The Challenge of Air Valves: A Selective Critical Literature Review

Ramezani, Leila; Karney, Bryan W.; Malekpour, Ahmad

doi:10.1061/(asce)wr.1943-5452.0000530

Cited by 45 publications

(34 citation statements)

References 21 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Whatever the origin of air in the pipes, its presence creates unwanted problems in the majority of cases. One of the most important problems is overpressure generation (Martin 1976;Hamam and McCorquodale 1982;Fuertes 2001;Zhou et al 2002;Ramezani et al 2015). Other problems include section reduction inside the pipe, which may cause collapse; additional generation of head losses, which cause an increase in the electricity consumption; problems with noise and vibrations; interior corrosion due to the oxygen transported by the air; failures in the measurement instrumentation; etc.…”

Section: Introductionmentioning

confidence: 99%

Numerical modelling of pipelines with air pockets and air valves

et al. 2016

View full text Add to dashboard Cite

This work considers the behaviour of air inside pipes when the air is expelled through air valves. Generally, the air shows isothermal behaviour. Nevertheless, when the transient is very fast, it shows adiabatic behaviour. In a real installation, an intermediate evolution between these two extreme conditions occurs. Thus, it is verified that the results vary significantly depending on the hypothesis adopted. To determine the pressure of the air pocket, the most unfavourable hypothesis (isothermal behaviour) is typically adopted.Nevertheless, from the perspective of the water hammer that takes place when the water column arrives at the air valve and abruptly closes, the most unfavourable hypothesis is the opposite (adiabatic behaviour). In this case, the residual velocity with which the water arrives at the air valve is higher, and, consequently, the water hammer generated is greater.

show abstract

Section: Introductionmentioning

confidence: 99%

Numerical modelling of pipelines with air pockets and air valves

et al. 2016

View full text Add to dashboard Cite

show abstract

“…Correctly designed and sized air valves release unwanted air out of the pipeline in a controlled and safe manner. Dynamic effects of poorly selected air valves may cause large pressure peaks (air valve slam) as found by Campbell [7] and recently reviewed by Ramezani et al [8].…”

Section: Introductionmentioning

confidence: 89%

Unsteady Pressures Influenced by Trapped Air Pockets in Water-Filled Pipelines

Bergant

Tijsseling²,

Kim

et al. 2018

SV-JME

View full text Add to dashboard Cite

mm). A trapped air pocket is confined at the downstream end of the pipeline. The transient event is initiated by rapid opening of a valve positioned at the initial air/water interface. The shut-down test case has been carried out in the University of Adelaide laboratory apparatus (length 37 m, internal diameter 22 mm). A trapped gas pocket is maintained near the midpoint of the pipeline. The shut-down event is initiated by rapid closure of the downstream-end valve. Results of numerical simulations and laboratory investigations are presented and they show profound effects of unsteady skin friction on pressure histories.Keywords: fluid transients, water hammer, trapped air pocket, discrete gas cavity model, unsteady skin friction, pipeline apparatus Highlights • Trapped air (gas) pockets cause changes in attenuation, shape and timing of pressure waves.• Gas pocket is incorporated as boundary condition in discrete gas cavity model (DGCM).• Start-up and shut-down experiments affected by one trapped gas pocket are investigated.• Unsteady skin friction may significantly increase damping of pressure waves.

show abstract

“…The installation of air valves is an efficient protection against this undesirable phenomenon. These valves regulate the quantity of air in the pipeline so as to reduce or prevent potentially destructive consequences of the moving and entrapped air [7]. In the system under study, air valves are positioned along the route and their purpose is to deaerate the system during everyday operation, introduce the air in cases when the pressure in the pipeline is lower that the atmospheric pressure, and release the air from the pipeline when the system is refilled with water.…”

Section: System Protected With Air Vesselmentioning

confidence: 99%

Water hammer in irrigation systems

2017

JCE

View full text Add to dashboard Cite

Water hammer in irrigation systemsSelf-propelled sectorial rain guns (typhones) and self-propelled automated devices for linear or circular irrigation are often used in irrigation systems. However, unwanted overpressure can occur due to sudden closure of valves at the entrance segment of these devices. The system is protected against such overpressure by gradual closure of valves. The protection of the system against excessive and insufficient pressures, and the impact of simultaneous closure of valves at peripheral parts of the network, are defined in the paper based on an example of hydraulic calculation of unsteady flows at the Blata -Cerna Irrigation System.

show abstract

The Challenge of Air Valves: A Selective Critical Literature Review

Cited by 45 publications

References 21 publications

Numerical modelling of pipelines with air pockets and air valves

Numerical modelling of pipelines with air pockets and air valves

Unsteady Pressures Influenced by Trapped Air Pockets in Water-Filled Pipelines

Water hammer in irrigation systems

Contact Info

Product

Resources

About