The flammable limits of methane by volume is...

Question 1 of 270705eccef9ebacbc34ba4d465a4

The flammable limits of methane by volume is 5% to 15%. If the combustible gas indicator reading is 50% when sampling a compartment containing methane, the flammable vapor concentration at the sample point is __________.

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Question 1 of 27070

🔍 Key Concepts

• Flammable (explosive) range of a gas (lower limit 5%, upper limit 15% for methane) • What a combustible gas indicator reading of 50% actually represents (percent of the lower explosive limit, not percent by volume) • How to convert a percent of LEL reading into an approximate volume percent of vapor

💭 Think About

• If the meter is calibrated so that 100% on the scale equals the lower explosive limit (LEL), what concentration in percent by volume does 100% represent for methane? • Once you know what 100% on the meter equals in percent by volume, how would you find the volume percent when the meter reads 50%? • Compare your calculated value with the flammable range (5%–15%); does your answer fall inside that range or somewhere below it?

✅ Before You Answer

• Confirm that the meter reading is percent of the lower explosive limit (LEL), not percent by volume. • Use a simple proportion between 100% of LEL (which equals 5% by volume for methane) and the meter’s 50% reading. • Verify that the final concentration you pick is less than 5% by volume but clearly related to it by a simple fraction.