What is the lower flammable limit of propane expressed as a percentage?

What is the lower flammable limit of propane expressed as a percentage?

• A. 1%
• B. 2.15%
• C. 3%
• D. 4%

Answer: (B)

The main idea here is the lower flammable limit, which is the smallest fraction of propane that must be present in air to allow ignition. This threshold is about 2.15 percent by volume. When propane is in the air at around or above this level, a spark or flame can ignite the mixture; below it, the mixture is too lean to burn. This concept is crucial for safety because propane is heavier than air and can accumulate in low spots, so proper ventilation and controlling ignition sources are essential. The other numbers don’t match the defined starting point of flammability: they’re either below the threshold or simply not the lowest concentration that can sustain ignition.

The main idea here is the lower flammable limit, which is the smallest fraction of propane that must be present in air to allow ignition. This threshold is about 2.15 percent by volume. When propane is in the air at around or above this level, a spark or flame can ignite the mixture; below it, the mixture is too lean to burn. This concept is crucial for safety because propane is heavier than air and can accumulate in low spots, so proper ventilation and controlling ignition sources are essential. The other numbers don’t match the defined starting point of flammability: they’re either below the threshold or simply not the lowest concentration that can sustain ignition.