To produce one cubic metre of compressed air with an overpressure of 10 bar, a compressor has to suck in eleven cubic metres of ambient air. Together with this air, it also sucks in all the impurities it contains, just like a large vacuum cleaner: dust, fumes, oil vapour, chemicals, etc. Added to this is the natural air humidity.
Despite high-quality intake filters, all these components of the intake air are found in the compressed air. The substances that were distributed over eleven cubic metres of ambient air before compression are now concentrated in a single cubic metre of compressed air. To ensure troublefree operation, dirt, water and oil must therefore be separated from the compressed air.

Humidity
Compressed air contains moisture depending on the ambient conditions. Depending on the application, this moisture must be extracted from the compressed air. There are the following possibilities:

• Cyclone separator: removes free water droplets from the compressed air
• Refrigeration dryer: possible dew point up to max. +3 °C
• Adsorption dryer: possible dew point down to -70 °C.

Which drying is required in individual cases depends on the consumers operated.
Symptoms of incorrectly designed drying are moisture in the compressed air network, icing in winter or increased component wear due to corrosion.
To drain moisture from the compressed air system and dispose of it properly, it is recommended to use:

• Condensate drain
• Oil- Water separators
   

Solid impurities/oil
In addition to moisture, the compressed air is also contaminated with particles and oil. To remove these components, it is recommended to use filters such as:

• Coarse filter
• Microfilter
• Submicrofilter
• Activated carbon filter
• Activated carbon adsorber

By combining different preparation methods, the purity classes prescribed or recommended for the respective applications can be achieved.


Compressed air storage
Compressed air tanks are used to store the generated compressed air. The required size is determined by calculation.

Compressed air quality classes according to ISO 8573-1:2010

The overview is intended to provide a general recommendation for action; the use of various processing components must be assessed individually on a case-by-case basis. This overview makes no claim to completeness.
1) Achievable particle class provided that the piping and commissioning are carried out correctly.
2) Achievable total oil content depending on the intake air and the compressor oils used.
The compressed air classes refer to standard conditions. When generating oil-free compressed air, the intake air and ambient conditions also have an influence on the quality. Different service lives for AFC and ALM-AC must be taken into account.