The effect of the location of an in-line tube bundle on orifice flowmeter performance

Abstract

The Gas Research Institute has sponsored many significant flow measurement studies at the National Institute of Standards and Technology. The main thrust of the 1988 research project was to determine the effect of the location of an in-line tube bundle flow conditioner on the orifice discharge coefficient. An in-line bundle was place at four locations-7, 12, 17 and 17 pipe diameters upstream of the orifice plate in a 100 mm (4 inch) orifice meter. This research has determined that if the in-line tube bundle is placed at 7 pipe diameters, the minimum distance specified in the flow measurement standards for a 0.75 beta ratio plate, as much as 1% error in the discharge coefficient occurs. At 17 pipe diameters, the discharge coefficients of all the beta ratios are statistically the same as would be determined in ‘ideal’ conditions. These new experimental data will help to improve the current flow measurement standards and suggest the direction of future reserach.