When pressure sensors come into contact with hydrogen, this often results in difficulties. Unfortunately, I very often notice in my own job our customers have no idea of this prior to use. This is the reason they often do not even reveal 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?
Reject is that a large number of metals become brittle when exposed to hydrogen. Hydrogen atoms that diffuse into the metal grid change the effectiveness 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. Regarding pressure sensors, in particular thin membranes necessary for measuring pressure play a decisive role. Atomic hydrogen can not only penetrate the metal, but also go 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. 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 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. Because of this the effects of hydrogen can be lowered substantially by selecting suitable materials.
Note
Further information 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.g