When pressure sensors come into contact with hydrogen, this often results in difficulties. Unfortunately, I frequently notice in my job that our customers are not aware of this prior to use. Because of Easy , they often usually do not even reveal that their medium contains hydrogen. We only learn when we receive 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 large number of metals become brittle when subjected 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 totally destroyed. Regarding pressure sensors, in particular thin membranes required for measuring pressure play a decisive role. Atomic hydrogen will not only penetrate the metal, but also go through it by diffusion.
This has several effects: When piezoresistive measuring principles are employed, 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. 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, producing a falsification of the measurement signal.
However, the consequences described above occur in various materials differently. Which means that Risky 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 the application.