The air that we breath and around us is in general a mixture of gases with a certain level of humidity. This mix of humid gases may contain steam and air.
Steam may be exchanged by other condensable elements, air by specific gases.
The dew point is defined as the temperature of a humid gas in condition of equilibrium where condensation and vaporization is in balance. The gas is therefore just saturated.
The dew point of compressed air at 6 bar is -40 °C. This dew point should be used to avoid water in the pneumatic system and/or water drops on plastic parts, when blown off.
To assure an efficient drying of plastic resins, the used heated air should provide a dew point of 0 °C.
This glossary of plastic industry is provided by PLEXPERT Canada Inc.