What is described as being found between the upper and lower flammable limits of a gas or vapor?

The term that refers to the range of concentration between the lower and upper flammable limits of a gas or vapor is known as the flammable/explosive range. This range is crucial for understanding the conditions under which a gas or vapor can ignite and sustain combustion.

The lower flammable limit (LFL) is the minimum concentration of the gas or vapor in the air that will ignite if an ignition source is present, while the upper flammable limit (UFL) is the maximum concentration of the gas or vapor that can still support combustion. If the concentration falls outside this range—either too low or too high—the mixture will not ignite.

This characteristic is essential for safety protocols in environments where flammable gases or vapors may be present, as it assists responders in assessing the risks associated with different concentrations during a hazardous materials incident. Understanding the flammable/explosive range helps emergency responders to implement appropriate safety measures and make informed decisions about evacuation, containment, and other response strategies.