Class A and B foam

[AustrianFF]

Hi,

I am new to this forum. For over a year now, I am reading the articles in the HotShots section. Serveral times I read about Class A or Class B foam? So what's the difference between these two foam classes?

Thanks in advance
Bernhard
VFD Wr. Neustadt, Austria

[Rayr49]

Class A foam is for ordinary combustibles such as wood, paper, etc. It is used on wildland fires and structure fires. It has the advantage of "penetrating" the fuel for a quick knockdown and lessens the chance for a rekindle.

Class B foam is used for hydrocarbons. It is used on liquid fuel fires. It "smothers" the fire by covering the surface with a "blanket" that reduces the oxygen available at the fuel surface and provides a barrier to slow the release of vapors. There are a number of types of class B foam, the most common being AFFF. There are also specialized class B foams that are used for alcohol fires and other applications.

Neither should be used on water reactive fuels.

Stay Safe
IACOJ

[AustrianFF]

@Rayr49: Thanks for your explanation.

But are there more than these 2 classes of foam?

Thanks,
Bernhard

[lutan1]

There's different types of foam for different classes such as protein foam, high-expansion foam, etc, etc....

Do a search on the web and I'm sure you'll come across heaps.

[Rayr49]

lutan 1 is correct. There are two basic classes (A & B) but there are a number of special foams in these classes for specialized applications. These foams are normally used only by industrial fire brigades for the specific hazard associated with the protected industry. Public departments may also have limited stocks of specialized foam for an industrial complex in their first response area.

Stay Safe
IACOJ