During a heavy black smoke condition, the burner flame will be what color?

In a heavy black smoke condition, the burner flame typically appears dark orange. This is because the presence of an excess amount of fuel relative to the available air (a fuel-rich condition) leads to incomplete combustion. As a result, the flame produces a greater amount of soot, which gives it a darker color.

Dark orange flames indicate that there is not enough oxygen for the combustion process, causing the flame to appear less efficient and more sooty. Optimal combustion would ideally produce a blue flame, which indicates complete combustion with sufficient oxygen. However, in the case of heavy black smoke, the combustion is poor, resulting in that characteristic dark orange color associated with the inefficient burning of fuel.