When pressure sensors come into contact with hydrogen, this often results in difficulties. Unfortunately, I very often notice in my own job our customers are not aware of this prior to use. This is why they often usually do not even reveal that their medium contains hydrogen. Astounded learn when we receive a complaint. But why do we get a complaint? Why is especially hydrogen so critical to pressure sensors?
A simple rule 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 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 can not only penetrate the metal, but additionally go through it by diffusion.
Failure has several effects: When piezoresistive measuring principles are used, it becomes critical if hydrogen reacts with the inner 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 process results in a detuning of the bridge at least temporarily, resulting in a falsification of the measurement signal.
However, the consequences described above occur in different materials differently. Therefore the consequences of hydrogen can be lowered substantially by selecting suitable materials.
Note
Further information on our pressure sensors and on the subject of 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.