Gas Fitter Practice Test

In a steam boiler system, what does the term "dry steam" refer to?

1. Steam with a low moisture content

2. Steam generated in a vacuum

3. Hot water at high pressure

4. Steam mixed with water vapor

The correct answer is: Steam with a low moisture content

The term "dry steam" refers specifically to steam that has a low moisture content, meaning it is essentially a vapor phase of water that has been heated to a point where it has transitioned from its liquid state, but without containing any liquid water droplets. In practical applications, dry steam is characterized by having high energy and efficiency because the absence of moisture means it carries more thermal energy and is ideal for heating processes or driving turbines. In contrast, steam that contains a significant amount of water droplets (often referred to as wet steam) would be less efficient, as the presence of liquid water can result in energy loss and can damage equipment if it enters turbines or heating systems. Therefore, dry steam is preferred in most steam boiler applications for its ability to transfer heat effectively without the complications that moisture contents introduce.