Inert Gas Systems Flashcards
7 cards from real Tanker Familiarization practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Inert Gas Systems flashcards as text
What does 'gas-freeing' of a cargo tank involve?
Answer: Ventilating the tank with fresh air to replace inert gas and reduce hydrocarbon vapors for safe entry
Gas-freeing ventilates a cargo tank with fresh air to displace inert gas and dilute hydrocarbon vapors to safe levels, restoring sufficient oxygen for personnel entry.
What is the primary function of the scrubber in an inert gas system?
Answer: To cool and clean the flue gas by removing sulfur dioxide and soot particles
The scrubber cools the hot flue gas and removes harmful impurities including sulfur dioxide (SO₂) and soot before the gas is delivered to the cargo tanks.
Before personnel enter a tank that has been held in an inerted condition, what action is absolutely essential?
Answer: Gas-free the tank until oxygen is at least 19.5% and hydrocarbon levels are below the LFL
Before entry, the tank must be fully gas-freed so oxygen is restored to a breathable level (≥19.5%) and hydrocarbon concentrations are confirmed below the lower flammable limit.
What is the correct procedure before loading flammable cargo into a tank that currently contains a normal air atmosphere (21% oxygen)?
Answer: Inert the tank to reduce oxygen below 8%, then proceed with loading
Before loading flammable cargo into a tank containing air, the tank must be inerted (oxygen reduced to below 8%) to eliminate the risk of an explosive atmosphere forming during loading.
What does a pressure/vacuum (P/V) valve on a cargo tank protect against?
Answer: Both excessive over-pressure and excessive vacuum within the cargo tank
P/V valves protect cargo tanks against structural damage by opening to relieve both excessive positive pressure buildup and dangerous negative pressure (vacuum) within the tank.
What minimum oxygen percentage must be present in a tank atmosphere before personnel may safely enter?
Answer: 19.5% or above
OSHA and international maritime standards require a minimum of 19.5% oxygen before personnel may safely enter an enclosed space such as a cargo tank.
What is 'purging' in the context of an inert gas system?
Answer: Using inert gas to dilute and displace hydrocarbon vapors until they fall below the lower flammable limit
Purging uses inert gas to dilute and displace hydrocarbon vapors inside a tank until the hydrocarbon concentration falls safely below the lower flammable limit (LFL).