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Chemical Hazards and Reactions |
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Explosive Limits |
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The range of concentrations of gases in air which will support the explosive
process is bounded by measurable limits called Upper Explosive Limits (UEL) or Upper
Flammable Limit (UFL) and Lower Explosive Limits (LEL) or Lower Flammable Limit (LFL). The flammable range is the optimal chemical fuel concentration in air for the ignition and the sustenance of combustion. The lowest concentration of fuel in this range is the LEL/LFL. The highest ratio that is flammable is the UEL/UFL. Concentrations less than the LEL/LFL are not flammable because there is too little fuel, that is, the mixture is too “lean” to burn. Concentrations greater than the UEL/UFL are not flammable because there is too much fuel displacing the oxygen (resulting in too little oxygen). The mixture is too “rich” to burn. |
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