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 job that our customers are not aware of this ahead of use. This is exactly why they often do not even tell us that their medium contains hydrogen. We only learn when we get a complaint. But why do we get yourself a complaint? How come especially Harsh 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 effectiveness 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 will not only penetrate the metal, but also pass 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 technique results in a detuning of the bridge at the very least temporarily, producing a falsification of the measurement signal.
However, the effects described above occur in different materials differently. Therefore the consequences of hydrogen can 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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