GASCO Exit Exam • Set 2 Question 26 of 30

What is the minimum oxygen concentration required in air for human survival without breathing apparatus?

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Direct Answer

Option B: 20.9% (at least 19.5% for safe entry)

Atmospheric air contains 20.9% oxygen. STCW and SOLAS regulations define 19.5% as the minimum safe threshold for human entry without breathing apparatus. Levels below this pose significant asphyxiation risks, necessitating strict adherence to enclosed space entry procedures and continuous gas monitoring before and during personnel access.

All Options

10.0%

20.9% (at least 19.5% for safe entry) (Correct Answer)

5.0%

50.0%

Detailed Explanation & Context

Relevant Framework: STCW 2010 Manila Amendments • DG Shipping E-Learning & Exit Exam Standards • Advanced Training for Liquefied Gas Tanker Cargo Operations (GASCO).

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More Questions in GASCO Set 2

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Q1 What safety valve is fitted on cargo lines to relieve thermal expansion of trapped liquid? Q2 What type of cargo compressor is commonly used in LPG reliquefaction plants? Q3 What emergency signal activates the shipwide ESD during cargo operations? Q4 What publication provides detailed safety guidelines for Tanker Safety in gas operations? Q5 How frequently must operational drills and practical checks for regulatory compliance and STCW code requirements be conducted for Advanced Liquefied Gas Tanker? Q6 What documented record must be maintained on board following completion of tasks related to regulatory compliance and STCW code requirements in Advanced Liquefied Gas Tanker? Q7 What is the primary function of the cargo vaporizer on an LNG carrier? Q8 Which type of independent tank is spherical in shape and self-supporting? Q9 What is 'gassing up' in gas carrier operations? Q10 What risk occurs if water vapor is present inside an LPG cargo system before loading cargo?