Reduction of Water Hammer Impact with Surge Tank

Abstract

Abstract

     Objective: To evaluate the difference in reducing the impact of water hammer with the surge tank application with and without a flexible diaphragm.

     Methods: The water hammer were simulated from 0.5 HP water pump, head maximum to 20 meters and control valve to adjust the flow rate. The water flowed through the PVC main pipes with ½ inch, ¾ inch, and 1 inch pipe sizes. The length of the PVC main pipe was 4 meters each. The study results were collected from pressure values at the surge tanks. The surge tanks were made out of PVC pipes. The pressure reduction values were compared in with and without the flexible diaphragm. The surge tanks studied were available in ½-inch, ¾-inch, 1-inch, 1.5-inch, and 2-inch sizes. The lengths of the surge tanks were 50, 75, 100 centimeters and were tested at each size of the surge tanks.

     Results: The water hammer pressure reduction efficiencies were 2%-5%, 7%-15%, and 20%-40% for ½ inch, ¾ inch, and 1 inch pipe sizes, respectively. These efficiencies were directly proportional to the diameters and lengths of the surge tanks, both without and with flexible diaphragm. The flexible diaphragm could reduce the pressure with the higher efficiency of 2%-7% than the without flexible diaphragm. Because of the water supply pipe sizes were inversely proportional to the pressure generated in the pipe system. Therefore, the sizes of the main water supply pipes affect the efficiency of reducing pressure. The water pressure reduction efficiencies were 20%-55%, 7%-29%, and 2%-10% for 1 inch, ¾ inch, and ½ inch of the main water supply pipe sizes, respectively. In addition, the design of the surge tanks length that took into account the energy loss due to friction in the pipelines could achieves the less maximum length of the surge tank than to ignore the loss of energy due to friction in the pipe.