Moisture in the air can cause fish eyes in paint and clog media blaster nozzles. Two of the most common dryer types are refrigerated and desiccant, the main difference between these two types is the drying agent inside the machine.
Cycling and non-cycling are the 2 sub-categories of Refrigerator Dryers. A non-cycling dryer runs all the time whereas a cycling dryer goes between secondary cooling fluids and then shuts off while the fluid dries the air. Refrigerated dryers are a low-cost option in terms of setup, operation and maintenance, they are resistant to airborne particles but the disadvantage is that they have minimal dew point capacity. Dew point is the temperature when the water and the airlines will start to condense.
They can be unheated, heatless, externally heated or internally heated. With a desiccant dryer, the air flows through one of the towers that then absorbs any moisture due the drying agents. The opposing tower is offline and being regenerated with purged air.
The have a better dew point capacity than refrigerated dryers. They can be used in remote hazardous environments, they tend to have high setup costs, and the desiccant bed needs to be replaced every three to five years. They will also require more filtration for airborne oil vapor and particulate carryover. Lastly they require source of purge air. Some consume purge air from the compressed air system which can make them less efficient than refrigerated dryers.