The compressed air is formed by compressing the ambient air. During this process, substances are taken with the ambient air and during the compression and delivery of the air, other substances are added.

• At the outlet of the compressor the air is saturated with water vapors which can reach 116°C. The air cools with the room temperature in the distribution lines and water condenses throughout the air distribution system. About 2/3 of the total water content of the air will be condensed when the air has cooled to 38°C. A condensate drain on the Air buffer will remove most of the water load from the system, additional filter located after the vessel will protect instrument after the tank. By adding a fridge dryer and filters located at end-use points which will be required to remove water condensed downstream from the main line filter, you will reach an air class 2.4.2 with a lubrificated compressor and 1.4.1 class with a non lubrificated compressor, which will be enough for certain application.
• The source of oil in compressed air is the compressor lubricant. To remove oil vapor from the air you can add an adsorption dryer after the fridge dryer with filtration adapted: just like water vapor, oil vapor will condense to liquid when the temperature reduced or the air pressure is increased at constant temperature. You can add also active carbon filter for residual oil vapor.
• To protect refrigerated dryer, you will need to use a coalescing pre filter to prevent oil and condensed water from entering the dryer. Oil entering dryer coats the cooling coil and reduces its efficiency, condensed water increases the cooling load and reduce dryer capacity.
• Desiccant dryer are very sensitive to water and oil droplets: water can saturate the desiccant and reduce its drying efficiency or even destroy it. Oil can coat the desiccant, rending it ineffective, that’s why it is always installed after adapted filtration and fridge dryer.
• Membrane dryers are sensitive to water and oil droplets. Oil can permanently damage the hollow fiber core. That’s why it’s always important to change filters, once per year. The filter cartridge can continue to coalesce indefinitely, but solids loading in the depth of the cartridge will cause a pressure drop. The element should be changed when the pressure drop reach 10 psi.