Aftercooler

Aftercoolers are the heat exchangers installed at compressor discharge. They reduce hot compressed air from typical 200-350 deg F discharge temperatures down to roughly 15-20 deg F above ambient, which condenses around 60-70 percent of the inlet moisture out as liquid before it reaches downstream piping, dryers, and tools.

What it is

An aftercooler is either air-cooled (a finned-tube radiator with a fan) or water-cooled (a shell-and-tube heat exchanger plumbed to a cooling-water loop). Modern packaged rotary screws integrate the aftercooler in the cabinet. Standalone aftercoolers are common on industrial reciprocating installs, where the compressor block is supplied separately from cooling.

Why it matters

Without an aftercooler, hot wet air enters the receiver and distribution piping, condensing in unpredictable locations and overwhelming any downstream dryer. Aftercoolers do roughly 70 percent of the moisture-removal work in a properly designed system; the dryer cleans up the remaining 30 percent. Skipping the aftercooler doubles or triples dryer load.

How it is used in our catalog

All packaged rotary screw compressors and most industrial reciprocating compressors in our catalog include an integral aftercooler. Standalone aftercoolers are listed separately under accessories. Pair with downstream dryers for full moisture management.

Common questions

Air-cooled or water-cooled aftercooler?

Air-cooled is the default for indoor installs under roughly 500 SCFM and outdoor installs with adequate airflow. Water-cooled is standard for larger plants and any install where ambient heat rejection is constrained.

What is the approach temperature?

Modern aftercoolers approach within 15-20 deg F of the cooling-medium temperature. Tighter approach is achievable but costs heat-exchanger area.