How are the terms flammability range and explosive limits related, if at all?

Flammability range and explosive limits both refer to the concentration of flammable gases or vapors in the air that can support combustion. While they are closely related concepts, they are not interchangeable terms, as each describes specific parameters of flammability.

The flammability range indicates the range of fuel-to-air concentrations that can ignite. It is defined by a lower flammability limit (LFL), below which the mixture is too "lean" to ignite, and an upper flammability limit (UFL), above which it is too "rich" to support combustion.

Explosive limits refer to the specific ranges of concentration at which a substance can cause an explosion, typically under confinement. This is a more critical safety concern in some contexts since it can lead to violent reactions when ignition occurs.

Both concepts are crucial in understanding the risks associated with handling and using flammable materials. They share similar definitions in that they both denote ranges of concentrations but apply to different phenomena—combustion for flammability and explosion for explosive limits, which is why they should not be treated as interchangeable.