Safety, Fire & Survival · Enclosed Spaces
Before entering a tank that has been closed, the atmosphere should be tested for:
- AColor and odor by smell alone
- BOxygen content, flammable vapors, and toxic gases✓ Correct
- CTemperature only
- DHumidity only
Explanation
A calibrated meter must confirm safe oxygen (about 20.9%), flammable vapor below the lower explosive limit, and toxic gases (such as H2S and CO) within safe limits — in that order of testing — before entry. Smell and appearance are unreliable and can be deadly.
Authority: SOLAS XI-1; IMO enclosed-space entry guidance
Practice the full Safety, Fire & Survival bank
Free spaced-repetition quizzing across 2190 USCG exam questions — it schedules your reviews so the ones you miss come back until they stick.
Related Safety, Fire & Survival questions
- Enclosed Spaces
The principal hazard when entering an enclosed or confined space aboard ship is:
- Enclosed Spaces
If a crew member collapses inside an enclosed space, a would-be rescuer should FIRST:
- Fire Theory
The three elements that must be present for a fire to burn (the fire triangle) are:
- Fire Theory
A fire involving flammable liquids such as gasoline, oil, or grease is what class of fire?
- Fire Theory
A fire in energized electrical equipment is class C. The first action that makes it safer to fight is to:
- Firefighting
Why is water the preferred agent for a Class A fire?