Experimental Study of the Effects of Orifice Plate Eccentricity on Flow Coefficients

Abstract

An experimental program was undertaken to evaluate orifice flow coefficient variations with changes in plate concentricity. The tests were conducted on four Beta ratio orifice plates, ranging from 0.4 to 0.7, mounted in a special flange tap test fixture in a four-inch water line. The results are presented as the percent variation in flow coefficient, from the centered value, for a given eccentricity in an X, Y coordinate system in the plane of the orifice plate. The results indicate that the change in flow coefficient is a function of the magnitude and direction of the eccentricity and the Beta ratio. The coefficients were higher than the centered value independent of orifice center motion with an X, Y coordinate system. The relationship of these results to the concentricity specifications of existing codes and available literature is also presented.