A combined water hammer protective method for optimizing the volume of the air vessel in water supply systems

Abstract

Abstract An air vessel, as an effective and reliable water hammer protective device, is widely used in long-distance water supply systems. However, the volume of the air vessel must be extra-large to guarantee security of the system, especially in a system with a high head and large flow. In this paper, to reduce the volume of the air vessel, a novel protective method combining an air vessel and over pressure relief valve was proposed and verified using a numerical simulation based on a practical project. In addition, the protection performance under the combined protective method was compared with the traditional method. The results show that the combined protective method can significantly reduce the volume of air vessel and exhibit a better protection performance. Furthermore, after analysis and optimization of the rule of opening and closing over the pressure relief valve, the valve should be opened in a short time to produce fast discharge so as to eliminate the large pressure rise rapidly. The duration of opening the over pressure relief valve has little effect on the maximum pressure. The closing time of the over pressure valve should be slow, as much as possible, to avoid producing large pressure wave.