Influence of the component composition of extinguishing fluids on the droplet distribution in an aerosol cloud

The key challenge in the process is to reliably predict the droplet size distributions of extinguishing liquids after they cover the distances from the drop/spray point to the flame combustion area when using aircraft, sprinkler systems, or high-altitude ground spraying systems. It is sensible to perform a comparative analysis of changes in the size of droplets of typical fire extinguishing composition free-falling or sprayed in a gas medium from a variable altitude. We used the compositions typical of fire-extinguishing systems: bishofite and fire-extinguishing agent solutions, bentonite suspension, foamer emulsion, and water. The variation rate of the average, minimum and maximum sizes of droplets in the aerosol composition was recorded. Experiments were performed with varying spray height and initial droplet size distribution to show significant differences in the resulting droplet size distribution of suspensions, emulsions and solutions. Conditions were established, in which the droplet distribution for different extinguishing compositions remains comparable. [Display omitted] •Free-falling droplet size of bentonite-based compositions does not change much.•Droplet size of foamer-based emulsions is significantly reduced moving in a gas.•Droplet size of different liquids becomes comparable after passing 2–3 m in the gas.•Rates of secondary droplet disintegration in flight are significantly slowed down.•Disintegration is combined with coagulation in an aerosol cloud.