a seal that does not prevent subsequent installation operations.
The present invention provides a sealing arrangement for a passageway carrying a transmission line package, the arrangement comprising a coupling portion for connection to respective passageway portions on each side thereof, a flexible seal located in the coupling portion and comprising a flexible body portion, the flexible body portion being arranged to collapse inwardly to seal around a transmission line package when the transmission line package is installed through the coupling portion, and the flexible body portion being arranged to open to permit fluid flow through the coupling poriton when the fluid flow pressure exceeds a predetermined level, wherein the coupling portion is provided with at least one vent disposed so that pressure externally of the coupling portion tends to cause inward deformation of the body portion of the seal to increase its resistance to opening.
Advantageously, the flexible seal comprises a tubular member having a waisted intermediate portion that forms the seal, and wherein the ends of the tubular member are secured to the inner wall of the coupling portion with the or each vent disposed between the locations at which the ends of the tubular member are secured. The flexible seal may have substantially flat opposing surfaces.
The invention will now be described in greater detail, by way of example, with reference to the accompanying drawings, in which:
FIG. 1 is a schematic section through a tube connector provided with a gas blocking seal according to a preferred embodiment of the invention;
FIG. 2 shows the embodiment of FIG. 1 with a fibre package installed;
FIG. 3 shows the embodiment of FIG. 1 during installation of the fibre package;
FIG. 4 shows a modified embodiment during fibre package installation;
FIG. 5 is a schematic section through a duct showing an alternative embodiment of seal according to the invention in an open condition; and
FIG. 6 is a schematic section through a duct showing the seal of FIG. 5 in a sealing condition.
The type of system with which the invention is concerned, and the context in which it is described, is in blown fibre installations. Fibre blowing is the process described in our European patent specification 108590, in which lightweight transmission lines are urged along ducts by the viscous drag of a fluid, usually compressed air. The propellant air is typically at an initial pressure of 3 to 10 bar. The transmission lines typically comprises a bundle of optical fibres encased in a lightweight outer covering, and this is termed a fibre package. Fibre packages may also consist of single fibres or lines, and may include electrical conductors.
Referring to the drawings, FIG. 1 shows a tube connector 1 provided with a flexible tubular liner 2 which co
REFERENCES:
patent: 4756595 (1988-07-01), Braun et al.
patent: 4997256 (1991-03-01), Sano et al.
British Telecommunications public limited company
Gonzalez Frank
Ngo Jun
LandOfFree
Gas seal does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Gas seal, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Gas seal will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-353315