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 job our customers have no idea of this ahead of use. Because of this , 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 a complaint? Why is especially Disastrous to pressure sensors?
A simple rule is that a large number 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 completely destroyed. In the case of pressure sensors, in particular thin membranes necessary for measuring pressure play a decisive role. Atomic hydrogen can not only penetrate the metal, but also go 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 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, resulting in a falsification of the measurement signal.
However, the consequences described above occur in various materials differently. Therefore 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 are using hydrogen as the medium, your contact will gladly recommend an optimum solution for your application.

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