Introduce several simple methods to identify the quality of optical cables

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I. Outer sheath: Indoor optical cables generally use polyethylene or flame-retardant polyethylene; their surface should be smooth and shiny, flexible, and easy to peel off. The surface finish of the outer sheath of low-quality optical cables is very poor, making it easy for them to stick to tight-fitting covers and aramid materials. The PE sheath of outdoor optical cables should be made of high-quality black polyethylene; after cable assembly, the outer surface should be smooth, shiny, of uniform thickness, and free of bubbles. The outer covering of low-quality optical cables is generally made from recycled materials; such cables have a rough surface due to the many impurities present in the raw materials. Upon close inspection, it can be seen that there are numerous very small pits on the cable’s outer layer, and after being installed for some time, these cables will crack and start to leak water. II. Optical fibers: Reputable cable manufacturers generally use grade A fiber cores from leading manufacturers, while some low-cost, inferior cables use grade C and D fibers as well as smuggled fibers of unknown origin. Due to their complex origins and long production times, such fibers often become damp and change color. In multimode fibers, single-mode fibers are frequently mixed in as well. Small manufacturers usually lack the necessary testing equipment to determine the quality of these fibers. Since such optical fibers cannot be distinguished by the naked eye, common problems encountered during installation are: a narrow bandwidth and a short transmission distance ； The thickness is uneven, and it cannot be connected to the fiber optic cable ； Fibers lack flexibility and break as soon as they are bent when coiled. III. Reinforcing steel wires: The steel wires in outdoor optical cables produced by reputable manufacturers are phosphated, giving them a gray surface. Such wires do not cause hydrogen-induced damage, do not rust, and possess high strength when used in cable construction. Low-quality optical cables are usually replaced with thin iron wire or aluminum wire; the identification method is simple – they appear white in color and can be bent easily when held in the hand. Cables produced with such steel wires suffer from high hydrogen loss; over time, the ends where the fiber optic boxes are attached will rust and break. IV. Steel armor: Reputable manufacturers use longitudinally wound steel strips coated with rust-proof paint on both sides, while inferior optical cables use ordinary iron sheets that are usually treated against rust only on one side. V. Loose tube: The loose tube used to hold the optical fibers in optical cables should be made of PBT material, as such tubes offer high strength, do not deform, and are resistant to aging. Low-quality optical cables typically use PVC material for their protective sleeves; such sleeves have a very thin outer diameter and can be flattened simply by pressing them with the hand – they are similar to drink straws – and they lose their ability to protect the optical fibers after one to three years. VI. Fiber paste: The fiber paste used in outdoor optical cables helps prevent the fibers from oxidizing, as well as from becoming damp due to moisture intrusion. Low-quality optical fibers contain very little fiber paste, which severely affects the lifespan of those fibers. VII. Water-blocking strip: The water-blocking strip used for optical cables utilizes the strong water-absorbing properties of the highly water-absorbent resin distributed evenly within the product. Thanks to the combined effects of osmotic pressure, affinity, and rubber elasticity, 1 gram of this highly water-absorbent resin can rapidly absorb pure water whose weight is more than 350 times greater than its own. Furthermore, once exposed to water, the water-repellent powder immediately swells and gels, and at this point, no matter how much pressure is applied, the water cannot be forced out. Therefore, by covering the cable with a water-blocking tape containing water-absorbing resin, in the event that the outer surface of the cable is damaged, the highly water-absorbing resin in the damaged area expands and provides a sealing effect, thereby minimizing water intrusion. Low-quality optical cables often use non-woven fabric or paper tape, and once the outer cover of such cables is damaged, it can lead to serious consequences. VIII. Aramid: Also known as Kevlar, it is a high-strength chemical fiber that is currently most widely used in the military industry; military helmets and bulletproof vests are made from this material. Currently, only DuPont and AkzoNobel in the Netherlands are capable of producing it, with the price at around over 300,000 per ton. Both indoor optical cables and power overhead optical cables (ADSS) use aramid yarns as reinforcement elements. Due to the high cost of aramid, lower-quality indoor optical cables typically have a very small outer diameter, in order to save costs by using fewer strands of aramid; such cables are prone to breaking when passed through conduits. ADSS optical cables determine the number of aramid strands to be used in the cable based on the span at the installation site and the wind speed per second; it is essential to conduct a thorough inspection and verification prior to construction.