In flooding, which statement best describes the immediate effect on the flame?

• A. The flame temperature tends to fall
• B. The flame temperature tends to rise
• C. The flame becomes more stable
• D. There is no effect on the flame

Answer: (A)

Flooding a flame with excess fuel creates a fuel-rich zone where there isn’t enough oxygen to burn all the fuel immediately. With limited oxidizer, combustion becomes incomplete, and a significant portion of the chemical energy goes into forming intermediate species and heating vaporized fuel rather than raising the flame’s temperature. The extra fuel also acts as a heat sink as it vaporizes and mixes with cooler surrounding gas, further lowering the local temperature. The immediate effect is a fall in flame temperature. A hotter flame would come from balanced or leaner conditions that allow more complete combustion, while flooding tends to reduce the temperature rather than improve stability.