Which statement correctly describes LPG's flammable range?

Which statement correctly describes LPG's flammable range?

• A. The flammable range is 0-1%
• B. The flammable range is 1.5-10%
• C. The flammable range is 5-15%
• D. The flammable range is 15-25%

Answer: (B)

Flammable range is the span of fuel concentration in air that can sustain ignition. For LPG, ignition is possible when the gas concentration in air is roughly between 1.5% and 10% by volume. Below about 1.5%, the mixture is too lean to burn; above about 10%, it’s too rich to support combustion. That’s why 1.5–10% is the best description. The other ranges fall outside the actual flammable limits, either being too lean or too rich to ignite reliably.

Flammable range is the span of fuel concentration in air that can sustain ignition. For LPG, ignition is possible when the gas concentration in air is roughly between 1.5% and 10% by volume. Below about 1.5%, the mixture is too lean to burn; above about 10%, it’s too rich to support combustion. That’s why 1.5–10% is the best description. The other ranges fall outside the actual flammable limits, either being too lean or too rich to ignite reliably.