| 摘要 |
<p>PURPOSE:To reduce the shrinkage amount of a PE tube to be used in real circumstances for a long period of time and to obtain high reliability by the application to a pneumatically feeding and mounting optical cable by determining the molding time remaining distortion of the tube to be used to a specific value or less. CONSTITUTION:In a pipe cable in which several pipes 2 each made of a PE tube to be used for a pneumatically feeding optical cable laying system are associated and a sheath 1 is provided thereon, the molding time remaining distortion of the tube 2 to be used is set to 1% or less. Thus, when the long term use is considered in normal temperature circumstances, i.e., in a temperature range of -40 to 80 deg.C, the shrinkage amount of the tube is small. Accordingly, the retraction of the tube 2 in the vicinity of the end of the cable is reduced. Therefore, an increase in the slack generated in the tube 2 of the contained optical fiber unit, i.e., a large increase in the excessive length is suppressed, and the optical fiber having high reliability after laying is obtained.</p> |
