The upper and lower concentrations of a vapor that will produce a flame at a given pressure and temperature are called?

The upper and lower concentrations of a vapor that will produce a flame at a given pressure and temperature are called?

• A. Flammable and explosive limits
• B. Lower flammable limit
• C. Upper explosive limit
• D. Autoignition range

Answer: (A)

This tests understanding of the flammable range of a vapor–air mixture. The two end points where combustion can be sustained are the flammable limits, also known as explosive limits. Between these limits, a flame can propagate when ignition is present. Below the lower limit, the mixture is too lean to burn; above the upper limit, it’s too rich to burn. The lower flammable limit and the upper explosive limit refer to each end of this range individually, while autoignition range is about ignition without an external flame. Using the combined term “flammable and explosive limits” correctly captures both ends of the range.

This tests understanding of the flammable range of a vapor–air mixture. The two end points where combustion can be sustained are the flammable limits, also known as explosive limits. Between these limits, a flame can propagate when ignition is present. Below the lower limit, the mixture is too lean to burn; above the upper limit, it’s too rich to burn. The lower flammable limit and the upper explosive limit refer to each end of this range individually, while autoignition range is about ignition without an external flame. Using the combined term “flammable and explosive limits” correctly captures both ends of the range.