H2FlowTrace is currently calibrating a set of six identical Critical Flow Venturi Nozzles (CFVN) to enhance the traceability of hydrogen for medium flow rates of up to 120 kg/h. This ongoing calibration will be carried out using the Small-Scale Transfer Skid (SSTS) to provide traceability to several master meters in pure hydrogen, and possibly also in Hydrogen Enriched Natural Gas (HENG), marking a significant milestone in the context of H2FlowTrace.    

NaTran has individually calibrated 6 CFVNs with SSTS with hydrogen traceability provided by other 6 smaller CFVNs (the calibrated CFVNs have a throat diameter of about 4.4 mm, the small ones have a throat diameter of about 1.6 mm). Moreover, one of the 6 CFVN has been calibrated with natural gas as an alternative fluid.    

This project aims to continue towards the establishment of a hydrogen, and possibly also HENG, traceability route for larger sonic nozzles via the SSTS. With 6 calibrated nozzles up to 120 kg/h, will allow traceable flow rates of 720 kg/h to be reached with the same SSTS. 

This activity will contribute to one of the project’s objectives, which is to provide knowledge about traceability for pure hydrogen. It will also provide traceability for HENG blends in small industrial meters (e.g., turbine, rotary and piston prover), with a targeted measurement uncertainty of 0.20% or less. This will provide the first step towards a traceability route for large-scale pure hydrogen and HENG flow meter calibrations.  

This activity, led by NaTran, has been supported by CESAME EXADERBIT, the Swiss Federal Institute of Metrology METAS, TÜV SÜD, the German National Metrology Institute (PTB), the Slovak Institute of Metrology and the National Metrology Institute from the Netherlands (VSL).