Properties and Characteristics of Natural Gas
You may occasionally need to evaluate natural gas equipment or appliances for leaks or other hazards. You can learn a lot from the color and type of the gas flame produced by the appliance.
When burning cleanly and properly, natural gas emits a blue flame. The flame burns at the burner ports, and the flame cones appear as distinct shapes. A very small amount of yellow or orange may be present in the center of the flame.
Orange sparks in the flame indicate rust, dust and other foreign particles in the gas pipes, and do not affect the combustion process or pose a hazard.
A mostly yellow flame indicates that the air supply to the burning gas is insufficient. This can be a dangerous situation, so if you see a yellow flame, we recommend you shut off the gas source and notify the local gas utility through your dispatcher as soon as practicable.