Tank Atmosphere Control 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 Tank Atmosphere Control flashcards as text
What is the primary purpose of an inert gas system on a tanker?
Answer: To replace oxygen in the cargo tank with a non-flammable gas
An inert gas system replaces oxygen in cargo tanks with a non-flammable gas (typically flue gas or nitrogen) to prevent flammable atmospheres.
Which of the following oxygen concentrations is considered safe for inerted cargo tanks?
Answer: Less than 8% by volume
Cargo tanks must be maintained at less than 8% oxygen by volume to ensure the atmosphere remains outside the flammable range.
What is the 'Lower Explosive Limit' (LEL) in the context of tank atmosphere control?
Answer: The minimum concentration of vapor in air at which ignition can occur
The LEL is the minimum concentration of flammable vapor in air below which a flame will not propagate.
When must a tanker maintain a positive pressure in inerted cargo tanks?
Answer: At all times while inerted, including during sea passage
Positive pressure must be maintained at all times in inerted tanks to prevent air ingress, which could create a flammable atmosphere.
What instrument is used to measure the oxygen content inside a cargo tank?
Answer: Oxygen analyzer
An oxygen analyzer measures the percentage of oxygen by volume in the tank atmosphere to verify safe inerted conditions.
Which condition describes a 'gas-free' tank atmosphere?
Answer: A tank where hydrocarbon vapor is below 1% LEL and oxygen is at normal atmospheric levels
A gas-free atmosphere contains negligible hydrocarbon vapors (less than 1% LEL) and normal oxygen levels, making it safe for personnel entry.
What happens to flammable cargo vapors in the 'Upper Explosive Limit' (UEL) zone?
Answer: The mixture is too rich in fuel to ignite
Above the UEL, there is too much fuel and not enough oxygen, so the mixture cannot ignite under normal conditions.