When pressure sensors come into contact with hydrogen, this often results in difficulties. Unfortunately, I frequently notice in my own job our customers have no idea of this ahead of use. Because of this , they often usually do not even tell us 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?
A basic rule is that a lot of metals become brittle when exposed to hydrogen. Hydrogen atoms that diffuse in to 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. In the case of pressure sensors, specifically thin membranes required for measuring pressure play a decisive role. Sampler 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 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, resulting in a falsification of the measurement signal.
However, the consequences described above occur in various materials differently. Which means that the consequences of hydrogen could be lowered substantially by selecting suitable materials.
Note
Devastating on our pressure sensors and about hydrogen are available on the WIKA website. If you are using hydrogen as the medium, your contact will gladly recommend an optimum solution for the application.