What does the term "lower explosive limit (LEL)" refer to?

The term "lower explosive limit (LEL)" refers specifically to the lowest concentration of a gas or vapor in air that can ignite and sustain combustion. When the concentration of a flammable substance in the air is below the LEL, there is insufficient fuel present to support a fire or explosion. This concept is critical for safety in environments where flammable materials are handled or stored, as it helps in determining safe operating conditions and ensuring adequate ventilation.

In practical applications, knowing the LEL allows engineers and safety personnel to implement measures to prevent dangerous situations, such as explosions or fires, by monitoring the concentration of gases and taking necessary actions if it approaches the LEL. Understanding LEL is vital for maintaining safety standards in industrial processes and storage areas.