1、 I n t e r n a t i o n a l T e l e c o m m u n i c a t i o n U n i o n ITU-T L.156 TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (03/2018) SERIES L: ENVIRONMENT AND ICTS, CLIMATE CHANGE, E-WASTE, ENERGY EFFICIENCY; CONSTRUCTION, INSTALLATION AND PROTECTION OF CABLES AND OTHER ELEMENTS OF OUTSIDE P
2、LANT Optical fibre cables Guidance and installation technique Air-assisted installation of optical fibre cables Recommendation ITU-T L.156 ITU-T L-SERIES RECOMMENDATIONS ENVIRONMENT AND ICTS, CLIMATE CHANGE, E-WASTE, ENERGY EFFICIENCY; CONSTRUCTION, INSTALLATION AND PROTECTION OF CABLES AND OTHER EL
3、EMENTS OF OUTSIDE PLANT OPTICAL FIBRE CABLES Cable structure and characteristics L.100L.124 Cable evaluation L.125L.149 Guidance and installation technique L.150L.199 OPTICAL INFRASTRUCTURES Infrastructure including node elements (except cables) L.200L.249 General aspects and network design L.250L.2
4、99 MAINTENANCE AND OPERATION Optical fibre cable maintenance L.300L.329 Infrastructure maintenance L.330L.349 Operation support and infrastructure management L.350L.379 Disaster management L.380L.399 PASSIVE OPTICAL DEVICES L.400L.429 MARINIZED TERRESTRIAL CABLES L.430L.449 For further details, plea
5、se refer to the list of ITU-T Recommendations. Rec. ITU-T L.156 (03/2018) i Recommendation ITU-T L.156 Air-assisted installation of optical fibre cables Summary Recommendation ITU-T L.156 describes air-assisted methods for installation of optical fibre cables in ducts. These methods can be used to i
6、nstall microcables into microducts, or larger cables into ducts or conduits. Installing conditions and equipment required should be different in each case. History Edition Recommendation Approval Study Group Unique ID* 1.0 ITU-T L.156/L.57 2003-05-14 6 11.1002/1000/6321 2.0 ITU-T L.156 2018-03-16 15
7、 11.1002/1000/13566 Keywords Air-assisted installation, air cooler, blowing, blown-in element, blown installation, cable insertion, coefficient of friction, compressor, crash test, duct, leakage piston, microcable, microduct, microelement, micro fibre unit, optical fibre cable, shuttle. * To access
8、the Recommendation, type the URL http:/handle.itu.int/ in the address field of your web browser, followed by the Recommendations unique ID. For example, http:/handle.itu.int/11.1002/1000/11830-en. ii Rec. ITU-T L.156 (03/2018) FOREWORD The International Telecommunication Union (ITU) is the United Na
9、tions 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 technical, operating and tariff questions and issuing Recommendation
10、s 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 which, in turn, produce Recommendations on these topics. The approval
11、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 IEC. NOTE In this Recommendation, the expression “Administration“
12、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 ensure, e.g., interoperability or applicability) and compliance wi
13、th 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 does not suggest that compliance with the Recommendation is requir
14、ed of any party. INTELLECTUAL PROPERTY RIGHTSITU 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 concerning the evidence, validity or applicability of claimed Intellectua
15、l 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 patents, which may be required to implement this Recommendation. Howev
16、er, 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 2018 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the pri
17、or written permission of ITU. Rec. ITU-T L.156 (03/2018) iii Table of Contents Page 1 Scope . 1 2 References . 1 3 Definitions 1 3.1 Terms defined elsewhere 1 3.2 Terms defined in this Recommendation . 1 4 Abbreviations and acronyms 2 5 Conventions 2 6 Installation of jacketed cables in ducts . 2 6.
18、1 Considerations when installing cable . 2 6.2 Variants of air-assisted installation 3 6.3 Operations . 4 7 Installation of microcables in microducts . 5 Appendix I Indian experience: Installation of optical fibre cables by air blowing method 6 I.1 Products required for air-assisted installation of
19、OFC . 6 I.2 Duct 6 I.3 Air-blowing machine 6 I.4 Advantages of air-assisted installation of OFC 6 I.5 Method to measure co-efficient of friction . 7 Bibliography. 8 iv Rec. ITU-T L.156 (03/2018) Introduction Air-assisted installation is based on forcing a continuous high-speed airflow along the cabl
20、e with an air source. The force of the moving air pushes the cable and makes it advance forward at a typical speed supported by the equipment. Generally, the tensile load on the cable is an order of magnitude lower than the typical force involved with other installation methods, like pulling techniq
21、ues, thus reducing installation hazards. Additionally, with this technique, bends in duct runs have somewhat less effect than with pulling techniques, so that installation speed increases and longer lengths of cable can be installed. Cables are installed virtually without stress, leaving the cable e
22、ffectively relaxed in the duct upon completion of the installation. There are several variants of air-assisted installation: with/without a piston at the front end of the cable, or with a leaking piston. For variants without a piston, there is no pulling force at the front end of the cable; airflow
23、exerts a distributed force along the entire cable. In addition, the connection to a pulling cord is not needed. Rec. ITU-T L.156 (03/2018) 1 Recommendation ITU-T L.156 Air-assisted installation of optical fibre cables 1 Scope This Recommendation describes air-assisted methods for installation of opt
24、ical fibre cables in ducts. These methods can be used to install microcables into microducts, or larger cables into ducts or conduits. Installing conditions and equipment required should be different in each case. 2 References The following ITU-T Recommendations and other references contain provisio
25、ns which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibilit
26、y of applying the most recent edition of the Recommendations and other references listed below. A list of the currently 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 Recommendati
27、on. IEC 60794-5-10 IEC 60794-5-10 (2014) Optical fibre cables Part 5-10: Family specification Outdoor microduct optical fibre cables, microducts and protected microducts for installation by blowing. IEC 60794-5-20 IEC 60794-5-20, Optical fibre cables Part 5-20: Family specification Outdoor microduct
28、 fibre units, microducts and protected microducts for installation by blowing. 3 Definitions 3.1 Terms defined elsewhere This Recommendation uses the following terms defined elsewhere: 3.1.1 blown-in element b-ITU-T L.108: A blown-in element consists of optical fibre(s), sheath and other materials a
29、nd can be inserted into the microduct by continuous high-speed airflow force. Some of the characteristics of this element are described in clause 7.2 of ITU-T L.108. 3.1.2 microcable b-ITU-T L.162: An optical fibre cable that is suitable for installation into a subducting microduct. 3.1.3 microduct
30、b-ITU-T L.108: A small, flexible tube with enough wall thickness to provide the mechanical protection required by the application, with its outer and inner diameter defined according to the dimension and the condition of the existing duct and the diameter of the microcable. 3.1.4 micro fibre unit b-
31、ITU-T L.108: This is a group of fibres (with a count starting at one) that can be installed in a microduct with the blowing technique. 3.2 Terms defined in this Recommendation This Recommendation defines the following terms: 3.2.1 cable insertion machine: The main component of a blowing machine whic
32、h pushes the cable into the duct with the help of compressed air. 3.2.2 leaking piston/open piston: A piston which allows the air stream to flow through its centre bore or other ports and exerts a low pulling force at the front end of the cable. 2 Rec. ITU-T L.156 (03/2018) 3.2.3 piston: A cylindric
33、al part attached to the lead end of the cable, relatively tightly fitting and moving within A duct forced by compressed air. 3.2.4 shuttle: An alternative term for piston. 4 Abbreviations and acronyms This Recommendation uses the following abbreviations and acronyms: HDPE High Density Polyethylene O
34、FC Optical Fibre Cable 5 Conventions None. 6 Installation of jacketed cables in ducts 6.1 Considerations when installing cable 6.1.1 Cable duct The combination of duct parameters and materials, critical in determining the installation requirements of specific cable designs when using air-assisted te
35、chniques (e.g., air tightness, circular shape, friction coefficient, wall thickness, pressure rating of duct, etc.), should be determined by prior testing. Maximum duct inner diameter depends on the type of machine used. See IEC 60794-5-10 and IEC 60794-5-20 for details of tests and criteria. 6.1.2
36、Cable The bounds on maximum and minimum duct inner diameter, and criteria such as noncircularity, compression and obstructions are important for correct installation of cable. Maximum installation length is influenced by the stiffness and weight of the cable. A very flexible cable can only be pushed
37、 with a low pushing force and it might be necessary to use an additional element at the front end of the cable, like an open shuttle, which allows the air stream to flow through its centre bore and exert a low pulling force at the front end of the cable. This element might also be necessary when the
38、 diameter of the cable is very small compared with the internal diameter of the duct. When using a piston at the front end of the cable, a pulling force is exerted on the cable. In this case, maximum cable stress, which depends on the cable design, should not be exceeded. Cable sheath friction coeff
39、icient and friction properties of the duct liner (low enough) are critical. It should be as low as possible. It could be influenced by the selection of the cable coating and duct characteristics. See b-IEC TR 62470 for guidance on appropriate tests. If necessary, the use of the appropriate lubricant
40、 is an important factor to obtain an optimum performance. 6.1.3 Cable route Very tight bends in the cable route should be avoided because maximum installation length depends on the number of bends, their location in the route, the shape, gradient of the cable route, etc. Usually, the straighter the
41、duct, the longer the permitted installation length. Prior to blowing, the cable route should be “proved“ to establish that the duct is clean and open, sufficiently round, and will allow passage of the cable or unit and any piston, if used. This can be accomplished by blowing a piston, ball or plug o
42、f appropriate size though the duct (see clause 6.3.1). Rec. ITU-T L.156 (03/2018) 3 6.1.4 Compressed air High-speed airflow that moves the cable into the duct is normally generated by a compressor on site. The maximum pressure of the compressor depends on the type of equipment used. Typically, this
43、pressure it might be approximately 10 to 12 bar. Flow rate at the compressor output depends on the type of equipment and also on the internal diameter of the duct. Usually, the smaller the duct diameter, the lower the airflow rate and also the shorter the installation length for a specific cable des
44、ign. Compressed-air temperature has a great influence on the relevant parameters. At high temperatures, the material used in the cable jacket and duct begins to soften. This increases the friction between cable and duct, causing a reduction in the system performance. For ambient temperatures exceedi
45、ng 30C, it is highly recommended to use an air cooler inserted between the compressor and the cable insertion machine. 6.1.5 Cable insertion machine A cable insertion machine consists of a mechanical device that applies a force on the cable and controls its speed into the duct, together with the air
46、-blowing nozzle. The mechanical element can be driven by an air or hydraulic motor with a manual and automatic run-stop device. This element is divided into two construction principles: pushing of the cable by a rubber block caterpillar drive belt or pushing by a notched wheel drive. 6.2 Variants of
47、 air-assisted installation The choice of method, described in this clause, depends on several factors: type of cable (diameter, weight, stiffness), duct diameter, shape of the route (number of bends, location of the bends, gradient) and the equipment to be used. In the same manner, the installed len
48、gths and laying speed depend on all of these factors. In all variants, the cable insertion machine may be used. 6.2.1 Installation method with a piston at the front end of the cable In this method, a piston is attached at the front end of the cable. It transfers a defined pulling force to the cable
49、which should not exceed the allowed tensile load. The piston exerts only a fraction of the maximum permissible pulling force on the cable. If the piston gets to an oval section of the duct, it may become stuck. To avoid such a situation, the piston should have flexible cup sleeves or similar. It is also possible to use a piston with a smaller diameter than the ducts internal diameter applied at the front end of the cable (also known as a leaking piston). It could be an open shuttle, which allows the air stream through its centre
