Abstract
M.Ing. (Engineering Management)
The lack of accuracy degradation data for residential meters in South Africa is a challenge for water utilities. This information is vital to allow utilities to predict the accuracy of their residential meters, plan replacement programmes and select suitable technology for specific conditions. This research aims to provide some answers for this problem by evaluating the effect that age and accumulated volume have on residential water meters in South Africa. These figures would assist utilities to plan their meter replacement schedules and choose optimal meter technologies for their networks. This was done by conducting empirical testing in a water meter verification laboratory on 100 units each of two commonly-used residential meter technologies in South Africa, namely the multijet-type velocity meter and the oscillating piston-type volumetric meter. Using the results obtained from these tests, a regression analysis was performed based on the meter age and accumulated volume to establish degradation rates. Results showed that degradation of the multijet-type velocity meters was linked to accumulated volume. The degradation rate calculated was -1.13% per 1,000kL for these meters, with an initial weighted error of -10.80%. It was not possible to find a relationship between meter degradation and age for either meter type. It was also not possible to find a relationship between volumetric meters and accumulated volume, and these meters exhibited a high rejection rate (45% of meters tested). These results indicate that for velocity meters, accumulated volume is a better predictor of meter accuracy than age, and as such when planning meter replacement programmes, they should be based on the accumulated volume of the meter. The lack of any definitive relationship between volumetric meters and either age or volume indicates that this meter technology is more susceptible to external factors such as water quality fluctuations than age-or accumulated volume based degradation. The findings of this research will assist utility managers to make informed decisions when planning meter replacement programmes, as well as selecting residential meter technologies for their applications.