The Challenge of Air Valves: A Selective Critical Literature Review

One key alternative for removing, preventing, and effectively coping with the often vexing presence of air in water pipelines is the combination air-vacuum valve. Despite their often effective role, such valves can be highly problematic if not well designed and maintained. This paper critically reviews the current design, application, functionality, and simulation of air valves and the associated shortcomings, with a primary focus on air/vacuum valves (AVVs). It is argued that the efficient number of air valves along undulating pipelines is yet to be fully articulated. Air-valve simulations should expressively consider their dynamic behavior, the physical behavior of any air pockets that might form below an air valve, and the varying character of the water surface at the air valve location. There is a pressing need for a comprehensive and systematic study on the proper sizing and location of AVVs for the transient protection of systems. Overall, the efficient application of AVVs requires broad research and development theoretically (i.e., their physical behavior and improved numerical simulations) and experimentally, as well as field studies to document their in situ dynamic behavior and operational efficiency.