The present work is concerned with the evaluation of the tightness of the components located on domestic and commercial gas lines from the gas meter to the end user appliance, in presence of a mixture 40%H2+60%CH4 at 35 mbar. The components were taken from installations being used currently in Germany, Denmark, Belgium and France. The current standard methods to evaluate natural gas distribution tightness propose testing duration of several minutes. In this work, the components tightness was first evaluated using such standard methods before carrying out tests on longer period of time and evaluate the potential influence of time, and the results were compared to admissible leakage rates for natural gas in distribution network and in appliances.

The main conclusion is that once a gas line is properly installed, following natural gas standards at low pressures (below 35 mbar), it can be expected that it will be tight for the gas blend.

Furthermore, the review and comparison of other projects results addressing tightness of gas distribution network/components in 100%H2 was added, enabling the formulation of recommendations on testing methods.