What is the air to propane ratio?

• A. 96% propane to 4% air
• B. 4% propane to 96% air or 1:24
• C. 50% propane and 50% air
• D. 1:1

Answer: (B)

Think of the air-to-propane ratio as how much air is mixed with propane. In a lean mixture like this, propane is a small part of the whole, about 4%, with the rest being air (96%). That means for every 1 part propane, there are 24 parts air, so the air-to-propane ratio is 24:1, and the propane-to-air ratio is 1:24.

The option that states 4% propane to 96% air (which corresponds to a propane-to-air ratio of 1:24) matches this common lean mixture description. It correctly reflects the relative amounts in the mix, unlike 50/50 or 1:1 options which would imply far more propane than is typical in such contexts.