Common Errors Found in Volumetric Hydrogen Capacity Measurements and How to Avoid Them

Philip A. Parilla, Kevin J. O'Neill, Katherine E. Hurst, Richard Knott, Thomas Gennett, Jeffery L. Blackburn, Chaiwat Entrakul, Justin B. Bult, Lin J. Simpson

Research output: Contribution to conferencePaperpeer-review


Recent comparisons of hydrogen capacity measurements among different laboratories on identical samples show a wide disparity of results and begs the questions: "How can this be?" and "What are the root causes for this disparity?" The volumetric technique for capacity measurements is based on a mass balance assumption and entails keeping track of the number of moles in the gas phase before and after a change of pressure for the sample. Each instrument must use a mass-balance model and has accompanying assumptions. We examine some of the common errors that occur and lead to large systematic measurement errors. Issues to be discussed include: proper absolute and null calibrations, uniformity and constancy of the temperature profile, choosing the correct mass-balance model and verification of instrument performance. Specific examples will show the large systematic errors that can occur with improper application of the volumetric technique.

Original languageAmerican English
Number of pages2
StatePublished - 2011
Event242nd ACS National Meeting and Exposition - Denver, CO, United States
Duration: 28 Aug 20111 Sep 2011


Conference242nd ACS National Meeting and Exposition
Country/TerritoryUnited States
CityDenver, CO

NREL Publication Number

  • NREL/CP-5200-53284


  • common errors
  • hydrogen capacity measurements


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