Refrigerant vs Desiccant Air Dryer

Why does compressed air need drying at all?

Compression raises the relative humidity, and cooling drops water out as condensate. This water rusts lines, washes the lubricating film out of cylinders and freezes valves in winter. The key figure is the pressure dew point: the temperature at which condensate forms again under working pressure. The lower the required dew point, the more effort the drying takes.

Refrigerant or desiccant dryer - which fits?

A refrigerant dryer cools the air to about 3 °C and separates the condensate, with a practical dew point around +3 °C. A desiccant dryer binds moisture to a drying agent such as silica gel and reaches -40 °C and below. Refrigerant units are cheap to run, while desiccant dryers deliver dry air for frost and process applications.

How do I size flow rate and pressure drop?

Size a dryer for the maximum flow rate at real conditions, not for the compressor rating on the datasheet. A higher inlet temperature and lower pressure cut the usable capacity sharply, so always apply the maker's correction factors. Plan a pre-filter against oil and particles as well, otherwise the desiccant or heat exchanger fouls.

• Determine the maximum flow in m³/h at working pressure and inlet temperature.
• Apply the temperature and pressure correction factors from the datasheet.
• Fit a pre-filter (particles and oil) and after-filter to match the purity class.
• Add a reserve of 10 to 20 percent for peaks and later expansion.

Frequently asked questions