Implements or apparatus for applying pushing or pulling force – Method or apparatus for placement of conductive wire – By fluid pressure differential in conduit
Patent
1990-11-21
1993-04-06
Watson, Robert C.
Implements or apparatus for applying pushing or pulling force
Method or apparatus for placement of conductive wire
By fluid pressure differential in conduit
B66F 324
Patent
active
051996898
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a method and apparatus for installing transmission lines in ducts or tubes.
BACKGROUND OF THE INVENTION
European Patent No. 108590 discloses a method and apparatus for installing optical fibre members within tubular ducts using fluid drag of a gaseous medium to propel the fibre member along the duct. In the illustrated examples in that patent, a fibre bundle is introduced to the duct via a feed head and wheels, in order to urge the bundle into the duct against a resistive force acting on the advancing end of the bundle.
A number of other methods of introducing fibres into ducts, for subsequent advancement along the ducts with the aid of viscous drag forces, have since been described.
One particular such method comprises introducing a fibre member to a duct at a point near a high local flow of compressed air, and bleeding some of the air through a vent some distance, typically around 1 meter, downstream. This method is fully described in our European Patent Application 0287225A1.
In all practical applications of the fibre blowing process, the nature of the fibre bundle to be installed has been an important factor. The present applicants and others working on the process have investigated a variety of different bundles, in an attempt to develop an optimum range of products. One product which has particularly good characteristics is described in our European Patent Application No. 0157610. One of the examples in that application is a seven-fibre bundle with a tight skin around the fibres, and an outer sheath of foamed material. The characteristics of this bundle are that it is lightweight, given its volume, and its large surface area provides a good surface for the action of fluid drag forces. There is the further advantage that the tight skin, or inner sheath, locks the fibres together, so that the rigidity is increased, and the fibres are unlikely to buckle. Recently, there has been a trend towards using more lightweight bundles with only a small number of fibres or even a single fibre. Generally for practical applications it has been thought important to create a package structure of some kind, usually comprising a foamed layer, to provide a surface area to weight ratio which results in the package being blowable over tortuous routes, which may extend over hundreds of meters. Typically, fibre members have been in the range 1 to 3.5 gm.sup.-1. Thus, a relatively bulky but light structure was seen as important for good blowing properties. Additionally, protection for the fibres was seen as essential, because any process carried out on fibres is seen as running some risk of damaging the fibres, for example by transmitting excessive tensile or compressive force to the fibres. Thus, robust packaging was used.
As is well known, the provision of a foamed layer in conjunction with optical fibres presents a number of practical difficulties, because shrinkage of the foam can introduce undesirable compressive forces which can adversely affect the transmission properties of the fibres. The above-described locking-effect of seven tightly encased fibres is one way of mitigating this problem. A loose layer of foam is another. Lengthy development has, however, been required to produce a robust product suitable for a wide range of working environments.
SUMMARY OF THE INVENTION
The present invention is a modification of the known fibre blowing process and method which, most surprisingly, gives excellent results. There are also advantages of cheapness and simplicity.
Thus, the present invention provides a method of advancing a transmission line along a duct with viscous drag of a fluid medium, comprising introducing the transmission line to a feed portion of duct, introducing said fluid medium and advancing the line along the portion and into the main duct, which has a larger diameter than the feed portion, and continuing the supply of fluid to the feed portion of duct during the installation of the transmission line.
Most surprisingly no venting is required, as
REFERENCES:
patent: 3610582 (1971-10-01), Passoni
patent: 3654114 (1972-04-01), Brandstaetter
patent: 3793732 (1974-02-01), Hamrick
patent: 4082423 (1978-04-01), Glista et al.
patent: 4105284 (1978-08-01), Olshansky
patent: 4181403 (1980-01-01), Macedo et al.
patent: 4185809 (1980-01-01), Jonnes
patent: 4230395 (1980-10-01), Dean et al.
patent: 4248035 (1981-02-01), Skillen et al.
patent: 4332436 (1982-06-01), Adorni et al.
patent: 4372792 (1983-02-01), Dey et al.
patent: 4408378 (1983-10-01), Ketteringham
patent: 4414942 (1983-11-01), Anderson
patent: 4446686 (1984-05-01), Panuska et al.
patent: 4552433 (1985-11-01), Titchmarsh et al.
patent: 4640576 (1987-02-01), Eastwood
patent: 4659174 (1987-04-01), Ditscheid et al.
patent: 4691896 (1987-09-01), Reeve et al.
patent: 4702404 (1987-10-01), Einsle
patent: 4756510 (1988-07-01), Klamm
patent: 4796970 (1989-01-01), Reeve et al.
patent: 4856760 (1989-08-01), Frost et al.
patent: 4948097 (1990-09-01), Reeve et al.
"Single-Ended Fiber Strain & Length Measurement on Frequency Domain", by Kashyap and Reeve, Electronic Letters, vol. 16, No. 18, Aug. 1980.
"Temperature Desensitisation of Delay in Optical Fibers for Sensor Applications" by Kashyap et al, Electronics Letters, vol. 19, No. 34, Nov. 1983.
S. A. Cassidy et al--"A radically new approach to the installation of optical fibre using the viscous flow of air"--Telecom Technol J. vol. 2 Bi Jan. 1, 1984, pp (4 pages).
"Sub-ducts: The Answer to Honolulu's Growing Pains" by Herman S. L. Hu and Ronald T. Miyahara, Apr. 7, 1980, pp. 23-35.
"Optical Fibre Jacketed with Electronics Lett", vol. 19, No. 17, Aug. 1983, pp. 674-675, Yamamoto et al.
"High Quality Optical Fibre Cable for Telecommunication" Conf. 27th Int. Wire & Cable Sym. Cherry Hill, N.J. Nov. 1978, pp. 394-403 by Pizzorno.
"Principles of Fiber-Optical Cable Design", IEEE vol. 123, No. 6, Jun. 1976, pp. 597-602 by Foord et al.
"Method of Introducing a Linear Body Into a Winding Tube" by Asano, Sep. 1987-No. 4468, pp. 1-4.
Freeman Robert A.
Proud Nicholas W.
British Telecommunications public limited company
Watson Robert C.
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