DETECTION OF DAMAGE TO OPTICAL FIBER PROTECTIVE PIPE FOR OPTICAL FIBER OF COMPOSITE OVERHEAD EARTH-WIRE

摘要

PURPOSE:To enable the detection of the presence of damage to a protective pipe, by forcing a gas into the protective pipe from one end to the other end of the protective pipe of an optical fiber filled overhead earth-wire. CONSTITUTION:First, a gas for inspection is forced into a protective pipe 4 via a gas introduction tube 8 from an inspection gas feeder 9, with the force pressure thereof set at about 0.4-3kg/cm2. Then, after the pressure in the protective pipe 4 is increased to 0.4-1.5kg/cm2, the forcing of the gas for inspection is stopped to observe a drop in the pressure of a pressure-gauge 15 connected to the other end side of the protective pipe 4, which allows the detection of the presence of damage such as breakage, cracking and the like of the protective pipe 4 based on the drop in the pressure. Thus, the presence of adverse effect on an optical fiber unit held in the protective pipe 4 is checked to prevent possible damage to an optical fiber thereby enabling the avoiding of the generation of disturbance in communication.