The effects of droplet size and injection orientation on water mist suppression of low and high boiling point liquid pool fires

This paper presents the results of an experimental parametric study of wate r mist suppression of large-scale liquid pool fires. The experiments were c onducted with 50cm diameter pan heptane and JP8 pool fires. Mist was inject ed into the fire from the base at 90 degrees and 45 degrees and from the to p at 90 degrees. The results show that base injection of droplets enhanced their suppression effectiveness by as much as two times. Secondly, optimum suppression effectiveness is obtained with small droplets injected at the b ase of the fire. This is because the droplets evaporated quickly within the lower region of the fire where a greater effect of oxygen dilution and wat er vapor higher heat capacity is fully realized. Finally, a comparison of t he results with the two fuels show that water mist is more effective in sup pressing the JP8 fires than the heptane fires. It is concluded that the add itional effects of direct surface cooling contributed significantly to the observed difference.