Because the optical fiber is afraid of moisture and water, it is required that the optical cable must have good waterproof performance. Waterproofing is divided into horizontal and vertical water blocking. Below, Optical Fiber Cable Factory introduces the water blocking requirements of optical fiber cables:
(1) Lateral water blocking
Due to the vapor pressure gradient inside and outside the optical cable, in a humid environment, moisture or moisture outside the optical cable will penetrate and migrate into the optical cable. Strictly speaking, the plastic sheath of the optical cable cannot prevent the intrusion of the tide for a long time. Once moisture penetrates into the optical fiber, it will cause corrosion of metal accessories, and then electrolytic hydrogen evolution, which will not only corrode the metal parts but also increase the loss of the optical fiber and affect the stability of the long-term transmission performance of the optical fiber. In order to prevent the lateral water seepage of the optical fiber, it is usually done with longitudinally clad aluminum strips (steel strips).
(2) Longitudinal water blocking
During the laying process of the optical cable, due to the partial damage of the protective layer of the optical cable or the accidental water seepage at the connection of the optical cable, the moisture intrudes into the optical cable and will penetrate along the longitudinal direction, which will not only affect the performance of the optical cable but also the accumulated water will enter the joint box, the terminal equipment that disrupts the work of the entire communication line. For the longitudinal water blocking of optical cables, the traditional method is to use optical cable grease to block the gaps in the optical cable structure to prevent the circulation of water in the optical cable. In addition, filling fiber paste, wrapping water-blocking tape or wrapping the water-blocking yarn, and applying hot melt glue at the overlap of steel belts can also play a certain longitudinal water-blocking role.