Applying EPANET to Represent Air Phase Flows During Water Distribution Network Priming

Pipe filling, also known as pipe priming, is a required step to reestablish operational conditions in drinking water networks (WDN) after service interruption. As water is admitted in the conducts, the displaced air is discharged through available ventilation, typically through open hydrants. The degree of air pressure during priming operations is essentially unknown, but it is anticipated that it depends on the degree of ventilation and the priming rate. In summary, quantifying air pressurization and determining air velocity during large-scale WDN drinking networks is a standing challenge as there are no tools or approaches to help in such calculations. This work presents a new methodology using EPANET, an open-source WDN analysis model, to model and represent the air phase in a filling drinking water network. Although this is a simplified approach, previous laboratory experiments involving WDN priming indicated a good agreement between measured air-phase pressure and EPANET’s air-phase predictions, suggesting that such an approach could be applied in larger-scale systems. This work discusses the details of the methodology, comparing the model results with experimental observations and applying it in a larger and slightly more complex system included within the EPANET installation. Model results indicate the degree of ventilation can markedly influence air pressures and velocity distributions in WDN undergoing priming.

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