Surfactants reduce the surface tension of liquids and thus enable foaming. In everyday use, you can find them in soaps, shampoos, and detergents. Extinguishing foam contains fluorinated surfactants, some of which are known environmental toxins – here’s an overview.
Foaming compound is added to extinguishing water not only for defensive fire protection, stationary extinguishing systems also use foam for cooling. Fields of application include hazardous material storage facilities, recycling facilities and sites, and places where larger quantities of combustible liquids are present, for example aircraft hangars. Water alone would have an insufficient extinguishing effect in these cases. The mixture is usually discharged automatically by sprinklers, spray flooding systems, or extinguishing turrets if targeted cooling is necessary across large areas.
What types of foaming agents exist?
Basically, a distinction is made between synthetic and protein-based foaming agents, where, in the first group, the surface tension of the water is reduced by artificially produced substances for the generation of foam. In contrast, protein-based foaming agents are natural proteins that facilitate foam generation.
However, problems can arise when the foaming agent contains so-called poly- and perfluorinated chemicals (PFC), as is the case with synthetic foaming agents. PFC is a substance used in water-film-forming concentrates, which are applied when combating liquid fires. It increases the extinguishing effect enormously, and it is a prerequisite for the successful extinguishing of certain fire types. Nevertheless, this substance must be handled carefully.
PFC is a chemical supergroup that includes a variety of substances. For example, perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) are problematic. These chemicals are toxic and, once introduced into the environment, can spread widely through waterways. Some of these substances can accumulate in the human body and have a toxic effect. In animal testing, PFOS and PFOA have also shown to be harmful to the reproductive system.
The EU has therefore banned the sale and use of PFOS since June 27, 2008. A grace period for using remaining quantities continued until June 2011. Further use after this date is prohibited. PFOA, on the other hand, is currently being monitored.
The right foaming agent for your extinguishing system
In light of this, operators of stationary extinguishing systems should inform themselves regarding the type of foaming agent used in their installation. For information on alternatives to fluorinated foaming agents, see the blog post “The curse and blessing of fluorine in extinguishing foams”. If it is unclear whether the foaming agent used in the extinguishing system contains PFOS or PFOA, an analysis can help. Reading the manufacturer’s information often clarifies matters as well.