Millwright Level 1 Practice Exam

Oxidizing flames are rich in which gas?

1. Nitrogen

2. Acetylene

3. Propane

4. Oxygen

The correct answer is: Oxygen

An oxidizing flame is characterized by a higher concentration of oxygen compared to a neutral or carburizing flame. This flame type is used in various welding and cutting applications where a hotter flame is required to produce a clean cut or weld. In this scenario, the gas that contributes to an oxidizing flame is oxygen, which, when mixed with a fuel gas, facilitates a combustion process that excessively burns fuel, resulting in higher temperatures. In contrast, the other gases listed, such as nitrogen, acetylene, and propane, serve different functions in combustion processes. Nitrogen is generally an inert gas in this context and does not contribute to the flames. While acetylene is a fuel gas commonly used for producing an acetylene flame (which can be neutral or carburizing), it is not characteristic of an oxidizing flame. Propane is also a fuel source that can produce varying flame types depending on how it is mixed with oxygen, but by definition, it does not establish an oxidizing environment on its own. Thus, the presence of oxygen is essential in defining and producing an oxidizing flame.