Deck General · Extinguishing Agents
The MOST critical danger to personnel when a fixed CO2 system discharges in an enclosed machinery space is:
- AFrostbite from the cold CO2 discharge
- BAsphyxiation due to oxygen displacement✓ Correct
- CToxic decomposition products from CO2 reacting with hot metal
- DOverpressure rupture of the space due to rapid gas expansion
Explanation
CO2 is colorless and odorless. When a fixed CO2 total-flooding system discharges, it rapidly displaces oxygen to levels immediately dangerous to life (below 6% O2 causes unconsciousness in seconds). Personnel must evacuate before or immediately upon discharge. There is no warning to the senses — a person can lose consciousness before realizing the danger. Pre-discharge alarms are mandatory for this reason.
Authority: Firefighting (USCG deck topic)
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