What does the lower flammable limit (LFL) indicate?

The lower flammable limit (LFL) indicates the minimum concentration of fuel vapor in the air required for ignition to occur. It represents the lowest percentage of fuel in the air that can sustain a flame. If the concentration of fuel vapor is below this limit, the mixture is too lean to burn, meaning there isn’t enough fuel present in the air to support combustion.

Understanding LFL is critical in fire safety and prevention, as it helps personnel assess risks associated with flammable gases or vapors in the environment. If the fuel concentration is above this limit, the mixture can ignite if an ignition source is present, highlighting the importance of maintaining safe concentrations of flammable materials in any operational setting.