What is the lower explosive limit (LEL)?

The lower explosive limit (LEL) is defined as the lowest concentration of a particular vapor or gas in the air that can ignite and sustain combustion. In practical terms, it represents the minimum amount of flammable substance needed mixed with air for an explosion or fire to happen when a proper ignition source is applied. If the concentration of the vapor in the air falls below this level, there won't be enough combustible material present to support a fire, even if there is an ignition source.

This concept is crucial in hazardous materials management because it helps identify safe operating conditions and potential risks in environments where flammable gases are used or stored. Monitoring the LEL can prevent situations where an accumulation of flammable substances could lead to dangerous explosions or fires. Understanding the LEL is therefore fundamental for safety protocols in handling and storing hazardous materials.