NCCER Millwright Practice Exam

What is the second type of chemical dryer used in compressed air systems?

1. Refrigerant dryer

2. Desiccant dryer

3. Cyclonic dryer

4. Membrane dryer

The correct answer is: Desiccant dryer

The second type of chemical dryer used in compressed air systems is the desiccant dryer. This type of dryer operates by utilizing desiccant materials, which are substances that absorb moisture from the air. Desiccant dryers can effectively remove water vapor from compressed air to prevent corrosion and other moisture-related issues in pneumatic systems and tools. Desiccant dryers are particularly beneficial in applications requiring very low dew point temperatures, making them essential in environments where moisture can adversely affect processes or equipment. The key advantage of desiccant dryers lies in their ability to achieve a lower dew point than other dryer types, ensuring that air is as dry as possible. Refrigerant dryers, while effective in cooling the compressed air and condensing moisture, do not achieve the low dew points that desiccant dryers can. Similarly, cyclonic and membrane dryers serve different functions and are not classified within the chemical drying category that desiccant dryers fall under. Cyclonic dryers focus on separating liquid from gas using centrifugal force, while membrane dryers employ selective permeation to separate moisture from the air. Therefore, the classification of desiccant dryers as a chemical drying method makes it the correct choice in this context.