Analysis of water application in large-scale residential structures

An experimental study is presented of the effect of water application on the fire environment in residential fires. Experiments were conducted in one-story and two-story residential structures, and water was applied to the fire with a combination nozzle set in either a straight stream or 30° fog stream. The amount of temperature reduction 60 s after water application in non-fire rooms, i.e. rooms without materials on fire, had a closely linear relationship with room temperature before water application. It was established that this relationship was different between straight streams and fog streams. Initially, fog streams achieved larger temperature reductions than straight streams, but as time after water application progressed, temperature reductions became larger for straight streams. Additionally, "pushing heat," i.e. the effect of water application increasing the temperature in the rooms adjacent to the fire room, was observed only in fog streams. "Pushing heat" was attributed to the entrainment of gases by the fog stream, which created an inflow of gases into the fire room, thus raising its pressure and sending hot gases into adjacent rooms. This effect was expectedly not observed for straight streams, since entrainment of gases in those streams was negligible.