Analysis of ageing effects on static gas meters

Static gas meters are currently being installed in increasing quantities within gas distribution networks across Europe due to their up-to-date technology which intrinsically allows to comply with current requests from Normation and fiscal bodies; on the other hand, the technology on which such meters are based is still relatively new, therefore confidence in it must be built. In particular, for instance in Italy, regulation agencies require more frequent verification of static meters with respect to “classical” technology meters due to the lack of information about their long-term stability. In the present paper, we present a study about the effects of ageing on static gas meters, that was performed based on the calibration of over 1500 G25 gas meters based on thermal (CTTMF - Capillary Type Thermal Mass Flowmeter) technology after 8 years from their installation; the size of the sample and its remarkable homogeneity provides a good level of confidence in the validity of the conclusions. We will show that most of the meters provided a response within legal limits, and that a very high percentage of them largely outperformed the requests. The technical reasons behind this performance and its implications for the evaluation of the capabilities of CTTMF technology will be discussed.