Evaluation of the measurement performance of water meters depending on water quality

Abstract

Water meters of different types and sizes are used to monitor and bill the water supply. Although the water is of drinking water quality, its chemo-physical properties often enough adversely affect the measuring behaviour of a meter after a while. There is thus the risk that they no longer meet the legal requirements and may no longer be used. In this paper a test regime with a focus on pH, total hardness and particle load is presented which allows water meters to be tested closer to their operating conditions prior to placing them on the market. The regime goes beyond the conventional continuous durability test as described in OIML R49:2013(E) and ISO 4064:2014. The feasibility and reliability of the test regime has been demonstrated through implementation at different facilities. In the study, the measurement performance of water meters of various types and from different manufacturers was also investigated. A heterogeneous spread of measurement errors was found for both, water meters in mint conditions and those which were exposed to a defined water quality. Furthermore, compared to the conventional continuous durability test, the test regime developed in the study generally leads to stronger changes in the measurement error of the water meters.

Overview of differences between electronic and mechanical domestic cold water meter

“…Furthermore, it was found that the largest effects do not necessarily occur at the lowest flow rates or the poorer water qualities. For several meters maximum effects occurred at a pH-value of 7.7 and flow rates between 0.8 m³/h and 1.8 m³/h [3]. The impression is that the manufacturing partly has a greater influence on the measurement quality than the measurement principle itself.…”

“…Eventual impact of different pH-values or total hardness is not clear so far. To assess the influence of different water properties a test regime was developed based on typical water consumption and water qualities in Europe [3]. The parameters pH value, total hardness, and particle load were changed accordingly.…”

“…If the water quality has an impact, it is in the sense that the meter often measures less volume compared to the one in as-new condition [3]. In the case of mechanical meters exposed to different water qualities wear and increased friction may lead to reduced smoothness in the mechanical devices and reduced mobility.…”

“…Furthermore, it is of interest how electronic water meters perform under real-world conditions compared to the traditional mechanical metersif the expectations of a reduced sensitivity to water properties are fulfilled. To gain insights here stress tests were performed by using test waters with different pH and total hardness values, and particle sizes and concentrations [3].…”