Using An Aftercooler With Filters Vs Using A Afercooler And Dryer With Filters?

aftercooler with filters
(Last Updated On: August 3, 2020)

A reader asks…”Can someone explain the differences between using an aftercooler with filters vs using a afercooler and dryer with filters?”

We responded:

Air compressors always generate warm or even very hot, moisture laden, compressed air.

If this hot, wet, compressed air is passed through an after cooler, the compressed air temperature falls and the compressed air can now “carry” less moisture. Water condenses, and the air naturally starts to become dryer as it passes through the after cooler. The same phenomenon can be experienced if the compressed air receiver is big enough to allow the compressed air to sit long enough to cool. It will de-water this way too, though an after cooler will cool the air much more quickly.

A general purpose compressed air filter will be installed downstream from the after cooler and it will strip much of the free water (actual liquid) from the air stream, furthering the work the after cooler has done.

At this point, and depending on how dry the compressed air has to be for your use (remember, the dryer it is the higher the cost to make it so) sometimes the compressed air is then passed through an air dryer.

Dryers work better with cooler compressed air, so it makes sense then, if your compressor is working hard and pumping really hot air into the mains, that this air gets passed through an after cooler and a compressed air filter before it gets to the dryer.

In order to get the compressed air dry enough for your application, you will place drying equipment between your application and the wet compressed air source, the compressor. Consider your compressed air wetness-treatment as a line from wettest to driest. At the “wettest” end you have the compressor, and the driest end the application that is using the air.

Working from the compressor to your application, you will commonly see after cooler(s), general purpose filters, refrigerant or desiccant air driers, more general purpose filters, point of use (often deliquescent) air dryers, more air filters and so on.

You keep treating your compressed air with the various types of air drying equipment available until it reaches your desired point dryness for your use.

That’s why some industrial plants have tons of “air-treatment” equipment, and others have less.

Hope this helps.



Hello, I am Bill, the Compressed-Air-Man. I have years of experience in industrial and residential compressed air applications, air compressors and general pneumatics. I created this site to help professionals, students, and DIYers understand and properly implement and maintain compress3ed air systems.


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