Fire-suppression capability of surfactant-free aqueous dispersions of submicron-sized ferrocene particles

The main objectives of this study are to directly prepare surfactant-free aqueous dispersions of submicron-sized ferrocene (ADSMFs) via an antisolvent-crystallization technique and to explore their fire-suppression ability. In this study, for the antisolvent crystallization, alcohol (ethanol and 1-propanol) and water were used as solvents and antisolvent, respectively. Particle-size measurements confirmed that the ferrocene diameters in most ADSMFs were in submicrometer (410 nm–2.92 μm). Spray droplet-size and spray flux measurements demonstrated no significant variations among the sprayed ADSMFs, allowing a direct comparison of the fire-suppression abilities among the ADSMFs. Fire-suppression tests involving n-heptane pool fires indicated that (i) the ADSMFs exhibited shorter extinguishing times by a factor of ca. 5 than the conventional wet-chemical agent and (ii) the fire-extinguishing ability was improved by reducing the ferrocene-particle sizes from microns to submicrons; however, no significant effects of the ferrocene concentration and diameter on the ADSMF's extinguishing times were observed in the ferrocene diameter range of submicrons. The interesting finding (ii) probably arises from the ease with which ferrocene readily decomposes/breaks down and then generates active inhibiting iron species in flames.