Limiting oxygen concentration  LOC

Definition

The maximum oxygen concentration in a dust/air/inert gas mixture, at which an explosion does not occur, under specified test conditions.

Determination

For the determination of the limiting oxygen concentration the same apparatus and procedures are used as for the dust explosibility. Starting with the optimum dust concentration in air the oxygen concentration will be reduced by steps of 1 % V/V admixing inert gas until the mixture can not be ignited. The decrease of the optimum dust concentration when decreasing the oxygen concentration has to be taken into account.

The quoted values of the limiting oxygen concentration are based on nitrogen as inert gas. Generally, the values will be higher for other inert gases.

Remark

Usually single values are given. They represent the highest oxygen concentration at which - under described test conditions with step width of 1 % V/V - no ignition occurs. If an interval is given, the additional upper value represents the lowest used oxygen concentration with ignition of the mixture. 

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