While the refrigeration air dryer low pressure is by far the most widely used category of compressed air dryer, it does not offer as low a dew point as can be attained with other categories. The big selling feature for the refrigeration air dryer low pressure is the the low initial investment in conjunction with a usually acceptable dew point for a wide range of industrial applications. 

The principle of operation is much like a typical home refrigerator or residential air conditioner system. The compressed air is cooled in an air-to-refrigerant heat exchanger down to about 350F. The moisture is condensed to a liquid state where it is removed by an internal separator and then drained from the unit with an automatic drain. The compressed air is then reheated in an air-to-air heat exchanger where the incoming compressed air first passes. This also pre-cools the incoming compressed air thus reducing the load on the refrigeration system.

This flow path allows the compressed air to exit the dryer with a pressure dew point of 350 to 400F. A lower dew point is not feasible with a refrigeration air dryer low pressure as the condensate would freeze at 320F or lower.

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