Effects of network pressure on water meter under-registration: an experimental analysis

Abstract

In water supply systems, a considerable amount of apparent loss is caused by meter under-registration. Water meters are subject to intrinsic systemic error depending on the actual flow rates passing through them. Furthermore, the moving parts of the meter are subject to wear and tear that progressively reduce meter accuracy. The increase in systemic error is especially evident at low flow rates because of growing friction in the rotating mechanism, which requires a higher flow to start the meter (starting flow). The aim of this paper is to experimentally investigate metering error in an attempt to find a direct link between meter age, network pressure and apparent losses caused by the inability of the meter to accurately register the volume passing though it at low flow rates. The study was performed through laboratory experiments in which worn-out water meters were tested using a test bench. The results of the laboratory experiments show that ageing and pressure are both relevant parameters for determining meter starting flow. These results were then applied to assess the effects on apparent losses of the age of the meter, varying pressure values upstream of the meter (the pressure in the network where the meter is installed) and different patterns of flow rates passing through the device (the consumption pattern of the user). The presented results are useful for understanding the effects of operating conditions on water meter under-registration, which can aid water managers in implementing effective replacement campaigns

Untitled

“…High under-registered errors at low flow rates can be explained by increasing friction in the rotary drive, which requires a higher flow rate to begin the movement. This friction wears moving parts and progressively reduces the accuracy of the meter (Fontanazza et al, 2013), which does not register lower than starting flow rates.…”

“…In Palermo, Italy, in the same way, meters with 0 to 45 years of use had negative errors that increased rapidly with age (Criminisi et al, 2009). Fontanazza et al (2013) indicates that age and pressure are relevant factors to determine the starting flow rate of the meter, considered the main parameter that influences operation. The wear caused by age increases the meter mechanism friction, increasing the resistance to begin the movement of the turbine, especially when the pressure is reduced.…”

Residential water meter selection using the analytical hierarchy process

“…These are mainly residential properties and represent a sizable investment for the utility. The combined influence of pressure, meter age, and tank filling significantly affects the ability of water meters to measure low flows (Fontanazza et al, 2013). The average age of meters is about 10 years, ranging from new meters (< 1 year) to old meters (18-20 years).…”

“…The problem of selecting the best residential water meter can be resolved only if the factors affecting in situ meter performance are better understood and quantified; such factors include distribution system characteristics (e.g., water quality, intermittent or regular supply, pressure ;Fontanazza et al, 2013), water use patterns and flow rates, installation, throughput volumes, and wear of measuring components (AWWA, 2012). These factors influence meter performance differently, particularly the ability to measure very low flows.…”

“…Such tanks have been found to cause metering errors because of low flows induced by the ball valves, which reduce the meters' ability to accurately measure water consumption (Criminisi et al, 2009). The combined influence of pressure, meter age, and tank filling significantly affects the ability of water meters to measure low flows (Fontanazza et al, 2013). In addition, intermittent supply introduces air into the distribution system; this is likely to accelerate wear and tear of meter components.…”