Emerald Group Publishing Limited
Copyright © 2008, Emerald Group Publishing Limited
Environment control: humidity sensor copes with chemical interference
Article Type: Environment and safety From: Anti-Corrosion Methods and Materials, Volume 55, Issue 2.
Vaisala has introduced a new generation Vaisala Humicap relative humidity sensor, the Vaisala Humicap180R used in Vaisala industrial humidity transmitters. This new type of capacitive humidity sensor has been developed especially to cope with chemical interference. In most humidity measurement applications, the sensors are also exposed to chemicals other than water vapour.
Such vapours are present in most environments, even in normal office air. As the responses to some gases and vapours are very slow, in many cases several weeks or months, the effects are often described as “drift” or “ageing” of the sensor and not as chemical interference. The resistance of the Humicap180R to chemical interference has been achieved by developing a new type of chemical resistant polymer and a special new structure. The structure slows down the migration of adverse chemicals, or completely prevents them, from entering the active polymer layer.
The chemical resistant active polymer further contributes to the stability of the sensor, making it the recommended Vaisala sensor for relative humidity measurement. The new Humicap sensor has been tested both in laboratory conditions as well as in typical humidity sensor applications. The results show that the new polymer makes the sensor highly resistant to chemical interference and therefore provides improved long-term stability for the relative humidity measurement.
For more information, please visit the web site: www.vaisala.com