What is a Compressed Air Dryer?

A compressed air dryer is used to remove moisture from compressed air. Moisture in compressed air can cause several problems, including corrosion of pipes and equipment, as well as reduced efficiency and effectiveness of pneumatic tools and machinery.

There are several different types of compressed air dryers, but the vast majority work by using a process called adsorption to remove moisture from the air. Adsorption is the process by which molecules of a gas or liquid are attracted and held on the surface of a solid material.

One common type of compressed air dryer is a desiccant dryer. These dryers use a desiccant material, such as silica gel or molecular sieves, to adsorb moisture from the air.  As the compressed air passes through the air dryer or desiccant cartridge, the moisture is attracted to and held by the desiccant material.

Deliquescent compressed air dryers use a special absorbent desiccant table which absorbs the moisture. This is a hygroscopic substance that is used as a drying agent. Rather than adsorbing water, deliquescent desiccant adsorbs water and slowly dissolves. Instead of disposing of the desiccant, the deliquescent desiccant drains along with the condensate for a hassle-free desiccant experience.

Another type of compressed air dryer is a refrigerated air dryer. These dryers use a cooling system to lower the temperature of the compressed air, causing the moisture in the air to condense and separate from the air. The moisture is then collected and removed from the system. Refrigerated compressed air dryers do not require desiccant.

For all compressed air dryers except for refrigerated air dryers, the process of removing moisture from the air involves several steps. First, the compressed air is filtered to oil mist, vapor and other liquids that could degrade the desiccant. Next, the air is passed through the air dryer, where it is treated to remove the moisture. Finally, the dry air is filtered again to remove any remaining desiccant particles before it is sent to the end user. For refrigerated dryers that don't require desiccant, the particulate filter is installed prior to the dryer. A coalescing after-filter is installed after the refrig dryer to remove any final condensate.

Compressed air dryers are an important part of any compressed air system. They are the main reason the compressed air being used is clean, dry, and free of moisture. By removing moisture from the air, compressed air dryers help to prevent corrosion, improve the efficiency and effectiveness of pneumatic tools and machinery, and extend the life of the compressed air system.