Hydrogen purity

We use a range of techniques (including gas chromatography and spectroscopy) to perform purity analysis of hydrogens samples according to ISO 14687-2:2012. Please note that some methods require higher volumes of gas sample.

We can also perform analysis of additional impurities to those listed above and in accordance with other standards (such as ISO 14687-1:1999 for hydrogen gas grids).

Our primary reference gas mixtures (PRGMs) are prepared gravimetrically from pure components and are validated using our suite of state-of-the-art gas analysers. We can provide the following levels of impurities in a hydrogen PRGM:

When purchasing hydrogen gas standards from NPL, you will receive the following:

• Customised PRGMs containing the desired amount fractions of impurities and matrix gas in a 10 L cylinder
• Validation of your mixture against our existing suite of PRGMs (to ensure traceability)
• PRGMs with exceptionally low uncertainties assigned for each impurity
• Stability data to ensure your mixture will remain unchanged for the stability period stated on the cylinder
• Our NPL logo which proves that your PRGM was provided by a National Metrology Institute
• UKAS calibration accreditation is available for the compounds highlighted in the above table

Ordering PRGMs from NPL

To obtain a quotation for a hydrogen PRGM in a 10 L cylinder, please contact us stating the following:

• Composition (with required uncertainties) of the hydrogen PRGM you need
• Cylinder pressure (usually 100 bar)
• Cylinder valve type

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Proficiency testing is defined as the evaluation of a laboratory's performance against pre-established criteria by means of interlaboratory comparisons. The participating laboratory will assess the accuracy of their results and comparability to peer laboratories over time. They will be asked to provide key information on technical issues and methodologies. Proficiency testing is an independent means of assuring the quality of testing and calibration results, as described in ISO/IEC 17025.

Interlaboratory proficiency testing schemes

A proficiency testing scheme involving other gas analysis laboratories can be arranged depending on the demand for such an intercomparison - please contact us if you would like to register your interest. A PRGM would be prepared at NPL and sent to the participants (generally there would be more than seven participants for an ideal intercomparison). Following the measurements, the PRGM would be returned to NPL for re-analysis and the participants' measurements would be compared to the reference value for the PRGM. This type of proficiency testing scheme allows each participant to compare their capabilities directly against other leading laboratories performing hydrogen purity analysis measurements. On completion of the testing a proficiency testing report and PRGM certificate will be sent to each participant. Each participant can choose to remain anonymous in the report.

On-demand proficiency testing schemes

An on-demand proficiency testing scheme follows the procedure for the interlaboratory intercomparison, but is performed with only one laboratory (a bilateral intercomparison). A proficiency testing report and PRGM certificate will be sent to the participant.

Enquire about a proficiency testing scheme

Depending on the demand for such a scheme, we will be able to provide either an on-demand or interlaboratory proficiency testing scheme. 

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