Flow Characteristics of Butterfly and Spherical Valves

Discharge coefficients of butterfly and spherical valves are given. The data were obtained from tests of 10-in. diam models. Four butterfly valve disks were tested, all lenticular in shape. One of them had the disk offset in relation to the shaft. Four spherical valve rotors were tested. These data can be used to predict the flow and torque for a given set of conditions as illustrated in the numerical examples. In testing spherical valve models, hydrodynamic force on the valve also was measured. These data can be used to size the trunnions of such valves. The tests were conducted with air as working fluid. The results can be applied to flow of liquids provided that cavitation does not occur.