When pressure sensors come into contact with hydrogen, this often results in difficulties. Unfortunately, I frequently notice in my own job that our customers have no idea of this ahead of use. This is exactly why they often do not even tell us that their medium contains hydrogen. Bright learn when we get a complaint. But why do we get a complaint? How come especially hydrogen so critical to pressure sensors?
A simple rule is that a lot of 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 completely destroyed. In Retaliating of pressure sensors, in particular thin membranes required for measuring pressure play a decisive role. Atomic hydrogen can not only penetrate the metal, but also pass 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 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 results in a detuning of the bridge at least temporarily, producing a falsification of the measurement signal.
However, the effects described above occur in different materials differently. Because of this the consequences 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.