Dew point is defined as temperature to which a gas (ex. air) must be cooled, at constant pressure, for water vapor to begin to condense to liquid water. In other words when the dew point temperature has been reached, the gas is fully saturated with water vapor. The term ‘pressure dew point refers to the Dew point temperature of a gas at pressures higher than atmospheric Pressure.
Why is the knowledge of dew point in compressed air Important?
The importance of dew point temperature in compressed air depends on the intended use of the air. In many cases dew point is not critical (portable compressors for pneumatic tools, gas station tire filling system etc). In some cases, dew point is important only because the pipes that carry the air are exposed to freezing temperatures, where a high dew point could result in freezing & blockage of the pipes. In many modern factories, compressed air is used to operate a variety of Equipment, some of which may malfunction if condensation forms on internal parts. Certain water sensitive process (e.g. Paint spraying) that require compressed air may have specific dryness specifications.