Low expansion foam is produced with a small mixture of air (to VZ 20). This results in a wet, fine-bubble foam, which is free flowing. Its high weight and low volume makes it particularly combustion-stable, gas-tight and prevents re-ignition. Depending on the composition, it has the property of adhering to three-dimensional surfaces.
The Extinguishing Effect
Its extinguishing effect is mainly due to the cooling effect and release effect, which can be exacerbated by water film formation or polymer film formation – it also has very good coverage. The very high flow is recommended for fighting liquid fires. In the case of solid fires, its high adhesion has a particularly favourable effect.
The Foam Production
Low expansion foam is produced by a foam pourer, foam sprinkler and foam tubes in fixed and mobile fire extinguishing systems.
The Fire Fighting Operation
Low expansion foam is quickly distributed over the entire fire surface, forming a gas-tight, insulating and cooling blanket over a longer period of time. The preventative use of the blanket effect effectively prevents the emission of toxic or flammable gases. Because of its heavy weight, it is especially suitable for fire fighting operations over long ranges from a safe distance to the fire.
With water film-forming foam extinguishing agents, it can be used either foamed and as an unfoamed water solution and is also suitable as an extinguishing agent for sprinkler and deluge systems. The large water excretion rate of such mixtures strengthens the fluidity, while reduced surface tension particularly favours spraying on solid fires.