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 automatic safety action is triggered if the oxygen content of the supplied inert gas rises above the set alarm point (typically 8%)?
Answer: The system automatically shuts down and isolates gas flow to the cargo tanks
If oxygen content exceeds the alarm set point, the system automatically shuts down and stops gas flow to the tanks to prevent oxygen-rich gas from creating an explosive atmosphere inside.
Why must the deck water seal be verified as operational before starting the inert gas system?
Answer: To prevent flammable cargo vapors from back-flowing through the inert gas main and reaching the engine room
Without an operational deck water seal, flammable cargo vapors could back-flow through the inert gas piping into the engine room, creating a severe explosion hazard.
Why is nitrogen blanketing used on some chemical and product tankers instead of flue gas inerting?
Answer: Pure nitrogen provides an inert atmosphere without the impurities (SO₂, soot, CO) found in flue gas that could contaminate sensitive cargoes
Nitrogen blanketing provides a clean, pure inert atmosphere over sensitive chemical cargoes that could be contaminated or react with the sulfur dioxide, carbon monoxide, or soot present in flue gas.
What minimum oxygen concentration in the tank atmosphere is required before personnel may occupy the space for extended work?
Answer: 19.5% by volume
A minimum of 19.5% oxygen by volume is required for safe human occupancy per OSHA and IMO guidelines; below this level the space is classified as oxygen-deficient and hazardous.
What is the main function of the high-velocity vent (P/V breaker) fitted on a tanker?
Answer: To relieve excess tank pressure at high velocity so that vapors are dispersed well above deck level
The high-velocity vent releases excess tank pressure as a high-speed jet that propels vapor upward and away from the deck, reducing the risk of ignition near personnel or equipment.
Under what condition should the inert gas in cargo tanks be 'topped up'?
Answer: Whenever the oxygen content rises above 8% or tank pressure drops below the minimum set point
Inert gas is topped up any time monitoring detects that oxygen content has risen above 8% or that tank pressure has fallen to an unacceptably low level, to restore and maintain the inerted condition.
What specific hazard does carbon monoxide (CO) present in flue gas pose to tanker personnel?
Answer: It is a highly toxic, colorless, odorless gas that can cause unconsciousness and death at low concentrations
Carbon monoxide is colorless, odorless, and highly toxic; even relatively low concentrations in flue gas can cause rapid incapacitation and death, requiring CO monitoring wherever personnel work near the inert gas system.