Study on water hammer prevention in pumping water supply systems by multi-valves

Air valves are widely used in water supply systems for their simple structure, low cost and easy installation. Many water hammer studies had proved that in order to effectively protecting water hammer, air valve should have both large air inflow area and small outflow area, i.e. the air inflow speed is fast while outflow slow. But research on how to implement that idea can hardly be found. Based on a real pumping water supply system, this paper presented a water hammer protection method using characteristic method of water hammer calculation, and the concept of air valve set proposed. The calculation results show that area ratio between air valve inlet and outlet has great influence on water hammer protection effect, and the ratio has an optimal value. Using both air valve set and butterfly valve two phase closing procedure can effectively prevent water hammer in pumping water supply systems.