What is the explosive range of methane in air?

What is the explosive range of methane in air?

• A. 0% to 5%
• B. 5% to 10%
• C. 10% to 20%
• D. 5% to 15%

Answer: (D)

Explosive range is the concentration window in which methane mixed with air can ignite and explode. This window is defined by the lower explosive limit (LEL) and the upper explosive limit (UEL). For methane in air, the LEL is about 5% by volume and the UEL is about 15% (often cited as 15–16%). Within roughly 5% to 15% methane in air, ignition is possible; below 5% the mixture is too lean to burn, and above 15% it’s too rich to ignite. That’s why the best answer is 5% to 15% — it covers the full combustible range. The other ranges miss part of the range, either excluding the lower limit or the upper limit.

Explosive range is the concentration window in which methane mixed with air can ignite and explode. This window is defined by the lower explosive limit (LEL) and the upper explosive limit (UEL). For methane in air, the LEL is about 5% by volume and the UEL is about 15% (often cited as 15–16%). Within roughly 5% to 15% methane in air, ignition is possible; below 5% the mixture is too lean to burn, and above 15% it’s too rich to ignite. That’s why the best answer is 5% to 15% — it covers the full combustible range. The other ranges miss part of the range, either excluding the lower limit or the upper limit.