Flame color and shape in a natural gas burner: what it can and cannot show

The visual appearance of the flame is a useful indicator, but it does not replace measurement with a flue gas analyzer.

Stable flame

A uniform and stable flame generally indicates good mixing and correct aerodynamic behavior.

Flame lift

It may be related to excessive air velocity or incorrect head positioning.

Pulsating flame

It may be associated with unstable pressure, poor mixing, or problems in the combustion chamber.

Limitations of visual assessment

We cannot reliably estimate CO or exact O₂ levels based solely on the color of the flame.