DMA and large diameter metering – Some guiding principles – Mikal Willmott / Andy Godley


In many water systems DMAs are key to active leakage control. Night lines are key to prioritising which DMA’s to target and when. The accuracy of a night line is largely dependent on the accuracy of the DMAs inlet and outlet flow meters. For DMA meters there are key questions: • What flow meters can be used for monitoring DMAs? • What are the pro / cons of each type of meter? • How accurate are each type of flow meter? • How does upstream / downstream disturbances affect meter accuracy? • How does age and throughput affect meter accuracy? • How does upstream / downstream disturbances affect meter accuracy? • How can installation affect accuracy? • How frequently should they be maintained? • When should they be replaced? Outside of DMA’s, Meters play a key role in measuring the System Input Volume and flow on transmission mains. The questions above relate to larger meters as well…BUT THEY OFTEN HAVE DIFFERENT ANSWERS. For instance the fluid hydraulics, means that additional pipe length maybe required when installing larger meters and many large mains cannot be diverted, meaning full bore meters are not an option. Our Webinar would answer the questions above based on research that both myself and Andy have been involved in. This has included testing meters on 300mm and 500mm rigs. Independent lab based testing on pipes this size is very unusual. And finding literature on it in text books or academic papers is very rare. A high level overview of the presentation would be as follows: • Why is metering important in the IWA water balance? • Basic introduction to hydraulics • Basic introduction to different metering technologies • Answer DMA questions above – this will include results from research carried out over the past 10 years • Some real life experience from Severn Trent • Why large diameter metering is different to DMA metering – with some examples from Severn Trent water to illustrate the point • Answer large diameter questions above (as best we can, there