Atlas Copco FD series Air Dryers

FD series Air DryersWhat is a refrigerant dryer?


A refrigerant dryer, such as the range of FD series Air Dryers, uses a refrigerant circuit and heat exchanger(s) to pre-cool air, refrigerate it to condense out moisture vapor, and then re-heat the air to prevent pipe sweating downstream. Refrigerant dryers can lead to a pressure dewpoint (PDP) as low as +3°C/+37.4°F for many applications where there is a need for dry air. They can be used at different pressures and consume no processed compressed air.


Main types of refrigerant dryers on the market


  • Direct expansion dryers
  • Fixed speed non-cycling dryers run continuously irrespective of varying load conditions.
  • Fixed speed cycling dryers shut down at lower loads to save energy and restart when required.
  • Variable speed dryers are on the cutting edge of energy efficiency. They automatically change the speed of the refrigerant compressor to adapt to varying loads.
  • Thermal mass dryers have a heat exchanger which typically contains a liquid thermal mass to store cold energy. Thermal mass dryers shut down when there is no or little air, or at low loads to save energy.
  • Digital scroll dryers have a refrigerant compressor that loads/unloads according to the demand.