When pressure sensors touch hydrogen, this often results in difficulties. Unfortunately, I very often notice in my own job our customers are not aware of this prior to use. This is exactly why 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 yourself a complaint? Why is especially hydrogen so critical to pressure sensors?
A basic rule is that a lot of metals become brittle when exposed to hydrogen. Hydrogen atoms that diffuse into 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 completely destroyed. In the case of pressure sensors, in particular thin membranes necessary 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 internal transmission medium or accumulates there. This initially only falsifies the measurement results, but can down the road also lead to complete destruction of the sensor in individual cases. Off-limits 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 effects described above occur in different materials differently. Which means that the consequences of hydrogen could be lowered substantially by selecting suitable materials.
Note
More info on our pressure sensors and about hydrogen can be found on the WIKA website. If you are using hydrogen as the medium, your contact will gladly recommend an optimum solution for your application.