Multigrade foaming agent

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More foam agent (MBS) are synthetic foam , by the fire department are used to extinguishing foam manufacture. The word "multi-area" refers to the different possible foaming rates and not to different types of fire ; MBS can be used to produce heavy, medium and light foam.

composition

Multi-purpose foaming agents are mostly clear and inherently colorless liquids, which, however, are often colored by the manufacturer. They are made on the basis of synthetically produced surfactants. The basic concept of multigrade foams corresponds to our detergents and is made up of surface-active substances, so-called detergents (hydrolyzed fatty alcohols or surfactants). These are added to the extinguishing water, this water-foam compound mixture is then swirled with air, causing it to foam.

Mode of action and provision

The extinguishing effect of burning liquids, the main area of ​​application of extinguishing foam, is based on the separation of the fire material from atmospheric oxygen (extinguishing effect suffocation). In addition - depending on the water content of the foam - a cooling effect comes into play (extinguishing effect cooling). In the case of burning solid substances of fire class A, the cooling effect can predominate. In contrast to fluorinated foaming agents ( AFFF and protein foaming agents ), MBS-based foams do not form a water film on burning liquids and are therefore more sensitive to re-ignition and tearing. However, since perfluorinated surfactants are generally not used at all, MBS are a more environmentally friendly and versatile alternative for municipal fire brigades, which rarely have to deal with larger liquid fires.

use

Conventional MBS are added to the extinguishing water with 3% if foam is to be generated and with 1% if mains water is required for solid fires . It is important to note that foam concentrates from different manufacturers and different products or types should not be mixed. The finished extinguishing foams, however, get along without any problems.

In the case of fires of fire class A, non-foamed multigrade foams can be used as wetting agents .

Class A foam concentrate

Special foaming agents for the production of class A foam (foam for fire class A) are a development from the USA. They are particularly environmentally friendly and were originally developed for fighting vegetation fires . However, they are also used more and more often unfoamed (see network water ) in fires in buildings, as they improve the penetration of the water into the fire material through the strong network effect and thus help to reduce damage from running water and improve the extinguishing power of the water.

In principle, these foaming agents are highly concentrated multigrade foaming agents based on particularly easily degradable, synthetic surfactants, which can be used as wetting agents at 0.1% - 0.5% and foamed at 0.3% - 0.5% . Little is known that all Class A foam agents available in Germany are approved as extinguishing agents for fire class B, although a proportioning rate of 1% is required for most products. Due to the significantly lower consumption compared to conventional 3% MBS, the somewhat higher purchase price is put into perspective.

See also

swell

  • Special issue 2/2006 of the fire department magazine, fire fighting with foam
  • Documents from Sthamer and other manufacturers