[China Glass Network] When the cable is cabled, there are two protection requirements for the fiber: one is that the fiber is less stressed; the other is that the fiber is waterproof. Experiments have shown that long-term immersion of the cable into the cable will increase the fiber sag, especially at the wavelength of 1.55 pm, as shown: The reason why the fiber is afraid of water is that the fiber is composed of glass (Si04) silicon tetrahedrons connected to each other, as shown in Fig. 1. In a Si-O-Si-network, oxygen atoms exist in the form of bridged oxygen. However, in the environment with water, after the adsorption of water vapor on the surface of the glass, the hydrolysis reaction occurs slowly, which causes the silicon-oxygen bond in the original network, Si-O-Si, to break, and the bridge oxygen becomes non-bridged. As a result, glass cracks are caused and cracks are continuously increased. Whether it is aquarium glass, window glass or fiberglass is afraid of water, the difference is that the fish tank glass, window glass are very thick, the thickness is 3mm, 5mm, l0mm, even if there is a crack of 0.05mm does not affect the strength of the glass, There is no change in the naked eye. Garment Material,Cotton Lining Fabric,Polyester Lining Cloth,Garment Lining Greige Fabric Nantong Guanheng Textile Co.,Ltd , https://www.ntghfabric.com
The outer layer of the cable is a plastic sheath, inside which is a metal sheath, and inside is a water-blocking layer that is expanded by water, and the core has an ointment and an optical fiber stuck together. The fiber has four waterproof seals, namely: plastic sheath, metal sheath, water blocking layer, grease. Then the question comes, why is the fiber so afraid of water, why the fish tank glass and window glass in the house are not afraid of water but waterproof? Why are the glasses so different?
It is generally believed that the fiber is not afraid of water because the glass has excellent water retention. But in fact, water is very harmful to fiber optic cables. If there is water in the cable, the expansion of the ice in the cold water will report the fiber, so the cable needs to be filled with grease to prevent moisture from entering.
The fiber glass is different. The glass diameter of the fiber is only 0.125mm, which is as thick as the hair. If there is a crack of 0.05mm, the fiber diameter is 0.075mm. Therefore, the fiber is easy to break, and the OH root will also appear. Increase the absorption loss of light by the fiber. This is why fish glass and window glass are not afraid of water, and fiber glass is afraid of water.
In this case, the cable is damaged, the joint box is not well sealed, and the exposure of the bare fiber will result in shortened fiber life and natural fiber breakage due to water.
October 21, 2022