Atlas Copco

Refrigerant Air Dryers
FD series (6-4000 l/s, 13-8480 cfm)

Why dry your compressed air?

Compressed air is used in a wide variety of industrial applications. Wherever it is used, compressed air must be clean and dry. Containing solid, liquid and gaseous contaminants, untreated compressed air poses a substantial risk as it can damage your air system and end product. Moisture, one of the main components of untreated air can cause corrosion in pipe work, premature failure of pneumatic equipment, product spoilage and more. An air dryer is therefore essential to protect your systems and processes

Limit the risks of moisture

When the air that surrounds us is compressed, its water vapor and particle concentration increases dramatically. For example, compressing ambient room air to 7 bar(e)/100 psig increases the vapor content or humidity by a factor of around 8, and subsequent cooling forms liquid water. The amount of water depends on the specific application. Compressed air can actually contain three forms of water: liquid water, aerosol (mist) and vapor (gas). An efficient means of removing water from compressed air is therefore vital.

Moisture in the air can be particularly problematic, causing:

Corrosion of compressed air piping.
 Damages & malfunction of air powered equipment.
 Compressed air leakages due to corroded pipes.
 Poor paint quality, deterioration of electrostatic painting processes.
 Deteriorated end product quality.

ISO quality air standard (ISO 8573-1:2010)

The quality of compressed air used in industrial processes is specified in the international standard ISO 8573-1. Untreated compressed air typically contains 3 types of contaminants: dirt, water and oil. The Quality Classes specify the maximum allowed limits.

What is a refrigerant dryer?

A refrigerant dryer 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.