5.1 Low operating temperature fuel cells such as proton exchange membrane fuel cells (PEMFCs) require high purity hydrogen for maximum performance. The following are the reported effects (SAE TIR J2719) of the compounds determined by this test method.

5.2 Carbon Dioxide (CO₂), acts largely as a diluent, however in the fuel cell environment CO₂ can be transformed into CO.

5.3 Water (H₂O), is an inert impurity, as it does not affect the function of a fuel cell stack; however, it provides a transport mechanism for water-soluble contaminants, such as Na⁺ or K⁺. In addition, it may form ice on valve internal surface at cold weather or react exothermally with metal hydride used as hydrogen fuel storage.

5.4 Inert Gases (N₂ and Ar), do not normally react with a fuel cell components or fuel cell system and are considered diluents. Diluents can decrease fuel cell stack performance.

5.5 Oxygen (O₂), in low concentrations is considered an inert impurity, as it does not adversely affect the function of a fuel cell stack; however, it is a safety concern for vehicle on board fuel storage as it can react violently with hydrogen to generate water and heat.

1.1 This test method describes a procedure primarily for the determination of carbon dioxide, argon, nitrogen, oxygen and water in high pressure fuel cell grade hydrogen by gas chromatograph/mass spectrometer (GC/MS) with injection of sample at the same pressure as sample without pressure reduction, which is called “Jet Pulse Injection”. The procedures described in this method were designed to measure carbon dioxide at 0.5micromole per mole (ppmv), Argon 1 ppmv, nitrogen 5 ppmv and oxygen 2 ppmv and water 4 ppmv.

1.2 The values stated in SI units are standard. The values stated in inch-pound units are for information only.

1.3 The mention of trade names in standard does not constitute endorsement or recommendation for use. Other manufacturers of equipment or equipment models can be used.

1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.