Water blocking properties of optical cables in various natural environments

At this stage, most of the fully dry-well optical cables used in the market use water-blocking cotton yarn and blue water-blocking tape to block water. Water-blocking yarn is placed in the loose waterproof casing, and super absorbent resin is used in the loose waterproof casing. (SAP) Powdered full dry-well optical cable is technically and long-term reliable. It is a brand-new upgraded optical cable production technology. Compared with the past full dry-well optical cable, it has a smaller structure, Quick advantage.

In this paper, we will explore the challenges of the design concept and testing of optical cables caused by the fully dry well water blocking material SAP, how to ensure the water blocking characteristics, temperature characteristics, wear resistance, etc. How to ensure the coupling force value between the optical fiber and the loose waterproof casing under the condition of flexible material, so as to ensure the stability and uniformity of the optical fiber excess length when the optical cable is inclined or released vertically.

At the same time, some test methods are developed and designed in this paper, taking into account the characteristics of SAP and the application scenarios of optical cables, it is convenient to evaluate the long-term reliability of SAP full dry-well optical cables more comprehensively. All outdoor optical cables require water blocking technology to prevent water from penetrating into the optical cable and spreading vertically in the optical cable.

As early as the 1980s, the outdoor optical cable mainly used grease colloid solution to exceed tightness, and grease filling type was used in the loose waterproof casing and between the loose waterproof casing and the grommet. In addition, the function of the grease in the loose waterproof casing is also: to produce the coupling between the optical fiber and the waterproof casing, which is conducive to the control of the waterproof casing manufacturing process and the moderate excess length of the optical fiber in the waterproof casing. Many customers are looking for more process-friendly fiber optic cables, so this manufacturing industry has migrated to the grease-free, paste-filled water blocking method, also known as full dry-well fiber optic cables. At a very high level, the evolution of "full dry well" instead of "grease filling" is driven by the change of application scenarios of optical cable deployment.

In the past, the vast majority of optical cables were deployed for overseas cross-regional long-distance backbone Internet. At that time, optical cable connections were not frequent and the number of continuations was not large. If the network optical fiber enters the access network and wiring the Internet, the large-scale continuous labor and the high efficiency of optical cable connection must be improved, thus promoting this kind of grease-free filling technology. In the 1990s, the large-scale development trend of fiber-to-the-home (FFTx), but with the increase in the total number and scope of fiber-to-the-home (FTTx) deployments, the technology of fully dry-well fiber optic cables has caused a growing interest in the world. .

Initially, many optical cable manufacturers applied moisture-absorbing blue water-blocking tape, which was longitudinally wrapped outside the optical cable core, instead of grease to block water between the cable core and the grommet. This reduces cleanup work by on-site staff when the stripped cable is ready for termination in advance. As everyone knows, this kind of semi-dry-well type optical cable, the waterproof casing is still filled with grease, this kind of grease not only shows the actual effect of water blocking, but also because of its high viscosity coefficient characteristics, the optical fiber and waterproof casing are very good. Coupling effect.

With the development of SAP technology and optical cable production technology, the grease filling in the optical cable waterproof casing can be completely removed and replaced by fully dry well water-blocking raw materials, such as polyester cotton yarn and SAP chemical fiber composite cotton yarn, or polyester The cotton yarn adheres to the SAP particles, and the water-blocking material is put into the waterproof casing along with the optical fiber during the extrusion process of the loose waterproof casing. This development greatly reduces the workload of construction site termination, and at the same time provides a cleaner fiber surface, and the fiber fusion quality is stronger.

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