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
When purging a cargo tank from inert to gas-free, what is the correct procedure?
Answer: Ventilate the tank through the top while monitoring hydrocarbon levels at the bottom
Purging displaces hydrocarbon-rich inert gas from the top while monitoring at the bottom ensures vapors pass through the explosive range as briefly as possible.
What is the danger of introducing air into a cargo tank that is in the 'rich' condition (above UEL)?
Answer: Diluting with air can bring the mixture into the explosive range
Adding air to a rich tank dilutes the hydrocarbon concentration, potentially passing through the explosive range between UEL and LEL.
Which type of inert gas is considered the highest quality source for tanker IG systems?
Answer: Nitrogen gas from a dedicated nitrogen generator
Nitrogen generators produce very high-purity inert gas with extremely low oxygen content, making them superior to boiler flue gas systems.
What does a 'scrubber' do in an inert gas system?
Answer: Cools and cleans the flue gas by removing sulfur dioxide and soot particles
The scrubber cools the hot boiler flue gas and removes corrosive impurities like SO₂ and particulates before the gas enters the cargo tanks.
A ship's IG deck seal serves what primary function?
Answer: To prevent cargo vapors from flowing back into the IG system machinery
The deck water seal acts as a non-return device preventing flammable cargo vapors from backflowing into the inert gas plant and ship machinery spaces.
At what minimum oxygen content in the IG supply must operations be stopped immediately?
Answer: 8% by volume
If the oxygen content of the inert gas supplied to tanks exceeds 8% by volume, inerting operations must be halted to prevent creating a flammable atmosphere.
What is 'topping up' in the context of tanker inert gas operations?
Answer: Adding inert gas to maintain positive pressure and correct oxygen levels in tanks
Topping up replaces inert gas lost through normal pressure fluctuations to maintain the required positive pressure and oxygen levels in cargo tanks.