Providing traceable gas measurements to industry
NPL’s Hydrogen Purity Laboratory provides state-of-the-art purity measurements to ensure European hydrogen refuelling stations can meet the mandatory technical specifications of ISO 14687. We also provide services for gas and particulate sampling at hydrogen refuelling stations and high accuracy primary reference materials.
Unlike petrol cars, hydrogen fuel cell vehicles are very sensitive to fuel purity. For example, in the Toyota Mirai even 4 ppb (parts per billion) of hydrogen sulphide can destroy the fuel cell.
Hydrogen purity analysis
NPL's hydrogen purity laboratory obtained a UKAS ISO 17025 testing scope of accreditation to provide quality assurance of fuel cell hydrogen against ISO 14687-2 (soon to become ISO 14687 Grade D). Our laboratory provides analysis using a range of state-of-the-art gas chromatography and spectroscopic techniques.
NPL has developed novel gas chromatography techniques to perform the challenging measurements required by ISO 14687 such as total sulphur at 4 ppb.
All measurements are performed against high accuracy primary reference materials prepared by NPL and containing the analytes of interest in a matrix of hydrogen. Indicative limits of detections for our hydrogen purity measurements are shown below. We also perform measurement of additional impurities and can provide sampling vessels on request.
Component
|
Limit of detection / µmol mol -1 (ppm)
|
Water*
|
3**
|
Total hydrocarbons*
|
0.01
|
Oxygen*
|
0.5
|
Helium*
|
20
|
Nitrogen*
|
1
|
Argon*
|
0.5
|
Carbon dioxide*
|
0.02
|
Carbon monoxide*
|
0.02
|
Total sulphur compounds*
|
0.002
|
Methane
|
0.02
|
Formaldehyde
|
0.1
|
Ammonia
|
0.1
|
Formic acid
|
0.15
|
Halogenated compounds (only organic halogenated compounds excluding HCl and Cl2)
|
0.01
|
Other compounds
|
Please contact us
|
* UKAS accreditation available for these components
** Lower amount fractions can be detected upon request
Sampling
It is important to ensure a representative sample is taken from the station before performing hydrogen purity analysis. Inadequate sampling may lead to false results either by artificially introducing additional impurities such as water or air, or by losing key impurities to the walls of the gas vessel during transport. NPL provides a sampling service to obtain high pressure hydrogen or particulates from operational hydrogen refuelling stations (350 or 700 bar) for hydrogen purity testing. This would usually require two NPL staff to attend the site to carry out the sampling.
NPL use a Qualitizer and HyDac to perform sampling of gas and particulates directly from the hydrogen refuelling station nozzle.
Primary reference materials
NPL has an ISO 17034 scope of accreditation to provide primary reference materials to support hydrogen purity measurements. Requested mixtures usually relate to the requirements of ISO 14687, but we also provide gas compositions for other applications. Each mixture is gravimetrically prepared, to reduce the overall uncertainty of the amount fraction, and is checked for stability over the specified shelf life.
Our primary reference materials are used by industry for validating calibration gas standards, calibrating gas analysers or for research purposes.
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