Optimal water meter selection system

  • EH Johnson


The comparison of the particular accuracy envelope of a water meter with a consumer's diurnal demand pattern by means of a common reference facilitates the optimal selection of water meters. The accuracy curve and envelope of a new water meter is governed by the type of water meter and relevant standards. Water demand patterns vary with time, period, seasons, consumers and combinations of these factors. The classical accuracy envelope and demand pattern are not directly comparable, and require a common comparison reference. The relative frequency of the volume of water passing through a meter at various flow rates and the weighted accuracies of these measured volumes play a pivotal role in establishing a common comparison reference. The time unit selected to calculate the volume of water passing through the meter is guided by the type of water reticulation infrastructure within which the meter is installed. However, experience and literature show that a flow interval of less than 1 min would result in the application of unrealistic high flow rates. A simplified example for the determination of the weighted accuracy of a water meter monitoring a theoretical demand pattern illustrates the methodology used to establish the common comparison reference. Economic/financial analysis based on an income statement together with capital budgeting techniques assist with the determination of the financial suitability of investing in a new replacement water meter. This financial analysis includes various potential income and expenditure components that will result from the installation of a new water meter. Sensitivity analysis facilitates the decision-making process. The analysis of flow data by a computer program developed in context with the described methodology illustrates that the savings achieved by the improved accuracy of matching the optimally selected meter and a particular demand profile can finance the costs of such an investment.

WaterSA Vol.27(4) 2001: 481-488

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eISSN: 0378-4738