In inert gas agent blends, which component can appear as a secondary component?

• A. Oxygen.
• B. Carbon dioxide.
• C. Helium.
• D. Neon.

Answer: (B)

Inert gas agent blends are designed to suppress fire by displacing and diluting the air without placing occupants at risk, so the mixture is made from a main inert gas and a carefully chosen secondary component to tune its effectiveness. The secondary component is used in small amounts to adjust how the blend behaves—its density, heat absorption, and overall extinguishing performance—while keeping the oxygen level above a survivable threshold.

Carbon dioxide fits that role in many common blends. It appears as a minor component to enhance extinguishing efficacy, yet the overall gas mixture remains within safety limits for occupied spaces. Oxygen is not used as a component because increasing oxygen would undermine the extinguishing effect. Helium and neon are not typical secondary components in these blends due to practicality and design standards. So carbon dioxide is the best answer.