Performance of a spray system in a full-scale tunnel fire test

In recent years, water spray systems have been accepted for protection of long tunnels in Taiwan. This research conducted two full scale tunnel fire experiments using 6 m2 pool fire of heptane while data from one test is presented in this paper; the ceiling could reach 1022 °C under free burn. If a tunnel with spray nozzles operating at a pressure of 3.43 bar and a water flow rate of 360 lpm were installed every 5 m in a 50 m range for a 6 m2 pool fire, not only could the temperature directly above the fire be lowered to below 500 °C within 30 s, the temperature of the other ceiling area would also be lowered below 300 °C and the heat flux would be lowered below 1 kW/m2, therefore preventing subsequent fire spread. Moreover, the visibility of the fire returned to above 25 m after 150 s. This newly designed spray system can be installed on one side wall under simple maintenance without the need to shut down the tunnel, while the water can also spray to another wall to provide adequate wall cooling for tunnel protection. It can be effectively applied to rescue and protection in tunnels.