P. Vigo

The future domestic gas meter: Review of current developments

Abstract This paper illustrates the gas flow rate measurement techniques that can be introduced in future domestic applications. First, the role of the gas meter in legal metrology is introduced. Then, the “intelligent” (or “smart”) gas meter is analyzed, since it should be used in the near future. Such a meter is an improvement of the current domestic diaphragm gas meter, also equipped with electronic components, so as to obtain a more flexible instrument and a more convenient measurement data processing (temperature compensation, remote reading, etc.). After that, static gas meters are analyzed. Such meters have no moving parts. Of this category, only ultrasonic and fluidic oscillator meters are reviewed here. At present they are in an advanced phase of experimentation for custody transfer gas metering. Thanks to their design, which does not include any moving parts, these meters may represent in the future the best solution to measure the consumption of natural gas for domestic use. This paper discusses the operating principles and metrological characteristics of the static meters mentioned above, and provides some experimental results regarding domestic gas measurement. Finally, their possible evolution and application on the international scene are briefly outlined.

Critical aspects of new domestic static gas meter

To promote the diffusion of smart metering, several National Authorities defined strict roll-out procedures of the existing meters with new smart meters. In such scenario, even if new static technologies in gas metering offer very significant potential (such as digital output, absence of moving parts, direct mass measurement), their reliability in some critical conditions typical of natural gas distribution networks (i.e. zero flow, minimum flow-rate, gas quality changes, presence of dust and contaminants, etc.) still has to be demonstrated. A very promising technology for natural gas domestic measurements is represented by thermal mass flow meters, but, unfortunately, gas quality is expected to significantly affect metrological performance of such meters. The authors conducted several metrological tests aimed to verify the sensitivity of such meter with natural gas quality changes. The results of these tests show a not full reliability when CO2 content increases and when gas composition varies.

Metrological characterization of a new direct heat accounting device

The new Energy Efficiency Directive leads to a strong incentive to the installation of heat accounting systems as an essential tool to increase energy efficiency of buildings. This is also facilitated by the spreading of district heating networks more and more extended and to the return to central heating plants in buildings, more efficient and less polluting than traditional individual ones. Heat metering and accounting is now carried out by the so-called direct systems (i.e. heat meters) and indirect (i.e. heat cost allocators, insertion time counters compensated whit flow temperature or with the degree-days). On the other hand, both the metrological characteristics of such systems and the constraints in terms of installation and managing of heating plants lead direct and indirect systems to uncertainties in heat accounting sometimes far above the accuracy limit of 5%. In this paper the authors present the results of an experimental characterization of an innovative integrated system for heat accounting made up of an electronic valve, a static flow-meter and a temperature sensor pair. The system can be installed on the return pipe of each radiator of the heating plant and connected with a remote control unit and with a single temperature sensor installed on the feed pipe immediately below the central boiler.