New York Low Pressure Boiler Certificate of Fitness (COF) Practice Test

What effect does too much air have on a flame?

1. It makes the flame blue

2. It causes a white flame and can blow out the flame

3. It stabilizes the flame

4. It cools the flame

The correct answer is: It causes a white flame and can blow out the flame

When too much air is introduced into a flame, it can lead to a condition known as secondary combustion, which can have several effects on the flame's characteristics. The presence of excess air can dilute the combustible gases, leading to reduced temperature and incomplete combustion. This can cause the flame to burn less effectively, often resulting in a white or pale appearance rather than a strong, vibrant color. Additionally, when the air-to-fuel ratio is too high, the flame may become unstable and lose its sustaining characteristics, leading to a situation where the flame can be blown out. This results because the overall temperature drops and the flame does not have enough fuel to maintain combustion in the presence of excess air. Thus, the presence of too much air not only affects the visual aspect of the flame by making it appear white, but also impacts the flame's ability to remain lit effectively.