Grade D Gaseous Hydrogen

Type I, Grade D gaseous hydrogen is the specified grade within ISO 14687 designated for use with PEM (proton exchange membrane) fuel cells used in on-road vehicles.

To ensure prolonged service life, PEM fuel cells require high purity hydrogen with less than 300 µmol impurities. Grade D hydrogen meets the 99.97% purity fuel index making it suitable for FCEV road transport. 

Grade D hydrogen is not suitable for aviation or aerospace applications that require a higher purity fuel index.

Grade D hydrogen fuel specifications are not process-dependent or feed-stock specific, however, it is easier to achieve the required purity levels when produced from an electrolyser.