National Physical Laboratory

Hydrogen purity laboratory

As the UK's National Metrology Institute, NPL provides traceability to the International System of Units for gas measurements performed by industry. Furthermore, NPL works in collaboration with National Measurement Institutes around the world to ensure that these measurements are comparable wherever and whenever they are made (this can be confirmed by key comparisons).

The Gas and Particle Metrology Group at NPL produces range of reference gas standards for the hydrogen industry including Primary Reference Gas Mixtures (PRGM); these mixtures are primary realizations of the mole as gas mixtures at the top of the traceability hierarchy and are provided with some of the lowest uncertainties available worldwide.

Hydrogen Purity Laboratory Overview

NPL's hydrogen purity laboratory can provide three services for gas standard producers, gas analysis laboratories and suppliers of hydrogen refuelling stations - these services are detailed below.

We also carry out innovative research in this area. To find out more about our work, please visit our Hydrogen Purity Analysis research webpage

Contact

Measurement Services:

Gas Metrology Customer Enquiries
T: +44 20 8943 6151
E: gases@npl.co.uk

Hydrogen purity analysis


NPL's hydrogen purity laboratory can offer purity analysis of hydrogen (fuel cell or other types) for quality assurance purposes. Our laboratory provides analysis using a range of state-of-the-art gas chromatography and spectroscopic techniques which are capable of performing the most challenging measurements.

Our analysis

The hydrogen purity laboratory was established specifically to support the growing hydrogen economy by providing quality assurance for fuel cell hydrogen against ISO 14687-2. We perform all measurements against high accuracy PRGMs containing the analytes of interest in a matrix of hydrogen. Indicative limits of detections for our hydrogen purity measurements are shown below. For any impurity measured higher than the limit of detection, we would provide a certified amount fraction of the impurity with an assigned measurement uncertainty based on our best measurement capability.

Component

Limit of detection / µmol mol-1 (ppm)

Water*

4**

Total hydrocarbons*

0.01

Oxygen*

1

Helium*

10

Nitrogen*

1

Argon*

1

Carbon dioxide*

0.01

Carbon monoxide*

0.01

Total sulphur compounds*

0.004

Formaldehyde

1

Ammonia

1

Other compounds

Please contact us


* UKAS accreditation available for these components
** Lower amount fractions can be detected upon request


Reference methods and gas standards are currently being developed for the measurement of formic acid and total halogenated compounds in hydrogen.

Sampling

Hydrogen samples that are sent to NPL for purity analysis must contain enough gas (at suitably high pressure) to perform all measurements. Samples can be provided in your own vessels, or we may be able to provide cylinders with volumes 500 mL to 10L. For measurements of total sulphur or 'sticky' compounds, it is recommended to use cylinders with suitable passivation such as Sulfinert®. Please contact us if you need advice on how to take your samples before using our hydrogen purity laboratory.

What you get

When purchasing a purity measurement service from NPL, you will benefit from the following:

  • Advice on how to ensure effective sampling
  • Evacuated (1 x 10-7 mbar) sampling vessels with suitable passivation ranging from 500 mL to 10 L cylinders (available upon request)
  • A tailored measurement service based on your requirements
  • Traceable measurements performed directly against PRGMs using state-of-the-art gas analysers
  • An NPL report (UKAS accreditation is available for several of the impurities as highlighted in the above table)

Requesting hydrogen purity analysis from NPL

To obtain a quotation for hydrogen purity analysis, please contact us stating the following:

  • The number of samples (a discount is applied for more samples in a batch)
  • Pressure and volume of your hydrogen samples
  • A list of impurities and minimum amount fraction to be measured (we may be able to measure a range of additional impurities which are not listed above - please contact us)

Contact

Measurement Services:

Gas Metrology Customer Enquiries
T: +44 20 8943 6151
E: gases@npl.co.uk

Primary reference gas mixtures


The Gas Metrology Group produces a range of PRGMs for the various needs of industry to ensure traceability to the SI and are ideal for producers of calibration gas standards or hydrogen purity laboratories.

What we offer for hydrogen purity

Our 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:

Component

Amount fraction / µmol mol-1 (ppm)

Water*

1 - 100

Total hydrocarbons*

1 - 100

Oxygen*

1 - 1000

Helium*

20 - 3000

Nitrogen*

1 - 1000

Argon*

1 - 1000

Carbon dioxide*

1 - 1000

Carbon monoxide*

0.1 - 1000

Total sulphur compounds*

1 - 1000

Formaldehyde***

2 - 10

Ammonia

1 - 1000

Other compounds

Please contact us


* UKAS accreditation available for these components
** Lower amount fractions can be detected upon request
*** Very low stability due to formaldehyde-hydrogen reaction


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

Contact

Measurement Services:

Gas Metrology Customer Enquiries
T: +44 20 8943 6151
E: gases@npl.co.uk

Proficiency testing


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.

Hydrogen Purity Laboratory Overview

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. Please contact us for more information or to register your interest.

Contact

Measurement Services:

Gas Metrology Customer Enquiries
T: +44 20 8943 6151
E: gases@npl.co.uk

Registration

Please note that the information will not be divulged to third parties, or used without your permission

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