Patent attributes
A flame-retardant optical cable is disclosed which includes a polymeric central loose tube housing optical fibres, a metallic armour surrounding the polymeric central loose tube, and a multi-layered sheath surrounding and in direct contact with the metallic armour. The multi-layered sheath includes an inner layer, an intermediate layer, and an outer layer, all made of a LSoH flame-retardant material. The LSoH flame-retardant material of the intermediate layer has a limiting oxygen index (LOI) higher than the LOI of the LSoH flame-retardant material of the inner layer and of the outer layer. Such cable has improved flame-retardant properties, particularly in terms of slowing flame propagation, heat release, droplets and emission of smokes, when it is exposed to flames during fire.
