1、 International Telecommunication Union ITU-T L.79TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (07/2008) SERIES L: CONSTRUCTION, INSTALLATION AND PROTECTION OF CABLES AND OTHER ELEMENTS OF OUTSIDE PLANT Optical fibre cable elements for microduct blowing-installation application Recommendation ITU-
2、T L.79 Rec. ITU-T L.79 (07/2008) i Recommendation ITU-T L.79 Optical fibre cable elements for microduct blowing-installation application Summary Recommendation ITU-T L.79 describes characteristics, construction and test methods for microduct fibre units and microduct cables to be used with the blowi
3、ng installation technique. The cable characteristics required for a cable to perform appropriately are described. Also, a method is described for determining whether or not the cable has the required characteristics. The required conditions may differ according to the installation environment; detai
4、led test conditions must be agreed upon between a user and a manufacturer for the environment in which a cable is to be used. Source Recommendation ITU-T L.79 was approved on 7 July 2008 by ITU-T Study Group 6 (2005-2008) under Recommendation ITU-T A.8 procedure. ii Rec. ITU-T L.79 (07/2008) FOREWOR
5、D The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying te
6、chnical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups whic
7、h, in turn, produce Recommendations on these topics. The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. In some areas of information technology which fall within ITU-Ts purview, the necessary standards are prepared on a collaborative basis with ISO and
8、IEC. NOTE In this Recommendation, the expression “Administration“ is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to
9、ensure e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words “shall“ or some other obligatory language such as “must“ and the negative equivalents are used to express requirements. The use of such words d
10、oes not suggest that compliance with the Recommendation is required of any party. INTELLECTUAL PROPERTY RIGHTS ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concern
11、ing the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by pate
12、nts, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at http:/www.itu.int/ITU-T/ipr/. ITU 2009 All rights reserved. No part of this publi
13、cation may be reproduced, by any means whatsoever, without the prior written permission of ITU. Rec. ITU-T L.79 (07/2008) iii CONTENTS Page 1 Scope 1 2 References. 1 3 Definitions 3 4 Abbreviations and acronyms 4 5 Environmental conditions. 4 5.1 Underground. 4 5.2 Aerial 4 5.3 Indoor . 4 6 Cable co
14、nstruction 4 6.1 Fibre protection 4 6.2 Protected microducts 5 6.3 Microducts 6 6.4 Hybrid protected microduct/cable 6 6.5 Blown-in elements 6 7 Test methods. 7 7.1 Test methods for cable elements 7 7.2 Methods for testing mechanical characteristics 8 7.3 Test methods for environmental characteristi
15、cs. 9 7.4 Test methods for fire safety 10 Appendix I Chinese experience 11 I.1 Product types of microducts . 11 I.2 Blowing performance test for micro-cable or fibre unit in microduct . 12 I.3 Layout location selection for microduct. 14 Bibliography. 16 iv Rec. ITU-T L.79 (07/2008) Introduction Air
16、blowing installation methods are based on viscous drag acting upon a cable while forcing a continuous high-speed airflow along it with a compressor. The velocity of the moving air propels the cable and makes it advance at a typical speed supported by the equipment. New generation cabling techniques,
17、 based on microduct cables, microduct fibre units and microduct systems, offer the possibility of branching without the need for splices. These techniques are extremely flexible and make it possible to grow in accordance with demand. This gives rise to the concept of “fibre on demand“, which involve
18、s the pre-installation of a multi-microduct system and then the subsequent, incremental installation of fibre based on individual customer demand. To support this “fibre on demand“ approach, a fibre cable product must allow the installation of only a few fibres at a time. Cable products should take
19、up the smallest possible amount of the service providers right-of-way (i.e., fit the smallest microduct) so that there is plenty of space to add fibre for future customers. Therefore, usually only a small number of the fibres that are installed are used immediately. Also state-of-the-art fibre techn
20、ology can be adopted. When using blowing techniques, there is no pulling force at the front end of the cable; airflow exerts a distributed force along the entire cable. In addition, connection to a pulling cord is not needed. Generally, the blowing force is an order of magnitude lower than the typic
21、al force involved in other installation methods, for example pulling techniques, thus reducing installation hazards. Additionally, with this technique, bends in a duct run are much less of a concern than with pulling techniques, so the installation speed increases and longer lengths of cable can be
22、installed. Cables are installed virtually without stress, leaving the cable relaxed in the duct once the installation has been completed. Rec. ITU-T L.79 (07/2008) 1 Recommendation ITU-T L.79 Optical fibre cable elements for microduct blowing-installation application 1 Scope This Recommendation: ref
23、ers to microduct fibre units and microduct cables to be used for telecommunications networks with blowing installation techniques; deals with mechanical and environmental characteristics of microduct fibre units and microduct cables. The optical fibre dimensional and transmission characteristics, to
24、gether with their test methods, should comply with IEC 60793-2-10, ITU-T G.652, ITU-T G.653, ITU-T G.654, ITU-T G.655, ITU-T G.656 and ITU-T G.657 which deal with multi-mode graded index optical fibres and single-mode optical fibres, respectively; deals with fundamental considerations related to opt
25、ical fibre cable from mechanical and environmental standpoints; acknowledges that some optical fibre cables may contain metallic elements, for which reference should be made to b-ITU-T Handbook and other L-series Recommendations; recommends that microduct fibre units and microduct cables should be p
26、rovided with end-sealing and protection during delivery and storage, as used for metallic cables. 2 References The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication,
27、the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the curren
28、tly valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. ITU-T G.650.1 Recommendation ITU-T G.650.1 (2004), Definitions and test methods for linear, deterministic attrib
29、utes of single-mode fibre and cable. ITU-T G.651.1 Recommendation ITU-T G.651.1 (2007), Characteristics of a 50/125 m multimode graded index optical fibre cable for the optical access network. ITU-T G.652 Recommendation ITU-T G.652 (2005), Characteristics of a single-mode optical fibre and cable. IT
30、U-T G.653 Recommendation ITU-T G.653 (2006), Characteristics of a dispersion-shifted single-mode optical fibre and cable. ITU-T G.654 Recommendation ITU-T G.654 (2006), Characteristics of a cut-off shifted single-ode optical fibre and cable. 2 Rec. ITU-T L.79 (07/2008) ITU-T G.655 Recommendation ITU
31、-T G.655 (2006), Characteristics of a non-zero dispersion-shifted single-mode optical fibre and cable. ITU-T G.656 Recommendation ITU-T G.656 (2006), Characteristics of a fibre and cable with non-zero dispersion for wideband optical transport. ITU-T G.657 Recommendation ITU-T G.657 (2006), Character
32、istics of a bending loss insensitive single mode optical fibre and cable for the access network. ITU-T L.1 Recommendation ITU-T L.1 (1988), Construction, installation and protection of telecommunication cables in public networks. ITU-T L.10 Recommendation ITU-T L.10 (2002), Optical fibre cables for
33、duct and tunnel application. ITU-T L.12 Recommendation ITU-T L.12 (2008), Optical fibre splices. ITU-T L.26 Recommendation ITU-T L.26 (2002), Optical fibre cables for aerial application. ITU-T L.35 Recommendation ITU-T L.35 (1998), Installation of optical fibre cables in the access network. ITU-T L.
34、43 Recommendation ITU-T L.43 (2002), Optical fibre cables for buried application. ITU-T L.59 Recommendation ITU-T L.59 (2004), Optical fibre cables for indoor applications. IEC 60189-1 IEC 60189-1 (2007), Low-frequency cables and wires with PVC insulation and PVC sheath Part 1: General test and meas
35、uring methods . IEC 60332-1 IEC 60332-1 (2004), Tests on electric and optical fibre cables under fire conditions Part 1: Test for vertical flame propagation for a single insulated wire or cable. IEC 60332-3-24 IEC 60332-3-24 (2000), Tests on electric and optical fibre cables under fire conditions Pa
36、rt 3-24: Test for vertical flame spread of vertically-mounted bunched wires or cables Category C. IEC 60754-1 IEC 60754-1 (1994), Test on gases evolved during combustion of materials from cables Part 1: Determination of the amount of halogen acid gas. Rec. ITU-T L.79 (07/2008) 3 IEC 60754-2 IEC 6075
37、4-2 (1991), Test on gases evolved during combustion of electric cables Part 2: Determination of degree of acidity of gases evolved during the combustion of materials taken from electric cables by measuring pH and conductivity. IEC 60793-1 IEC 60793-1 (2001), Optical fibres Part 1: Generic specificat
38、ions. IEC 60793-1-32 IEC 60793-1-32 (2001), Optical fibres Part 1-32: Measurement methods and test procedures Coating strippability. IEC 60793-2-10 IEC 60793-2-10 (2007), Optical fibres Part 2-10: Product specifications Sectional specification for category A1 multimode fibres. IEC 60794-1-1 IEC 6079
39、4-1-1 (2001), Optical fibre cables Part 1-1: Generic specification General. IEC 60794-1-2 IEC 60794-1-2 (2003), Optical fibre cables Part 1-2: Generic specification Basic optical cable test procedures. IEC 60794-2 IEC 60794-2 (2002), Optical fibre cables Part 2: Indoor cables Sectional specification
40、. IEC 60794-2-10 IEC 60794-2-10 (2003), Optical fibre cables Part 2-10: Indoor cables Family specification for simplex and duplex cables. IEC 61034-1 IEC 61034-1 (2005), Measurement of smoke density of cables burning under defined conditions Part 1: Test apparatus. IEC 61034-2 IEC 61034-2 (2005), Me
41、asurement of smoke density of cables burning under defined conditions Part 2: Test procedure and requirements. 3 Definitions This Recommendation defines the following terms (the definitions for other terms are given in ITU-T G.650.1, and ITU-T G.651.1 apply): 3.1 blown-in element: A blown-in element
42、 consists of optical fibre(s), sheath and other materials and is inserted into the microduct by continuous high-speed airflow force. Some of the characteristics of this element are described in clause 6.5. 3.2 hybrid protected microduct cable: A hybrid protected microduct cable is a bundle containin
43、g both microducts and optical fibre cable. They are combined and surrounded by a tight or loose protective sheath, perhaps with another optional protective layer such as a humidity shield. 3.3 microduct: A microduct is a small, flexible lightweight tube with an outer diameter typically less than 16
44、mm. Some of the characteristics of this element are described in clause 6.2. Plastic microducts are sized to allow the fibre unit to be blown freely into the duct, and the inner surface of the microduct is designed to minimize sliding friction with the blown-in element (see clause 3.1). 4 Rec. ITU-T
45、 L.79 (07/2008) 3.4 microduct cable: This is an optical fibre cable that can be installed in a microduct with the blowing technique. 3.5 microduct fibre unit: This is a group of fibres (with a count starting at one) that can be installed in a microduct with the blowing technique. 3.6 parent blowing
46、duct: There are three kinds of parent blowing ducts: outer protective ducts, protected microducts and hybrid protected microduct cable. 3.7 protected microduct: This kind of duct comprises a number of microducts that are loosely or tightly packed together and jacketed, in much the same way as an opt
47、ical cable without the fibre (small guide tubes running through a network of protective tubes typically made of polyethylene, with a typical external diameter of 25 to 63 mm). 4 Abbreviations and acronyms None. 5 Environmental conditions The required characteristics depend strongly on the environmen
48、tal conditions at the location where the optical cables are installed. Therefore, it is important to know these conditions. 5.1 Underground 5.1.1 Conduits and tunnels The environmental conditions of conduits and tunnels are described in ITU-T L.10. 5.1.2 Direct buried The environmental conditions fo
49、r buried applications are described in ITU-T L.43. 5.2 Aerial The environmental conditions for aerial applications are described in ITU-T L.26. 5.3 Indoor The environmental conditions for indoor applications are described in ITU-T L.59. 6 Cable construction 6.1 Fibre protection 6.1.1 Primary coated fibre Primary coated fibres must comply with the relevant ITU-T G.65x-series Recommendations. 6.1.2 Buffered fibre When using a tight or semi-tight buffer
