GB2207562A - Installing optical fibre transmission lines - Google Patents

Installing optical fibre transmission lines Download PDF

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Publication number
GB2207562A
GB2207562A GB08817758A GB8817758A GB2207562A GB 2207562 A GB2207562 A GB 2207562A GB 08817758 A GB08817758 A GB 08817758A GB 8817758 A GB8817758 A GB 8817758A GB 2207562 A GB2207562 A GB 2207562A
Authority
GB
United Kingdom
Prior art keywords
return valve
optical fibre
planar surface
core
fibre ribbon
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
GB08817758A
Other versions
GB8817758D0 (en
GB2207562B (en
Inventor
John Edward Taylor
Andrew Kan Mckeown
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Balfour Beatty PLC
Original Assignee
BICC PLC
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by BICC PLC filed Critical BICC PLC
Publication of GB8817758D0 publication Critical patent/GB8817758D0/en
Publication of GB2207562A publication Critical patent/GB2207562A/en
Application granted granted Critical
Publication of GB2207562B publication Critical patent/GB2207562B/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02G—INSTALLATION OF ELECTRIC CABLES OR LINES, OR OF COMBINED OPTICAL AND ELECTRIC CABLES OR LINES
    • H02G1/00—Methods or apparatus specially adapted for installing, maintaining, repairing or dismantling electric cables or lines
    • H02G1/06—Methods or apparatus specially adapted for installing, maintaining, repairing or dismantling electric cables or lines for laying cables, e.g. laying apparatus on vehicle
    • H02G1/08—Methods or apparatus specially adapted for installing, maintaining, repairing or dismantling electric cables or lines for laying cables, e.g. laying apparatus on vehicle through tubing or conduit, e.g. rod or draw wire for pushing or pulling
    • H02G1/086—Methods or apparatus specially adapted for installing, maintaining, repairing or dismantling electric cables or lines for laying cables, e.g. laying apparatus on vehicle through tubing or conduit, e.g. rod or draw wire for pushing or pulling using fluid as pulling means, e.g. liquid, pressurised gas or suction means
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/46—Processes or apparatus adapted for installing or repairing optical fibres or optical cables
    • G02B6/50—Underground or underwater installation; Installation through tubing, conduits or ducts
    • G02B6/52—Underground or underwater installation; Installation through tubing, conduits or ducts using fluid, e.g. air

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Light Guides In General And Applications Therefor (AREA)

Abstract

A non-return valve component for use in blowing an optical fibre ribbon along a previously installed tubular duct comprises a tubular body 1 having a throughbore 16 of transverse cross-section of elongate form, a major surface (14, Fig. 1) of the throughbore being of planar form. At the downstream end of the tubular body 1, a non-return valve 21 comprises a planar surface 15 integral with and inclined at an acute angle to the planar major surface (14) of the throughbore 16 and, overlying the inclined planar surface, a flexible membrane 22 lying in a plane substantially parallel to the inclined planar surface. The flexible membrane 22 is urged towards the inclined planar surface to effect a fluid-tight seal around an optical fibre ribbon travelling between the membrane and the inclined planar surface 15 by the pressure of air employed to propel the optical fibre ribbon along the previously installed tubular duct. <IMAGE>

Description

OPTICAL FIBRE TRANSMISSION LINES This invention relates to the manufacture of an optical fibre transmission line of the kind consisting of or comprising a previously installed tubular duct which extends along the length of the transmission line and in the bore of which is loosely housed at least one optical fibre ribbon comprising a plurality of optical fibres extending side by side in the directions of their lengths with their axes lying in a substantially common plane, the or each optical fibre ribbon being so loosely housed in the tubular duct that the optical fibre ribbon can move transversely and longitudinally within the bore of the duct with respect to the transmission line.
It has been proposed to manufacture an optical fibre transmission line of this kind by introducing the leading end of a length of optical fibre ribbon into an end of the bore of a previously installed tubular duct and by propelling the optical fibre ribbon along the bore of the tubular duct by fluid drag of a gaseous medium which will have no deleterious effect on the optical fibres of the ribbon or on the tubular duct and which is passed through the bore in the desired direction of advance so that the optical fibre ribbon is carried along the tubular duct until a length of optical fibre ribbon is loosely housed in and throughout the required length of the tubular duct.In carrying out this method, it has been proposed to feed the optical fibre ribbon into the inlet end of a tubular chamber, connected to one end of the tubular duct, by means of a pair of rubber drive wheels, driven by a constant torque driving mechanism. The optical fibre ribbon is fed into the inlet end of the tubular chamber through a fluid seal - which is either a narrow channel which is only slightly larger in cross-sectional area than that of the optical fibre ribbon or which is a non-return valve in the form of a pair of opposed rubber lips - through the chamber and into the tubular duct. Gaseous medium, e.g.
air or nitrogen, under pressure is fed into the tubular chamber through a prt at a position intermediate of the ends of the chamber and flows from the chamber into the previously installed tubular duct. Pushing of the optical fibre ribbon into the previously installed tubular duct by the driving mechanism continues until the surface area of the optical fibre ribbon which is exposed to the flow of gaseous medium is sufficiently large to produce a drag force which will cause further advance of the optical fibre ribbon along the tubular duct, the rate of feed being controlled by means of the rubber drive wheels.
Where the fluid seal at the inlet end of the tubular chamber is a narrow channel, it is undesirable to permit an optical fibre ribbon being fed from a source of supply into the tubular chamber through the narrow channel to bear continuously against the wall bounding the narrow channel and, as a consequence, the narrow channel is made so much larger than the cross-sectional area of the optical fibre ribbon that there is an unavoidable leakage of gaseous medium from the chamber such as to cause an undesirable drag force in a direction opposite to that in which advance of the optical fibre ribbon is to be effected.Where the fluid seal at the inlet end of the tubular chamber is a non-return valve in the form of opposed rubber lips, the rubber lips bear continuously against the optical fibre ribbon advancing therebetween to cause an undesirable frictional force in a direction opposite to that in which advance of the optical 'fibre ribbon is to be effected.
It is an object of the present invention to provide, for use in a method of propelling a flexible optical fibre ribbon.along a previously installed tubular duct by fluid drag of a gaseous medium to form an optical fibre transmission line, an improved non-return valve component which is simple in form and inexpensive to manufacture.
According to the invention, the improved non-return valve component comprises a tubular body which has a throughbore of a transverse cross-section of substantially elongate form at least one major surface bounding said throughbore throughout its length being of substantially planar form and, at the downstream end of the tubular body, a non-return valve comprising a planar surface integral with and inclined at an acute angle to said planar major surface bounding said throughbore and, overlying said inclined planar surface, a flexible membrane which lies in a plane substantially parallel to said inclined planar surface and which is adapted to be urged towards said inclined planar surface to effect a substantially fluid-tight seal around a flexible optical fibre ribbon travelling therebetween by the pressure of the gaseous medium to be employed to propel the optical fibre ribbon along the bore of the previously installed tubular duct.
The cross-sectional size of the throughbore relative to the cross-sectional size of an optical fibre ribbon to be propelled therethrough will be such as to prevent substantial buckling of the ribbon as it travels through the non-return valve component towards the non-return valve itself.
Preferably, the tubular body includes a substantially rigid central elongate core having over at least a major part of its length a longitudinally continuous surface of planar form constituting said planar major surface and a sleeve which surrounds the central core and whose internal surface co-operates with the longitudinally continuous planar surface of the core to form the bore of the tubular body. In a preferred embodiment, the longitudinally continuous planar surface of the central core is constituted by the surface of the bottom wall of a longitudinally extending groove having a transverse cross-section of elongate form formed in the outer surface of the central core.The central elongate core preferably has an overall transverse cross-sectional shape of approximately circular form and is preferably made of a material having a low coefficient of friction with respect to an optical fibre ribbon, e.g. polytetrafluoroethylene or other suitable plastics material. The sleeve surrounding the core preferably has a bore of approximately circular transverse cross-section.
Preferably, in the non-return valve at the downstream end of the tubular body, the plaflar surface integral with and inclined at an acute angle to said planar major surface bounding said bore is a planar surface on the leading end part of the central elongate core and the flexible membrane which lies in a plane substantially parallel to said inclined planar surface tightly overlies a planar surface carried by the leading end part of the sleeve, which inclined surface of the sleeve has in its leading edge a recess so that a part of the flexible membrane directly overlies and can be urged by pressure of the gaseous medium into direct contact with the underlying planar surface on the leading end part of the central elongate core.
The central elongate core preferably is so detachably or permanently secured to the surrounding sleeve that the planar surfaces on the leading end parts of the central core and of the sleeve are maintained substantially parallel.
Over a part of the length of the tubular body upstream of the non-return valve and intermediate of the ends of the tubular body, preferably a part of the circumferential wall of the sleeve surrounding the central elongate core is removed to expose the underlying part of the longitudinally continuous planar surface of the central elongate core and a wheel having a circumferentially continuous smooth peripheral surface is freely rotatable in a hole in the central elongate core about an axis extending substantially normal to the longitudinal axis of the core with an exposed part of the peripheral surface of the wheel lying in substantially the same plane as the longitudinally continuous planar surface of the core, the arrangement being such that an optical fibre ribbon travelling along the throughbore will pass over the freely rotatable wheel and, by means of a spring-loaded wheel which can be rotatably driven about an axis extending substantially parallel to the axis of the freely rotatable wheel, can be urged into contact with the freely rotatable wheel and driven through the non-return valve.
The sleeve of the non-return valve component may constitute, or may be detachably secured to, a housing which surrounds the non-return valve and which is adapted to be detachably connected to the tubular chamber into which air or any other gaseous medium under pressure is fed through a port at a position intermediate of the ends of the chamber. In this case, preferably the housing, or a substantially rigid tube attached to the housing, protrudes part way into the tubular chamber and beyond the inlet port for the air or other gaseous medium so that an optical fibre ribbon when travelling there through will be protected from transverse flow of air or other gaseous medium being fed into the tubular chamber through the inlet port.In a preferred embodiment, however, the housing constituted by, or detachably secured to, the leading end of the sleeve also serves as the tubular chamber into which air or other gaseous medium can be fed through an inlet port in the side wall of the housing at a position upstream of the outlet of the non-return valve so that an optical fibre ribbon travelling through the component is protected from transverse flow of air or other gaseous medium being fed into the housing. In this latter case, the leading end of the housing preferably is adapted to be connected to a previously installed tubular duct into which an optical fibre ribbon is to be propelled.
To enable the improved non-return valve component to be employed intermediate of two previously installed tubular ducts to propel an optical fibre ribbon emerging from one of the ducts along the bore of the other duct, preferably the sleeve, and when present the housing, of the component are divided in the directions of their lengths into two separately formed parts so that, after an optical fibre ribbon has been loosely housed in the second tubular duct, the component can be removed by separating the parts of the sleeve and housing and removing the elongate core without damaging the length of optical fibre ribbon extending between the two tubular ducts.
The invention is further illustrated by a description, by way of example, of a prfeferred non-return valve component with reference to the accompanying drawings, in which: Figure 1 is a view from above of the preferred non-return valve component, and Figure 2 is a sectional side view of the component taken on the line II-II in Figure 1.
Referring to the drawings, the preferred non-return valve component comprises a tubular body 1 which has a throughbore 16 of a transverse cross-section of elongate form and, at the downstream end of the tubular body, a non-return valve 21.
The tubular body 1 comprises a rigid central elongate core 2 having over a major part of its length a longitudinally extending groove 12 having a transverse cross-section of elongate form formed in the outer surface of the central core, the bottom wall of the groove constituting a longitudinally continuous major surface 14 of planar form which bounds the throughbore 16 of the tubular body, and a sleeve 3 which surrounds the central core and which has a bore of circular cross-section whose internal surface co-operates with the major planar surface 14 to form the throughbore 16 of the tubular body.
The sleeve 3 is built up of two separately formed parts, a leading part 4 constituted by a gland and, detachably secured to the trailing end of the gland, a tube 5. The gland 4 has an external screwthread 7 to which is screwed a housing 8 which surrounds the non-return valve 21 and which, at its leading end 11, is adapted to be detachably connected to a previously installed tubular duct into which an optical fibre ribbon is to be propelled. The housing 8 serves as a tubular chamber into which air can be injected under pressure through a port 10.
At the leading end of the central core 2 is a planar surface 15 which is integral with and inclined at an acute angle to the major planar surface 14 of the groove 12. At the leading end of the gland 4 is an external inclined planar surface 17 which has in its leading edge a recess 18. A flexible membrane 22 is secured to the inclined surface 17 and, by virtue of the recess 18 in this inclined surface, directly overlies and can be urged by pressure of air into direct contact with the underlying inclined planar surface 15 on the leading end part of the central core 2. The inclined planar surface 15 and the flexible membrane 22 effectively constitute the non-return valve 21.
Over a part of the length of the tube 5 near the upstream end of the non-return valve component, a part of the circumferential wall of the tube is removed to form a window 29 exposing the underlying part of the major planar surface 14 of the central core 2.
Extending through the central core 2 in the part of the core exposed by the window 29 is a hole 26 whose axis is normal to the longitudinal axis of the core andin which is rotatably mounted a wheel 27 which is freely rotatable about an axis which is normal to the longitudinal axis of the core and to the axis of the hole. An exposed part of the peripheral surface of the freely rotatable wheel 27 lies in the same plane as the major planar surface 14 of the core.
When an optical fibre ribbon is travelling through the throughbore 16 of the non-return valve component and into a previously installed tubular duct to which the component is connected, a spring-loaded wheel (not shown) which can be rotatably driven about an axis extending parallel to the axis of the freely rotatable wheel 27 and employed to urge the travelling optical fibre ribbon into contact with the part of the freely rotatable wheel exposed through the window 29 so that the ribbon is driven through the non-return valve component.

Claims (15)

Claims:
1. For use in a method of propelling a flexible optical fibre ribbon along a previously installed tubular duct by fluid drag of a gaseous medium to form an optical fibre transmission line, a non-return valve component comprising a tubular body which has a throughbore of a transverse cross-section of substantially elongate form at least one major surface bounding said throughbore throughout its length being of substantially planar form and, at the downstream end of the tubular body, a non-return valve comprising a planar surface integral with and inclined at an acute angle to said planar major surface bounding said throughbore and, overlying said inclined planar surface, a flexible membrane which lies in a plane substantially parallel to said inclined planar surface and which is adapted to be urged towards said inclined planar surface to effect a substantially fluid-tight seal around a flexible optical fibre ribbon travelling therebetween by the.ressure of the gaseous medium to be employed to propel the optical fibre ribbon along the bore of the previously installed tubular duct.
2. A non-return valve component as claimed in Claim 1, wherein the tubular body includes a substantially rigid central elongate core having over at least a major part of its length a longitudinally continuous surface of planar form constituting said planar major surface and a sleeve which surrounds the central core and whose internal surface co-operates with the longitudinally continuous planar surface of the core to form the bore of the tubular body.
3. A non-return valve component as claimed in Claim 2, wherein the longitudinally continuous planar surface of the central core is constituted by the surface of the bottom wall of a longitudinally extending groove having a transverse cross-section of elongate form formed in the outer surface of the central core.
4. A non-return valve component as claimed in Claim 2 or 3, wherein the central elongate core has an overall transverse cross-sectional shape of approximately circular form.
5. A non-return valve component as claimed in any one of Claims 2 to 4, wherein the central elongate core is made of polytetrafluoroethylene or other material having a low co-efficient of friction.
6. A non-return valve component as claimed in any one of Claims 2 to 5, wherein the sleeve surrounding the core has a bore of approximately circular transverse cross-section.
7. A non-return valve as claimed in any one of Claims 2 to 6, wherein, at the downstream end of the tubular body, the planar surface integral with and inclined at an acute angle to said planar major surface bounding said bore is a planar surface on the leading end part of the central elongate core and the flexible membrane which lies in a plane substantially parallel to said inclined planar surface tightly overlies a planar surface carried by the leading end, part of the sleeve, which inclined surface of the sleeve has in its leading edge a recess so that a part of the flexible membrane directly overlies and can be urged by pressure of the gaseous medium into direct contact with the underlying planar surface on the leading end part of central elongate core.
8. A non-return valve component as claimed in Claim 7, wherein the central elongate core is so detachably or permanently secured to the surrounding sleeve that the planar surfaces on the leading end parts of the central core and of the sleeve are maintained substantially parallel.
9. A non-return valve component as claimed in any one of Claims 2 to 8, wherein1 over a part of the length of the tubular body upstream of the non-return valve and intermediate of the ends of the tubular body, a part of the circumferential wall of the sleeve surrounding the central elongate core is removed to expose the underlying part of the longitudinally continuous planar surface of the central elongate core and a wheel having a circumferentially continuous smooth peripheral surface is freely rotatable in a hole in the central elongate core about an axis extending substantially normal to the longitudinal axis of the core with an exposed part of the peripheral surface of the wheel lying in substantially the same plane as the longitudinally continuous planar surface of the core, the arrangement being such that an optical fibre ribbon travelling along the throughbore will pass over the freely rotatable wheel and, by means of a spring-loaded wheel which can be rotatably driven about an axis extending substantially parallel to the axis of the freely rotatable wheel, can be urged into contact with the freely rotatable wheel and driven through the non-return valve.
10. A non-return valve component as claimed in any one of Claims 2 to 9, wherein the sleeve constitutes, or is detachably secured to; a housing which surrounds the non-return valve and which is adapted to be detachably connected to the tubular chamber into which air or any other gaseous medium under pressure is fed through a port at a position intermediate of the ends of the chamber.
11. A non-return valve component as claimed in Claim 10, wherein the housing, or a substantially rigid tube attached to the housing, protrudes part way into the tubular chamber and beyond the inlet port for the air or other gaseous medium so that an optical fibre ribbon when travelling therethrough will be protected from transverse flow of air or other gaseous medium being fed into the tubular chamber through the inlet port.
12. A non-return valve component as claimed in any one of Claims 2 to 10, wherein the housing constituted by, or detachably secured to, the leading end of the sleeve also serves as the tubular chamber into which air or other gaseous medium can be fed through an inlet port in the side wall of the housing at a position upstream of the outlet of the non-return valve so that an optical fibre ribbon travelling through the component is protected from transverse flow of air or other gaseous medium being fed into the housing.
13. A non-return valve component as claimed in Claim 12, wherein the leading end of the housing is adapted to be connected to a previously installed tubular duct into which an optical fibre ribbon is to be propelled.
14. A non-return valve component as claimed in any one of Claims 2 to 13, wherein, to enable the non-return valve component to be employed intermediate of two previously installed tubular ducts to propel an optical fibre ribbon emerging from one of the ducts along the bore of the other duct, the sleeve, and when present the housing, of the component are divided in the direction of their lengths into two separately formed parts so that, after an optical fibre ribbon has been loosely housed in the second tubular duct, the component can be removed by separating the parts of the sleeve and housing and removing the elongate core without damaging the length of optical fibre ribbon extending between the two tubular ducts.
15. For use in a method of propelling a flexible optical fibre ribbon along a previously installed tubular duct by fluid drag of a gaseous medium to form an optical fibre transmission line, a non-return valve component substantially as hereinbefore described with reference to and as shown in the accompanying drawing.
GB8817758A 1987-07-27 1988-07-26 Optical fibre transmission lines Expired - Lifetime GB2207562B (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB878717715A GB8717715D0 (en) 1987-07-27 1987-07-27 Optical fibre transmission lines

Publications (3)

Publication Number Publication Date
GB8817758D0 GB8817758D0 (en) 1988-09-01
GB2207562A true GB2207562A (en) 1989-02-01
GB2207562B GB2207562B (en) 1991-03-13

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GB878717715A Pending GB8717715D0 (en) 1987-07-27 1987-07-27 Optical fibre transmission lines
GB8817758A Expired - Lifetime GB2207562B (en) 1987-07-27 1988-07-26 Optical fibre transmission lines

Family Applications Before (1)

Application Number Title Priority Date Filing Date
GB878717715A Pending GB8717715D0 (en) 1987-07-27 1987-07-27 Optical fibre transmission lines

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GB (2) GB8717715D0 (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL9200823A (en) * 1992-05-08 1993-12-01 Theodorus Andreas Van Hameren Cable insertion apparatus
EP0691557A3 (en) * 1988-10-05 1996-04-24 British Telecomm Gas seal
WO2000050947A1 (en) * 1999-02-22 2000-08-31 Telefonaktiebolaget Lm Ericsson (Publ) A fibre feeding device

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0691557A3 (en) * 1988-10-05 1996-04-24 British Telecomm Gas seal
NL9200823A (en) * 1992-05-08 1993-12-01 Theodorus Andreas Van Hameren Cable insertion apparatus
WO2000050947A1 (en) * 1999-02-22 2000-08-31 Telefonaktiebolaget Lm Ericsson (Publ) A fibre feeding device
US6694085B2 (en) 1999-02-22 2004-02-17 Telefonaktiebolaget Lm Ericsson (Publ) Device for feeding optical fibres into a duct

Also Published As

Publication number Publication date
GB8717715D0 (en) 1987-09-03
GB8817758D0 (en) 1988-09-01
GB2207562B (en) 1991-03-13

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Legal Events

Date Code Title Description
732E Amendments to the register in respect of changes of name or changes affecting rights (sect. 32/1977)
PE20 Patent expired after termination of 20 years

Expiry date: 20080725