What is the color of the flame when an atmospheric gas fired burner is burning fuel properly?

The color of the flame from an atmospheric gas-fired burner when it is burning fuel properly is blue. A blue flame indicates complete combustion, which means that the fuel is being burned efficiently with an adequate supply of oxygen. This blue coloration is a result of the high temperature at which the combustion process occurs and indicates that carbon and other unburned particulates are not present in significant amounts.

When a burner operates with a blue flame, this often signals minimal emissions of pollutants and the proper functioning of the burner. This blue hue is characteristic of natural gas flames, as natural gas typically burns cleanly under optimal conditions.

In contrast, other flame colors, such as yellow, red, or green, indicate incomplete combustion or the presence of impurities. For instance, a yellow flame can suggest that the burner is not receiving enough air or that there is a buildup of soot, which can lead to increased emissions and decreased efficiency.