Experimental analysis of air valve behaviour during hydraulic transients

The dynamic behaviour of air valves is still, to date, not very well known and, despite numerous scientific contributions, a standard approach for their dimensioning is yet to be found. Several analytical and experimental laboratory studies have been conducted for rapid pressurizing of entrapped air in a pipeline system, but most of these analyses have been performed with an air valve located at the end of a horizontal pipeline. In this study, an experimental analysis is carried out for several orifice sizes installed on a viscoelastic pipe for different boundary conditions. A brief description of the experimental hydraulic circuit and test procedures is provided, presenting the results of this laboratory experience. Experimental results show that the overpressure, due to entrapped air in a pressurized system, may depend on several factors such as pipeline slope.