Investigation of Air Pressurization during the Filling of Complex Pipe Networks

Drinking water systems (DWS) frequently undergo maintenance operations in which emptying and subsequent filling (i.e., priming) operations are necessary. Air pressurization is an undesired effect during priming operations, but there are limited studies that have focused on this problem. The various interactions between the air and water phases, the air discharge through multiple ventilation points, and the complex pipe topologies are among the complexities associated with modeling priming processes. Experimental studies considering rapid filling in nonlinear topologies are very limited, and even fewer have combined these with limited air ventilation, which poses additional challenges in studying the dynamics of DWS priming. This work combines a systematic experimental study of a lab-scale looped pipe network with varying water inflows and air ventilation configurations. The work also proposed simple changes to how Environmental Protection Agency Network Evaluation Tool (EPANET) models may represent air flows and anticipate air-phase pressures in the early stages of a priming event. EPANET modeling results indicated a reasonable agreement with the collected air pressure experimental data. This suggests that, within the discussed EPANET limitations, the tool may be useful in estimating air pressures in the early stages of priming.