FIRE-RESISTANT FIBRE OPTICAL CABLE WITH A LARGE FIBRE AMOUNT Russian patent published in 2023 - IPC G02B6/44 H01B7/295 

FIELD: fire-resistant fibre optic cable.

SUBSTANCE: optical cables suitable for operation during and after a fire, in particular to a fire-resistant fibre optic cable having a large number of fibres and having a long-term fire resistance of up to 180 minutes. The claimed fire-resistant fibre optic cable contains: a core containing a central carrier and a plurality of buffer tubes located around the central carrier, each buffer tube containing a plurality of optical fibres; a layer of mica located around the core; a glass fibre yarn layer surrounding and in direct contact with the mica layer; a metal reinforcement surrounding the glass fibre yarn layer; and a multilayer shell surrounding and in direct contact with the metal reinforcement. Moreover, the multilayer shell contains the first layer, the second layer, surrounding and in contact with the first layer, and the third layer, located in a radial internal location relative to the first layer and in direct contact with it, the first, second and third layers are made of a refractory material with low smoke zero halogen (LS0H). At the same time, the LS0H material of the first layer has a limiting oxygen index (LOI) greater than the LOI of the LS0H material of the second layer and the third layer, and the second layer is the outermost layer of the cable.

EFFECT: increase in the fire resistance and durability of the cable both during a fire and after a specified period of time after a fire (cooling time), to increase safety.

14 cl, 1 ex, 1 dwg