When referring to the L.E.L. of a flammable or combustible liquid, what does the L.E.L. mean?

• A. Lowest Efficiency Level
• B. License Equivalency Label
• C. Lower Explosive Limit
• D. Lowest Evaporation Limit

Answer: (C)

Lower Explosive Limit means the smallest amount of flammable vapor in air that can ignite and sustain a flame if there’s an ignition source. It’s expressed as a percent by volume in air. If the vapor concentration is below this limit, the mixture is too lean to burn. Between the lower and upper explosive limits, a mixture can ignite when exposed to a spark or flame. Detectors and safety procedures use percent of LEL to gauge how close the environment is to a flammable or explosive condition, helping workers keep ventilation and controls adequate to prevent ignition.