Improving compressed air quality: through filter and dryer systems

Dust, pollen, aerosols, viruses and bacteria: The ambient air is never pure. In addition, the air quality in the workshop can be contaminated by other pollutants, such as welding fumes or paint mist, depending on the work being carried out. Compressed air treatment is therefore indispensable - not only to ensure adequate compressed air quality, but also to prevent premature wear of the machines.

Water, oil and dust reduce compressed air quality

The water, dust and oil content in the compressed air is an indicator of the quality of the compressed air. While moisture and dust enter the compressed air with the ambient air drawn in, oil can be introduced into the compressed air via the compressor during the compression process. In any case, the compressed air generated must be processed using special components and devices in order to achieve the quality required for the relevant application. These include:

• Filters (coarse filters, fine filters, nanofilters)
• Dryers (refrigerant dryers, membrane dryers, adsorption dryers)
• Oil-water separator
• Cyclone separator

Filter systems for solid particles

Filter systems are used in compressors at different points. The purpose of the intake filter is to filter solid contaminants such as dust and soot out of the air before it is compressed. It is important to keep these particles out of the compressed air system, as they can damage the downstream pneumatic application through deposits and abrasion. Activated carbon filters and nanofilters are used at a later stage of the compressed air process and remove solid particles as well as odours and vapours from the compressed air.

Dry compressed air and drain condensation

The ambient air is always enriched with more or less moisture, depending on the season and temperature. When the air is sucked in, moisture automatically enters the compressor. It becomes problematic when the moisture condenses and water thus enters the compression process, because this can lead to premature wear, rust and corrosion. The compressed air is therefore subjected to a drying process in order to lower the pressure dew point, which means the temperature at which the moisture contained in the compressed air would condense. Refrigerant dryers and membrane dryers are usually used for this purpose. While the former are usually used at the beginning of the compressed air system, the latter are often placed near the application, which means the extraction point as a so-called end-point dryer. Adsorption dryers are suitable for very large volume flows and achieve very low pressure dew points. The moisture created during the treatment process is removed from the compressed air using a cyclone separator.

The condensed water produced during compressed air generation is usually enriched with oil, which enters the compressed air either before or during the compression process. According to existing environmental regulations, the oil must be separated from the water and dirt components and disposed of separately. An oil-water separator is therefore an important component in the treatment process, which extracts the oil from the liquid using an activated carbon filter.

Compressed air treatment for better quality and less wear

Poorly prepared compressed air can lead to a variety of malfunctions. Premature wear of compressed air components and thus higher maintenance requirements and a shorter service life are often the result. In particular, too much residual moisture in the compressed air can cause long-term corrosion damage and, in unprotected, cold environments, even cause icing of pipes, lines and valves. Furthermore, the quality of projects or products created with compressed air can also be reduced by incorrectly prepared compressed air. For example, bubbles can be trapped during painting activities or sticking can occur in the production process when processing hygroscopic products that attract water, such as powders, spices, salt or sugar. Compressed air treatment should therefore be considered right from the start and integrated into the planning process of a compressed air system. This is the only way to ensure that you not only have the required pressure in the vessel, but that your compressed air quality also meets the highest demands.