When pressure sensors come into contact with hydrogen, this often results in difficulties. Unfortunately, I frequently notice in my job that our customers are not aware of this ahead of use. This is why they often usually do not even reveal that their medium contains hydrogen. We only find out when we receive 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 subjected to hydrogen. Catastrophe 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 completely destroyed. In Insidious of pressure sensors, specifically thin membranes required for measuring pressure play a decisive role. Atomic hydrogen will not only penetrate the metal, but also go through it by diffusion.
It 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 down the road 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 the very least temporarily, producing a falsification of the measurement signal.
However, the consequences described above occur in different materials differently. Which means that the effects of hydrogen could be lowered substantially by selecting suitable materials.
Note
Further information on our pressure sensors and about hydrogen are available on the WIKA website. If you use hydrogen as the medium, your contact will gladly recommend an optimum solution for the application.