Dew-point transmitters are calibrated to measure dew point against a chilled mirror reference hygrometer at various dew-point temperatures across their range. The more calibration points provided across the range provides a guarantee of accuracy across that range.Dew point temperature is an important measurement for many industrial processes because it tells operators at what temperature liquid water will condense. In applications such as compressed air used for medical gases, as an example, its important the gas is kept dry to avoid liquid water condensing in the pipework to avoid blockages or the growth of mold.Dew-point transmitters work through impedance. The sensor consists of layers two electrodes either side of an absorbent layer. As the gas passes over the sensor, the technology absorbs water vapor onto a porous hygroscopic dialectric area between two conductive layers built on top of a base ceramic substrate. Water molecules changes dielectric constant (Ke) of the dialectric which causes a change in impedance of the sensor