When pressure sensors come into contact with hydrogen, this often results in difficulties. Unfortunately, I frequently 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 find out when we receive a complaint. But why do we get a complaint? Why is especially hydrogen so critical to pressure sensors?
A basic rule is that numerous metals become brittle when subjected to hydrogen. Hydrogen atoms that diffuse into 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 additionally pass through it by diffusion.
This has several effects: When piezoresistive measuring principles are used, 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 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 leads to a detuning of the bridge at the very least temporarily, producing a falsification of the measurement signal.
However, Idiot described above occur in various materials differently. Therefore the effects of hydrogen can 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 use hydrogen as the medium, your contact will gladly recommend an optimum solution for the application.