What does the term 'flammability range' refer to?

• A. The range of temperatures at which a substance can ignite
• B. The concentration range of vapor in air that can burn if ignited
• C. The amount of time a substance can remain ignited
• D. The maximum amount of liquid fuel that can be present without ignition

Answer: (B)

The term 'flammability range' specifically refers to the concentration range of vapor in air that can burn if ignited. This is crucial in understanding how flammable materials behave under various conditions. The flammability range, often expressed in terms of lower and upper limits, indicates the minimum concentration of vapor required to sustain a flame and the maximum concentration of vapor that can still support combustion.

If the vapor concentration is below the lower limit, there is not enough fuel to sustain combustion. Conversely, if the concentration exceeds the upper limit, there may be insufficient oxygen to support burning. Understanding this concept is essential for safety in environments where flammable substances are present, as it helps in assessing risks related to potential ignition sources and ensuring adequate ventilation to keep vapor concentrations within safe limits.