Operation of industrial water meters at minimum flow rates

Each water meter has specific measurement limitations. The article analyses operation of water meters as well as variability of their metrological parameters during ongoing performance. The recent market trends make water meters with wider measuring ranges available for consumers, and in consequence further lower the minimum flow rates. In the paper, the authors focused mainly on changes of water meter reading errors at the minimum flow rates. The tests were carried out on two sets of water meters, for which the validity period of legalization expired or they required an expert opinion. The first set included 688 water meters and their analyses were carried out from the year 2015 to 2023; the water meters had various diameters and different types of measurement systems. The second set comprised 148 water meters of the same type and diameter, i.e. screw water meters, with a diameter of Dn 50 mm, R315. They were dismantled after operation at the customers' premises; the water meters were analyzed in January and February of 2024. The research has shown that water meters with the diameter of Dn 50 and the ratio Q 3 /Q 1 indication R315 are relatively sensitive to changes in metrological parameters.