Hydrogen and pressure sensors ? What must be observed?

When pressure sensors come into contact with hydrogen, this often results in difficulties. Unfortunately, I frequently notice in my own job our customers are not aware of this ahead of use. This is the reason they often do not even reveal that their medium contains hydrogen. We only find out 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 lot of 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, in particular thin membranes necessary for measuring pressure play a decisive role. Atomic hydrogen can not only penetrate the metal, but additionally go through it by diffusion.
This 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 down the road also result in complete destruction of the sensor in individual cases. Thug 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 least temporarily, resulting in a falsification of the measurement signal.
However, the consequences described above occur in various materials differently. This means that the effects of hydrogen can be lowered substantially by selecting suitable materials.
Note
Further information on our pressure sensors and on the subject of hydrogen are available on the WIKA website. If you are using hydrogen because the medium, your contact will gladly recommend an optimum solution for the application.

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