What is the upper explosive limit of methane?

What is the upper explosive limit of methane?

• A. 12%
• B. 15%
• C. 17%
• D. 20%

Answer: (C)

The upper explosive limit is the highest concentration of methane in air that can still sustain a flame. Beyond this point, the mixture is too rich in fuel for enough oxygen to support combustion, so flame propagation can’t occur. For methane, this flammable range is commonly cited as about 5% to around 15% by volume, but many standard references list the upper limit as 17%, depending on temperature, pressure, and testing methods. So 17% is a commonly accepted upper limit under certain conditions, which is why it’s chosen as the correct answer.

The upper explosive limit is the highest concentration of methane in air that can still sustain a flame. Beyond this point, the mixture is too rich in fuel for enough oxygen to support combustion, so flame propagation can’t occur. For methane, this flammable range is commonly cited as about 5% to around 15% by volume, but many standard references list the upper limit as 17%, depending on temperature, pressure, and testing methods. So 17% is a commonly accepted upper limit under certain conditions, which is why it’s chosen as the correct answer.