Page 15 - PNEUMATIC AND HYDRAULIC

1.2 Air dehydration

In pneumatic systems, compressors draw in ambient air that always contains some

amount of water vapor. The process of compressing air to around 100 psi raises the
air’s temperature, but also dew point and water-holding capacity. Any subsequent

cooling downstream will likely cause some water vapor to condense. Liquid water in

pneumatic systems creates problems such as corrosion and bacteria growth, which,
in turn, leads to sluggish controls or component breakdowns. Thus, air dryers are

often needed to mitigate water issues.

In a typical system, air flows from the compressor to an aftercooler that lowers the
temperature, causes condensation and removes the majority of water. Sometimes

coalescing filters are installed to remove additional water. But if a circuit requires

further treatment, air dryers are a must. They remove most or all of the water in
compressed air before it reaches critical components or processes.

Figure 1.7: Air dehydration system

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