Hydrogen and pressure sensors ? What must be observed?

When pressure sensors touch hydrogen, this often results in difficulties. Unfortunately, I frequently notice in my own job our customers have no idea of this ahead of use. That is why they often usually do not even tell us that their medium contains hydrogen. We only learn when we receive a complaint. But why do we get yourself a complaint? How come especially hydrogen so critical to pressure sensors?
Super is that a large number of metals become brittle when exposed to hydrogen. Hydrogen atoms that diffuse into 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. In the case of pressure sensors, in particular thin membranes required for measuring pressure play a decisive role. Atomic hydrogen will not only penetrate the metal, but also pass through it by diffusion.
Great has several effects: When piezoresistive measuring principles are employed, it becomes critical if hydrogen reacts with the internal transmission medium or accumulates there. This initially only falsifies the measurement results, but can later on 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 process results in 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 consequences of hydrogen could 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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