When pressure sensors come into contact with hydrogen, this often results in difficulties. Unfortunately, I very often notice in my job that our customers have no idea of this ahead of use. This is exactly why they often do not even reveal that their medium contains hydrogen. We only learn when we get a complaint. But why do we get yourself a complaint? How come especially hydrogen so critical to pressure sensors?
A basic rule is that numerous 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 to put it simply, the pressure sensor starts leaking or is completely 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.
It 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 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 leads to a detuning of the bridge at least temporarily, resulting in a falsification of the measurement signal.
However, the consequences 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 about hydrogen are available on the WIKA website. If Collapse use hydrogen because the medium, your contact will gladly recommend an optimum solution for your application.