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In an article published in AWE (Air - Water - Environment) International in June, RPS explains how AccuflowT technology is likely to form an important part of the future leakage consultancy offered by RPS Water. |
The article describes how the AccuflowT device uses several technologies to enable flowrates to be measured accurately, quicky - and very cost-effectively. The technology is expected to have much wider applications within the utility and process control markets.
First published in AWE International, June 2007
Case Study
AccuflowT Metering via Sluice Valves
RPS Water, part of the RPS international consultancy, has developed, in conjunction with the electronics company Technolog and Dwr Cymru Welsh Water, a new way to measure flow in pipelines.
The measuring device, known as AccuflowT, opens and closes sluice valves in the manner of a conventional valve key. However, by monitoring and analysing the noise generated by the turbulent flow through the closing valve, it provides an immediate reading of the full-bore flow in the pipeline. This means that any sluice valve in a distribution network can be used as a flow meter - resulting in major benefits in system management, especially in accurately identifying leakage in water distribution systems.
The initial development of the AccuflowT technology focused on leakage control for water distribution systems. However, the technology is expected to have much wider applications within the utility and process control markets - and RPS is keen to collaborate with organisations in these sectors to evaluate such potential applications.
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The principle The AccuflowT device uses existing sluice valves on water distribution systems as metering points. Flow estimations are based on the noise pattern created by the turbulence generated as flow passes through the increasing constriction as a valve is progressively closed. The greater the flow - for a given input pressure, pipe size and valve combination - the greater the noise or acoustic signature. This principle |
forms the basis of the AccuflowT methodology. Extensive research and development has been carried out to establish the algorithms for the relationships between flow rate and the resulting acoustic signature for different pipe sizes and pressures.
The technologies
Accuflow™ uses several technologies combined within a single device to measure flow at sluice valves. In summary, it consists of:
Development has focused on pipeline diameters between 50mm and 150mm. Flow rate and inlet pressure need to be fairly constant during the period of the measurement. The sluice valve needs to be in good condition, with leakproof closure and a clean valve head to provide a good contact with the acoustic sensor. There must be a facility to measure pipeline pressure upstream of the selected valve. Taking a flow reading requires the valve to be closed in a controlled way as instructed by the device. The valve needs to remain completely closed for around 10 seconds before being reopened.
Analysis of test results shows that the AccuflowT achieves overall accuracy levels of +/- 10% at flow rates ranging from 0.3 litres/sec to 3 litres/sec. In relation to leakage control work, accuracy at low flows is an important and highly relevant characteristic of the AccuflowT. By comparison, the minimum flow specified for measurement by a typical 100 mm helical vane meter is 0.5 litres/sec.
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The benefits The ability to easily measure flow at sluice valves across distribution systems provides many new possibilities. Accurately locating and measuring water main leakage has remained a major challenge for the water industry worldwide. Conventional step-testing provides flow information but requires expensive installations for each metering point and can cause disruption to customersí supplies. Acoustic logging techniques can indicate leakage but often provide a poor indication of the size of a leak. |
AccuflowT overcomes these problems. It can be used on any working distribution sluice valve and requires no excavation of, or modification to, the valve. Because sluice valves are located throughout distribution systems, metering flows across networks has at last become a realistic option for leakage engineers. This allows not only cost-effective pinpointing of leaks, but also better quantification of the volume of leakage.
During the last six months, leakage control teams from RPS Water, trained in using the AccuflowT, have been working with six water industry clients throughout the UK. This has enabled them to use the device in a wide range of operational situations - and has provided valuable experience in refining the principles of step-testing to maximise the advantages of using the AccuflowT.
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The cost to the UK water industry of repairing leaks is estimated to be in excess of £100 million per year. Research carried out by Dwr Cymru Welsh Water indicates that of the total number of leaks repaired, around 33% produce no measurable benefit in terms of reducing overall leakage levels. If, by using Accuflowô based step-testing, the number of these ìno measurable benefitî repairs could be reduced by, for example, 50%, a saving of around £17 million could, potentially, be made across the UK each year. |
The ultimate ambition of leakage control teams is to be able to accurately identify the location and volume of leaks - without the cost of expensive fixed installations. The AccuflowT technology is a major step towards this goal and is likely to form an important part of the future leakage consultancy offered by RPS Water. The technology is also expected to have a range of other potential applications across
the wider utility and process sectors.
The RPS Group is an international consultancy providing advice on the responsible development of natural resources, land and property, the management of the environment and the health and safety of people.
For more information please contact:
RPS Exeter - Water
T: 01392 677333