Hydrogen and pressure sensors ? What should be observed?

When pressure sensors come into contact with hydrogen, this often results in difficulties. Unfortunately, I frequently notice in my own job that our customers have no idea of this prior to use. This is the reason they often 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?
Blushing is that a large number of metals become brittle when exposed 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 to put it simply, the pressure sensor starts leaking or is completely destroyed. Regarding pressure sensors, specifically thin membranes necessary for measuring pressure play a decisive role. Atomic hydrogen will not only penetrate the metal, but additionally 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. This initially only falsifies the measurement results, but can later on also lead to 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 results in a detuning of the bridge at least temporarily, producing a falsification of the measurement signal.
However, the consequences described above occur in various materials differently. Therefore the effects of hydrogen could be lowered substantially by selecting suitable materials.
Note
Further information on our pressure sensors and about hydrogen are available on the WIKA website. If you use hydrogen because the medium, your contact will gladly recommend an optimum solution for the application.

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