Which of the following is the primary function of the screens that are fitted to the Fuel oil tank vents?

Correct Answer: Option C — flames on deck from entering the tank vent

Vent screens are critical safety devices required by 46 CFR to prevent external ignition sources, such as sparks or flames on deck, from traveling through the vent piping into the fuel oil tank. This prevents a catastrophic explosion by isolating the flammable atmosphere inside the tank from external fire.