| 摘要 |
<p>PURPOSE:To enable accurate detection of the presence or absence of permeation of water and the position of permeation by providing a water absorption heated layer in one of temperature detecting members in a pair which are constructed of distribution type optical fiber temperature sensors. CONSTITUTION:This high-tension flexible tube 10 has metal reinforcement layers 18 and 20 provided on an inner plastic tube 16 and an outer plastic jacket 22 provided on the layers. Inside this jacket 22, a pair of temperature detecting members 28 and 28' constructed of distribution type optical fiber temperature sensors 26 and 26' are provided. When the jacket 22 is damaged and water permeates thereinto, a water absorption heated layer 32 provided in one member 28 generates a heat and this is detected. Since the member 28 is constructed to a distribution type optical fiber, besides, a temperature distribution along the optical fiber can be known and the position of the permeation can be checked up. The other member 28' detects the temperature lowered by the permeation and the temperature of internal heating due to other causes. Accordingly, the heating due to the permeation can be distinguished from those due to other causes.</p> |
