Technical Standards and Safety Authority (TSSA) G3 Practice Exam

What could occur if a natural gas flame is adjusted to produce more than 11.9% carbon dioxide?

1. Carbon monoxide may be produced

2. Combustion efficiency will fluctuate

3. The flame will be noisy and lift off the burner

4. There will be little overall effect

The correct answer is: Carbon monoxide may be produced

When a natural gas flame is adjusted to produce more than 11.9% carbon dioxide, one significant risk is the potential for carbon monoxide production. This occurs because an increased amount of carbon dioxide in the combustion process indicates incomplete combustion. In complete combustion, the fuel (natural gas) combines adequately with oxygen to produce carbon dioxide and water as the primary by-products. However, if the flame is starved of oxygen or if there is insufficient heat, it can result in the formation of carbon monoxide. This gas is particularly dangerous as it is colorless, odorless, and highly toxic. The reference to the 11.9% carbon dioxide level is derived from optimal combustion efficiency, which is generally aimed to minimize the production of harmful by-products. Therefore, when carbon dioxide levels exceed this percentage, it serves as an indicator that combustion is not occurring as it should, leading to the formation of carbon monoxide as a byproduct. While other options may address aspects of combustion efficiency or flame characteristics, the direct relationship between high carbon dioxide levels and the risk of carbon monoxide production is paramount in ensuring safety and efficient operation in natural gas systems.