Question 35 TK02 - Tank Vessel Assistant - Liquefied Gas

The Correct Answer is D **Why option D ("prevent flames on deck from entering the tank vent") is correct:** The screens fitted to fuel oil tank vents are specifically designed to act as flame screens or flame arresters. These vents are crucial safety devices because the fuel oil (especially when heated) can release flammable vapors. If a fire or stray spark occurs on deck, these screens prevent the flame from propagating down the vent line and igniting the flammable vapor mixture inside the tank, which could lead to a catastrophic explosion. This is a fundamental fire safety requirement for ships carrying flammable liquids, aligning with SOLAS (Safety of Life at Sea) regulations. **Why the other options are incorrect:** * **A) prevent air from entering the tank vent:** Air (oxygen) must be allowed to enter the tank as oil is pumped out (to prevent vacuum collapse) and must also be allowed to exit. Restricting airflow would defeat the primary purpose of the vent. * **B) prevent oil from flowing out of the tank vent:** While the vent design often includes a high-level bend to discourage liquid splashing out, the screen itself is a mesh and is not the primary mechanism for preventing liquid overflow. The vent's height and arrangement (often a U-bend or gooseneck) handle liquid containment; the screen handles flame propagation. * **C) prevent vapors from leaving the tank vent:** The entire purpose of the vent is to allow vapors (or air) to enter and leave the tank freely as the liquid level changes or temperature fluctuates. If vapors were trapped, pressure/vacuum risks would arise. The screen allows vapor to pass unimpeded while blocking the flame front.