Electricity: conductors and insulators – Conduits – cables or conductors – Single duct conduits
Patent
1997-09-23
1999-07-13
Reichard, Dean A.
Electricity: conductors and insulators
Conduits, cables or conductors
Single duct conduits
174 17CT, H02G 318
Patent
active
059229900
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to the provision of environmental protection around wires, optical fibres or other elongate substrates.
It is often necessary to seal wires at their points of entry into housings in order to protect connectors or electronic components within the housing from moisture or other contaminants that might otherwise enter the housing through the opening provided for the wire. This problem frequently occurs in telecommunications networks where devices for connection, electrical protection or isolation, are positioned outside buildings and are expected to have a long life-time under unfavourable weather conditions.
The invention is therefore particularly concerned with a device comprising some form of housing which has means for sealing wires at or adjacent their points of entry.
U.S. Pat. No. 4,859,809 (Jervis) discloses a splice case for sealing connectors joining small pair count telecommunications cables. First and second half-shells contain a gel sealing material and are held together by springs that function also to deform surfaces of the half-shells to put the sealing material therein under compression. The conductors enter the half-shells at their ends and lie between two layers of gel.
A two part closure for sealing wire connectors is also disclosed in U.S. Pat. No. 4,849,580 (Reuter). Again, each part contains a sealing material.
Reference may also be made to U.S. Pat. No. 4,963,700 (Olsen), U.S. Pat. No. 3,879,575 (Dobbin et al), U.S. Pat. No. 4,610,738 (Jervis), U.S. Pat. No. 3,757,031 (Izraeli) and DE G9004669.2 (3M). These documents confirm the common practice of providing sealing material in each of two half-shells that are brought together around the conductor to be sealed.
We have discovered that, particularly with careful choice of sealing material, a more economical sealing device can be produced.
Surprising, a single layer of sealing material can be caused to fold, or wrap, around a conductor to be sealed by lateral displacement of the conductor into the sealing material. This preferably occurs as parts of a sealing device are closed around the conductor.
SUMMARY OF THE INVENTION
Thus, the invention provides a device for forming a seal around an elongate member which comprises: be placed; the sealing material; and elongate member, thereby putting the sealing material under pressure.
Displacement of the elongate member into the sealing material will, in general, cause the sealing material to fold or wrap around the elongate member so that it forms a seal around its entire periphery. It is preferably the displacement itself which produces this result without any other displacement of the sealing material being required.
Those skilled in the art, after reading the specification, will be able to select sealing materials having the properties necessary to produce this result. The material is preferably sufficiently soft that the elongate member can be displaced laterally into it without damage to the elongate member. Where the elongate member is a wire typically used in a telecommunications network, we prefer that the sealing material have a Stevens Voland hardness of less than 60 g, preferably less than 45 g, more preferably less than 40 g, especially less than 35 g. In order that the material have sufficient stability during its service life we prefer that its Stevens Voland hardness be greater than 10 g, preferably greater than 15 g, Stevens Voland hardness is measured on a Stevens Leatherhead Food Research Association (LFRA) Texture Analyser having a stainless steel circular spindle of diameter of about 0.64 cm, rotating in slow mode at 0.2 mm/second and in fast mode at 2 mm/second, the measurement being taken at a penetration of 4 mm. The material preferably has a certain elasticity, and in particular preferably has an elongation to break of at least 100%, preferably at least 200%, more preferably at least 300%.
We prefer that, after displacement of the wire, not only that first and second parts of the surface of the sealing material
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Alaerts Roger
Buekers Valere
Delvaux Roger
Vanonckelen Marc
Burkard Herbert G.
N.V. Raychem S.A.
Reichard Dean A.
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