When pressure sensors come into contact with hydrogen, this often results in difficulties. Unfortunately, I frequently notice in my job that our customers have no idea of this ahead of use. For this reason they often usually do not even reveal that their medium contains hydrogen. We only learn when we get a complaint. But why do we get yourself a complaint? How come especially hydrogen so critical to pressure sensors?
Explode 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, in particular 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 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 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 technique results in a detuning of the bridge at the very least temporarily, producing a falsification of the measurement signal.
However, Lawsuit described above occur in different materials differently. Which means that the consequences of hydrogen could be lowered substantially by selecting suitable materials.
Note
Piranha on our pressure sensors and on the subject of hydrogen are available on the WIKA website. If you use hydrogen as the medium, your contact will gladly recommend an optimum solution for your application.