Flow Measurement

By Square-Edged Orifice Plate Using Corner Tappings

1st Edition - January 1, 1965
Author: W. J. Clark
Language: English
eBook ISBN:
9 7 8 - 1 - 4 8 3 1 - 4 9 9 1 - 2

Flow Measurement By Square-edged Orifice Plate Using Corner Tappings deals comprehensively with the subject of flow measurement through pipes by a square edge orifice plate using… Read more

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Flow Measurement By Square-edged Orifice Plate Using Corner Tappings deals comprehensively with the subject of flow measurement through pipes by a square edge orifice plate using corner tappings. The object is to present in easily readable and applicable form a consideration of all the many factors involved in accurate measurement, thus enabling readers to appreciate what is involved in good flow metering practice, to design if desired their own installations to predetermined standards of accuracy, and to make reliable assessments of existing installations. The book is organized into four parts. Part 1 discusses basic principles, approved design and installation conditions, and recommended follow-up maintenance for various predetermined standards of accuracy, with special attention given to requirements concerned with the metered fluid, working conditions, orifice design, pipe layout and pipe conditions. Part 2 deals with the practical application of Part I and describes the method of using a Flowmeter Data Sheet specially designed both to ensure that the numerous factors involved in accurate flow measurements are taken into account. Part III consists of a number of representative and well-detailed specimen calculations designed to illustrate and clarify all aspects of the method of calculation advocated in Part II. In Part IV a considerable amount of relevant data on the physical properties of fluids, and many tables, graphs and alignment charts are assembled together for easy reference when making orifice calculations.

Foreword

Acknowledgment

Symbols and Units Facing

Part 1. Basis of Measurement

Introduction

Chapter 1. Characteristics of Flow through Square-Edged Orifice Plates

Laminar or Stream Line Flow

Turbulent Flow

Relationship between Pressure-Drop and Flow Rate

Chapter 2. Flow Measurement within Predetermined Standards of Accuracy-Factors Involved and Accuracy Obtainable

1. Requirements for Metered Fluid

2. Required Operating Conditions

3. The Overall Discharge Coefficient C

4. The Fluid Density (S0 and S8)

5. Upstream Temperature (T8)

6. Upstream Pressure (P8)

7. The Pressure-Difference (h)

8. Miscellaneous Installation Features

9. Special Metering Problems

10. Correction of Readings of Flow Rates and of Integrated Flows

11. Overall Accuracy of Measurement

12. Follow-up Maintenance for Accurate Flow Measurement

13. Assessment and Certification of Installations

Part 2. REcommended Procedure for Calculating Orifice Plates - Use of Flow-meter Data Sheet

1. Use of Flow-meter Data Sheet

2. Explanatory Details of Flow-meter Data Sheet

2.1 Section 1 - General Data

2.2 Section 2 - Basic Formula

2.3 Section 3 - Units and Symbols

2.4 Section 4 - Design Data

2.5 Section 5 - Calculations

2.6 Section 6 - Installation Assessment

2.7 Section 7 - OrderData

2.8 Section 8 - Recording Flow-meter Data

2.9 Section 9 - Indicating Flow-meter Scale Data

2.10 Section 10 - Maintenance Record

Part 3. Specimen Calculations

Example 1 - Flow-meter Required Using Indicating Meter to Measure Water from Heating Set

Example 2 - Flow-meter Required Using Indicating Meter to Measure 'Air to Plant', Illustrating Calculation of non-square-root Scale

Example 3 - Flow-meter Required Using Indicating Meter to Measure 'Steam from Boilers', Illustrating Use of Enlarged Pipe

Example 4 - Flow-meter Required Using High-pressure Ring Balance Recording Meter to Measure 'Make-up Gas to Plant', Illustrating the Application of Gas Law Deviation Coefficients

(The case of Pulsating Flow is Dealt with on Page 188)

Example 5 - Flow-meter Required Using a Foxboro-type Indicating Meter to Measure 'Dry Hydrogen from Scrubber'

Example 5A - Flow-meter Required Using a Foxboro-type Indicating Meter to Measure 'Wet Hydrogen from Scrubber'

Part 4. Tabulated and Graphical Data

The Contents of Part 4, Which Comprises Figs. 7 to 44, is Shown on Pages 97 to 99

Appendix 1. Tolerances

1. Meaning of the Term 'Tolerance'

2. Tolerances for Single Measurements

3. Details of Possible Sources of Error in Flow Measurement

4. The Combination of Tolerances

5. Systematic and Random Errors

6. Application

7. Notes on 'Standard Deviation'

Appendix 2. Recommended Layouts of Pressure Pipes, Orifice Plates and Meters

Appendix 3. The Effects of Pulsations on Flow Measurement by Orifice Plate

1. Pulsation Factors Affecting Accuracy of Measurement

2. Assessment of Limiting Conditions Such That Errors Due to Pulsation Factors Will Be Negligible or Will Not Exceed ±0.5%

2.1 The 'Root-Mean-Square' Effect

2.2 Inapplicability of the Laws of Steady Flow

2.3 Asymmetrical Response to Pressure Changes in the Instrument Lines and Manometer

3. Reduction of Severe Pulsations to an Extent Sufficient to give an R.M.S. Effect Not Exceeding 1% Using the Hodgson Method

3.1 Method of Calculating the Hodgson Number

3.2 Estimation of Waveform Factor WF

4. Practical Application of Findings

4.1 Negligible Pulsations

4.2 Minor or Suspected Pulsations

4.3 Suspected or Known Severe Pulsations

5. Worked Examples

5.1 Example 1 - Measurement of Gas Flow at 300 atm from Compressor

5.2 Example 2 - Estimate of Error due to Pulsations for an Installation Measuring Circulating Gas after a Booster

Appendix 4. A Slide-rule for the Rapid Calculation of Orifice Plate Dimensions

1. Basis of Slide-rule Design

2. Design Details

3. Method of Use for Approximate Calculations and for Determining the General Suitability of a Given Set of Factors

4. Method of Use for Calculations to a Class-B Standard of Accuracy

5. Extension of Use to Venturi Tube and Nozzle Calculations

6. Extension of Use to (D—D/2) Tapping's

7. Extension of Use to Flange Tapping's

8. Application and Advantages

Appendix 5. Notes on Flow Measurement Using (D-D/2) Tapping's

Appendix 6. Notes on Flow Measurement Using Flange Tapping's

References

Index