OMEGA AIR A-DRY Series, Installation And Operating Manual

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1.3 Basics
Compressed air contains contaminants such as water, oil and particulates which must be
removed or reduced to the acceptable level based on specific application requirements.
Standard ISO8573-1 specifies air purity/quality classes for these contaminants. Humidity (water
vapour content) is expressed in the terms of Pressure Dew Point (PDP) where Dew point is the
temperature at which air is 100% saturated with moisture. When the temperature of the air
reduces to or below the dew point, condensation will occur. Reduction of water content down to
pressure dew point +3°C is usually achieved with refrigerant dryers while for lower pressure dew
points adsorption (also called desiccant) dryers are typically used.
1.4 Adsorption Dryers
Typical applications for the adsorption dryers are outdoor installations where the risk of freezing
occurs and applications with high quality requirements in terms of air dryness (PDP < +3°C) such
as the process air in process industry (food and beverage, pharmaceutical, electronic, chemical,
…).
The most common adsorption dryers are heatless regeneration adsorption dryers due to their
simplicity, reliability and relatively low investment costs.
1.5 Adsorption
Adsorption is a process where specific molecules adhere to the surface of a highly porous solid
(adsorbent/desiccant) by electrostatic and molecular forces. The adsorbent is normally formed
in sphere form beads. Process of adsorption takes place while air flows through column filled
with the beads. Rate of adsorption depends on several factors (type of adsorbent, relative
humidity, inlet temperature, contact time, face velocity) and therefore adsorption process is
usually set/optimized for every individual application.