There are two main methods of humidity measurement: wet and dry bulb and electronic humidity sensor. The two schemes are compared below, so that customers can choose suitable humidity measurement methods.
The maintenance of wet and dry ball is quite simple. In practice, it is only necessary to add water to the wet ball and change the wet ball gauze regularly. Compared with the electronic humidity sensor, the wet and dry bulb method does not cause aging and accuracy degradation. Therefore, the wet and dry bulb method is more suitable for high temperature and harsh environment.
Electronic humidity sensor has developed rapidly in recent 20 years. Before leaving the factory, humidity sensor manufacturers should use standard humidity generator to calibrate one by one. The accuracy of electronic humidity sensor can reach 2% - 3% RH.
In practical use, due to the influence of dust, oil and harmful gases, the humidity sensor will be aged and its accuracy will be reduced after a long time of use. The annual drift of humidity sensor is generally about ± 2%, or even higher. In general, the manufacturer will indicate that the effective service time of one calibration is 1 year or 2 years, and it needs to be recalibrated when it expires.
Generally speaking, the long-term stability and service life of electronic humidity sensor are not as good as that of dry and wet bulb humidity sensor.