Foam extinguishing fire system for repressing fire of underground common tunnel

The present invention relates to a foam fire extinguishing systems for fighting the underground common duct fire, in particular at the same time by configuring the space into two firewall inside underground common duct blocking the spread of fire, in the space inside the existing connection sprinkler formula digestive system in relate to foam head and the common duct underground fire fighting foam extinguishing system for employing the configuration of the air-foam mixer.