What do we call the range of gas or vapor concentration in air between flammability limits?

The term used to refer to the range of gas or vapor concentration in air between flammability limits is known as the flammable range. This range defines the concentrations of a substance in the air that can ignite and sustain combustion. It is specifically measured by the lower flammability limit (LFL) and upper flammability limit (UFL). When the concentration is below the LFL, the mixture is too lean to ignite, and when it is above the UFL, the mixture is too rich to burn.

Understanding the flammable range is crucial for safety in environments where combustible gases are present, as it helps in risk assessment and the implementation of safety measures. This knowledge aids firefighters and emergency responders in managing hazardous situations effectively.