Gas Fitter Practice Test

When venting spillage occurs and flue gases pass back through combustion zones, what change occurs?

1. Flue gases are hotter and rise faster through chimney

2. Flue CO2 gases are more efficient

3. Flue CO2 gases change to N2

4. Flue CO2 gases change to CO

The correct answer is: Flue CO2 gases change to CO

When venting spillage occurs, it indicates that flue gases are not properly exiting the system and instead are mixing back into the combustion zones. In this scenario, the combustion process is disrupted, leading to incomplete combustion of natural gas. This incomplete combustion results in the production of carbon monoxide (CO), a harmful byproduct. The presence of insufficient oxygen during combustion can prevent gases from fully converting to carbon dioxide (CO2). Consequently, while ideally CO2 is the primary gas produced during the combustion of hydrocarbons, when venting spillage happens, the combustion is less efficient, leading to an increase in CO production instead. Therefore, it's crucial for gas fitters to ensure that venting is functioning correctly to avoid such dangerous conditions, emphasizing the potential hazards associated with improper venting. This understanding is key for certification and safe practices in gas fitting.