Humidity Sensor


Humidity Sensor
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- Tyre of Humidity Measurement Methods

① Absolute Humidity

Absolute humidity is the amount of water vapor contained in the atmosphere, it shows the mass of water vapor per unit volume(g/m³). Use units of grams per cubic meter or pounds per cubic feet. This value varies with atmospheric pressure, so it is not often used in engineering.
The mass of water vapor per unit volume of gas, and absolute humidity means the density of water vapor content. Absolute humidity uses grams per cubic meter or pounds per cubic feet. This value varies with atmospheric pressure, so usually it is not used in engineering.

② Relative Humidity

Relative humidity of air is defined as the ratio of the vapor pressure of air to its saturation vapor pressure.
At temperatures above the boiling point, the atmospheric pressure is equal to the vapor pressure of the water because the water pressure replaces the pressure of all other gases in the enclosed space.
Therefore, the saturation pressure cannot be greater than atmospheric pressure because the relative humidity cannot exceed 100% at temperatures above 100℃.
Therefore, at a temperature of 100°C at normal atmospheric pressure, the relative humidity is 100%, and at 200°C, it is only 6%.

③ Dewpoint Temperature

The pressure of water vapor is maximum or the temperature of saturated steam.
In other words, when a mixture of gas-water vapor is cooled under constant pressure, it is defined as the temperature at which frost or ice is produced, meaning the temperature at which the relative humidity is 100%.
When the temperature is lowered to the dew point, the air is saturated, resulting in fog, dew, or frost.

④ Type of Humidity Sensor according to the measurement method

Our humidity sensor is “Capacitive Humidity Sensor”. Humidity is measured through relative humidity, which expresses the amount of water vapor in the air compared to the maximum amount of water vapor at the current temperature.
He unit used is %RH. Humidity Sensor is widely used as a Temp/Humidity Sensor that can measure the temperature by using the electrical properties that change as water molecules are absorbed.

Large Classification
Middle Classification
Measurement Method
Principle of measurement
· Direct Measurement · Saturation Method · Dew Point Humidity Sensor · Dew Point
· Lithium Chloride Dew Point Humidity Sensor · Transition Point Temperature
· Absorption Method · Volume Humidity Sensor · Water Vapor Volume
· Electrolytic Humidity Sensor · Electrolytic Current of Absorbed Water
· Gravimetric Humidity Sensor · Weight Change of Adsorbent
· Evaporation Method · Dry and Wet Bulb Humidity Sensor · Determination of Cooling by Evaporation
· Indirect Measurement · Moisture adsorption Method · Hair-Tension Humidity Sensor · Hair Length Change
· Carbon Film Humidity Sensor · Changes in Electrical Conductivity
· Resistance Humidity Sensor · Change in Surface Conductivity
· Capacitance Humidity Sensor · Change in Dielectric Constant
· Color Humidity Sensor · Discoloration
· Spectroscopic Method · Near-Infrared Humidity Sensor · Near Infrared Absorption
· Other Method · Microwave Humidity Sensor · Dielectric
· Diffusion Humidity Sensor · Pressure Difference Due to Diffusion Rate Difference
· Dischage Type Humidity Sensor · Change in Ionization Potential

Please look high-quality, precise and stable SENTECH ENG's humidity sensor.