Which concentration range of methane in air is considered explosive?

Which concentration range of methane in air is considered explosive?

• A. 5% to 15%
• B. 0% to 5%
• C. 15% to 25%
• D. 25% to 35%

Answer: (A)

Methane in air forms an ignitable mixture only within a specific concentration window, known as the explosive limits. For methane, those limits are about 5% by volume on the low end and about 15% on the high end. Within this range, an ignition source can start a flame and the flame can propagate. Below the lower limit, there isn’t enough fuel to sustain combustion; above the upper limit, the mixture is too rich to burn because there isn’t enough oxygen to complete the reaction. So the explosive range is 5% to 15% methane in air. The other ranges are either too lean or too rich to be explosive.

Methane in air forms an ignitable mixture only within a specific concentration window, known as the explosive limits. For methane, those limits are about 5% by volume on the low end and about 15% on the high end. Within this range, an ignition source can start a flame and the flame can propagate. Below the lower limit, there isn’t enough fuel to sustain combustion; above the upper limit, the mixture is too rich to burn because there isn’t enough oxygen to complete the reaction. So the explosive range is 5% to 15% methane in air. The other ranges are either too lean or too rich to be explosive.