Liquids limiting oxygen concentrations

All materials have a limiting oxygen concentration (LOC). If the oxygen content in the vapor space above the liquid being stored is below the LOC, then the vapor space is not flammable. The values given in Table 3.4 are LOC values for commonly used chemicals. They are taken from NFPA 69 (2014), the Table of Contents for which is given in Table 3.5. 

If the oxygen concentration in the bulk liquid phase is limited, for an oxygen partial pressure below 50 torr, two additional ways of radical recombination result. Reactions (4.16) and (4.17) ... 

The oxygen concentration in the liquid hydrocarbon can be accurately controlled so that it does not exceed any predetermined value by providing adequate release valves in the compressed air line and at the bubble tower used for satnration. As long as the air pressure and hydrocarbon temperature at the saturator remain fixed, the extent of oxygen solubility is limited to a value that approaches equilibrium for the particular set of conditions. 

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