Air Treatment & Distribution

A complete treatment train typically includes: an aftercooler to cool discharge air, a refrigerated or desiccant air dryer to remove moisture to a target dew point, a coalescing filter to remove oil aerosols and fine particulates, a particulate filter for solid particles, and an oil-water separator for condensate disposal. Specific components depend on the air quality requirements of each end-use application.

A refrigerated dryer cools compressed air to approximately 35 to 50 degrees F using a refrigeration circuit, condensing moisture which is then drained automatically. The dried air is reheated slightly before delivery to prevent pipe condensation. Refrigerated dryers achieve a pressure dew point of around 38 degrees F — adequate for most automotive air tools, production equipment, and general shop air applications.

Desiccant dryers are needed when applications require very low dew points — typically below 32 degrees F, for piping through freezing environments, or in spray applications requiring ISO Class 1 air quality. They are also used for precision measurement equipment and any process where residual moisture is unacceptable. Desiccant dryers are more expensive to operate than refrigerated models.

A coalescing filter removes oil aerosols and fine water mist that pass through the dryer — particles as small as 0.01 micron. Oil contamination in air lines comes from the compressor lubrication system and shows up as oily residue in tools, staining in spray finishes, and contamination of sensitive equipment. A 0.01-micron coalescing filter is recommended after the dryer in any spray or precision application.

Automatic drains remove condensed moisture from filters, dryers, aftercoolers, and receiver tanks without manual intervention. Without automatic drains, accumulated water is pushed downstream into tools and processes. Timer-based and zero-loss electronic drains are available — zero-loss electronic drains are preferred in applications where compressed air waste must be minimized for energy efficiency.

Use properly sized main lines sloped slightly toward a drop leg and drain point. Install branch connections from the top of the main line to prevent liquid drainage into branches. Loop distribution systems equalize pressure in larger shops. Proper pipe sizing based on total flow, pipe length, and allowable pressure drop is critical — contact Alamo Equipment for layout consulting.

Aluminum compressed air piping is the modern standard — lightweight, corrosion-free, easy to reconfigure, and certified for rated pressure. Schedule 40 galvanized steel is cost-effective but can scale internally over time. PVC pipe should never be used for compressed air — it is rated for water only and can shatter under pressure. Copper is acceptable but expensive for large installations.