安全防范系统是建筑智能系统中的重中之重，好的安防系统对于安全的保障是不言而喻的。而一个好的安防系统，其线缆传输系统，更是在整个安防系统中起着举足轻重的地位，而安防系统中，光纤的应用更是一个非常大的部分。今天咱们说说，在实际中光纤的一些注意事项。
Security system is the most important part of building intelligent system. It is self-evident that good security system can guarantee the safety. And a good security system, its cable transmission system, is playing an important role in the entire security system, and in the security system, the application of optical fiber is a very large part. Today, let's talk about some precautions of optical fiber in practice.
光纤的选用除了根据光纤芯数和光纤种类，还要根据光纤的使用来选择光纤的外护套，在选用时要注意以下几点：
In addition to the number of optical fiber cores and types of optical fiber, the outer sheath of optical fiber should be selected according to the use of optical fiber. The following points should be paid attention to when selecting optical fiber:
1. 户外用光纤直埋时，宜选铠装光纤，架空时，可选用两根或多根加强筋的黑色塑料外护套的光纤。
1. When the outdoor optical fiber is directly buried, the armored optical fiber should be selected; when overhead, the optical fiber with two or more reinforcing ribs with black plastic outer sheath can be selected.
2. 建筑物内用的光纤在选用时应该注意其阻燃，毒和烟的特性，一般在管道中和强制通风处，可选用阻燃和有烟的类型，暴露的环境中应选用阻燃、无烟和无毒的类型。
2. In the selection of optical fiber used in buildings, attention should be paid to the characteristics of flame retardant, toxic and smoke. Generally, flame retardant and smoke-free types can be selected in pipelines and forced ventilation places, and flame-retardant, smokeless and non-toxic types should be selected in exposed environment.
3. 楼内垂直布线时，可选用层绞式光纤;水平布线式，可选用分支光纤。
3. For vertical wiring in the building, layer stranded optical fiber can be selected; for horizontal wiring, branch optical fiber can be selected.