Fire Safety Science Digital Archive

Effects of Different Suppression Tactics on the Firefighter and Compartment Environment MATTHEW OBACH, ELIZABETH WECKMAN, and ALLAN STRONG Department of Mechanical and Mechatronics Engineering University of Waterloo 200 University Ave. W. Waterloo, ON, N2L 3G1 ABSTRACT Experiments are conducted to study the effects of different water-based indirect initial attack methods on the compartment environment and firefighter during compartment fire suppression. Hot layer temperatures typical of room fire conditions are developed in the test compartment using wood cribs. Five suppression methods including straight stream, penciling, continuous wide and narrow fog, and a wide angle burst method are examined for two different spray angles and nozzle pressures. Temperatures, heat flux, gas velocity, and gas concentrations are monitored throughout the fire compartment. Realistic, yet extreme, fire conditions are repeatedly established in the test compartment, allowing up to nine tests per fire. Differences in average compartment temperature before and during suppression indicate that penciling tactics provide little cooling of the compartment. In narrow fog attacks, the hot layer is pushed toward the floor, resulting in increased temperatures in the lower layer, generally an undesired result. Wide angle fog methods have greater impact on compartment temperature as compared to straight stream or narrow fog methods; however, they may also result in large increases in temperature at the firefighter. Wide angle burst tactics less effectively cool the compartment gases than continuous methods, but also lead to less impact on the firefighter. Greater numbers of bursts increase cooling of the compartment, but at the expense of increased impact on the firefighter. Including impact on the firefighter, continuous straight stream methods, at a nozzle pressure of 700 kPa and aimed to the top of the rear compartment wall, appear the best choice for initial attack on fires developed in these experiments. Due to variability between real fire scenarios and experiments such as these, significantly more study of the various suppression tactics is required before the most effective methods of suppression can be determined even for a given set of fire scenarios.