Limiting Oxygen Concentration and Inerting

The LFL is based on fuel in air. However, oxygen is the key ingredient and there is a minimum oxygen concentration required to propagate a flame. This is an especially useful result, because explosions and fires can be prevented by reducing the oxygen concentration regardless of the 

The LOC has also been called the minimum oxygen concentration (MOC), the maximum safe oxygen concentration (MSOC), and other names. 

The LOC has units of percentage of moles of oxygen in total moles. If experimental data are not available, the LOC is estimated using the stoichiometry of the combustion reaction and the LFL. This procedure works for many hydrocarbons. 

The LFL for butane (from appendix B) is 1.9% by volume. From the stoichiometry 

The combustion of butane is preventable by adding nitrogen, carbon dioxide, or even water vapor until the oxygen concentration is below 12.4%. The addition of water, however, is not recommended because any condition that condenses water would move the oxygen concentration back into the flammable region. 

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Limiting Oxygen Concentration and Inerting Table 6-2 Limiting Oxygen Concentrations (LOCs) (volume percent oxygen concentration above which combustion can occur)1 239... 

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