What is dew point?
Dew point is the temperature to which air must be cooled for water vapor in it to condense into dew or frost. At any temperature there is a maximum amount of water vapor that the air can hold. This maximum amount is called water vapor saturation pressure. Addition of more water vapor results in condensation.
Why is moisture problematic?Condensation in pressurized air is problematic because it causes blockages in pipes, machinery breakdowns, contamination and freezing.
What is the effect of pressure on dew point?
Air compression increases water vapor pressure and thus dew point. It is important to take this into consideration if you are bleeding the air to atmosphere before taking a measurement. The dew point at the measurement point will be different from the dew point in the process.
What is the typical range of dew point?
Dew point temperatures in compressed air range from ambient even down to -80 °C (-112 °F) in special cases. Compressor systems without air drying capability tend to produce compressed air that is saturated at ambient temperature. Systems with refrigerant dryers pass the compressed air through a cooled heat exchanger, causing water to condense out of the air stream. These systems typically produce air with a dew point no lower than 5 °C (41°F). Desiccant drying systems absorb water vapor from the air stream and can produce air with a dew point of -40 °C (-40 °F) and drier if required.
How is dew point reliably measured?
Download Vaisala Compressed Air eGuide or contact us for more information.
Miniature size dew point transmitters DMT143 and DMT143L are ideal choices when you want to measure dew point accurately in small compressed air dryers, plastic dryers, additive manufacturing and other OEM applications.
The Vaisala DRYCAP® Dewpoint Transmitter DMT152 is designed for measuring low dew point in OEM applications, even down to -80°C.
Condensation-resistant DMT340 is designed for industrial low-humidity applications
Vaisala HUMICAP® Dewpoint Transmitter DMT132 is an affordable dew point measurement instrument designed to verify the functionality of refrigerant dryers.