What type of fire is a foam extinguisher primarily effective against?

A foam extinguisher is primarily effective against Class B fires, which involve flammable liquids such as gasoline, oil, paint, and solvents. The foam works by creating a blanket over the burning liquid, preventing the release of flammable vapors, thus cutting off the fire's supply of oxygen and cooling the flames. This characteristic makes foam extinguishers particularly suited for emergencies where liquid combustibles are present.

While foam extinguishers can occasionally be used for Class A fires (solid materials such as wood and paper) due to their cooling properties, they are not typically the first choice for these types of fires. It is important to note that foam extinguishers are not suitable for Class C fires, which involve electrical equipment, as the foam can conduct electricity and create additional hazards. Therefore, focusing on Class B fires highlights the primary purpose and effectiveness of foam extinguishers in fire safety and prevention practices.