Which fuel gas has the largest explosive range in air?

Which fuel gas has the largest explosive range in air?

• A. Acetylene
• B. Hydrogen
• C. Propane
• D. Methane

Answer: (A)

Flammability range is the span of air-to-fuel mixtures that can ignite and sustain a flame. It sits between the lower explosive limit (lean side) and the upper explosive limit (rich side). Acetylene has the broadest range because it can form ignitable mixtures over a wide spectrum—from fairly lean up to quite rich compositions. Its lower limit is only a few percent in air, and its upper limit is high (many tens of percent, often cited around 80% acetylene in air). The other fuels burn in much narrower bands, so their explosive ranges are smaller. This wide tolerance to mixture ratios makes acetylene the correct choice.

Flammability range is the span of air-to-fuel mixtures that can ignite and sustain a flame. It sits between the lower explosive limit (lean side) and the upper explosive limit (rich side). Acetylene has the broadest range because it can form ignitable mixtures over a wide spectrum—from fairly lean up to quite rich compositions. Its lower limit is only a few percent in air, and its upper limit is high (many tens of percent, often cited around 80% acetylene in air). The other fuels burn in much narrower bands, so their explosive ranges are smaller. This wide tolerance to mixture ratios makes acetylene the correct choice.