Aftercoolers

Aftercoolers

The compressed air discharged from an air compressor is hot (fig. AC1-1). Compressed air at these temperatures contains large quantities of water in vapor form. As the compressed air cools this water vapor condenses into a liquid form. As an example if an aftercooler is not used, a 200 scfm compressor operating at 100 psig introduces 45 gallons of water into the compressed air system each day.

Learn more about the aftercoolers eCompressedair.com offers by viewing our product selection of aftercoolers. Compressor Outlet TemperaturesCompressor Outlet Temperatures.
Compressor Outlet Temperatures
Type of Compressor Average Outlet Air Temperature (°F) Average Outlet Air Temperature (°C)
Oil Flooded Rotary 200 93.3
Oil Free Rotary 350 176.6
2-Stage Reciprocating 300 148.8
Centrifugal 225 107.2
Figure AC1-1

Additionally by reducing the air temperature condensate forms. Most air aftercoolers are sized to cool the air to within 5°F to 20°F (2.7°C to 11°C) of ambient air temperature. As the compressed air cools up to 75% of the water vapor present condenses to a liquid and can be removed from the system.

A moisture separator installed at the discharge of the aftercooler removes most of the liquid moisture and solids from the compressed air. Utilizing centrifugal force, moisture and solids collect at the bottom of the moisture separator. An automatic drain should be used to remove the moisture and solids.