Recent research studies and surveys have shown that air pockets in wastewater transmission systems cause extensive damage and hindrance. Air pockets decrease flow capacity, they induce significant head losses and energy losses, they prompt serious corrosion, and they can trigger and/or enhance pressure surges. In the advent of concern for energy conservation, more and more research is invested in studying the effect of air pockets on flow efficiency and energy consumption.
Conclusions are that air pockets have a very significant impact on these, especially in wastewater force mains.
Much has been written in the past about Hydrogen Sulfide corrosion in wastewater pipelines. The EPA published a number of papers, pamphlets, and reports to Congress on this subject. More and more papers and studies today, attribute Hydrogen Sulfide corrosion to air pockets, including a number of papers presented at the ASCE Pipelines 2009 Conference in San Diego. Most of these papers refer to detection, monitoring, evaluation, assessment and management of corrosion, but not of prevention. They point out the contribution of air pockets to Hydrogen Sulfide corrosion, but they do not discuss the means and ways of preventing air pocket accumulation.
Though, for many years, it was commonly accepted by surge experts that air pockets dampen surges, it was determined in recent research studies that air pockets of certain sizes and in certain locations along a pipeline, can induce and/or enhance surges. These surges, especially in force mains weakened by corrosion, can cause intensive and severe damage to pipelines, resulting in soil and water source polluting leakage, and health endangering pathogen and contaminant intrusion to drinking water transmission systems.
In the advent of concern for energy conservation, more and more research is invested in studying the effect of air pockets on flow efficiency and energy consumption. Conclusions are that air pockets have a very significant impact on these, especially in wastewater force mains.
This paper will show that, even though there is a great mistrust of air valves for wastewater applications, modern, innovative air valves are reliable and efficient, and are an extremely cost efficient and readily available device for preventing the accumulation of air pockets and for averting the above-mentioned damages and hindrances.