🔍 Key Concepts

• Enclosed space entry requirements on tankers and cargo vessels • Safe oxygen percentage for human respiration in confined spaces • Testing for oxygen content, toxicity, and flammable (explosive) gases before entry

💭 Think About

• Think about what checks must ALWAYS be completed before anyone goes into a space that has been closed for a long time, especially if it held hazardous liquids. • Consider the minimum oxygen level that is generally regarded as safe for entry without breathing apparatus—how does 14% compare to normal air? • Ask yourself which statement describes a standard, routine safety procedure rather than something situational or relying on assumptions.

✅ Before You Answer

• Verify what normal atmospheric oxygen content is (approximately 21%) and what is generally considered the minimum safe level for entry (usually around 19.5%). • Confirm that enclosed space entry procedures require testing for oxygen, toxicity, and flammable gases in tanks that carried hazardous cargo. • Check whether natural ventilation alone is considered sufficient under enclosed space entry guidelines, or whether forced ventilation and gas testing are normally required.