🔍 Key Concepts

• Confined space entry procedures on vessels, especially fuel tanks • Difference between oxygen indicators and combustible gas indicators • Which instruments are designed to detect explosive or flammable vapor concentrations

💭 Think About

• When entering a recently cleaned fuel tank, what is the main danger besides lack of oxygen? • Which of the listed devices is specifically used to measure the presence of flammable or explosive vapors in the air? • Which options are older technologies or used for other types of gas analysis rather than routine shipboard safety checks?

✅ Before You Answer

• Verify which device is standard equipment in tank-entry safety procedures on modern vessels • Eliminate any devices that are primarily for gas analysis in laboratories rather than shipboard safety • Confirm which instrument is designed to detect flammable vapor concentrations as a percentage of the lower explosive limit (LEL)