In the daily life of production and manufacturing, most of what you see or come into contact with are ordinary cables, but in some places that require a high safety precaution index, flame-retardant cables must be selected. In fact, many construction teams or staff do not know much about the characteristics and structure of flame-retardant cables, which leads to the inability to purchase the most suitable cables when purchasing. Therefore, it is necessary to understand the characteristics of flame retardant cables and how to choose them.
Flame retardant cable refers to: under a certain experimental standard, the sample is ignited, when the experimental flame is removed, the ignited sample flame only burns within a limited range, and the after flame can be automatically extinguished within a certain period of time. cable. The flame retardant cable maintains the characteristics of ordinary cables, but also has the ability to not easily ignite, or when the cable catches fire due to its own reasons or other open flames ignite, the cable will not continue to burn after the open flame is extinguished. These excellent fire properties.
Generally speaking, the most fundamental feature of flame-retardant cables is that they may be damaged and cannot operate normally in the event of a fire accident, but they can prevent the fire from spreading outward. If the cable catches fire, the total area of fire can be controlled within a certain range, and it is not allowed to spread outward to minimize damage.
The structure of flame-retardant cables is the same as that of general cables. According to different fire-resistant materials, flame-retardant cables are divided into two categories: halogen-containing flame retardant and halogen-free low-smoke flame retardant.
Halogen-containing flame-retardant cables: All or part of the high-pressure polyethylene (PVC) type fire-retardant materials with halogen elements are used in the raw materials of these cables, so they have excellent flame-retardant characteristics. However, there are also defects, that is, when the cable catches fire, it will cause a lot of smoke and halogen acid vapor, and the halogen acid vapor will corrode the surrounding staff and other objects. Rescue workers need to carry gas masks with them to get close to the fire. Rescue on the spot.
Halogen-free low-smoke flame-retardant cables: All or part of the raw materials of this type of cables are high-density polyethylene (XLPE) fire-retardant materials without halogen elements, which not only have excellent flame-retardant characteristics, but also can be used when the cable catches fire. It is not easy to cause a lot of smoke and halogen acid vapor. However, its reflectivity and conductivity are worse than that of ordinary cables. With the continuous development trend of society, flame retardant cables have gradually changed from halogen bulb flame retardant to today's low-smoke halogen-free flame retardant. Such types of flame retardant cables not only have excellent electrical equipment characteristics , and also changed the shortcomings of the flame retardant cables in the past.
Among the flame-retardant cables, according to the experimental data of the cables, the flame-retardant cables are divided into three categories: A, B, and C, which are respectively indicated as: ZA, ZB, and ZC. ZC is usually represented by ZR in the product. Class A is the highest level of flame retardant, with the best flame retardant properties and of course the highest price. And so on.
The staff of the purchase and installation design scheme should not only select suitable cables for installation according to the characteristics of flame-retardant cables, but also pay attention to the following conditions during the purchase process:
(1) According to the characteristics of flame-retardant cables when they are ignited, flame-retardant, low-smoke, halogen-free cables should be selected as far as possible in key areas with a large population or in public places.
(2) According to the fire safety requirements, the purchasing staff shall carry out the purchase of flame retardant cables according to the fire rating.
(3) Since the human eye cannot distinguish the types A, B, and C of the flame-retardant cable from the appearance, it depends on the manufacturer's logo to distinguish it. Therefore, the cable manufacturer should be carefully selected when selecting. Manufacturers with user evaluations on the sales market.
