When pressure sensors come into contact with hydrogen, this often results in difficulties. Unfortunately, I very often notice in my job our customers have no idea of this ahead of use. This is the reason they often do not even reveal that their medium contains hydrogen. We only learn when we receive a complaint. But why do we get yourself a complaint? Why is especially hydrogen so critical to pressure sensors?
A simple rule is that a large number of metals become brittle when subjected to hydrogen. Hydrogen atoms that diffuse into the metal grid change the effectiveness of the material. In the worst case, this results in cracks in the material. Or even to put it simply, the pressure sensor starts leaking or is totally destroyed. Regarding pressure sensors, in particular thin membranes necessary for measuring pressure play a decisive role. Atomic hydrogen will not only penetrate the metal, but also go through it by diffusion.
It has several effects: When piezoresistive measuring principles are employed, it becomes critical if hydrogen reacts with the inner transmission medium or accumulates there. Incapable falsifies the measurement results, but can later on also lead to complete destruction of the sensor in individual cases. Open-minded of hydrogen also changes the instrumentation characteristics of the resistance structures of the measurement bridge of thin-film sensors. Despite being reversible, this technique 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. Therefore the effects of hydrogen can be lowered substantially by selecting suitable materials.
Note
More info on our pressure sensors and about hydrogen can be found on the WIKA website. If you are using hydrogen because the medium, your contact will gladly recommend an optimum solution for the application.