To prevent reignition of a liquid fuel fire after foam has been applied, do NOT:

• A. apply a solid or straight stream of water to the foam blanket
• B. increase foam to build a blanket
• C. ventilate the area
• D. apply dry chemical to the foam blanket

Answer: (A)

The key idea is that keeping a stable foam blanket over the fuel is essential to prevent reignition. A solid or straight stream of water directed at the foam blanket disrupts that blanket by washing away the foam’s surfactants and collapsing the film. When the blanket is disturbed, its insulating and cooling effect is lost, fuel vapors can heat up again, and reignition becomes possible. Instead, use a fog or broken-spray pattern that cools and blankets the fuel without breaking the foam, and ensure enough foam is applied to maintain a thick, continuous layer.

Ventilating the area helps by reducing accumulated vapors and heat, which supports preventing reignition. Increasing foam to deepen and strengthen the blanket is a direct, effective approach. As for adding dry chemical to the foam blanket, that is not a standard or reliable method for preventing reignition and can contaminate or degrade the foam, reducing its effectiveness.