How long must AFFF bilge sprinklers be actuated prior to re-entry after a major Class B fire has been extinguished?

How long must AFFF bilge sprinklers be actuated prior to re-entry after a major Class B fire has been extinguished?

• A. 1 Minute
• B. 2 Minutes
• C. 3 Minutes
• D. 4 Minutes

Answer: (B)

Two minutes is used to let the space stabilize before re-entry. After a major Class B fire, the AFFF bilge sprinklers blanket and cool the area, absorbing heat and suppressing flammable vapors. Keeping them actuated for about two minutes gives time for the foam to cool hot surfaces and for vapors to drop to safer levels, reducing the risk of reflash when you re-enter. One minute is usually too short to achieve meaningful cooling and vapor control, while longer than two minutes doesn’t add safety and would unnecessarily delay operations.

Two minutes is used to let the space stabilize before re-entry. After a major Class B fire, the AFFF bilge sprinklers blanket and cool the area, absorbing heat and suppressing flammable vapors. Keeping them actuated for about two minutes gives time for the foam to cool hot surfaces and for vapors to drop to safer levels, reducing the risk of reflash when you re-enter. One minute is usually too short to achieve meaningful cooling and vapor control, while longer than two minutes doesn’t add safety and would unnecessarily delay operations.