ANÁLISIS DEL COMPORTAMIENTO DE VENTOSAS DURANTE LA EXPULSIÓN DE AIRE EN TRANSITORIOS HIDRÁULICOS

Abstract

The operations consisting in filling and emptying pipe systems involve the movement of big quantities of water and air. This kind of operations, as the possible fluid pressure alterations during the normal operation of the installation are some of the possible causes that may provoke the presence of trapped air. The trapped air pockets in a pipe system reduce the transport capacity of the pipes, at the same time they can produce damage in the pipe and in the different elements. In the hydraulic transients with trapped air pressures bigger than the Allievi pressure can be generated. It is also true that in some occasions and in certain circumstances, the air pockets may mitigate the water hammer produced in a hydraulic transient acting as a cushion. The elements used usually in pipe systems to eliminate or to admit air in the pipes are the air valves. The conventional air valves open and close automatically, so its behaviour can’t be modified externally. There is little information about the air valves behaviour in no steady flow conditions, and even less information about the effects and damage on the system during a hydraulic transient. This document tries to provide more information about this item by realising laboratory tests, in a big dimension installation. In these tests, the influence of the air valves on the registered pressures during the transient generated under controlled conditions was analysed. Keywords: Air, trapped, system, pipe, distribution, water, air valves, pressures, transient, hydraulic.