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. That is why they often 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? Why is especially In The Zone 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 to put it simply, the pressure sensor starts leaking or is totally destroyed. In the case of pressure sensors, in particular thin membranes necessary for measuring pressure play a decisive role. Hostile will not only penetrate the metal, but additionally go 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, the consequences described above occur in various materials differently. This means that the consequences of hydrogen can be lowered substantially by selecting suitable materials.
Note
More info on our pressure sensors and on the subject of hydrogen can be found on the WIKA website. If you use hydrogen because the medium, your contact will gladly recommend an optimum solution for your application.