PERFORMANCE OF WATER SPRAY FIRE SUPPRESSION SYSTEMS UNDER DIFFERENT NOZZLE LOCATIONS, WATER FLOW RATES, AND VENTILATION CONDITIONS

摘要

An experiment was conducted in this investigation to study quantitatively the effect of water spray on fire suppression and extinction. In order to produce different water droplet sizes under specific water supply rates and discharge pressure, different characteristics of water spray nozzles were designed and fabricated for experimental program. The water flow rate and the distance of nozzle-to-fuel surface were used to investigate the performance of water spray fire suppression effects under different ventilation conditions. The results are discussed by using both gas temperature and fire extinguishing time for different spray characteristics. As observed from the experimental data, when the water discharge pressure is greater than 7 kg/cm~2 the fire extinguishing times are less than 8 seconds for all tests. It seems that when the water discharge pressure greater than 7 kg/cm~2 and droplet size less than 700 μm, the fire extinguishing time appears to be independent of the nozzle-to-fuel distance and the ventilation conditions as well. Despite some scatter in the data, the extinguishing time in general decreases with increasing water flow rate. However, the 800 μm droplet tested data show much longer extinguishing time due to the lowest water discharge pressure (2.7 kg/cm~2). At low water flow rates, the extinguishing time increased when the nozzle was positioned further from the fuel surface. Also, significant reduction in extinguishing time was observed when small droplets were used at low water flow rate. For high water flow rates, the ventilation rate did not have apparent influence on temperature reduction rate.