Refrigerant dryers remove water content from compressed air to reach the required dew point. Relative air humidity, which amounts to 100% before drying, decreases only to 21% (0.75g H2O) after the refrigerant dryer (for dew point +30C).

Compressed air that flows into the dryer has a temperature of +300C ÷ +450C and is initially cooled, in air/air pre-cooler, down to +140C ÷ +230C. Subsequently, compressed air is cooled down in the main cooler to the required +30C dew point.