# Refrigeration dryer

A refrigeration dryer removes water from compressed air by cooling the air so that its water vapour condenses, then draining the condensate away; it does not reach the much lower dew points of an adsorption dryer.

The dryness it reaches is stated as [pressure dew point](https://library.ultracontrolo.com/glossary/pressure-dew-point/), and ISO 8573-1 classes compressed air by its water content among other contaminants. Where drier air is needed, an [adsorption dryer](https://library.ultracontrolo.com/glossary/adsorption-dryer/) passes the air through a desiccant instead.

ULTRASEC is the refrigeration dryer in the Ultra Controlo range. Its aluminium heat exchanger accepts inlet air up to 70 °C, or 100 °C in the ULTRASEC-HT version, a hot gas bypass valve keeps the dew point constant, and the control panel has a digital temperature indicator and an electronically controlled condensate drain. An ULTRASEC refrigeration dryer is part of the ULTRAAR SCA modular medical air unit.

## Sources

- [ULTRASEC datasheet, p. 1 and p. 2](https://www.ultracontrolo.com/products/ultrasec)
- [ULTRAAR SCA datasheet, p. 2](https://www.ultracontrolo.com/products/ultraar-sca)
- [Ultra Controlo, Medical gas answers: refrigeration vs adsorption dryer](https://www.ultracontrolo.com/medical-gas-answers)
- [ISO 8573-1:2010, Compressed air, purity classes (ISO summary)](https://www.iso.org/standard/46418.html)

Reviewed: 2026-10-22. Ultra Controlo engineering. https://library.ultracontrolo.com/glossary/refrigeration-dryer/