D4 -- Report on the development, comparison and validation of sampling systems (using back-to-back sampling and repeated sampling)

Hydrogen fuel quality is essential for the durability and reliability of fuel cell systems, particularly in heavy-duty (HD) vehicles operating under demanding conditions. Ensuring compliance with purity standards requires validated sampling systems at hydrogen refuelling stations. While established methods exist for light-duty (LD) refuelling, their suitability for HD applications has not been fully proven. This study evaluates three sampling systems (DirSAM, ENGIE sampler, and HySaM) through back-to-back HD refuelling experiments and comparison with LD configurations. Most gaseous impurities specified in ISO 14687:2025 showed statistical equivalence across systems within measurement uncertainties. Differences in nitrogen, water, and sulfur were system-dependent without consistent bias. LD sampling was found unreliable for representing HD conditions, particularly regarding water. No correlation was observed between particulate matter and dispensed hydrogen or vehicle state of charge.
These results support adapting existing sampling methods to HD refuelling while highlighting the need for further validation and standard development.

The deliverable was written as a peer-reviewed article entitled “Equivalence Assessment of Hydrogen Sampling Systems for Heavy Duty Refuelling Applications” which was submitted to the International Journal of Hydrogen Energy the 21st of May 2026.