1. Ointment. Oil paste mainly includes fiber paste and cable paste. Under normal circumstances, the fiber paste shall be filled with the whole loose tube, while the cable paste shall be filled with every gap of the cable core under pressure. At present, there is a way to fill half or less of the fiber paste. Some of the cable paste is only applied to the outside of the cable core, while others are not filled between the two ends of the cable. In this way, the optical fiber will not be well protected, which will affect the transmission performance of optical fiber attenuation, and the poor water-proof performance will not meet the national standard. Once the optical fiber cable accidentally seeps water, the whole link will be abandoned. Under normal circumstances, even if the accidental water seepage only needs to repair the water seepage section, it does not need to be renewed. (according to the national standard, the water blocking performance is: three meters of optical cable, one meter of water column pressure, no water seepage for 24 hours.) If the poor paste is used, the above problems will also occur, and the poor thixotropy of the paste may cause micro bending loss of the optical fiber, resulting in unqualified transmission characteristics of the whole link; if the paste is acidic, it will react with the metal material in the optical cable to produce hydrogen molecules, and the attenuation of the optical fiber in case of h will increase rapidly, resulting in the interruption of transmission of the whole link.
2. Sheath. The optical cable sheath shall not only adapt to many different and complex climatic environments, but also ensure long-term (at least 25 years) stability. The sheath of optical cable should not only have certain strength, lower thermal deformation, abrasion, water permeability, thermal shrinkage and friction coefficient, but also have strong environmental stress resistance and good material processing performance. Although the less or bad sheathing material can pass the factory acceptance, it will crack and seep after being used for a period of time due to quality defects. It is more serious to replace the high-quality polyethylene sheathing material with recycled plastic. The outer skin of the optical cable made of high-quality sheath material is flat, bright, uniform and free of bubbles after cable forming, otherwise, the surface of the optical cable will be rough, and because there are many impurities in the raw material, it can be found that there are many very small pits on the outer skin of the optical cable, and because of the thin thickness, the overall outer diameter of the optical cable will be much smaller than that of the high-quality optical cable. Indoor optical cable is generally made of high-quality flame-retardant PVC, with smooth and bright appearance, good flexibility and easy peeling; otherwise, it will have poor skin finish and easy adhesion with tight sheath fiber and aramid fiber.
3. Steel strip, aluminum strip. The steel strip and aluminum strip in the optical cable are mainly used to protect the optical fiber from mechanical side pressure, moisture-proof and other functions, and the chromium plated steel strip is generally used in the better optical cable. The common iron sheet or black sheet (uncoated steel strip) with only one side antirust treatment is used to replace the chromium plated steel strip for the inferior optical cable. After a long time, the corrosion will occur in the optical cable, and the hydrogen loss of the optical fiber will also be intensified. Moreover, because it is easy to separate from the sheath, it cannot form a comprehensive bonding layer, and its moisture retention performance is also very poor. Some of them replace the chromium plated steel strip with the tin plated steel strip, and the surface of the tin plated steel strip is*** , bubbles, etc. are inevitable, so they are prone to corrosion under humid atmosphere and surface condensation or water immersion conditions, especially under acid conditions. Tin coating has poor heat resistance, melting point is only 232 ℃. Due to the high temperature of extruded sheath in application, the peel strength is uncertain, which affects the moisture resistance of optical cable. The melting point of chromium is 1900 ℃, and its chemical property is very stable. It will not rust when it is placed in the air or immersed in water at room temperature. Its corrosion resistance is very good, because the surface is easy to oxidize to form a passivation layer, so its environmental resistance is very good. In general, the unqualified hot-dip coated aluminum strip will replace the tape casting qualified coated aluminum strip, 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 tensile force of 1500N or 3000n. The inferior optical cable will be replaced by iron wire or ordinary steel wire with small diameter, which is easy to rust on the one hand; on the other hand, because the tensile strength is far less than 1500N, the optical fiber may be pulled during construction. The phosphatized steel wire with high modulus is generally cyan gray, with good toughness and is not easy to bend; while the substitute steel wire can be bent at will and for a long time when it is pinched on the hand, the two ends of the fiber box will rust and fracture.
5. Loosen the sleeve. Optical fiber cable loose fiber casing generally uses polymer PBT material (poly butylene terephthalate), such loose casing strength is high, no deformation, anti-aging. The loose tube of poor quality optical cable is sometimes replaced by other materials. The outer diameter is very thin, and it is flat when being pinched by hand. It is the same as the drinking straw and cannot bear the protection of optical fiber.
6. Waterstop. Water blocking tape or yarn for optical cable has strong water absorption performance through the super absorbent resin with uniform distribution inside the product. Under the combined action of immersion pressure, affinity and rubber elasticity, the super absorbent resin can quickly absorb water several times of its own weight. Moreover, the water blocking powder will expand the gel immediately after encountering water. No matter how much pressure it exerts on it, the water will not be squeezed out. Therefore, in case the outer wall of the cable is damaged, the super absorbent resin of the wound part will play a sealing effect due to expansion, which can prevent the water from entering to the minimum. The non-woven fabric or paper tape is usually used for inferior optical cable. Once the outer skin of optical cable is damaged, the consequences will be very serious.
7. Aramid. Kevlar, also known as Kevlar, is a kind of high-strength chemical fiber, which is widely used in military industry at present. Bulletproof vest is made of this material. It is DuPont's patented product and the main cost component of indoor optical cable. It is mainly used to protect the tight sheath 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, which can save cost by reducing several strands of aramid fiber, or use a polyester yarn with similar appearance to aramid fiber to replace it (which has become more common), and polyester yarn can hardly bear any pulling force. In this way, the optical fiber is easy to be pulled or broken during laying.
8. Optical fiber. Optical fiber is the most core raw material in optical cable, and good optical cable generally adopts the high-quality core of large factory. Inferior optical cables usually use low-grade optical fibers and smuggled optical fibers of unknown origin. These optical fibers are difficult to guarantee due to their complex sources. Sometimes, single-mode optical fibers are often mixed in multimode optical fibers. However, small factories generally lack the necessary testing equipment to judge the quality of optical fibers, which makes the quality difficult to be guaranteed. In addition, some of them use the short optical fiber purchased at a low price to fuse and then make the optical cable. Because the naked eye can't distinguish such optical fiber, the common problems encountered in the construction are: low transmission speed, short distance, large attenuation of optical fiber, unable to connect with tail fiber, lack of flexibility, easy to break when spinning, and even one optical fiber is multi-mode at one end and single-mode at the other.
9. Coloring ink. In order to facilitate the division of optical fiber in construction time zone, the national standard requires that the optical fiber and loose tube should have bright colors. The high-quality optical fiber cables should be colored with high-quality ink according to the standard, and the color is very bright and not easy to fall off. The low-quality optical fiber cables will be colored with low-quality ink or not at all. The low-quality ink color is not bright and sometimes easy to dissolve in the paste, resulting in the color can not be distinguished, Non - coloring brings great inconvenience to construction.
10. Product packaging. Generally, the optical cable is packed in wooden or iron wooden reels, and the wooden sealing plate will be sealed on the outside of the reel to ensure that the stress, bending radius and other conditions of the bulky optical cable in the whole transportation are within the standard requirements. In order to save cost, poor quality optical cable usually uses poor packing plate, which is almost scattered when it is transported to the destination. Some of them simply do not use the plate, and they ship the optical cable after winding it, or they do not need to be sealed with wooden strips.
To sum up, the real advantages and disadvantages of optical fiber cable come from the comprehensive differences of its structural design, materials and production process. Because fiber optic cable is still not widely used, although there are many hidden dangers in poor quality products, many users and even integrators are still using it on the same site. It is for this reason that the negative impact of poor quality optical cable on the industry will be greater, because as far as the optical cable itself is concerned, its value is not large, but the cost of its laying process (direct burial, overhead, pipe threading, etc.) is very amazing, and time-consuming and laborious. In addition, it is the basic medium in the whole communication link, so once there is a problem, no matter how expensive and high the hardware equipment at both ends of you are End, the whole system will be completely paralyzed without exception, and the repair cycle will be very long, resulting in a loss of tens of millions of times the difference between good and bad.
Generally speaking, after so many years of adjustment in China's optical fiber and cable market, the cost performance of domestic high-quality optical fiber cable has been the most in the world, but also blindly participate in the competition at a low price at the expense of product quality and customer benefit. The final result will be the displeasure between the buyer and the seller, hoping that all practitioners and users will be careful.