Fire Safety Science Digital Archive

Experiments have been performed in a 2.5 x 2.5 x 5 m² enclosure with various water spray nozzles fighting a 1MW propane fire. Ventilation is provided through an inlet opening at floor lever, and an outlet opening at ceiling level. Fire induced ventilation has been examined the fire source is propane forming an equivalent pool fire with dimensions 0.3 x 1.3 m². The nozzles produce sprays with full cone coverage, with mean nominal water droplet diameter varying from about 0.5 mm to 1.6 mm. The results are presented as a heat balance for the water spray, the compartment and the ventilated smoke, by a ratio SHAR - Spray Heat Absorption Ratio. A general observation is that the fire is extinguished when the spray absorbs a certain fraction of the heat release rate. The extinction mechanisms seem to be a combination of inerting the combustion zone with evaporated water, and consequently a reduction of temperature. When the water spray absorbs only a lesser fraction of the released heat, the smoke temperature and the total heat flux to the compartment is considerably reduced. There is a distinct connection between water droplet size and the ability to extinguish the fire, in favor of the smallest droplets.