Author(s): Nicola Fontana; Enzo Galdiero; Maurizio Giugni
Keywords: Air vent; entrapped air pocket; hydraulic transient; laboratory studies; pipeline filling
Abstract: Air release through venting devices during filling operations of an empty pipeline can give rise to vast transients which can result in serious damages to the pipes. However, despite a large number of studies, there is still a significant lack of knowledge regarding the physical processes involved. The present paper aims to address this issue by comprehensive laboratory tests. Two configurations were analysed and both air release valves and orifices were used for air venting. In the first configuration, the air vent was fitted at the downstream end of the pipeline, and the transient showed significant pressure surges consequent to the high velocity impact of the water column on the orifice (or the valve). In the second configuration, the air vent was fitted at an intermediate high point of the pipe profile. In this case, the transient showed very low velocity of the water column at the impact and, consequently, generally negligible pressure surges.