Canadian Entry To Practice (CETP) Practice Test

If a propane burner is operating with the ideal combustion ratio and additional air is introduced, what type of burn would occur?

1. Rich

2. Lean

3. Neutral

4. Partial

The correct answer is: Lean

When a propane burner operates with the ideal combustion ratio, it means that the fuel (propane) is mixed with the exact amount of air required for complete combustion. If additional air is introduced into the system, the mixture of propane and air becomes richer in oxygen relative to the amount of propane available for combustion. This leads to a lean burn condition. In a lean burn scenario, there is more air than is needed for combustion, which can result in increased efficiency and lower emissions of unburned hydrocarbons and carbon monoxide. However, too much air can also lead to incomplete combustion if the propane is insufficient, but within certain limits, it is characterized as lean burn due to the surplus air. Understanding the conditions that result in lean combustion is crucial for optimizing burner performance and mitigating potential issues like soot formation. Hence, the introduction of additional air transforms the combustion from ideal to lean, which is reflected in the correct answer choice.