What type of equipment will be used in extremely high concentrations of toxic gases and vapors for personnel entering a fuel tank?

• A. Supplied-air hood
• B. Full-face respirator
• C. Self-contained breathing apparatus
• D. Air line respirator

Answer: (D)

Breathing air from a clean external source is essential when entering a space with extremely high toxic gas levels. An air line respirator delivers air from outside the tank through a hose to the wearer’s facepiece or helmet, ensuring the breathing air is not contaminated by the tank atmosphere and allowing longer, safer entry times. This setup avoids relying on the gas inside the tank, which could overwhelm cartridges in a filter-type respirator or exhaust an onboard supply in a short period.

A supplied-air hood provides external air to a hood over the head, which helps, but its protection of the breathing zone is less precise and mobility can be more restricted in a confined space. A full-face respirator relies on filters or cartridges that may saturate quickly in heavily contaminated vapors, making it less reliable in extremely high concentrations. A self-contained breathing apparatus carries a finite onboard air supply that may run out before the task is complete, which is riskier in a space with intense contamination.