Humidity Measurement - Basics and Instrument used for humidity measurement


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3 types of Humidity

Relative Humidity
Absolute Humidity
Dew point

Relative Humidity can be defined as the the actual quantity of water vapor present in a given space expressed as a percentage of the quantity of water vapor that would be present in the same space under saturated conditions at the existing temperature

Absolute humidity can be defined as mass of vapor per unit mass of dry gas

Dew point can be defined as the saturation temperature of the mixture at the corresponding pressure.

Methods used to measure humidity
Relative Humidity Measurement
1.Mechanical
2.Wet and dry bulb thermometers
3.Surface resistivity devices
4.Crystal frequency change

Absolute Moisture Measurement
1.Gravimetry
2.Electrolysis
3.Infrared
4.Conductivity
5.Capacitance

Dew point measurement
1.Chilled mirror
2.Lithium Chloride
3.Wet bulb thermometer