How does foam extinguish a fire by forming a blanket on burning fuel?

Foam extinguishes a fire effectively by forming a blanket on burning fuel, which excludes oxygen from the combustion zone. Fire requires three elements to sustain combustion: heat, fuel, and oxygen, commonly referred to as the fire triangle. By creating a physical barrier, the foam prevents oxygen from coming into contact with the burning material, thereby disrupting the chemical reactions necessary for the fire to continue.

Foam also serves to cool the fuel and suppress flammable vapors, but the primary mechanism by which it extinguishes fire is through oxygen exclusion. The foam's composition helps to prevent the vaporization of fuel, which further reduces the chances of fire reigniting.

Understanding this principle is crucial for airport firefighters, as many incidents involve flammable liquids that require a quick and effective response to ensure both safety and containment of the fire.