Technical Standards and Safety Authority (TSSA) G3 Practice Exam

What are the lower and upper flammable limits of propane in air?

1. 2.0%-11.0%

2. 2.4%-9.5%

3. 4.0%-14.0%

4. 5.5%-14.5%

The correct answer is: 2.4%-9.5%

The lower and upper flammable limits of propane in air, typically expressed as a percentage by volume, indicate the range within which propane can ignite and sustain combustion when mixed with air. The correct answer identifies the lower flammable limit at 2.4% and the upper flammable limit at 9.5%. In this context, the lower flammable limit represents the minimum concentration of propane in the air required for combustion to occur; below this level, the mixture is too lean to ignite. Conversely, the upper flammable limit establishes the maximum concentration of propane that can exist in air while still allowing for combustion; above this level, the mixture is too rich and cannot sustain a flame. Understanding the flammability limits is essential for safety practices when working with propane in various applications, such as heating and cooking, as it helps in preventing potential fire hazards. Thus, the rationale behind choosing this range is grounded in well-documented safety data regarding propane's behavior in air.