Question 25 TK01 - Tank Vessel Assistant - Dangerous Liquids

The Correct Answer is D **Explanation of Option D (Correct):** The primary function of the inert gas (IG) system on a tanker (especially crude oil and product carriers) is safety. It works by generating a large volume of oxygen-depleted gas (typically 5% or less O$_{2}$) and injecting it into the cargo tanks. By continuously introducing this inert gas, the system dilutes the hydrocarbon vapor concentration within the tank atmosphere, ensuring that the oxygen level remains too low (usually below 8% O$_{2}$) to support combustion. By reducing the oxygen concentration, the tank atmosphere is kept outside the flammable range, specifically ensuring that any hydrocarbon gas concentration is effectively inerted, thus preventing the possibility of explosion. **Explanation of Incorrect Options:** * **A) prevent fires in the pumproom by continually displacing flammable vapors:** The inert gas system is designed to inert the **cargo tanks**, not the pumproom. Ventilation systems handle vapor displacement in the pumproom. * **B) blow out cargo lines to prevent gas concentrations:** Blowing out cargo lines is typically done using cargo pumps, steam, or sometimes compressed air/nitrogen during stripping or tank cleaning, but it is not the function of the main inert gas system. The IG system focuses on the main tank atmosphere. * **C) prevent the generation of flammable or combustible gas in tanks:** The inert gas system does not prevent the generation of hydrocarbon vapors (which are naturally given off by the cargo); rather, it manages and controls the atmosphere *after* those vapors have been generated to prevent them from igniting.