What is steam called when heat is added without increasing the moisture content?

• A. Wet steam
• B. Super heated steam
• C. Condensed steam
• D. Dry steam

Answer: (B)

When heat is added to steam without increasing its moisture content, it is referred to as superheated steam. This process occurs when steam is heated beyond its boiling point at a given pressure while remaining in a gaseous state. Superheated steam has a higher temperature than saturated steam, which is steam that is in equilibrium with its liquid form at the same pressure and temperature.

The significance of superheated steam lies in its applications, especially in sterilization processes where precise temperature control is essential. Superheated steam can penetrate materials more effectively and is less likely to condense, which can lead to effective disinfection without the risk of wetness that could be caused by saturated steam.

In contrast, wet steam contains moisture and is not ideal for processes requiring absolute dryness. Dry steam, while similar to superheated steam in that it does not contain liquid droplets, generally refers to steam that is close to its saturation point, rather than being heated further. Condensed steam is the result of steam cooling and turning back into liquid water, which is the opposite of the process described in the question. Thus, superheated steam is distinct in its ability to remain fully gaseous and at an elevated temperature without additional moisture, making it the correct answer.