Performance of models to determine flow rate using orifice plates

Nicolas D Cano,Gustavo L Muniz,Jonesmar De Oliveira,José A Frizzone,José G Dalfré Filho,Antonio P De Camargo

doi:10.1590/1807-1929/agriambi.v25n1p10-16

Abstract

ABSTRACT This study aimed to evaluate three methodologies for orifice-plate water-flow estimation by quantifying errors in the flow determinations to propose an appropriate measurement range for each evaluated condition. Two orifice-plate models (nominal diameters of 100 and 150 mm) with 50% restriction in the flow section were evaluated. In the theoretical equations, the discharge coefficient was obtained using the Reader-Harris/Gallagher equation (Method 1) and approximated from experimental data using the angular coefficient of a zero-intercept straight line (Method 2). The recommended measurement ranges for errors that were lower than 5% for the 100 and 150 mm plates were 30 to 65 m3 h-1 and 70 to 130 m3 h-1 using the theoretical equation and 20 to 65 m3 h-1 and 40 to 130 m3 h-1 using the empirical equation, respectively. The Reader-Harris/Gallagher equation (Method 1) adequately estimated the discharge coefficient of the orifice plates; however, the use of empirical equations (Method 3) demonstrated smaller measurement errors and greater rangeability of the evaluated flow meters.

Highlights

Differential-pressure flow meters use the differentialpressure principle to determine fluid flow (Delmée, 2003)
The discharge coefficient was obtained using the Reader-Harris/Gallagher equation (Method 1) and approximated from experimental data using the angular coefficient of a zero-intercept straight line (Method 2)
The recommended measurement ranges for errors that were lower than 5% for the 100 and 150 mm plates were 30 to 65 m3 h-1 and 70 to 130 m3 h-1 using the theoretical equation and 20 to 65 m3 h-1 and 40 to 130 m3 h-1 using the empirical equation, respectively

Summary

Introduction

Differential-pressure flow meters use the differentialpressure principle to determine fluid flow (Delmée, 2003). An orifice plate or diaphragm is a differential-pressure flow meter that basically consists of a perforated circular plate that provides restriction to the flow section, causing a differential pressure that is proportional to the flow into the pipe. Orifice plates are the most common differential-pressure flow meters for determining the flow rate in pipes (Shah et al, 2012) and stand out owing to their simple construction, contain no moving parts, ease in installation, lower cost among other differential-pressure flow meters, and suitability for various fluids and in multiphase flows (Campos et al, 2014). Cd can be estimated from experimental data collected by calibration procedures or from equations. In the latter, the ReaderHarris/Gallagher (R-H/G) equation stands out (ISO 5167-2, 2003; Reader-Harris, 2015)

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Results

Conclusion