ASTM D7941_D7941M-14 - Standard Test Method for Hydrogen Purity Analysis Using a Continuous Wave Cavity Ring-Down Spectroscopy Analyzer

1.1 This test method describes contaminant determination in fuel-cell-grade hydrogen as specified in relevant ASTM and ISO standards using cavity ring-down spectroscopy (CRDS). This standard test method is for the measurement of one or multiple contaminants including, but not limited to, water (H₂O), oxygen (O₂), methane (CH₄), carbon dioxide (CO₂), carbon monoxide (CO), ammonia (NH₃), and formaldehyde (H₂CO), henceforth referred to as “analyte.”

1.2 This test method applies to CRDS analyzers with one or multiple sensor modules (see 3.3 for definition), each of which is designed for a specific analyte. This test method describes sampling apparatus design, operating procedures, and quality control procedures required to obtain the stated levels of precision and accuracy.

1.3 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.

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.