What type of flame is indicative of incomplete combustion in gas burners?

A bright yellow flame is indicative of incomplete combustion in gas burners. This type of flame often occurs when there is an insufficient supply of oxygen, which leads to a mixture of unburned fuel and soot being produced. The yellow color is primarily due to the presence of tiny particles of carbon that are not fully oxidized during the combustion process, resulting in that distinct yellow-orange glow.

In contrast, a bright blue flame signifies complete combustion, with adequate oxygen leading to efficient burning of the gas, producing water vapor and carbon dioxide without excess soot. Flickering flames can indicate varying conditions but do not specifically denote incomplete combustion, while a soft green flame typically suggests the presence of certain metal compounds rather than reflecting combustion efficiency. Thus, the bright yellow flame is a clear sign of incomplete combustion, highlighting an issue with fuel efficiency and potentially dangerous carbon monoxide production.