Which statement best describes the flammable range?

Which statement best describes the flammable range?

• A. The percentage of gas or vapor concentration in air
• B. The portion of a mixture that will evaporate at room temperature
• C. The interval of air concentrations at which ignition can occur
• D. The total volume of vapor produced by a substance

Answer: (C)

The flammable range is the interval of fuel-air concentrations in which ignition can occur. It’s defined by the lower and upper explosive limits: below the lower limit the mixture is too lean to ignite, and above the upper limit it’s too rich to burn. Only within this range can a flame or spark trigger combustion. The other statements describe concentration or vapor behavior without addressing whether ignition is possible.

The flammable range is the interval of fuel-air concentrations in which ignition can occur. It’s defined by the lower and upper explosive limits: below the lower limit the mixture is too lean to ignite, and above the upper limit it’s too rich to burn. Only within this range can a flame or spark trigger combustion. The other statements describe concentration or vapor behavior without addressing whether ignition is possible.