How to distinguish the quality of optical cable

Optical cable is composed of optical fiber (glass fiber as thin as hair), plastic protective sleeve and plastic sheath, which is widely used in communication lines. Compared with copper cable, it has the advantages of large transmission capacity, long relay distance, small volume, light weight and no electromagnetic interference. It is precisely because of these advantages that it quickly replaces the traditional copper cable communication in the communication field. Due to the extensive use of optical cable, the market of optical cable is gradually expanding, and the expansion of the market will inevitably bring some bad phenomena. In order to make huge profits, some merchants produce some inferior optical cables as high-quality sales. In view of this kind of problem, Lvliang optical cable is cheaper, and Lvliang Juhai wire and cable tells you how to distinguish the quality of optical cable. 1, ointment Ointment mainly includes fiber ointment and cable ointment. In general, fiber paste should fill the whole loose tube, while cable paste should fill every gap of cable core under pressure. At present, the fiber paste is half full or less, while the cable paste is only coated with a layer outside the cable core, and the others are filled in the middle of the two ends of the cable. In this way, the optical fiber can not be well protected, which affects the transmission performance such as optical fiber attenuation, and the waterproof performance can not reach the national standard. Once the optical cable accidentally leaks water, the whole link will be scrapped. Under normal circumstances, even if there is accidental water seepage, only one section of water seepage needs to be repaired, and it is not necessary to start all over again. (The national standard requires that the water-blocking performance is: three meters of optical cable, one meter of water column pressure, and no water seepage for 24 hours. ) If bad oil paste is used, the above problems will also occur. The poor thixotropy of oil paste may cause micro-bending loss of optical fiber and unqualified transmission characteristics of the whole link; If the ointment is acidic, it will react with the metal materials in the optical cable to precipitate hydrogen molecules, and the attenuation of the optical fiber will increase rapidly when it meets H, resulting in the interruption of the whole link. 2. Sheath. Optical cable sheath should not only adapt to many different and complex climatic environments, but also ensure long-term (at least 25 years) stability. Optical cable sheath should not only have certain strength, low thermal deformation, wear, water permeability, thermal shrinkage and friction coefficient, but also have strong environmental stress resistance and good material processing performance. Although rarely used or badly used sheath materials can pass the factory acceptance, they will crack and leak water after a period of use due to quality defects. If recycled plastics are used instead of high-quality polyethylene sheath materials, the situation will be more serious. The cable sheath made of high-quality sheath material is smooth, bright, uniform in thickness and free of bubbles, otherwise the cable sheath will be rough, and because there are many impurities in the raw materials, you can find many tiny pits on the cable sheath, and because of its thin thickness, the overall outer diameter of the cable will be much smaller than that of the high-quality cable. Indoor optical cables are generally made of high-quality flame-retardant PVC, which has smooth and bright appearance, good flexibility and easy peeling. Otherwise, the skin smoothness is poor, and it is easy to stick tight sleeve fibers and aramid fibers. 3. Steel strip and aluminum strip. Steel strip and aluminum strip in optical cable are mainly used to protect optical fiber from mechanical lateral pressure and moisture, and chrome-plated steel strip is generally used for better optical cable. For inferior optical cables, the chrome-plated steel strip is replaced by ordinary iron sheet or black leather (uncoated steel strip) with only one rusty surface. After a long time, the optical cable will corrode and the hydrogen loss of the optical fiber will increase. Moreover, because it is easy to separate from the sheath to form a comprehensive bonded sheath, the moisture-proof performance is also very poor. There are also tin-plated steel belts instead of chromium-plated steel belts, and the surface of tin-plated steel belts and bubbles are inevitable. Therefore, in humid atmosphere, under the condition of surface condensation or immersion, especially under acidic conditions, corrosion is easy to occur. Tin coating has poor heat resistance, and its melting point is only 232 degrees Celsius. In application, because of the high temperature in the sheath extrusion process, the peeling strength is uncertain, which affects the moisture resistance of optical cable. The melting point of chromium is 1900 degrees Celsius, and its chemical properties are very stable. It will not rust when placed in air or immersed in water at room temperature, and its corrosion resistance is very good. Because the surface is easy to be oxidized to form a passivation layer, the environmental resistance is very good. Generally speaking, unqualified hot-bonded aluminum-coated tape will be cast instead of qualified aluminum-coated tape, which will also affect the performance of optical cable. 4. Steel wire. The steel wire in the optical cable is mainly used to protect the optical fiber from mechanical tension. Good optical cables generally use high-modulus phosphating steel wire, with short-term tension 1500N or 3000N n. Inferior optical cables will be replaced with small-diameter iron wires or ordinary steel wires, which is easy to rust on the one hand; On the other hand, because the tensile strength is much less than 1500N, the optical fiber may be strained during construction. High-modulus phosphating steel wire is generally blue-gray, with good toughness and not easy to bend; The replaced iron wire will bend at will if held in your hand for a long time, and both ends of optical fiber box will rust and break. 5. The casing is loose. PBT (Poly (butylene terephthalate)) is generally used for loose tube of optical fiber in optical cable, which has high strength, no deformation and anti-aging. The loose tube of inferior optical cable is sometimes replaced with other materials, and its outer diameter is very thin, so it will be flat when pinched by hand, just like a drink straw, which can't protect the optical fiber. 6. Water blocking hose. Water-blocking tape or yarn for optical cable has strong water absorption performance through super absorbent resin evenly distributed in the product. Under the combined action of soaking pressure, affinity and rubber elasticity, super absorbent resin can quickly absorb several times its own weight of water. Moreover, the water-blocking powder will swell the gel immediately when it meets water, and no matter how much pressure is applied to it, the water will not be squeezed out. Therefore, if the cable core is wrapped with water-blocking tape containing water-absorbing resin, in case the outer wall of the cable is damaged, the super-absorbent resin at the winding part will play a sealing role due to expansion, which can prevent water from entering to the maximum extent. Non-woven fabrics or paper tapes are usually used for inferior optical cables. Once the cable sheath is damaged, the consequences will be very serious. 7. Aramid. Kevlar fiber, also known as Kevlar fiber, is a kind of high-strength chemical fiber, which is widely used in military industry at present, and bulletproof vests are made of this material. It is a patented product of DuPont, which is the main cost component of indoor optical cable. It is mainly used to protect the tightly sheathed optical fiber in indoor optical cable from mechanical tension. However, due to the high cost of aramid fiber, the outer diameter of inferior indoor optical cable is generally made very thin, so that the cost can be saved by reducing a few strands of aramid fiber, or polyester yarn with similar appearance to aramid fiber can be used instead (more common), and polyester yarn can hardly bear any tension. Therefore, the optical fiber is easy to be broken when it is laid. 8. Optical fiber. Optical fiber is the core material of optical cable, and a good optical cable generally adopts the high-quality fiber core of a big factory. Inferior optical cables usually use low-grade optical fibers and smuggled optical fibers from unknown sources. These fibers are difficult to guarantee because of their complex sources, and sometimes multimode fibers are often mixed with single-mode fibers. However, ordinary small factories lack the necessary testing equipment, so it is impossible to judge the quality of optical fiber, and it is even more difficult to ensure the quality. In addition, some people buy short-length optical fibers at low prices and then make them into optical cables after welding. Because the naked eye can't distinguish such optical fiber, the problems often encountered in construction are: low transmission rate, short distance, large fiber attenuation, inability to connect with pigtail fiber, lack of elasticity, easy to break when winding optical fiber, and even one end of an optical fiber is multimode and the other end is single mode. 9. Colored ink. In order to distinguish optical fibers during construction, national standards require that both optical fibers and loose tubes should be painted with bright colors. High-quality optical cable is colored with high-quality ink according to the standard, and the color is very bright and not easy to fall off. Inferior optical cables will be colored with inferior ink or not at all. Inferior ink is not bright, and sometimes it is easy to dissolve in fiber pulp, resulting in color indistinguishability. No coloring will bring great inconvenience to the construction. 10, product packaging. Generally, optical cables are packed in the shaft with wooden or iron wooden pallet, and the wooden sealing plate will be sealed on the outside of the tray to ensure that the stress and bending radius of heavy-duty optical cables are within the standard requirements during the whole transportation process. In order to save costs, inferior optical cables generally use poor packaging trays and almost fall apart at the destination. Some cables are shipped without pallets or sealed with pallets without battens. To sum up, the real difference between optical fiber and optical cable comes from the comprehensive difference in structural design, materials and production technology. Because optical cables have not been widely used, although there are many hidden dangers in inferior products, many users and even integrators are still using them regardless of the situation. It is precisely for this reason that the negative impact of inferior optical cable on the industry will be even greater, because the value of optical cable itself is not great, but the cost of its laying process (direct burial, overhead, threading in the pipe, etc.). ) it's amazing, and it takes time and effort. In addition, it is the basic medium in the whole communication link, so once there is a problem, no matter how expensive or high-end the hardware equipment at both ends of you is, the whole system will be completely paralyzed without exception, and the repair cycle will be very long. Generally speaking, the domestic optical fiber and cable market has been adjusted for so many years, and the price-performance ratio of domestic high-quality optical cables has been the first in the world. Simply participating in the competition at a low price must be at the expense of product quality and customer interests, and the final result is that buyers and sellers broke up in discord. I hope all practitioners and users will be cautious.