Evaluation of Pipe Elbows as Flow Meters

Abstract

A number of flanged, 90○ commercial elbows of several sizes, ranging from 3 in. to 12 in. in diameter are calibrated as elbow flow meters. The accuracy to which a calibration equation can be predicted using only the nominal elbow size and the average calibration results of several similar elbows is determined. This accuracy can be improved if precise measurements of the elbow diameter and radius of bend are obtained and incorporated into the calibration equation. A relatively simple and inexpensive method for accurately determining the radius of bend with casting plaster is presented. The effects of installing the elbow flow meters in the proximity of other piping components are investigated and a modification of the classical vortex velocity profile analysis for elbow flow meters is presented.