Classic argument: air humidity (referred to as humidity) is that the air moisture content and moisture levels of physical quantities. Humidity in daily life is often referred to as relative humidity, expressed in % RH (Relative Humidity), that is, the gas vapor pressure and its gas saturated vapor pressure percentage, its value shows how high the water vapor saturation. Relative humidity depends on temperature and the pressure of the system of interest. more water vapour is required to attain high relative humidity in warm or hot air.Temperature and humidity chamber in most cases referred to the relative humidity also refers to humidity.
In the environmental test chambers field. There are two ways of humidity data collection: the one is wet-bulb pluses, another is electronic humidity sensor.Now we introduce the advantages and disadvantages of the two methods for your reference.
1) Wet-bulb Pluses:
Reliable, simple technology
Easy to operate and maintenance
No calibration required
Easy to determine if malfunctioning (starts reading 100%)
Wicks are cheap to replace
There are two typical failure modes: wick needs changing or water supply is gone.
2) Electronic humidity sensor
No wick to change
Can read humidity below freezing and above boiling (although normal chambers can't control at these conditions)
Malfunction (loss of calibration) cannot be detected easily
Some times can be damaged by extreme temperatures
Can be damaged (temporary or permanent) by condensation (when operated near 100% RH)
Needs regular calibration (every 6 months)
Requires specialized equipment for proper calibration and adjustment
Accuracy varies depending on temperature
Expensive to replace
Since there are so many shortcomings of electronic humidity sensor, so it is not difficult to understand why the current mainstream temperature and humidity test chamber are like use wet-bulb pluses method of measuring humidity, rather than the use of electronic humidity sensor.It seems that sometimes new technology does not completely replace the old methods.