What percentage of oxygen is targeted in the inerting process?

• A. 2-3 percent
• B. 0 percent
• C. <5 percent
• D. Less than 1 percent

Answer: (D)

Inerting aims to keep the space where fuel vapors can gather as free of oxygen as practical, so combustion can’t start. The oxygen level is reduced by replacing ambient air with an inert gas such as nitrogen. For a robust safety margin, the targeted oxygen concentration is kept very low—well under one percent by volume. This near-zero level means there isn’t enough oxidizer to support ignition even if a spark or vapor cloud is present. Since achieving exactly 0% oxygen isn’t practical due to leaks and measurement limits, aiming for less than 1% provides the strongest defense against ignition. Lower targets like 2–3% or under 5% would not offer the same safety margin for every possible condition, so the strict less-than-1% target is the best choice.