1、Orifice Metering of Natural Gas and Other Related Hydrocarbon FluidsConcentric, Square-edged Orifice MetersPart 1: General Equations and Uncertainty GuidelinesAGA Report No. 3Part 1Manual of Petroleum Measurement StandardsChapter 14.3.1American Gas Association400 North Captiol Street, NWWashington,
2、DC 20001American Petroleum Institute1220 L Street, NWWashington, DC 20005FOURTH EDITION, SEPTEMBER 2012ERRATA, JULY 2013An American National StandardANSI/API MPMS Ch. 14.3.1/AGA Report No. 3, Part 1Special NotesThis AGA/API publication necessarily addresses problems of a general nature. With respect
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19、s.aspx.iiiContentsPage1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.1 Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
20、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.2 Organization of Standard . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Normative References. . . . . . . . . . . . . . . . . . . . . . . . .
21、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 Terms, Definitions, and Symbols. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33.1 Terms and Definitions. . . . . . . . . . . . . . . .
22、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33.2 Symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74 Field of Applicat
23、ion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84.1 Applicable Fluids. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
24、. . . . . . . 84.2 Types of Meters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94.3 Uncertainty of Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
25、 . . . . . . . . . . . . . . . . . . . 105 Method of Calculation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106 Orifice Flow Equation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
26、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106.1 Velocity of Approach Factor (Ev) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126.2 Orifice Plate Bore Diameter (d). . . . . . . . . . . . . . . . . . . . . .
27、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126.3 Meter Tube Internal Diameter (D). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127 Empirical Coefficient of Discharge . . . . . . . . . . . . . .
28、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137.1 Regression Database . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147.2 Empirical Coefficient of Discharge Equation f
29、or Flange-tapped Orifice Meters . . . . . . . . . . . . . . . . . . . . 157.3 Reynolds Number (ReD) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167.4 Flow Conditions. . . . . . . . . . . . . . . . . . . . . . . .
30、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167.5 Pulsating Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178 Empirical Expansion Factor (
31、Y ) for Flange-tapped Orifice Meters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 198.1 Upstream Expansion Factor (Y1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 208.2 Downstream Expansion Factor (Y2). . . .
32、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 219 In-situ Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 229.1 General . . . . . . .
33、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 229.2 Meter Factor (MF). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
34、 . . . . . . 2210 Fluid Physical Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2310.1 Viscosity () . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
35、. . . . . . . . . . . . . . . . . . . . . . . 2310.2 Density (t,p, b) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2310.3 Isentropic Exponent (). . . . . . . . . . . . . . . . . . . . . . . . . . . . .
36、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2411 Unit Conversion Factors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2411.1 Orifice Flow Equation . . . . . . . . . . . . . . . . .
37、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2411.2 Reynolds Number Equation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2511.3 Expansion Factor Equation . . . .
38、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2511.4 Flow Rate per Unit of Time Conversion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2512 Practical Uncertainty Gui
39、delines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2812.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
40、 2812.2 Uncertainty Over a Flow Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2812.3 Uncertainty of Flow Rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
41、. . . . . . . . . . 2812.4 Typical Uncertainties. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3112.5 Example Uncertainty Calculations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
42、. . . . . . . . . . . . . . . . . . . . 37vContentsPageAnnex A (informative) Discharge Coefficients for Flange-tapped Orifice Meters . . . . . . . . . . . . . . . . . . . . . . . 40Annex B (informative) Adjustments for Instrument Calibration and Use . . . . . . . . . . . . . . . . . . . . . . . . .
43、. . . . . 51Annex C (informative) Buckingham and Bean Empirical Expansion Factor (Y) for Flange-tapped Orifice Meters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52Bibliography . . . . . . . . . . . . .
44、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56Figures1 Orifice Tapping Location . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
45、 . 52 Orifice Meter Elements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93 Contribution to Flow Error Due to Differential Pressure Instrumentation . . . . . . . . . . . . . . . . . . . . . . . . . 294 Empiri
46、cal Coefficient of Discharge: Uncertainty at Infinite Reynolds Number . . . . . . . . . . . . . . . . . . . . . 325 Relative Change in Uncertainty: Dependence on Reynolds Number . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 326 Practical Uncertainty Levels. . . . . . . . . . . . . . . .
47、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34Tables1 Linear Coefficient of Thermal Expansion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132 Orifice Flow Rate Equation: Unit Conversion Fact
48、or (N1). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 263 Reynolds Number Equation: Unit Conversion Factor (N2). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 274 Empirical Expansion Factor Equation: Unit Conversion Factor (N3) . . . . . . .
49、 . . . . . . . . . . . . . . . . . . . . . . 275 Uncertainty Statement for Empirical Expansion Factor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 336 Example Uncertainty Estimate for Liquid Flow Calculation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 387 Example Uncertainty Estimate for Natural Gas Flow Calculation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39A.1 Discharge Coefficients for Flange-tapped Orifice Meters: Nominal 2-in. (50-mm) MeterD = 1.939 in. (49.25 mm) . . . . . . . . . . .
