Final answer:
LFL and UFL represent the flammable concentration range in air.
Step-by-step explanation:
LFL stands for Lower Flammable Limit, which represents the minimum concentration of a flammable substance in the air that can ignite. UFL stands for Upper Flammable Limit, which represents the maximum concentration of a flammable substance in the air that can ignite.
Both LFL and UFL are related to the flammable concentration range in air. They are used to determine the safety limits for handling and storing flammable materials. Knowing these limits helps prevent potential accidents and ensures the safety of workers.