When pressure sensors touch hydrogen, this often results in difficulties. Unfortunately, I very often notice in my own job that our customers are not aware of this prior to use. For this reason 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 hydrogen so critical to pressure sensors?
A basic rule is that numerous metals become brittle when exposed 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 completely destroyed. Regarding diaphragm seal , 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 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, resulting in a falsification of the measurement signal.
However, the effects described above occur in different materials differently. Because of this 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 are available on the WIKA website. If you are using hydrogen as the medium, your contact will gladly recommend an optimum solution for the application.