Introduction
Hydrogen applications are increasing due to the rapid development of Fuel cell technologies and the need for increased generation of this valuable energy source. This overview is designed as a guide to understanding Pressure sensors and their applications for use with this media. The main challenges are approvals, media compatibility and cost.
Approvals
Directives (EC) 79/2009 which specified components for gaseous Hydrogen and (EU) 406/2010 were repealed in July 2022 and as such no longer apply. Most sensor manufacturers, however, will still use these regulations as a basis for design and manufacture in the absence of current legislation. Whilst these apply to Hydrogen powered vehicles, the other consideration is equipment used in the generation, cleaning, drying and storage of Hydrogen which may dictate the use of ATEX certified product.
Media Compatibility
Two fundamental challenges are hydrogen permeation and embrittlement. Hydrogen ion permeation can occur through thin metal isolation diaphragms at elevated pressures, which is a major consideration when measuring low pressure Hydrogen. Our experience tells us that using a 316L stainless steel diaphragm when measuring Hydrogen below 50 PSI (3.5 Bar) will not be prone to permeation. Pressures above this level require alternative materials, thicker diaphragms or appropriate coatings such as Gold plating to prevent the permeation. Hydrogen Embrittlement (HE), also known as hydrogen-assisted cracking or hydrogen induced cracking (HIC) reduced a metals ductility due to hydrogen absorption. This is one of the reasons why we suggest on thin metal structures, only low pressures can be applied. For higher pressures, either an appropriate coating should be used, or thicker diaphragms…
