عنوان مقاله [English]
Discharge control valve is a device for volumetric water delivery purposes without using electronic facilities. For analytical modeling of pressurized pipe networks, valves are introduced with their head loss properties. Therefore, any information about the valve head loss is very crucial. In this study, the head loss coefficient in discharge control valves is estimated. For this purpose, control valves were fabricated for the design discharges of 5 and 10 l/s and their performances were tested experimentally. The results indicated that the discharge control valves could accurately deliver an almost constant discharge, irrespective to the pressure fluctuations. The head-loss of entrance and all parts of the valve were investigated experimentally. Measuring the associated head loss coefficients indicated that the entrance head loss is significant in low differential pressures. Also, it was observed by increasing the differential pressure, the total head loss increases as well. From the hydraulic point of view, the main reason creating a relatively constant discharge through the valve is increasing/decreasing the head-loss proportional to increasing/decreasing the differential pressure. Finally, based on Buckingham analysis, empirical formulas were presented to define the head-loss coefficients.