When Spotlight come into contact with hydrogen, this often results in difficulties. Unfortunately, I very often notice in my job our customers are not aware of this ahead of use. For this reason they often usually do not even tell us that their medium contains hydrogen. We only learn when we get a complaint. But why do we get a complaint? How come especially hydrogen so critical to pressure sensors?
A simple rule is that numerous 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 completely destroyed. Regarding 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.
This 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 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 technique results in a detuning of the bridge at least temporarily, resulting in a falsification of the measurement signal.
However, the consequences described above occur in various materials differently. Which means that the effects of hydrogen could be lowered substantially by selecting suitable materials.
Note
Incapacitated on our pressure sensors and on the subject of hydrogen are available on the WIKA website. If you use hydrogen because the medium, your contact will gladly recommend an optimum solution for your application.