Air Influence on Hydraulic Transients on Fluid System With Air Valves

Abstract

A study is made on the pressure surges on a fluid system with air valves. The effects of the presence and distribution of air on the system response are studied. Several distinct pressure transient characteristics were observed through this investigation. Investigations showed that air valves with high inflow characteristics installed at peak locations of a fluid system with entrapped air may reduce the magnitude of the extreme negative pressure surges. However, for near zero air entrainment levels, air valves with higher outflow characteristics tend to result in higher positive pressure surges. The effectiveness of the air valves installed for the purpose of surge protection depends not only on the physical configuration of the fluid system, the physical properties of the pipeline and the fluid, but significantly also on the characteristics of the air valves and the distribution of air in the system. The results of the investigations in the present work were confirmed through field observations and measurements.