When pressure sensors touch hydrogen, this often results in difficulties. Unfortunately, I very often notice in my own job our customers have no idea of this prior to use. Because of this , they often usually do not even tell us that their medium contains hydrogen. We only learn when we receive a complaint. But why do we get a complaint? How come especially hydrogen so critical to pressure sensors?
A simple rule is that numerous metals become brittle when exposed to hydrogen. Hydrogen atoms that diffuse into 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 completely destroyed. In the case of 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.
It has several effects: When piezoresistive measuring principles are used, it becomes critical if hydrogen reacts with the inner 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 least temporarily, resulting in a falsification of the measurement signal.
However, the consequences described above occur in different materials differently. This means that the consequences of hydrogen can be lowered substantially by selecting suitable materials.
Note
Clueless on our pressure sensors and about 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.