Technical Standards and Safety Authority (TSSA) G3 Practice Exam

An indication of excessive primary air is a:

1. Quenched flame

2. Lifting flame

3. Luminous flame

4. Yellow flame

The correct answer is: Lifting flame

A lifting flame is an indication of excessive primary air in a combustion system. When there is too much primary air, the flame tends to burn higher than normal and can appear elongated or lifted away from the burner. This phenomenon occurs because the additional air increases the turbulence and mixes more completely with the fuel, which can lead to combustion efficiency issues and a hotter flame. In contrast, a quenched flame signifies insufficient air causing the flame to go out or diminish sharply at the burner surface due to an inadequate fuel-to-air ratio. A luminous flame indicates incomplete combustion, often caused by too little air, and tends to produce a yellow or orange hue due to the presence of unburned carbon particles. Similarly, a yellow flame typically results from inadequate air, leading to incomplete combustion. Therefore, a lifting flame serves as the primary indicator of excessive primary air.