Why is low expansion foam not suitable for polar solvent fires?

Low expansion foam is not suitable for polar solvent fires primarily because polar solvents are miscible with water, which allows them to mix and become more difficult to control. While low expansion foam is designed to help suppress flammable liquids by creating a barrier that isolates the fuel from the atmosphere, it is specifically formulated for use with non-polar solvents. Polar solvents, such as alcohols or acetone, can break down the film that low expansion foam creates, leading to the failure of the foam to effectively suppress the fire.

Additionally, low expansion foam does not provide the necessary extinguishing capability for polar solvent fires. The foams that are suitable for polar solvents typically have high expansion and are designed to create a thicker, more durable blanket over the surface to prevent flammable vapors from igniting. This is a crucial factor in effectively mitigating polar solvent fires.

In contrast, options that touch upon cost or ignited versus unignited fires do not accurately capture the foam’s incompatibility with polar solvents. Low expansion foam can be effective in certain applications but is not adequate for the unique challenges presented by polar solvents.