NATE Gas Heating Practice Exam

Propane and butane are classified as heavier than air due to their molecular composition and the fact that, when released into the atmosphere, they tend to accumulate at ground level rather than rise. The specific gravity of propane is approximately 1.5, and for butane, it's about 2.0, both of which are significantly greater than that of air, which has a specific gravity of approximately 1.0. This property means that in the event of a leak, propane and butane can create potential hazards as they will settle in low-lying areas and can displace oxygen, leading to dangerous situations. Understanding this classification is crucial for safe handling and storage, as well as for mitigating risks associated with gas leaks or accidental releases.