Compressed air purification
Author : Richard Moore of Parker Hannifin
18 July 2012
Having identified the different types of contamination found within a compressed air system, the purification technologies available for its removal can now be explained.
Water separators are used to protect coalescing filters in systems where excessive cooling takes place in air receivers and distribution piping.Using mechanical separation techniques, water separators will remove in excess of 92% bulk liquid contamination.
Coalescing filters are probably the single most important purification equipment in a compressed air system. They are designed to not only remove aerosols (droplets) of oil and water using mechanical filtration techniques, but also to remove solid particulate to very low levels (as small as 0.01micron in size). Installed in pairs, the first filter is a ‘general purpose filter’ which protects the second ‘high efficiency filter’ from bulk contamination. The dual filter installation from Parker Domnick hunter ensures a continuous supply of high quality compressed air with the additional benefits of low operational costs and minimal maintenance.
Water vapour is removed from compressed air using an adsorption dryer. Adsorption dryers remove moisture by passing air over a regenerative desiccant material, which strips the moisture from the air. This type of dryer is extremely efficient and a typical pressure dew point for adsorption dryers is -40°C. As adsorption dryers are designed to remove only water vapour and not water in a liquid form, they require the use of coalescing filters to work efficiently.
Dust removal filters
Dust removal filters are used for the removal of dry particulates that may be carried over from the desiccant material in the dryer. They provide identical particulate removal performance to the equivalent coalescing filter and use the same mechanical filtration techniques to provide up to 99.9999% particle removal efficiency.