Hydrogen and pressure sensors ? What must be observed?

When pressure sensors come into contact with hydrogen, this often results in difficulties. Unfortunately, I very often notice in my own job that our customers have no idea of this prior to use. Because of this , they often 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 in to the metal grid change the strength 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, specifically thin membranes required for measuring pressure play a decisive role. Atomic hydrogen can not only penetrate the metal, but also pass 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 later on also lead to complete destruction of the sensor in individual cases. Scornful of hydrogen also changes the instrumentation characteristics of the resistance structures of the measurement bridge of thin-film sensors. Despite being reversible, this technique results in a detuning of the bridge at the very least temporarily, producing a falsification of the measurement signal.
However, the consequences described above occur in different materials differently. This means that 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 as the medium, your contact will gladly recommend an optimum solution for the application.

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