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Providing reference gases and standards

We support organisations so that they can make accurate and traceable measurements for energy gases.

Natural gas

Gas distribution network operators need to determine the composition of natural gas supplied to their customers. This allows them to calculate the calorific value and to determine the presence of any impurities that may negatively affect home appliances. In the UK, operators need to meet the technical specifications set out in the Gas Safety (Management) Regulations 1996, but other countries will have alternative standards or regulations they must meet.

NPL provides the UK’s Primary Reference Materials that underpin traceability for natural gas quality measurements. The high accuracies that we provide make these mixtures suitable for directly calibrating natural gas analysers and verifying calibration gas standards provided by gas suppliers.

In addition to the components usually found in synthetic natural gas standards (C1 to C5 alkanes, n-hexane, nitrogen and carbon dioxide), our standards can also contain C6 to C10 hydrocarbon components, as well as high levels of hydrogen which are suitable for hydrogen enriched natural gas. We can provide the hydrocarbon dew point for our mixtures, reassuring the gas transporter that condensation of the mixture will not take place in the gas pipeline.


Sulphur-containing compounds are added to natural gas to provide a distinctive odour, thus allowing any potentially hazardous leaks to be detected. The very low odour thresholds of these compounds enable detection by the human nose at minute concentrations. We provide Primary Reference Materials to underpin quantification of odorants in natural gas, hydrogen and biogas.

In addition to conventional odorants such as Odorant NB, NPL also supplies a range of non-sulphur odorant mixtures. These provide traceability for the measurement of components which are increasingly being used to odorise natural gas across Europe. Mixtures are available containing the components most commonly used as non-sulphur odorants: methylacrylate, ethylacrylate and 2-ethyl-3-methylpyrazine.

Additionally, we are working with grid operators to supply new odorants that would be suitable for a 100% hydrogen grid in the UK. The new odorant will need to be suitable for existing or new (polyethylene) pipeline, compatible with home appliances and easily detectable by customers.


Biogas and biomethane are becoming an increasingly important means to deliver a sustainable, low carbon energy economy. Currently in the UK, nearly 100 biogas plants are injecting biomethane into the grid. However, biomethane produced from biogas may contain impurities such as siloxanes that are not monitored, since they do not fall under any current regulations. These compounds, if present, could significantly deteriorate performance of home appliances by allowing the build-up of silica following combustion.

NPL provides a service that allows biogas plants to check the quality of their biomethane against the recent set of European standards for biomethane quality: EN 16723. We can provide measurements for additional impurities on request and have experience with gas sampling.

Hydrogen for vehicles

Hydrogen vehicles, along with battery vehicles, are being trialled in many countries as a way of decarbonising transportation. Fuel cell electric vehicles provide advantages over battery vehicles, such as quick refuelling time and longer range, but they are very susceptible to degradation. If low level impurities are present in the hydrogen they can degrade the fuel cell (even 4 parts-per-billion of hydrogen sulphide in the hydrogen can cause degradation).

NPL’s Hydrogen Purity Laboratory provides a full service for performing quality assurance of hydrogen refuelling stations according to ISO 14687. It includes sampling from the station, purity analysis and provision of an NPL test report (UKAS testing available). Additionally, we provide Primary Reference Materials containing low level impurities in hydrogen which are suitable for laboratory testing or calibration of analysers.

In addition to providing a quality assurance service for hydrogen vehicles, NPL is leading a project to determine whether it would be feasible to supply fuel cell vehicles directly using hydrogen transported through the existing natural gas grid. This project comprises several aspects that include risk analysis of hydrogen quality, review of suitable purification techniques and techno-economic analysis.

Find out more about NPL's Energy gases services

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Contact our Customer Services team on +44 20 8943 7070