When pressure sensors come into contact with hydrogen, this often results in difficulties. Unfortunately, I very often notice in my own job that our customers are not aware of this ahead of use. This is the reason they often do not even reveal that their medium contains hydrogen. We only find out when we receive a complaint. But why do we get a complaint? How come especially hydrogen so critical to pressure sensors?
A basic rule is that a lot of metals become brittle when subjected to hydrogen. Hydrogen atoms that diffuse in to the metal grid change the effectiveness of the material. In Obnoxious , 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 will not only penetrate the metal, but also pass through it by diffusion.
It 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 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 least temporarily, producing a falsification of the measurement signal.
However, the effects described above occur in various materials differently. Which means that the effects of hydrogen can be lowered substantially by selecting suitable materials.
Note
More info on our pressure sensors and on the subject of 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.