Experimental study on fire performance of optical cables used in utility tunnel: Influence of cable spacing and heat flux

Optical cable is an important part of modern telecommunications infrastructure. In this study, cone calorimeter experiments are conducted on the optical cables which are widely being applied in utility tunnels in China. The coupling effect of the spacing between optical cables (8, 10, 12, 15 mm) and the heat flux (30, 40, 50 kW/m(2)) on fire performance of optical cables is studied. It is highlighted that the optical cables conform to the ignition time model of the thermally thin material. The ignition time of the optical cables decreases when increasing the heat flux. When the heat flux is 30 kW/m(2), the ignition time of the optical cable with different spacing varies greatly. When the heat flux is greater than 30 kW/m(2), the difference in the ignition time between the optical cable samples with different spacing is small. Furthermore, the average mass loss rate of the optical cables increases when increasing either the heat flux or the spacing between optical cables. The heat release rate of the optical cables also increases when increasing either the heat flux or the spacing between optical cables. The curves of the heat release rate versus time show two peaks, the second one being significantly smaller.

Automated summary

This study conducted cone calorimeter experiments on optical cables widely used in utility tunnels in China to investigate the coupling effect of spacing and heat flux on the fire performance of optical cables. The results showed that the optical cables conformed to the ignition time model of thermally thin material. Increasing the heat flux decreased the ignition time of the cables. The difference in ignition time between cables with different spacing was significant at a heat flux of 30 kW/m(2), but became small when the heat flux was higher. Additionally, both the average mass loss rate and heat release rate of the cables increased with increasing heat flux and spacing. The heat release rate versus time curves exhibited two peaks, with the second peak being significantly smaller.