KST about Water seepage problem

Permeability problems and solutions

 The fiber optic cable seepage appears to be a very simple question, but failed often occur in the previous test (including the selection of test). In the first use of fiber optic cable failure, water seepage, fiber optic cable is not the obvious question. But in the long-term use of water or moisture into the cable internal, water can increase the fiber in the 1383 nm water peak attenuation, the fiber surface of the micro-cracks continue to expand until the fiber breaks at the same time also corrode metal reinforcement and react with metallic materials caused by the hydrogen loss of the fiber, which can seriously affect the performance and service life of the cable. Therefore, the optical fiber cable water-blocking measure is one of the important issues of cable design.

The seepage of the fiber optic cable can be divided into a lateral water seepage and vertical seepage. Lateral seepage is due to the fiber optic cable inside and outside the vapor pressure gradient, water or moisture along the cable radial penetration and migration from outside to inside; and longitudinal water penetration is the penetration of water along the fiber length direction. To prevent lateral seepage, usually longitudinally applied aluminum or steel structure; waterproof ointment to prevent longitudinal water penetration in the cable core and sheath gap fill or place waterproof tape and other waterproof material. The following analysis of seepage from several aspects of the failure causes and their corresponding countermeasures.