Which gas has a flammability range that includes 2-10 percent?

Which gas has a flammability range that includes 2-10 percent?

• A. CH4
• B. C3H8
• C. CO
• D. H2

Answer: (B)

Gases ignite only when their concentration in air falls between the lower and upper explosive limits, known as the lower explosive limit (LEL) and upper explosive limit (UEL). The LEL is the minimum concentration needed for ignition, while the UEL is the maximum concentration at which ignition can occur; outside this range, the mixture is too lean or too rich to burn. Propane has a flammability range of roughly 2% to 9–10% in air. That places the entire 2–10% span within its ignitable range, so mixtures from about 2% up to near 10% can ignite if an ignition source is present. Methane’s range is about 5–15%, so it does not cover the lower part near 2%. Carbon monoxide is flammable in air roughly 12–74%, which misses the 2–10% window. Hydrogen is flammable from about 4–75%, so the portion near 2% lies below its LEL. Therefore, propane best fits a flammability range that includes the 2–10 percent interval.

Gases ignite only when their concentration in air falls between the lower and upper explosive limits, known as the lower explosive limit (LEL) and upper explosive limit (UEL). The LEL is the minimum concentration needed for ignition, while the UEL is the maximum concentration at which ignition can occur; outside this range, the mixture is too lean or too rich to burn.

Propane has a flammability range of roughly 2% to 9–10% in air. That places the entire 2–10% span within its ignitable range, so mixtures from about 2% up to near 10% can ignite if an ignition source is present. Methane’s range is about 5–15%, so it does not cover the lower part near 2%. Carbon monoxide is flammable in air roughly 12–74%, which misses the 2–10% window. Hydrogen is flammable from about 4–75%, so the portion near 2% lies below its LEL.

Therefore, propane best fits a flammability range that includes the 2–10 percent interval.