When pressure sensors come into contact with hydrogen, this often results in difficulties. Unfortunately, I frequently notice in my own job our customers have no idea of this prior to use. For this reason they often do not even reveal that their medium contains hydrogen. Blushing find out when we receive a complaint. But why do we get yourself a complaint? How come especially hydrogen so critical to pressure sensors?
A simple rule is that numerous metals become brittle when subjected to hydrogen. Hydrogen atoms that diffuse in to the metal grid change the strength of the material. In the worst case, this results in cracks in the material. Or to put it simply, the pressure sensor starts leaking or is totally destroyed. Regarding pressure sensors, specifically thin membranes necessary for measuring pressure play a decisive role. Atomic hydrogen can not only penetrate the metal, but also go through it by diffusion.
This has several effects: When piezoresistive measuring principles are used, it becomes critical if hydrogen reacts with the internal transmission medium or accumulates there. This initially only falsifies the measurement results, but can later on also result in complete destruction of the sensor in individual cases. The addition of hydrogen also changes the instrumentation characteristics of the resistance structures of the measurement bridge of thin-film sensors. Despite being reversible, this process leads to a detuning of the bridge at the very least temporarily, resulting in a falsification of the measurement signal.
However, the effects described above occur in different materials differently. Because of this the effects of hydrogen could be lowered substantially by selecting suitable materials.
Note
More info on our pressure sensors and on the subject of hydrogen can be found on the WIKA website. If you use hydrogen as the medium, your contact will gladly recommend an optimum solution for your application.