Seal for a joint or juncture – Seal between relatively movable parts – Relatively rotatable radially extending sealing face member
Patent
1993-10-08
1999-05-11
DePumpo, Daniel G.
Seal for a joint or juncture
Seal between relatively movable parts
Relatively rotatable radially extending sealing face member
277 34, 277 343, 137223, F16J15/46
Patent
active
059019620
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to environmental sealing of substrates such as cables or pipes, particularly within a duct, or a splice case. This may be done to prevent water, gas or other contaminant from passing along a duct into a manhole etc, or to protect a cable splice from the environment. The invention will be described primarily in terms of a duct seal, (which term includes "feedthroughs") but the invention is also applicable to other instances of sealing, including splice cases, pipe protection and grommets etc.
The reason that a seal (rather than an adhesive bond of no significant thickness) may be required is a disparity in size or shape between the substrate to be sealed and some other object such as a housing within which it lies. For example, a duct may be from several millimetres to several centimetres larger than the cable or other substrate that it carries, an oval cable may lie within a circular duct, or the installed size of a splice case housing may be larger than the spliced cables within it. Also, when a branch-out between two or more cables is to be sealed it will generally be necessary to convert their combined concave cross-section to a convex shape that can be enclosed by, say, a rigid wrap-around or other casing or by half-shells or a dimensionally-recoverable (generally heat-shrinkable) sleeve.
Such seals have usually been formed by the use of a conformable sealing member, for example an O-ring, or the use of a mass of sealant or a hot-melt adhesive. Whilst these seals in general work in a satisfactory manner, problems sometimes occur. For example, by their nature, conformable sealing members have a low modulus and especially where they are used to fill large voids, may have a tendency to creep over extended periods of time. Also, leak paths may occur if it has not been possible to introduce sufficient heat into a hot-melt adhesive to melt it. It is for example difficult to introduce heat into a duct.
Difficulties may also arise due to the materials needed for ducts and cables, which may be incompatible. Cables are often made of polyethylene or lead, and ducts of polyvinyl chloride, steel or cement which may be dirty or crumbly and difficult to clean.
A widely used duct seal, disclosed in GB 1594937 (Raychem), comprises a hollow body member provided on its inner and/or outer surface with a plurality of spaced apart flanges, each flange extending away from and around said surface and at least a portion of the flange remote from said surface being deformable, but only at an elevated temperature, and at least part of said surface(s) and/or the surface of the flanges having a sealant thereon.
EP 0179657 (Raychem) discloses a duct seal especially for sealing about four cables which contains a spring which, when operated, radially-expands that part of the duct seal that is to seal to the duct. The cables are sealed by heat-shrink outlets of the duct seal. The spring is operated after heating the part of the duct seal in which it lies. Heating may soften the material of the seal and activate an adhesive.
EP 0152696 (Raychem) discloses an assembly for sealing an aperture (such as that between a duct and a cable it carries) which comprises a flexible envelope that is arranged to be wrapped on itself for insertion into the aperture, the envelope having an opening therein for receiving an expansible or expanding filler material, for example a curable foam, for expanding the envelope, a container containing said expansible filler material, and means arranged to connect the container to the envelope to conduct the filler thereto for effecting expansion of the envelope, characterized in that an adhesive or sealant is located on or associated with at least part of the outer surface of the envelope. The disclosure of EP 0152696 (corresponding U.S. Patent is U.S. Pat. No. 4,790,544) incorporated herein by reference.
Other patent specifications disclosing hollow envelopes for sealing include the following. EP 0100228 (Raychem) discloses a method forming a seal between at least one elongate object
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Burkard Herbert G.
DePumpo Daniel G.
N. V. Raychem S. A.
Novack Sheri M.
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