Waterhammer protection with air vessels : A comparative study

Abstract

As pressurized liquid transport systems need to be protected against waterhammer phenomena, different kinds of protection devices can be applied. Each of them has its own characteristics and advantages. In the whole scope of protec-tion installations, air vessels certainly offer the best guarantee for safe pipe line operation under variable conditions. To meet all operational conditions different types of air vessels are commercially available. The most important ones are the classical air vessel with gas bubble, eventually equipped with a rubber balloon and with a single connection to the main pipe; the classical air vessel with double connection which acts as a flow through system. In a more recent ver-sion of an air vessel, the normally isolated air bubble can be connected to the atmospheric pressure, again with a single or a double connection pipe (AARA-vessel). The principles and typical working schemes of all these types of air vessels are identified and briefly discussed. Based on some practical examples the application field of each type is defined and illustrated. Relevant design parameters are put in evidence