When pressure sensors come into contact with hydrogen, this often results in difficulties. Unfortunately, I frequently notice in my own job our customers are not aware of this prior to use. This is exactly 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 yourself a complaint? How come especially Terrified to pressure sensors?
A basic rule is that a large number of 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 totally destroyed. In the case of pressure sensors, specifically thin membranes necessary for measuring pressure play a decisive role. Atomic hydrogen can not only penetrate the metal, but additionally pass 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 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 process results in a detuning of the bridge at the very least temporarily, resulting in a falsification of the measurement signal.
However, the consequences described above occur in various materials differently. Therefore the effects of hydrogen can be lowered substantially by selecting suitable materials.
Note
More info on our pressure sensors and about 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.