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In a piping system, butterfly valves are often used as a flow controller to either modulate the flow throttling range or control the flow's on/off positions. Because butterfly valves are usually light-weighted and low cost, they have a wide range in size selection and possess a small flow resistance, therefore, they are widely accepted in many industrial applications. After a certain period of service, a butterfly valve and its downstream pipe wall may be damaged by erosion. The elimination or mitigation of this kind of erosion problem is actually the most important issue for a valve user. An experiment setup is used in this study to investigate the erosion problem. The water tunnel is 3 inches in diameter and the pipes are made by transparent PE for the ease of flow visualization and photograph purpose. At certain key positions, the pressure and flow vibration level are also measured to support the observation of possible erosion phenomena. The results indicate the most serious erosion problem may occur when the valve open angle is between 20-40 degrees. In this paper, five different valve disks are used to perform the tests, the results shows the model 5 have the smallest vibration level both on the valve stick and its downstream pipe wall under the critical valve opening angle. These results implies that a suitable buffer attached on the back side of disk surface near the orifice side could mitigate the erosion phenomena.
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