Essential conformity requirements of the 2014/32/EU Measuring Instruments Directive for the gas meters that are used with renewable gases

The aim of this work package is to develop traceable calibration and verification procedures, for all of the gas flow meters that are used to measure renewable gases, in compliance with the requirements of the 2014/32/EU Measuring Instruments Directive (MID) with a particular focus on accuracy and durability and to determine the uncertainty budget. In addition, this work package aims to study and evaluate the integrity of the internal components of the meters, the durability of the materials, the behaviour of the electronic components and other possible technical issues (which will be dependent on the composition of the gas).

Task 2.1 will require an expert group to be formed to discuss the compliance requirements for gas meters that are implied by the MID when renewable gases are used. Specifically, the conformity requirements set out in CEN/TC 237 standards for different types of gas meters, and in OIML R137:2012, will be evaluated for renewable gases. The extent to which these requirements can be met given current metrological verification procedures will be assessed, potential pitfalls and their solutions will be identified, and recommended practices for the certification/calibration/verification of gas-meters using renewable gases will be proposed, with particular attention being paid to the accuracy and durability requirements of the MID.

Task 2.2 will undertake metrology and durability tests. These will include assessing the effects of renewable gas flow on durability, turn down ratios, and accuracy tests (with air) being performed before and after the durability tests.

The outputs of both tasks will result in recommendations on the certification/calibration/verification of gas-meters using renewable gases (test gases, flow rates, meter flow range) and the identification of (potential) additional uncertainty sources with estimates of their magnitudes. Recommendations will be prepared on improving/modifying current natural gas certification/calibration/verification facilities and gas meters so that they become more suitable for renewable gases. The recommendations will be provided to CEN/TC 237 and OIML TC8/SC7 and to the Stakeholder Committee.