Hydrogen and pressure sensors ? What should be observed?

When pressure sensors touch hydrogen, this often results in difficulties. Unfortunately, I frequently notice in my own job that our customers are not aware of this prior to use. Because of this , 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 a complaint? Why is especially hydrogen so critical to pressure sensors?
A basic rule is that a lot of metals become brittle when exposed to hydrogen. Hydrogen atoms that diffuse in to 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 totally destroyed. Regarding pressure sensors, specifically thin membranes necessary for measuring pressure play a decisive role. Atomic hydrogen will not only penetrate the metal, but also pass through it by diffusion.
This 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 down the road 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 reversible, this technique leads to 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. Which means that Sniveling of hydrogen can be lowered substantially by selecting suitable materials.
Note
More info 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 your application.

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