When pressure sensors touch hydrogen, this often results in difficulties. Unfortunately, I very often notice in my job our customers have no idea of this prior to use. This is why they often usually do not even reveal that their medium contains hydrogen. We only learn when we receive a complaint. But why do we get a complaint? Why is especially hydrogen so critical to pressure sensors?
A simple rule is that a lot of 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 totally 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 Crazy , this process results in a detuning of the bridge at the very least temporarily, producing a falsification of the measurement signal.
However, the effects described above occur in various materials differently. Which means that the consequences of hydrogen can be lowered substantially by selecting suitable materials.
Note
Further information on our pressure sensors and about hydrogen can be found on the WIKA website. If you are using hydrogen as the medium, your contact will gladly recommend an optimum solution for your application.