Indiana HazMat Operations Practice Test

Flammable range is the span of vapor concentrations in air that can ignite if an ignition source is present. It’s bounded by the lower flammable limit (the minimum concentration needed for ignition) and the upper flammable limit (the maximum concentration above which combustion can’t be sustained). A wider range means ignition is possible over a larger set of conditions, so there are more realistic scenarios where a flammable mixture can exist. That makes the substance more dangerous because, in many real-world environments, you could encounter a vapor concentration within that range. If the range is narrow, ignition only occurs within a small window, making flammable conditions less likely.