A tank has been sealed and unventilated for...

🔍 Key Concepts

• Enclosed space / confined space hazards on ships (lack of oxygen, presence of toxic gases, unknown atmosphere) • The need for testing the atmosphere (oxygen content, flammability, toxicity) before entry into a sealed tank • Difference between a statement that is always true vs. something that might be true under certain conditions

💭 Think About

• Think about what happens to the air in a space that has been closed and unventilated for a long time. Is it predictable and safe, or uncertain and potentially hazardous? • Which option describes a condition that is guaranteed to be correct every time a tank has been sealed, rather than something that could be true only in some situations? • On real ships, what is the standard safety attitude toward any tank or compartment that has been closed up for a long period?

✅ Before You Answer

• Identify which choice reflects the standard rule for enclosed space entry: assume danger until tested and declared safe. • Eliminate any options that state a specific gas is present without any information about cargoes, residues, or previous use of the tank. • Watch for answers that sound "reassuring" but ignore the need for gas testing and ventilation before entry.

A tank has been sealed and unventilated for a long period of time. Which of the following statements is true?

The tank is safe to enter.

The tank is especially dangerous to enter.

Carbon monoxide is present.

Water vapor present when the tank was sealed has oxidized.

🔍 Key Concepts

💭 Think About

✅ Before You Answer