What is the most common gas used to inert a space to prevent ignition?

• A. Nitrogen
• B. Oxygen
• C. Argon
• D. Helium

Answer: (A)

Displacing the oxygen in a space with an inert gas stops most fuels from igniting by removing the oxidizer flames need. Nitrogen is the go-to choice because it’s abundant, inexpensive, and nonreactive with most fuels under normal conditions. It’s easy to store and deliver as a purge gas, making it practical for wide use in many industrial settings.

Oxygen, by contrast, is the one you want to limit rather than use for inerting, since it supports combustion. Argon and helium are inert too, but they’re much more expensive and have specific handling or process considerations, so they’re used only in specialized situations.