Film-forming fire extinguishing chemical composition for automatic fire extinguishing systems, supplied by spraying

Abstract

Purpose. Development of a universal film-forming fire extinguishing chemical composition for fire extinguishing systems and water foam based on fluorinated surfactants for extinguishing class A and B fires (combustion of solid and liquid flammable substances), supplied for extinguishing by spraying.

Methods. Empirical research methods (measurement of surface and interfacial tension of solutions), the method of randomization and full factorial experiment to obtain regression models, as well as the «Desirability Profiles» module of the STATISTICA software package. The determination of the coefficients of surface and interfacial tension of solutions of surfactants in aqueous systems was carried out by the method of tearing off the Du Nouy ring on an automatic tensiometer KRÜSS-K20.

Findings. The choice of components of the film-forming fire extinguishing chemical composition is substantiated: fluorinated surfactants (FS), hydrocarbon surfactants (HS) and a co-solvent. The results of a full factorial experiment are presented, on the basis of which regression models were obtained that describe the change in the value of the coefficient of spreading of the water film on the surface of the flammable liquid, interfacial tension coefficient, wetting time of a cotton fabric sample, the time of existence of the water film on the surface of the flammable liquid, the thickness of the water film on the surface of the flammable liquid and the extinguishing time of a model Class B fire depending on the ratio of the components of the film-forming fire extinguishing chemical compositions. From the established dependences of the extinguishing time of model fires on the mass fraction of the components of the film-forming fire extinguishing composition, the range of interfacial tension of 1.7–1.9 mN·m⁻¹ and the spreading coefficient of 3.0–3.2 mN·m⁻¹ were determined, at which the fire extinguishing efficiency of the film-forming fire extinguishing composition is maximum and makes 55 s, which is 35 % higher than the fire extinguishing efficiency of commercially available film-forming foaming agents. Based on the established dependencies of the extinguishing time of model fires on the coefficient of interfacial tension of aqueous solutions of FS, HS with a co-solvent, a formulation of a film-forming fire extinguishing composition has been developed, consisting of 2.9±0.1 wt.% amphoteric FS, 1.5±0.1 wt.% nonionic HS, 3.0±0.1 wt.% anionic HS, 10.0±0.1 wt.% organic solvent and 82.9±0.1 wt.% water, which differs from the investigated compositions and existing analogues by the greatest fire extinguishing efficiency when applied by spraying.

Application field of research. The obtained results can be used in developing the formulation of film-forming fire extinguishing compositions for extinguishing fires.