Abstract

Aim: The aim of this article is to discuss the physicochemical reactions which occur during a fire and to present the mechanism of action of fire inhibitors used in fire-extinguishing aerosols. The article also presents the results of research into the impact of fire-extinguishing aerosols on museum items. Introduction: Typically, there are two mechanisms used to extinguish fire, i.e. by lowering the temperature of the fire (e.g. by applying water or powders) or by cutting off the supply of oxygen or its significant reduction (with the exception of so-called chlorinated gases) by blanketing it with fire-extinguishing foams. However, in the case of fire-extinguishing aerosols, their action principle is different. It is based on the stopping of combustion reactions by binding active radicals which probably result from the conversion of water molecules through the active surface effect (whether local or by volume) of aerosol nano- grains. This method is very efficacious. It does not reduce the level of oxygen in the air but, in contrast to the powders, leaves a trace amount of impurities. Most of all, however, it does not adversely affect the environment by ozone depletion or enhance the greenhouse effect due to there being no release of halogen-based fire retardants (in the latest type of aerosols). Methodology: The first part of the article includes a review of the literature on fire mechanisms, with the involvement of water in these processes. The second part focuses on the presentation of the mechanism of action of fire-extinguishing aerosols. This presentation is supported by an analysis of the preliminary research results concerning the use of aerosols type AGS 11/1 for the purposes of museum exhibits protection, i.e. wooden figures and old prints. Conclusions: The literature analysis in the field of combustion reactions mechanisms and action of fire-extinguishing aerosols, as well as the preliminary results of the research, allowed us to draw the following conclusions: – water is an effective inhibitor of combustion at the initial stage of the fire, but at later stages, active radicals generated by its decomposition can maintain the flame combustion reaction; – fire-extinguishing aerosols do not affect the colour of wooden figures, nor change the properties of old prints, which is why they can be successfully used in museums and historical buildings.

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