Dryers remove water vapor from compressed air to protect downstream components from damage caused by traces of moisture in the air supply. Moisture reduces the quality of compressed air delivered to air tools and can cause corrosion and freezing in air supply lines. Dryers function by dropping the dew point of the compressed air, which is the temperature at which the air is saturated with more water vapor than it can hold. When the dew point is reached the air produces condensation, or dew.