The search for the proper form of an equation for the coefficient of discharge of an orifice metering section has led to a five-term equation which expresses the variability of geometry, the effect of the boundary layer, and the effect of velocity profile. The first such equation was published in 1997 for the geometry where the pressure taps were located at one pipe diameter upstream and 1/2 diameter downstream of the orifice plate (the D & D/2 taps). In this paper, the applicability of this form of the equation has been extended to the cases of corner taps and flange taps. The method applied is identical to that of the previous paper; the same assumptions and hypotheses were used and tested, resulting in connatural conclustions. An uniform equation was developed which covers all three tap geometries within the experimental uncertainty of the data for all Reynolds numbers above approx 25,000 to 30,000 and pipe sizes aboveapprox2.8 inch. Because this equation is soundly based on the laws of fluid dynamics, extrapholation of the coefficient of dischearge ofr any calibrated orifice flowmetering section beyond the range of the calibration data is permissible. Such extrapolation often is necessary in Performance Test Code work.
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