Charlotte Compressor

FAQ: The Benefits of Aftercoolers and Coalescing Filters

In the natural air, moisture is present even if you live in an area with low humidity. The problem is, water vapor will return to its liquid state when the air in a compressed air system gets too cold which can cause a plethora of issues throughout the entire operation. Before air dryers for compressed air systems were implemented, manufacturing operations faced problems such as rust, texture inconsistencies, and corrosion because of excess water in the system.

To help avoid these devastating problems, the demand for water vapor-free air has risen, and many solutions were established to provide operations with water-free air that is safe for all uses along the operation.

Today we’ll look at two of the most effective tools to combat moisture: coalescing filters and aftercoolers.

Coalescing Filters

Coalescing filters work to eliminate individual water droplets, compressor lubricant, and various other particles; however, they don’t’ remove water vapor from the compressed air system. The coalescing process follows this sequence: air enters into the system through the filter housing and then flows through the filter cartridge. The coalesced liquid comprised of water and oil then collects into the drainage bowl while the clean air exits through the outlet port.

Depending on the application, you may need to install multiple coalescing filters at different points of the compressed air system.

You should install coalescing filters downstream of the receiver tank. The distance between the two components doesn’t really matter, but for convenience sake, you should consider keeping them close to one another.


Aftercoolers work to the reduce the temperature and water content of compressed air which results in cleaners, water-free air that is safe for most applications. Experts advise that every compressed air system have an aftercooler installed directly after the compressor to remove condensed water from the system immediately.

This is vital to the life and performance of the compressed air system. For example, as air at 68°F enters a 3500 scfh compressed air system and then exits at 248°F, it will release around 13 gallons of water per day throughout the entire air distribution system.

Aftercoolers can significantly reduce the amount of water that enters into your compressed air system and will save your tools and equipment from corrosion, rust, and the growth of micro-organisms. Aftercoolers typically come in two varieties: air-cooled and water-cooled.

Air-cooled aftercoolers will require more ventilation space to keep the compressor running with optimal temperature ranges. On the other hand, water-cooled systems will need less ventilation space