LEL stands for Lower Explosive Limit.

• A. Lower Explosive Limit
• B. Lower Explosive Level
• C. Lower Emission Level
• D. Lower Energy Level

Answer: (A)

Understanding what LEL stands for and what it represents in fire safety. The lower explosive limit is the minimum concentration of a fuel in air that can ignite. If the fuel concentration is lower than this, the mixture is too lean to burn; as the concentration increases toward the upper explosive limit, the mixture becomes flammable. Gas detectors often report a percentage of the LEL to show how close the environment is to ignition. The correct phrase is Lower Explosive Limit. The other options pair similar-sounding words with concepts that don’t describe flammability limits—level implies a different idea, emission relates to outputs rather than mixtures, and energy is a separate concept entirely.