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. Because of this , they often do not even reveal that their medium contains hydrogen. We only find out when we get a complaint. But why do we get yourself a complaint? How come especially hydrogen so critical to pressure sensors?
A simple rule is that a large number of metals become brittle when subjected 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. In the case of pressure sensors, in particular thin membranes required for measuring pressure play a decisive role. Atomic hydrogen can not only penetrate the metal, but additionally go through it by diffusion.
It has several effects: When piezoresistive measuring principles are used, 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. Courageous 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 least temporarily, resulting in a falsification of the measurement signal.
However, the effects described above occur in different materials differently. Which means that the consequences of hydrogen could be lowered substantially by selecting suitable materials.
Note
Further information on our pressure sensors and on the subject of hydrogen can be found on the WIKA website. If you are using hydrogen as the medium, your contact will gladly recommend an optimum solution for the application.

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