MIcromotion Proving Coriolis

Proving Coriolis

Flowmeters

October 1998

Proving Coriolis

Flowmeters

Copyright ©1998, Micro Motion, Inc. All rights reserved.

Micro Motion, ELITE and ProLink are registered trademarks, and ALTUS is a trademark of Micro Motion, Inc., Boulder, Colorado. Rosemount and SMART FAMILY are registered trademarks of Rosemount, Inc., Eden Prairie, Minnesota. HART is a registered trademark of the HART Communication Foundation, Austin, Texas. Modbus is a registered trademark of Modicon, Inc., North Andover, Massachusetts. Microsoft and Windows are registered trademarks of Microsoft Corp., Redmond, Washington. Intel is a registered trademark of Intel Corporation, Santa Clara, California. Hastelloy is a registered trademark of Haynes International, Inc., Kokomo Indiana. Minigrabber is a registered trademark of ITT Corp., New York, New York.

Foreward

This manual was published primarily to support the application of Micro Motion Coriolis flowmeters used in custody transfer service, where the meters are proved by common proving methods. This is a comprehensive manual, in that it can be used for training those people who have minimal knowledge of Coriolis meters, and those people who know very little about proving techniques in general. For those experienced with the application of Coriolis flowmeters, or those experienced at proving other types of flowmeters, the manual has been designed in brief sections that can be referred to quickly and completely. It is not necessary to read this entire book to prove a meter.

For example: If an experienced, conventional prover operator wants to prove a Micro Motion meter for the first time, he can turn to Section 8.3 and use the proving form in Appendix A. If an instrumentation engineer is designing a Coriolis meter run, he can refer to the information in Chapters 5 and 6. No need to read the entire manual.

It is hoped that this proving manual will help anyone who is involved in the application of Micro Motion meters that are being proved. For further assistance, please call the Micro Motion Customer Service Department:

• In the U.S.A., phone 1-800-522-MASS (1-800-522-6277)• Outside the U.S.A., phone 303-530-8400• In Europe, phone +31 (0) 318 549 443• In Asia, phone 65-770-8155

Proving Micro Motion Coriolis Meters i

Contents

Terminology and Mathematical Variables . . . . . . . . . xv

1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

2 General Proving Concepts . . . . . . . . . . . . . . . . . . . . . . . . . . 7

3 Proving Procedures: Conventional and Small Volume Provers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

4 Recommended Meters for Custody Transfer. . . . . . 33

5 Coriolis Meter Installation Recommendations . . . 37

6 Interfacing to Coriolis Meter Output Signals. . . . . 43

7 Proving Instrumentation Requirements . . . . . . . . . . . 59

8 Flow Rate Proving Devices . . . . . . . . . . . . . . . . . . . . . . . . . 67

9 Proving Calculations Summary. . . . . . . . . . . . . . . . . . . . . 119

10 Flow Proving Summary and Troubleshooting . . . . . 131

11 Coriolis Meter Density Measurement and Density Proving . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139

Appendixes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163

Index. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 255

Contents

ii Proving Micro Motion Coriolis Meters

Terminology and Mathematical Variables . . . . . . . . . xix

1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

1.1 Coriolis Meters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2 General Proving Concepts. . . . . . . . . . . . . . . . . . . . . . . . . . . 7

2.1 What Is Proving Versus Calibration? . . . . . . . . . . . . . . . . 9

2.2 Why Is Proving Performed? . . . . . . . . . . . . . . . . . . . . . . . . . 9Custody Transfer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9Quality Audit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10Environmental Audit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

2.3 What Is the Outcome of Proving?. . . . . . . . . . . . . . . . . . . . 10

2.4 When Do You Need To Prove a Coriolis Meter? . . . . . . 11

2.5 How Often Should a Coriolis Meter Be Proved? . . . . . . 11Trend Charts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12Varying Process Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . 12Increasing the Time Between Provings . . . . . . . . . . . . . . . . . . 12Pay and Check Meters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

3 Proving Procedures: Conventional and Small Volume Provers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

3.1 Meter Configured For Volume Measurement . . . . . . . . . 17Minimum Volume Proving Requirements . . . . . . . . . . . . . . . . 18Maximum Volume Proving Requirements. . . . . . . . . . . . . . . . 20

3.2 Meter Configured For Mass Measurement . . . . . . . . . . . 22Minimum Mass Proving Requirements . . . . . . . . . . . . . . . . . . 22Using a Density Meter at the Prover . . . . . . . . . . . . . . . . . . . . 25Using the Coriolis Meter Density Measurement. . . . . . . . . . . 27Proving in Volume Units/Measuring in Mass Units . . . . . . . . 29

3.3 Transfer Standard Proving. . . . . . . . . . . . . . . . . . . . . . . . . . 30

Contents

Proving Micro Motion Coriolis Meters iii

4 Recommended Meters for Custody Transfer. . . . . . 33

5 Coriolis Meter Installation Recommendations . . . 37

5.1 Sensor Mounting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

5.2 Sensor Flow Tube Orientation . . . . . . . . . . . . . . . . . . . . . 40Liquid Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40Gas Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40Vertical Pipeline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

5.3 Provisions to Allow Meter Zeroing. . . . . . . . . . . . . . . . . . 40

5.4 Minimizing External Influences on the Meter . . . . . . . 42

5.5 Location of Proving Connections . . . . . . . . . . . . . . . . . . . 42

6 Interfacing to Coriolis Meter Output Signals. . . . . 43

6.1 Digital Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46Interface to Digital Information . . . . . . . . . . . . . . . . . . . . . . . 47Using the RS-485 Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47Using the Bell 202 Standard . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

6.2 Analog Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48Interfacing to Analog Outputs . . . . . . . . . . . . . . . . . . . . . . . . . 49

6.3 Frequency/Pulse Output . . . . . . . . . . . . . . . . . . . . . . . . . . . 49Interfacing to Frequency/Pulse Output . . . . . . . . . . . . . . . . . 49K-Factor or Pulse Scaling Factor Determination . . . . . . . . . 52Troubleshooting the Frequency/Pulse Output . . . . . . . . . . . 53

6.4 Additional Flow Measurement Information . . . . . . . . . 53Response Time/Damping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53Effects of Damping on Proving Accuracy . . . . . . . . . . . . . . . 54Low-Flow Cutoff . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56Meter Zero . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

6.5 Wiring to Allow Field-Access to Meter Information . . 57

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iv Proving Micro Motion Coriolis Meters

7 Proving Instrumentation Requirements . . . . . . . . . . . 59

7.1 Proving Computer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

7.2 Pulse Counting Device . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62Frequency Totalizers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62Single-Channel Proving Counters. . . . . . . . . . . . . . . . . . . . . . . 62Dual-Channel Proving Counters . . . . . . . . . . . . . . . . . . . . . . . . 62

7.3 Temperature Measurement Device . . . . . . . . . . . . . . . . . . 63

7.4 Pressure Measurement Device . . . . . . . . . . . . . . . . . . . . . . 63

7.5 Density Measurement Device . . . . . . . . . . . . . . . . . . . . . . . 64

7.6 Density Averaging Device . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

7.7 Density Proving Device . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

8 Flow Rate Proving Devices . . . . . . . . . . . . . . . . . . . . . . . . . . 67

8.1 Gravimetric Tank Proving . . . . . . . . . . . . . . . . . . . . . . . . . . 71Required Equipment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72Meter Factor Calculation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73Gravimetric Proving Uncertainty . . . . . . . . . . . . . . . . . . . . . . . 74Precautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75Batch Size Recommendation . . . . . . . . . . . . . . . . . . . . . . . . . . 76Number of Test Batches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77Repeatability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77Damping Factor Recommendation . . . . . . . . . . . . . . . . . . . . . 78

8.2 Volumetric Tank Proving . . . . . . . . . . . . . . . . . . . . . . . . . . . 78Required Equipment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79Meter Factor Calculation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79Volumetric Tank Proving Uncertainty . . . . . . . . . . . . . . . . . . . 80Precautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82Batch Size Recommendation . . . . . . . . . . . . . . . . . . . . . . . . . . 83Number of Test Batches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83Repeatability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83Damping Factor Recommendation . . . . . . . . . . . . . . . . . . . . . 84

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Proving Micro Motion Coriolis Meters v

8.3 Conventional Pipe Prover . . . . . . . . . . . . . . . . . . . . . . . . . . 84Required Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85Meter Factor Calculation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85Conventional Pipe Proving Uncertainty . . . . . . . . . . . . . . . . . 86Precautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89Prover Size Recommendation . . . . . . . . . . . . . . . . . . . . . . . . . 90Number of Proving Runs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90Repeatability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90Damping Factor Recommendation . . . . . . . . . . . . . . . . . . . . . 90

8.4 Small Volume Prover . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91Required Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94Meter Factor Calculation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94Small Volume Prover Uncertainty. . . . . . . . . . . . . . . . . . . . . . 95Precautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98Small Volume Prover Size Recommendations. . . . . . . . . . . . 100Number of Proving Passes/Runs . . . . . . . . . . . . . . . . . . . . . . . 101Repeatability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103Damping Factor Recommendations . . . . . . . . . . . . . . . . . . . . 103

8.5 Volumetric Master Meters and Transfer Standards . . 104Master Meters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104Transfer Standard Meters. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104Proving Equipment and Procedures . . . . . . . . . . . . . . . . . . . . 105Required Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106Meter Factor Calculation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107Volumetric Transfer Standard Meter Uncertainty . . . . . . . . 108Precautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110Proving Duration Recommendation . . . . . . . . . . . . . . . . . . . . 111Number of Proving Runs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111Repeatability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111Damping Factor Recommendation . . . . . . . . . . . . . . . . . . . . . 111

8.6 Coriolis Master Meter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111Required Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113Meter Factor Calculation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113Coriolis Master Meter Uncertainty . . . . . . . . . . . . . . . . . . . . . 114Precautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117Recommended Proving Duration . . . . . . . . . . . . . . . . . . . . . . 117Number of Proving Runs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117Repeatability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118Damping Factor Recommendation . . . . . . . . . . . . . . . . . . . . . 118

Contents

vi Proving Micro Motion Coriolis Meters

9 Proving Calculations Summary . . . . . . . . . . . . . . . . . . . . . 119

9.1 Volume Meter Factor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121

9.2 Mass Meter Factor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122Alternate Method for Determining Mass Meter Factor . . . . . 123

9.3 How Many Proving Runs Are Required? . . . . . . . . . . . . . 123

9.4 Repeatability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123Meter Configured for Volume . . . . . . . . . . . . . . . . . . . . . . . . . . 123Meter Configured for Mass . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124Stability of Process Conditions. . . . . . . . . . . . . . . . . . . . . . . . . 124Repeatability Specification for Coriolis Meters . . . . . . . . . . . 125

9.5 Meter Factor Uncertainty. . . . . . . . . . . . . . . . . . . . . . . . . . . 125

9.6 Reproducibility and Trend Charting . . . . . . . . . . . . . . . . . 126

9.7 Applying the Meter Factor to Inventory Calculations 128RFT9739 with Software Version 3.0 or Higher . . . . . . . . . . . . 128RFT9712 and RFT9739 with Software Version Lower

Than 3.0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129

10 Flow Proving Summary and Troubleshooting . . . . . 131

10.1 Summary Recommendations . . . . . . . . . . . . . . . . . . . . . . . . 133Meter Recommendations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133Sensor Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133Transmitter Outputs and Configuration . . . . . . . . . . . . . . . . . 134Proving Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134

10.2 Proving Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . 135Poor Repeatability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135Poor Meter Factor Reproducibility . . . . . . . . . . . . . . . . . . . . . 136

Contents

Proving Micro Motion Coriolis Meters vii

11 Coriolis Meter Density Measurement and Density Proving . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139

11.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141

11.2 Recommended Meters for Density Measurement . . . . 142

11.3 Interfacing to Coriolis Meter Density Output Signals 143Digital Density . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143Analog Density. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144

11.4 Field Proving the Coriolis Meter Density Measurement 146Density Proving Installations. . . . . . . . . . . . . . . . . . . . . . . . . . 148Density Proving Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . 151Density Proving Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . 154Density Proving Calculations. . . . . . . . . . . . . . . . . . . . . . . . . . 155Density Factor Reproducibility/Trend Charting . . . . . . . . . . 158Applying the Density Factor to Correct the Coriolis

Meter Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158

11.5 Summary Recommendations and Troubleshooting . . . 159Summary Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . 159Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160

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viii Proving Micro Motion Coriolis Meters

Appendixes

A Proving Forms for Volume Measurement . . . . . . . . . . . . 163

B Proving Forms for Mass Measurement . . . . . . . . . . . . . . . 173

C Proving Forms for Density Measurement . . . . . . . . . . . . 183

D Proving Charts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 189

E Determining How Often a Coriolis Meter Should Be

Zeroed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195

F Mass Flow Measurement. . . . . . . . . . . . . . . . . . . . . . . . . . . . 205

G Density Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 223

H Volume Measurement. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 239

I Equation for Predicting Number of Passes Per Run . . 245

J Proving Equipment Manufacturers . . . . . . . . . . . . . . . . . . 251

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Proving Micro Motion Coriolis Meters ix

Figures

Figure 1-1 Components of a Coriolis meter . . . . . . . . . . . . . . . . 3Figure 1-2 Components of a Coriolis sensor . . . . . . . . . . . . . . . 4Figure 2-1 Sample proving trend chart . . . . . . . . . . . . . . . . . . . . 13Figure 3-1 Minimum volumetric proving configuration . . . . . . 19Figure 3-2 Maximum volumetric proving configuration . . . . . 21Figure 3-3 Minimum mass proving configuration . . . . . . . . . . . 23Figure 3-4 Mass proving with a density meter . . . . . . . . . . . . . . 25Figure 3-5 Mass proving using Coriolis density. . . . . . . . . . . . . 28Figure 3-6 Transfer standard proving configuration. . . . . . . . . 31Figure 5-1 Typical sensor installation. . . . . . . . . . . . . . . . . . . . . 39Figure 5-2 Recommended Coriolis sensor orientation . . . . . . . 41Figure 6-1a RFT9739 standard frequency schematic . . . . . . . . . 50Figure 6-1b RFT9739 open collector frequency schematic . . . . 50Figure 6-1c Decreased/limited voltage RFT9739 frequency

schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50Figure 6-2 Connection of multiple pulse-counting devices . . . 51Figure 6-3 Coriolis meter response during proving . . . . . . . . . 55Figure 6-4a RFT9739 field-mount local access terminals. . . . . . 57Figure 6-4b RFT9739 rack-mount local access terminals. . . . . . 57Figure 8-1a Gravimetric proving with weigh tank. . . . . . . . . . . . 72Figure 8-1b Gravimetric proving with tanker truck . . . . . . . . . . 72Figure 8-2 Tank proving flow rate ramp-up/ramp-down . . . . . 76Figure 8-3 Outlet piping design for filling tank provers . . . . . . 77Figure 8-4 Volumetric tank proving . . . . . . . . . . . . . . . . . . . . . . 78Figure 8-5 Volumetric proving against a storage tank . . . . . . . 79Figure 8-6 Conventional pipe prover . . . . . . . . . . . . . . . . . . . . . 85Figure 8-7 Small volume prover. . . . . . . . . . . . . . . . . . . . . . . . . . 92Figure 8-8 Double-chronometry pulse interpolation . . . . . . . . 93Figure 8-9 Average meter factors for multiple proving runs . . 102Figure 8-10 Transfer standard proving with volumetric

master meter . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105Figure 8-11 Coriolis master meter proving. . . . . . . . . . . . . . . . . . 112Figure 9-1 Meter Factor trend chart . . . . . . . . . . . . . . . . . . . . . . 127Figure 11-1 Double-walled vacuum-sphere pycnometer . . . . . . 148Figure 11-2 Series density proving installation . . . . . . . . . . . . . . 149Figure 11-3 Parallel density proving installation. . . . . . . . . . . . . 150Figure 11-4 Typical density proving report . . . . . . . . . . . . . . . . . 157

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x Proving Micro Motion Coriolis Meters

Tables

Table 6-1 Typical Coriolis meter operating frequencies . . . . . 54Table 8-1 Traceability of proving methods to a fundamental

measure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71Table 8-2 Buoyancy correction factors . . . . . . . . . . . . . . . . . . . 73Table 8-3 Typical sensor operating frequencies . . . . . . . . . . . . 99Table 8-4 Brooks Compact prover — maximum flow rate for

Micro Motion meters . . . . . . . . . . . . . . . . . . . . . . 101Table 8-5 Repeatability versus number of passes per run . . . . 103Table 9-1 Trend Chart data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128

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Proving Micro Motion Coriolis Meters xi

Figures in Appendices

Figure F-1 Components of a Coriolis flow sensor . . . . . . . . . . . 207Figure F-2 Simplified model of an operating Coriolis sensor . 208Figure F-3 RFT9739 signal processing block diagram . . . . . . . 209Figure F-4 Temperature effect on mass flow rate

measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211Figure F-5 Pressure effect on mass flow rate measurement . . 212Figure F-6a RFT9739 wiring connections for pressure

compensation with HART (digital) communications. . . . . . . . . . . . . . . . . . . . . . . . . . 213

Figure F-6b RFT9739 wiring connections for pressure compensation with analog input . . . . . . . . . . . . 214

Figure F-7 Meter uncertainty versus flow rate for ELITE® sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215

Figure F-8 Zero offset error and uncertainty for an ELITE® sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 216

Figure F-9 Mounting for sensor vibration isolation. . . . . . . . . . 219Figure G-1 Components of a Coriolis flow sensor . . . . . . . . . . . 225Figure G-2 RFT9739 signal processing block diagram . . . . . . . 227Figure G-3 Temperature effect on density measurement . . . . . 228Figure G-4 Pressure effect on density measurement. . . . . . . . . 229Figure G-5a RFT9739 wiring connections for pressure

compensation with HART (digital) communication . . . . . . . . . . . . . . . . . . . . . . . . . . 230

Figure G-5b RFT9739 wiring connections for pressure compensation with analog input . . . . . . . . . . . . 231

Figure G-6 Fluid flow rate effect on density measurement . . . 232Figure G-7 Mounting for sensor vibration isolation. . . . . . . . . . 234Figure G-8 Effect of wall thickness reduction on density

measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . 236Figure H-1 Temperature effect on volumetric flow rate

measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . 242Figure H-2 Pressure effect on volumetric flow rate

measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . 242Figure H-3 Effect of mass flow rate on volumetric flow rate

measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . 242Figure I-1 Meter factors and repeatability versus flow rate . . 247

Contents

xii Proving Micro Motion Coriolis Meters

Tables in Appendices

Table A-1 Proving conversion factors . . . . . . . . . . . . . . . . . . . . . 172Table A-2 Buoyancy correction factors . . . . . . . . . . . . . . . . . . . 172Table B-1 Proving conversion factors . . . . . . . . . . . . . . . . . . . . . 182Table B-2 Buoyancy correction factors . . . . . . . . . . . . . . . . . . . 182Table C-1 Density conversion factors . . . . . . . . . . . . . . . . . . . . . 187Table F-1 Pressure coefficients for flow . . . . . . . . . . . . . . . . . . 210Table F-2 Zero uncertainty specifications . . . . . . . . . . . . . . . . . 217Table F-3 Typical sensor operating frequencies . . . . . . . . . . . . 219Table G-1 Pressure coefficients for density . . . . . . . . . . . . . . . . 230Table G-2 FD and K3 values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233Table G-3 Typical sensor operating frequencies . . . . . . . . . . . . 234Table G-4 Velocity of sound . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 237Table I-1 Number of passes per run. . . . . . . . . . . . . . . . . . . . . . 248

Contents

Proving Micro Motion Coriolis Meters xiii

Forms and Charts

Form A-1 Coriolis Meter Volume vs. Conventional Pipe Prover . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166

Form A-2 Coriolis Meter Volume vs. Small Volume Prover . . 167Form A-3 Coriolis Meter Volume vs. Volumetric Tank

Prover . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168Form A-4 Coriolis Meter Volume vs. Volumetric Master

Meter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169Form A-5 Coriolis Meter Volume vs. Coriolis Master Meter

Mass. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170Form A-6 Coriolis Meter Volume vs. Gravimetric Tank

Prover . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171Form B-1 Coriolis Meter Mass vs. Conventional Pipe Prover 176Form B-2 Coriolis Meter Mass vs. Small Volume Prover . . . . 177Form B-3 Coriolis Meter Mass vs. Volumetric Tank Prover . . 178Form B-4 Coriolis Meter Mass vs. Volumetric Master Meter . 179Form B-5 Coriolis Meter Mass vs. Coriolis Master Meter

Mass. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 180Form B-6 Coriolis Meter Mass vs. Gravimetric Tank Prover . 181Form C-1 Coriolis Meter Density Proving Report . . . . . . . . . . 186Form C-2 Correcting the Coriolis Meter Density to Prover

Conditions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187Form D-1 Meter Factor Chart . . . . . . . . . . . . . . . . . . . . . . . . . . . 192Form D-2 Density Factor Chart . . . . . . . . . . . . . . . . . . . . . . . . . 193Form E-1 Meter Zero Chart. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 204

xiv Proving Micro Motion Coriolis Meters

Proving Micro Motion Coriolis Meters xv

Terminology and Mathematical Variables

The following terms and mathematical variables are used throughout this document.

Coriolis Meter Terms

Driver or drive coil — Coil and magnet assembly, used to vibrate the sensor flow

tubes.

Flow calibration factor — A coefficient, initially determined during factory calibration, which is used to convert sensor pickoff signals to a mass flow rate. The calibration factor resides in the transmitter. The calibration factor usually is not adjusted after the initial factory calibration.

K-factor or pulse scaling factor — Pulses per unit mass (volume); an adjustable value that is configured into the transmitter by the manufacturer or a user. The K-factor is a value that is divided into the pulses output from the meter, to determine the total mass or gross volume measured by the Coriolis meter.

Maximum full-scale flow — The maximum flow rating of the meter. This value is defined by the meter manufacturer.

Maximum operating flow rate — The maximum flow rate at which the meter is to be used. This value is defined by the meter user.

Meter or flowmeter — Combination of the mechanical flow sensor and the electronics transmitter. To have a functional Coriolis flowmeter, both components are required. See Figure 1-1, page 3.

Meter factor — A number obtained by dividing the actual quantity of fluid passed through the meter (as determined from the prover) by the quantity registered by the meter.

Minimum full-scale flow — The minimum flow rate that enables the meter to produce the maximum analog output of 20 mA. This value is defined by the meter manufacturer.

Nominal full-scale flow — The nominal flow rating of the meter. This value is defined by the meter manufacturer.

Peripheral device — An additional electronic instrument used for supplementary computations, totalization, or display of the meter’s output information.

Pickoffs or pickoff coils — Coil and magnet assembly, used to measure the effect of the Coriolis force on the vibrating sensor

flow tubes and to monitor tube vibration.

Process connections — Flanges or fittings that are used to connect the sensor to the process piping.

RTD — Resistance temperature detector, used to compensate the meter measurement for the effect of temperature on the elasticity of the sensor flow tube.

Sensor — The mechanical component of a Coriolis meter, through which the process fluid flows. The sensor consists of the components shown in Figure 1-2, page 4

Sensor flow tubes — Tube or tubes, which are vibrated using the driver, through which the process fluid flows. Small-scale distortion of the tubes caused by the Coriolis force, which is induced by the flowing fluid, is measured to determine the mass flow rate of the fluid.

xvi Proving Micro Motion Coriolis Meters

Terminolo gy and Math ematica l Variables Proving Terms

Sensor case — The housing that surrounds the sensor flow tubes to prevent them from being damaged and to keep potential environmental contamination from the sensor pickoffs. Optional devices such as burst disks, drains and vents can be supplied to accommodate hazardous area installations.

Stored zero — The zero value stored in the transmitter, determined when the meter is zeroed.

Transmitter — The electronics assembly that powers the driver and processes the signals from the sensor pickoffs to provide meaningful mass flow and density output.

True zero — The true zero value of the meter under the current process conditions. This is the value that represents the time difference between the right and left sensor pickoff signals when there is no flow through the sensor.

Zero stability or zero uncertainty — A number that represents the statistical variation in the stored zero value, obtained from multiple meter zeroings. The source of this uncertainty is limitations in the transmitter’s ability to sample and measure the small signal levels from the pickoffs. Each sensor size and model has a unique zero stability value, which can be found in the sensor specifications.

Zero offset — The difference between the true zero value and the stored zero value, caused by external influences such as changes in temperature or mounting conditions.

Zeroing — A procedure to determine a zero value that represents the baseline offset between the sensor pickoffs at zero flow. The zero value is used by the transmitter to calculate flow rate. (The zeroing operation should not be confused with resetting the totalizer).

Proving Terms

Base prover volume — The volume of the prover corrected to standard conditions of 60°F and 14.73 psia or 15°C and 101 kPa.

Calibration — The process of using a reference standard to determine a calibration factor. Calibration adjusts the output of the meter to bring it to a value which is within the specified accuracy tolerance. This process is normally conducted by the meter manufacturer.

Prover prerun — The time between launching the piston or ball and the start of pulse accumulation from the meter.

Proving — The process of comparing the indicated quantity that passes through a meter under test, at operating conditions, to a

reference of known quantity, in order to establish a meter factor that equates the two quantities. This process is normally conducted in the field.

Proving pass — The operation of the prover displacer traversing the calibrated volume of the prover, between its detector switches.

Proving run — A complete proving cycle, which can consist of one or more proving

passes.

Waterdraw — The process of calibrating a volumetric proving device against a NIST-certified volumetric field-standard test measure.

Proving Micro Motion Coriolis Meters xvii

Terminol ogy and Math ematic al Variables Mathematical Terms

Density Terms

Base density — The density of the liquid at the base conditions (typically at 60°F and 14.73 psia or 15°C and 101 kPa).

Density factor — A number obtained by dividing the actual density of the fluid measured by a density reference (typically a pycnometer), by the density registered by the meter.

Flowing density — The density of the liquid at actual flowing temperature and pressure.

Pycnometer — A vessel of known volume and mass, which is filled with fluid and weighed to determine the density of the fluid.

Mathematical Terms

ρp — Fluid density at flowing conditions at the prover

ρm — Fluid density at flowing conditions at the meter

BPV — Base prover volume

Ctsp — Correction for thermal expansion of steel at the prover

Cpsp — Correction for pressure effect on steel at the prover

Ctlp — Correction for thermal expansion of process fluid at the prover

Cplp — Correction for pressure effect on process fluid at the prover

Ctlm — Correction for thermal expansion of process fluid at the meter

Cplm — Correction for pressure effect on process fluid at the meter

DF — Density factor

MFm — Meter factor when the meter is configured to indicate mass

MFv — Meter factor when the meter is configured to indicate volume

Pm — Fluid pressure at the meter

Pp — Fluid pressure at the prover

Tm — Fluid temperature at the meter

Tp — Fluid temperature at the prover

xviii Proving Micro Motion Coriolis Meters

Proving Micro Motion Coriolis Meters 1

1 Introduction

1.1 Coriolis Meters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Figure 1-1 Components of a Coriolis meter . . . . . . . . . . . . . . . . . . . . . 3Figure 1-2 Components of a Coriolis sensor. . . . . . . . . . . . . . . . . . . . . 4

2 Proving Micro Motion Coriolis Meters


1 Introduction

1.1 Coriolis Meters

A unique feature of Coriolis meters is that they measure mass flow rate directly. The mass flow rate measurement is not calculated from volume and density measurements. The volume of a fluid will change with varying temperature, due to thermal expansion; and pressure, due to fluid compression. The advantage of measuring mass is that mass is unaffected by changes in process conditions.

A Coriolis meter consists of a mechanical sensor and an electronic transmitter, as shown in Figure 1-1. The sensor’s primary measurement components are vibrating flow tubes and flow detectors (pickoffs), which are illustrated in Figure 1-2. The pickoffs provide a signal from which the mass flow rate can be determined. A density measurement, which is independent of the mass flow measurement, is also obtained from the vibrating flow tube. If desired, the

Figure 1-1. Components of a Coriolis meter. Shown are an ELITE® CMF200 sensor and

RFT9739 field-mount transmitter in an explosion-proof housing.


Introduction1Figure 1-2. Components of a Coriolis sensor. Shown is an ELITE® CMF300 sensor.

Coriolis meter mass flow and density measurements can be used to calculate the volumetric flow rate of the fluid.

Coriolis meters have inherent features that are well suited to custody transfer measurement. The sensors have no rotating parts such as bearings or gears, which provides the following advantages:

• Low maintenance, because there are no parts that wear with time.

• Solids can flow through the sensor without damage; strainers are optional.

• Vapor/gas in the process fluid will not cause damage due to overspin, as is common with turbine meters.

• The meters can be significantly overranged without causing damage to the sensor.

Coriolis meters provide a multivariable measurement:

• Mass flow rate to ±0.1%• Density to ±0.0005 g/cc• Volumetric flow rate to ±0.15%• Temperature to ±1°C

Because Coriolis meters measure mass flow rate directly, they are ideally suited to products that are accounted for on a mass basis, such as LPG, NGL, ethylene, and CO2. Traditionally, mass measurement is achieved indirectly by using a volumetric meter, a density meter, and a flow computer. The flow

computer determines the mass from the measured volume and density. A Coriolis meter replaces these three pieces of equipment, reducing the requirements for installing and maintaining multiple instruments. Because a Coriolis meter measures the entire process fluid stream, the need for a sampling system for density measurement is eliminated. Sampling systems are prone to maintenance problems, and there is always uncertainty as to whether the sample is representative of the actual fluid stream. In addition, Coriolis meters are capable of measuring flow in either the forward or reverse direction, which is particularly advantageous in loading/unloading applications.

Custody transfer measurement typically requires the meter accuracy to be proved in the field. Commonly available field proving devices are volume references, which are used to verify a meter’s volumetric flow rate measurement. If the Coriolis meter is configured for volumetric flow rate measurement, it is proved just like any volumetric meter would be proved. However, if the meter is being used to measure mass, then the fluid density must be determined to convert the prover volume measurement to mass units, to allow comparison to the meter mass measurement. Another concern is the time required for performing a proving run. There are timing considerations associated with proving a Coriolis meter that can result

Resistancetemperature

detector (RTD)

Pickoff coil andmagnet

Drive coil and magnet

Flow tubes

Pickoff coil and magnet

Introduction 1


in poor results if the proving time is too short. Because the prover volume is fixed, higher flow rates will result in shorter proving times. Using a prover that is too small for the Coriolis meter will affect the accuracy and repeatability of the proving results.

The purpose of this document is to discuss the methods available for proving, and to provide guidelines to help ensure that the

proving results are reliable. Significant details about the operation of Coriolis meters are included, to enhance the understanding of technical issues that may arise during meter proving. Both flow rate and density proving will be discussed. However, the primary focus is flow rate proving. This document focuses on proving for custody transfer, but the principles presented are applicable to any type of proving application.


2 General Proving Concepts

2.1 What Is Proving Versus Calibration? . . . . . . . . . . . . . . . . . . . . . 9

2.2 Why Is Proving Performed? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9Custody Transfer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9Quality Audit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10Environmental Audit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

2.3 What Is the Outcome of Proving? . . . . . . . . . . . . . . . . . . . . . . . . 10

2.4 When Do You Need To Prove a Coriolis Meter? . . . . . . . . . . . 11

2.5 How Often Should a Coriolis Meter Be Proved? . . . . . . . . . . . 11

Trend Charts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12Varying Process Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12Increasing the Time Between Provings. . . . . . . . . . . . . . . . . . . . . . . 12Pay and Check Meters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Figure 2-1 Sample proving trend chart. . . . . . . . . . . . . . . . . . . . . . . . . . 13


2 General Proving Concepts

2.1 What Is Proving Versus Calibration?

Calibration is typically performed in a laboratory at several different flow rates, densities, or temperatures. When a calibration is performed, the meter’s calibration factors are determined. Every Micro Motion® meter is calibrated in a gravimetric calibration lab to determine the meter’s fundamental mass flow calibration factor, and to verify that meter accuracy is within specification over a range of flow rates.

The Micro Motion calibration lab employs weigh scales whose calibration is traceable to the National Institute of Standards and Technology (NIST). The calculated uncertainty of the calibration facility is better than ±0.05%, based on ISO 5168. The calibration lab employs water as the flowing medium. The weigh-scale readings are corrected for buoyancy effect. During the flow calibration procedure, the density calibration factors for the meter are also

determined. The density calibration is performed using two fluids — air and water.

Proving differs from calibration in that it is performed in the field under operating conditions. When a meter is proved in the field, a meter correction factor is determined. The correction factor is multiplied by the reading from the meter to offset the meter measurement. Proving is usually performed under one set of conditions, and should be conducted when the operating conditions are most representative of the typical operating conditions. If the operating conditions vary significantly during operation, it is beneficial to prove the meter under the different operating conditions, to determine if different meter factors are needed for each set of conditions.

This is accomplished by comparing the reading from the meter to a calibrated reference device.

2.2 Why Is Proving Performed?

The need for proving arises because operating conditions differ significantly from the conditions under which the meter is calibrated. Verification is necessary to determine whether variations in fluid properties and process conditions cause a shift in the meter’s calibration under actual operating conditions. The proving process allows the user to correct the reading from the meter to provide the true quantity of fluid that went through the meter.

The meter measurement being proved can be flow rate or density. Meter proving is generally conducted for one of three reasons:

• Custody transfer

• Quality audit• Environmental audit

Custody Transfer

There are two types of custody transfer measurement: (1) legal, which falls under government Weights and Measures requirements, and (2) contract, under which a contractual agreement between a buyer and seller specifies requirements. Custody transfer flow measurements are performed for accounting of product quantities in order to establish monetary value of deliveries between sellers and buyers. The meter is proved to ensure product inventory accounting is of the highest accuracy.


General Proving ConceptsWhat Is the Outcome of Proving?2

Proving must be performed under actual operating conditions. A field reference device is used to prove the meter.

Quality Audit

A routine meter verification plan should be established to comply with ISO 9000 quality requirements, to ensure product quality remains consistent. If a meter is used for controlling the addition of various fluid components to make a final product, meter performance must be repeatable to ensure product quality does not decline.

Environmental Audit

An environmental audit might be required by the EPA, OSHA, or other governing body, to ensure material balances in manufacturing and pipeline transfers are correct. The primary purpose of such an audit is to verify that transferred material is accounted for, so that there is no loss of product along the way.

Because environmental regulation requirements are escalating, it is more important today than ever to have a sufficient number of measurement points to provide evidence that no environmental violations have occurred at a site. As part of this environmental accounting, it is essential to show that a plan is in place for routinely verifying equipment accuracy, and to provide evidence that meter verification is being conducted on a regularly scheduled basis.

For quality and environmental audits, field proving is not specifically required. A more flexible meter verification plan can be used. The objective is to verify the meter is performing within specification, and to recalibrate if it is out of specification. Therefore, the meter can be removed and tested in a separate calibration facility or be sent out for reverification by the manufacturer. Master meter verification methods are also acceptable.

2.3 What Is the Outcome of Proving?

The objective of proving a meter is to determine what the meter reading is, compared to a known reference. The basic calculation that applies to all provings, whether the measurement being proved is flow or density, is described by Equation 2-1.

(Eq. 2-1)

The meter correction factor defined in Equation 2-1 is commonly referred to as a meter factor. The information obtained from proving can be used in a number of ways:

• The meter reading can be multiplied by the meter factor to obtain the correct measurement.

• Proving results can be used to determine new meter calibration factors.

• A decision can be made whether to return equipment to the manufacturer for checkup/recalibration.

The most common result of proving is to use a calculated meter factor to correct the meter’s flow rate indication. The meter’s flow measurement is multiplied by the meter factor to provide the correct inventory. Therefore, a meter factor greater than 1.0000 indicates that the meter is under-registering (reading low). A meter factor less than 1.0000 indicates that the meter is over-registering (reading high).

The discussion thus far has been general, and can be applied to proving either the meter’s flow rate or density measurement. The remaining discussion, presented in Sections 3 through 10, applies only to flow rate proving. Density proving is covered in Section 11.

Meter Correction FactorProver Value

Meter Reading-------------------------------------------=

General Proving ConceptsHow Often Should a Coriolis Meter Be Proved? 2


2.4 When Do You Need To Prove a Coriolis Meter?

For custody transfer measurement it is common practice to prove the meter when it is first put into service, and on a regularly scheduled basis thereafter. Also, proving is typically performed anytime the meter is subjected to changes in conditions which might cause a change in measurement accuracy. The following list details all of the conditions under which a meter might need to be proved. However, these are not requirements.

1. When the meter is initially brought into service.

2. If the meter is being used to measure bi-directional flow (forward and reverse flow), provings should be performed to establish meter factors for each direction. Although, the meter calibration factor does not change between forward and reverse flow, a zero offset would result in different meter factors for the forward and reverse directions. Refer to Appendix E, page 195, for a discussion on meter zeroing.

3. As required by the contract or proving schedule.

4. Anytime the accuracy of a meter is ques-tioned by either party involved in the cus-tody transfer.

5. When the sensor is returned to service

after having been removed from the pro-cess pipeline, or anytime the sensor mounting conditions are changed.

6. When the sensor or transmitter is replaced.

7. When the meter is rezeroed. (Characteriz-ing the meter’s zero can preclude having to prove when the meter is zeroed. Refer to Appendix E, page 195.)

8. When a change in flow rate occurs, if the change might cause the meter to exceed the accuracy limits set forth in the con-tract. Proving the meter over a range of flow rates might be necessary to deter-mine acceptable flow rate tolerances. In lieu of any test data, the meter should be reproved if the flow rate varies signifi-cantly from the normal operating flow rate.

9. When there is a significant change in the system temperature, pressure, or density, that would affect meter accuracy. (Refer to Appendix F, page 205.)

Because the objective of proving is to obtain the most accurate product accounting that is possible, more provings might be required for a new installation. As confidence in the meter performance becomes established, the level of proving can be decreased.

2.5 How Often Should a Coriolis Meter Be Proved?

Typically, the proving contract specifies how often proving must be performed. However, the real determinant should be the performance of the meter from one proving to the next. One way to determine the frequency of proving is to collect proving data on an initial group of meters, and the proving frequency determined for these meters can be applied to all meters on similar service. If there is little or no change in meter factor between provings, the proving frequency can be reduced. Conversely, if the

meter factor changes each time the meter is proved, then more frequent proving is appropriate.

It is generally recommended that new users who have little experience with Coriolis meters should prove their first meters at least monthly, to provide data on their particular applications. Proving the meter more frequently after the meter is initially installed will speed up the process of determining the required meter proving frequency.


General Proving ConceptsHow Often Should a Coriolis Meter Be Proved?2

Trend Charts

A trend chart of meter factor and meter repeatability should be developed. It is desirable to record the parameters listed below directly on the trend chart, for each proving, to gain an understanding of any influences on the meter.

• Date• Name of proving company• Flow rate• Temperature at meter• Pressure at meter• Density at meter• Ambient temperature• Whether the meter was zeroed or not• Prover base volume• Temperature at prover• Pressure at prover• Density at prover

Figure 2-1 shows an example of a meter trend chart, which could be used for tracking meter performance. A blank trend chart, which may be reproduced, is included on page 192. It is common practice that the meter factor vary by no more than ±0.25% from one proving to the next. However, the actual requirement is either specified in the contract or required by Weights and Measures authorities. Additional information on using trend charts is presented in Section 9.6, page 126.

Varying Process Conditions

If the meter will be operated over a range of process conditions, it is useful to perform several provings across the entire operating range, to determine whether using a single meter factor will suffice for all operating conditions, or whether multiple meter factors are necessary for different operating conditions. If the operating conditions will

not be constant from one day to the next it is beneficial to characterize the influence of the following parameters on the meter factor:

• Flow range• Temperature range• Pressure range• Different products, varying composition

and viscosity

Trend charts can be used to collect this type of information. Trend charts are also an excellent means of tracking variations in the meter’s zero offset, and establishing requirements for rezeroing the meter. Refer to Appendix E, page 195, for a discussion on determining meter zeroing requirements.

Increasing the Time Between

Provings

After sufficient data is accumulated, it might be acceptable to increase the time between provings — quarterly, semiannually or annually. The ability to go to longer times between provings depends on collecting sufficient data to convince the user of meter factor stability. The frequency of proving will also depend on contract requirements. Semiannual or annual provings might be sufficient for ISO 9000 certification, but might not be acceptable for custody transfer measurement. Corrosive or erosive process fluids warrant more frequent proving. It is never recommended to go any longer than one year between meter provings.

After the user has demonstrated the required proving frequency on an initial group of meters, all subsequent meters that are used on similar applications can have this proving frequency applied without having to repeat the entire confidence determination for every new meter.

General Proving ConceptsHow Often Should a Coriolis Meter Be Proved? 2


Figure 2-1. Sample proving trend chart.

Location Sensor Model

Fluid Sensor Serial Number

Proving Co. Transmitter Model

Prover Base Volume Transmitter Serial No.

Passes Per Run Calibration Factor

Meter Measuring/Mass or Volume K–Factor

Met

er F

acto

r

1.0075

1.0050

1.0025

1.0000

0.9975

0.9950

0.9925

Date: 2/4/98 3/8/98 4/5/98 5/3/98 6/7/98 7/5/98 8/2/98 9/6/98

Flow Rate: gal/min 420 400 395 440 450 445 435 410

Tmeter: °F – – – – – – – –

Pmeter: psig – – – – – – – –

Densitymeter: g/cc – – – – – – – –

Tambient: °F 70 65 75 85 92 95 94 93

Was meter rezeroed? No No No No No No No No

Tprover: °F 73 73 76 78 80 82 84 82

Pprover: psig 87 90 88 88 90 89 87 89

Densityprover: g/cc .6196 .6175 .6154 .614 .6126 .6112 .6098 .6111

Rep

eata

bilit

y

0.15%

0.10%

0.05%

0.00%

ABC Company

Butadiene

CMF300

123456789

RFT9739

987654321

667.584.75

Mass 60 pulse/lb

XYZ Proving Co.

3.08661

• • • • • • • •

• • •• • • •

•

4


General Proving ConceptsHow Often Should a Coriolis Meter Be Proved?2

Pay and Check Meters

Another common means for checking meter performance is to install two or more meters in a single pipeline. The multiple meters verify one another’s performance. This is most commonly performed with a “pay” meter and a “check” meter. The pay meter is used for billing purposes and the check meter is used to ensure the pay meter is reading properly.

In a typical pay-and-check metering application, multiple meters are proved upon installation. Then the inventory readings of the meters are checked against one another on a regular basis — usually monthly or weekly. It is important that the readings of the meters be taken at the same time every

reporting period, to minimize discrepancies between the readings of the meters. If possible, it is advantageous to record the inventory readings from both meters simultaneously.

The larger the reporting period, the smaller the errors associated with recording the inventory readings will be. The meters should agree with each other within some predefined specification. If the deviation between the meters exceeds the specification, both meters should be proved to determine where the source of the discrepancy lies. In addition, it is considered good practice to prove the pay meter on at least an annual basis.


3 Proving Procedures: Conventional and Small Volume Provers

3.1 Meter Configured For Volume Measurement. . . . . . . . . . . . . . 17

Minimum Volume Proving Requirements . . . . . . . . . . . . . . . . . . . . . 18Proving Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19Proving Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19Proving Calculations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Maximum Volume Proving Requirements . . . . . . . . . . . . . . . . . . . . 20Proving Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21Proving Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21Proving Calculations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

3.2 Meter Configured For Mass Measurement . . . . . . . . . . . . . . . . 22

Minimum Mass Proving Requirements . . . . . . . . . . . . . . . . . . . . . . . 22Proving Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23Proving Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23Proving Calculations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Using a Density Meter at the Prover . . . . . . . . . . . . . . . . . . . . . . . . . 25Proving Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25Proving Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25Proving Calculations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Using the Coriolis Meter Density Measurement . . . . . . . . . . . . . . . 27Proving Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27Proving Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27Proving Calculations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Proving in Volume Units/Measuring in Mass Units . . . . . . . . . . . . . 29Proving Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29Proving Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29Proving Calculations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

3.3 Transfer Standard Proving . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

Proving Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31Proving Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31Proving Calculations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

Figure 3-1 Minimum volumetric proving configuration . . . . . . . . . . . 19Figure 3-2 Maximum volumetric proving configuration . . . . . . . . . . . 21Figure 3-3 Minimum mass proving configuration . . . . . . . . . . . . . . . . 23Figure 3-4 Mass proving with a density meter . . . . . . . . . . . . . . . . . . . 25Figure 3-5 Mass proving using Coriolis density . . . . . . . . . . . . . . . . . . 28Figure 3-6 Transfer standard proving configuration . . . . . . . . . . . . . . 31


3 Proving Procedures: Conventional and Small Volume Provers

Proving is performed by using a field reference device to verify the meter’s flow measurement accuracy. The field reference device can be stationary or portable. Although the methods for proving Coriolis meters and volumetric meters are very similar, there are differences in the operation of the Coriolis meter that will require special consideration. Available equipment for proving Coriolis meters includes:

• Gravimetric tanks• Volumetric tanks• Conventional pipe provers• Small volume provers• Volumetric master meters• Mass (Coriolis) master meters

This section provides a general overview of the procedures required to prove a Coriolis meter with a conventional pipe prover. These

procedures are also directly applicable to small volume provers (or Compact Provers™). Both conventional pipe provers and small volume provers are flow through volumetric proving device. These procedures are generally applicable to master meters methods and tank proving methods, with some modification. Proving methods using other equipment listed above are discussed in detail in Section 8, page 67.

This discussion on proving procedures is divided into three main topics:

1. Proving a Coriolis meter configured for volume measurement;

2. Proving a Coriolis meter configured for mass measurement; and

3. Using a transfer standard to prove a Coriolis meter when the prover is undersized.

3.1 Meter Configured For Volume Measurement

A Coriolis meter measures mass flow rate and density independently. Details of how these measurements are performed are presented in Appendices F and G. Because the meter measures both mass and density, it can also be used for determining volumetric flow rate. The measured volume is calculated as shown in Equation 3-1.

(Eq. 3-1)

where

q =Calculated volume flow

=Measured mass flow

ρ =Measured density

When a Coriolis meter is configured for volume flow measurement, it can be treated like any volumetric meter. Additional technical details about the meter’s volume measurement are presented in Appendix H, page 239.

For reasons of accounting tradition, many companies prefer to account for product on a standard volume basis. Standard volume is generally determined by applying temperature and pressure correction factors to the actual volumetric flow rate to adjust the volume to standard conditions, generally 60°F and 14.73 psia, as shown in Equation 3-2.

qm·

ρ-----=

m·


Proving Procedures: Conventional and Small Volume ProversMeter Configured For Volume Measurement3

(Eq. 3-2)

where

qstd = Standard volume

qactual = Actual measured volume

Ctlm = Correction factor for thermal expansion of process fluid at the meter

Cplm = Correction factor for pressure effect at the meter

Actual volume cannot be used for product accounting, because product volume changes with variations in temperature and pressure. If a Coriolis meter’s volumetric flow rate is corrected to a standard volume, the calculation being performed is:

(Eq. 3-3)

where

ρactual = Actual measured density

The correction factors Ctlm and Cplm are used to correct for the effect of temperature and pressure on the density of the fluid, so what is actually being calculated is:

(Eq. 3-4)

where

ρstd=Standard density

The method described above is a roundabout way to obtain a flow rate measurement that is independent of changes in process conditions. Accounting on a mass basis is less complicated.

Model RFT9739 and RFT9712 transmitters have a special units feature, which can be used to display a standard volume. If the product being measured is a pure product, the standard density (ρstd) is known, and a special units conversion factor can be entered into the transmitter. With the conversion factor in place, the transmitter

performs the calculation shown in Equation 3-4. The meter then measures mass flow, yet displays the flow rate and flow total in standard volume units for accounting purposes. This approach cannot be used for products with a composition that varies.

For petroleum products the RFT9739 transmitter is capable of performing a standard volume computation using API equation 2540. The measured temperature from the sensor is used to correct to a standard temperature of 60°F. The transmitter is not capable of correcting to standard pressure. The algorithm used by an RFT9739 is only for generalized petroleum products.

The advantage of configuring the meter for volume measurement is that it can be proved in the same fashion as any volumetric meter. This simplifies the proving process, because the meter’s measured volume can be compared directly to the prover volume. Details of proving equipment and procedures are presented in the following sections.

Minimum Volume Proving

Requirements

Figure 3-1 illustrates the minimum equipment requirement for proving a Coriolis meter configured for volumetric measurement. This system can only be used under the following conditions:

1. Pressure and temperature at the prover and meter are essentially the same. Requirements for temperature and pressure agreement and distance between the meter and prover will depend upon the properties of the fluid.

2. A single shutoff valve can be used to completely halt fluid flow through the sensor, to allow zeroing. Products that expand significantly when flow is halted will require two valves to block the meter in.

qstd qactual* Ctlm* Cplm=

qstd

m·

ρactual

----------------* Ctlm* Cplm=

qstd

m·

ρstd

---------=

Proving Procedures: Conventional and Small Volume ProversMeter Configured For Volume Measurement 3


Figure 3-1. Minimum volumetric proving configuration. Minimum requirements for

proving a Coriolis meter configured for volumetric measurement.

Proving Equipment

Key components of this volume metering/proving system include:

• Coriolis meter• Proving connections consisting of block

and bleed valves: V1, V2, and V3. Valve V2 is also used to halt flow to allow zeroing of the Coriolis meter.

• Prover that has a calibrated volume between the prover detectors

• Pressure measured at the prover to correct for the effect of pressure on the prover volume (Cpsp)

• Temperature measured at the prover to correct for the effect of temperature on the prover volume (Ctsp)

• Pulse counter, which is used to accumulate flow pulses from the Coriolis meter. The counter is triggered by the prover detectors.

Proving Procedure

The steps involved in proving a meter are:

1. Prior to proving, the Coriolis meter’s zero reading should be checked as discussed on page 56, and in Appendix E, page 195.

2. Connect the prover to the proving connections. For stationary provers, the piping should already be in place. For portable proving systems, the connection is typically made with flexible hose. Make sure the hose is rigid enough that its volume doesn’t change during proving, and that its pressure rating is adequate. Ground the proving skid to prevent potential sparking.

3. Divert fluid through the prover by opening valves V1 and V3, and closing valve V2. Fluid should flow through the prover for at least 10 minutes to allow the prover steel temperature to stabilize to the process fluid temperature.

Flow Sensor

Prover loop

Coriolis meter

Pulse counter

Pressure

TemperatureProver

detectors

Transmitter


Proving Procedures: Conventional and Small Volume ProversMeter Configured For Volume Measurement3

4. Check for leaks, and bleed any gas out of the prover as necessary.

5. Connect the meter’s pulse output to the proving counter. Connect the prover detector outputs to the pulse counter. For stationary provers this is typically accomplished by activating an electrical switch.

6. Enable the prover pressure and temperature instrumentation. Specific procedures will depend on whether the instrumentation is manual or electronic.

7. Insert the proving ball into the receiver.

8. Perform two or three trial proving runs to ensure the temperature and pressure has stabilized (generally done by tripping a switch that releases the prover ball from the receiver into the prover). A proving run is completed once the prover ball has gone through an entire measurement cycle.

9. Conduct the actual proving by performing a series of proving runs. Five proving runs are recommended for conventional provers, and three runs of 10 to 15 passes each is recommended for small volume provers.

10. Record the pressure and temperature at the prover during each proving run. Record the approximate fluid flow rate during the proving. After each run record the pulses accumulated from the meter from the pulse counter.

11. Perform proving calculations.

Proving Calculations

The repeatability of the proving is determined by taking the results of the three or five provings and performing the following calculation:

(Eq. 3-5)

Generally the proving results must have a repeatability of less than 0.05% in order for the proving to be considered to be valid. If the repeatability is acceptable, Equation 3-6 is used to calculate the meter factor for the proving. The Ctsp and Cpsp correction factors for the effects on the prover steel are determined from standard equations, using the appropriate coefficients for the prover material of construction.

(Eq. 3-6)

where

MFv = Meter factor, meter configured to indicated volume

BPV = Base prover volume

Ctsp = Correction factor for thermal expansion of steel at the prover

Cpsp = Correction factor for pressure effect on steel at the prover

Section 9, page 119, provides additional details on proving calculations. Proving form A-1, page 166 (Appendix A), can be used to record the proving data and perform the proving calculations.

Maximum Volume Proving

Requirements

Figure 3-2, page 21, illustrates the maximum equipment requirement for proving a Coriolis meter configured for volumetric measurement. Components have been added to the minimum system to accommodate the following special circumstances:

1. Pressure and temperature at the prover is not representative of the conditions at the meter.

2. The flow of process fluid cannot be stopped to allow the meter to be zeroed, and must be diverted around the meter.

3. The meter must be blocked in to obtain zero flow through the meter.

Repeatability(%)PulsesMAX PulsesMIN–

PulsesMIN

----------------------------------------------------------* 100=

MFv

BPV * Ctsp* Cpsp

Meter Pulses

K–Factor-------------------------------------

----------------------------------------------=

Proving Procedures: Conventional and Small Volume ProversMeter Configured For Volume Measurement 3


Figure 3-2. Maximum volumetric proving configuration. Maximum requirements for

proving a Coriolis meter configured for volumetric measurement.

Proving Equipment

Additional components of this system, beyond those shown in Figure 3-1, page 19, include:

• Bypass loop, which includes valves V1, V2, and V3. The bypass allows flow to be diverted around the meter to allow meter zeroing. This is required for applications in which the flow through the pipeline cannot be stopped.

• Pressure measured at the meter to correct the measured fluid volume to standard pressure (Cplm)

• Temperature measured at the meter to correct the measured fluid volume to standard temperature (Ctlm)

• Pressure measured at the prover is also used to correct the fluid volume to standard pressure (Cplp)

• Temperature measured at the prover is also used to correct the fluid volume to standard temperature (Ctlp)

Proving Procedure

The additional steps involved in proving a meter, beyond those described on page 19, are described below:

1. If the fluid is expansive, closing a single valve downstream of the meter may result in reverse flow through the meter. This would result in an incorrect zero value being determined. Therefore, the meter may have to be blocked in by closing both valves V2 and V3, which are depicted in Figure 3-2.

2. If the process demands that flow through the system cannot be halted, then the process fluid must be diverted around the meter by opening valve V1 during the zeroing operation.

3. If pressure and temperature instrumentation at the meter is required, these devices will also have to be enabled.

4. In addition to recording the pressure and temperature at the prover, it might be necessary to record pressure and temperature at the meter.

Flow Sensor

Prover loop

Coriolis meter

Pulse counter

Pressure

Temperature

Prover detectors

Transmitter

TemperaturePressureBypass loop (optional)


Proving Procedures: Conventional and Small Volume ProversMeter Configured For Mass Measurement3


The repeatability of the proving is determined by taking the results of the three or five provings and performing the calculation shown in Equation 3-5. A repeatability of less than 0.05% is commonly required. If the repeatability is acceptable, Equation 3-7 is used to calculate the meter factor for the proving, using the average number of pulses from the proving runs. The Ctlp and Cplp correction factors are

determined from API MPMS look-up tables, or from API equation 2540 and compressibility equations.

(Eq. 3-7)

These calculations are detailed in proving form A-1, page 166 (Appendix A).

3.2 Meter Configured For Mass Measurement

When a Coriolis meter is configured for mass measurement and is being proved against a volumetric prover, the prover volume must be converted to mass units to allow comparison to the mass measured by the meter. In order to convert the prover volume to mass, an accurate density determination at the prover must be made. Any error in the determination of the density will result in an equivalent error in the meter factor. The fluid density can be determined from any of the following methods:

1. Calculated from measured temperature and pressure. This method is limited to well characterized products of known composition.

2. Determined from an in-line density meter located at the prover. A density sampling system is used to determine a density factor for the density meter.

3. Determined from the Coriolis meter density measurement. The Coriolis meter should be located close to the prover. A density sampling system is used to determine a density factor for the Coriolis meter.

For many process fluids the actual flowing density (not the density at standard conditions) does not remain constant, due to fluctuations in product composition or process conditions. This is particularly true of light hydrocarbons. If the fluid density varies while the meter is being proved, it will be difficult to obtain acceptable repeatability, and the meter factor may be in error. In this

situation, it is recommended that the average fluid density during the proving run be determined, and this average density be used in the meter factor calculation.

If a density measurement device is used, it will be necessary to prove the density measurement to obtain a density factor (DF). It would be reasonable to prove the density measurement every time the Coriolis meter’s flow measurement is proved. The frequency of determining the density factor may be reduced if the density factor continually remains consistent from one proving to the next. Actual field practice may vary from these recommendations based on the required accuracy levels.

Minimum Mass Proving

Requirements

Figure 3-3 illustrates the minimum equipment requirement for proving a Coriolis meter configured for mass measurement. This system can only be used under the following conditions:

1. The fluid density at the prover can be accurately determined from the pressure and temperature measurements.

2. A single shutoff valve can be used to completely halt fluid flow through the sensor to allow zeroing. Products that expand significantly when flow is halted will require two valves to block the meter in.

MFv

BPV * Ctsp* Cpsp* Ctlp* Cplp

Meter Pulses

K–Factor---------------------------------

* Ctlm* Cplm

---------------------------------------------------------------------------=

Proving Procedures: Conventional and Small Volume ProversMeter Configured For Mass Measurement 3


Figure 3-3. Minimum mass proving configuration. Minimum requirements for proving

a Coriolis meter configured for mass measurement.

Proving Equipment

Key components of this mass metering/proving system include:

• Coriolis meter• Proving connections consisting of block

and bleed valves V1, V2, and V3. Valve V2 is used to halt flow to allow zeroing of the Coriolis meter.

• Prover that has a calibrated volume between the prover detectors

• Pressure measured at the prover to correct for the effect of pressure on the prover volume (Cpsp)

• Temperature measured at the prover to correct for the effect of temperature on the prover volume (Ctsp)

• Density at the prover, determined from the process fluid temperature and pressure

• Pulse counter, which is used to accumulate flow pulses from the Coriolis meter. The counter is triggered by the prover detectors.

Proving Procedure

The steps involved in proving a meter configured for mass measurement are described below:

1. Prior to proving, the Coriolis meter’s zero reading should be checked as discussed on page 56, and in Appendix E, page 195.

2. Connect the prover to the proving connections. For stationary provers, the piping should already be in place. For portable proving systems, the connection is typically made with flexible hose. Make sure the hose is rigid enough that its volume doesn’t change during proving, and that its pressure rating is adequate. Ground the proving skid to prevent potential sparking.

3. Divert fluid through the prover by opening valves V1 and V3, and closing valve V2. Fluid should flow through the prover for at least 10 minutes to allow the prover steel temperature to stabilize to the process fluid temperature.

4. Check for leaks and bleed any gas out of the prover as necessary.

5. Connect the meter’s pulse output to the proving counter. Connect the prover detector outputs to the pulse counter. For stationary provers this is typically accomplished by activating an electrical switch.

V1

V2

V3

Flow Sensor

Prover loop

Coriolis meter

Pulse counter

Pressure

Temperature

Prover detectors

Transmitter Density determined from P

& T


Proving Procedures: Conventional and Small Volume ProversMeter Configured For Mass Measurement3

6. Enable the prover pressure and temperature instrumentation. Specific procedures will depend on whether the instrumentation is manual or electronic.

7. Insert the proving ball into the receiver.

8. Perform two to three trial proving runs to ensure the temperature and pressure has stabilized (generally done by tripping a switch that releases the prover ball from the receiver into the prover). A proving run is completed once the prover ball has gone through an entire measurement cycle.

9. Conduct the actual proving by performing a series of proving runs. Five proving runs are recommended for conventional provers, and three runs of 10 to 15 passes each is recommended for small volume provers.

10. Record the pressure and temperature at the prover during each proving run. Record the approximate fluid flow rate during the proving. After each run record the pulses accumulated from the meter from the pulse counter.

11. Perform proving calculations.


A significant difference between mass and volume proving is the method that is used to determine proving repeatability. For volume-to-volume proving, the repeatability can be based on the number of pulses accumulated. However, for mass-to-volume proving, the pulse repeatability would not account for variations in product density. If the product density were to vary during the proving, the pulse repeatability may be unacceptable. Therefore, when performing a mass-to-volume proving, the repeatability should be based on the meter factor for the individual provings, not the accumulated pulses. This

calculation is shown in Equation 3-8. The meter factors for the individual proving runs are determined from Equation 3-9, and the repeatability is based on the maximum and minimum meter factors from the runs.

(Eq. 3-8)

Generally the proving results must have a repeatability of less than 0.05% in order for the proving to be considered to be valid. The product density during the proving should vary by no more than 0.0002 g/cc. Based on a fluid with a density of 0.8 g/cc, this level of density variation would take up 0.025% of the repeatability specification. This leaves only a 0.025% repeatability allowance for the meter and the rest of the proving system.

Before calculating the meter factor, the product density must first be determined. A look-up table or an equation is used to obtain the density of the fluid from the recorded pressure and temperature. Next, the Ctsp and Cpsp correction factors for the effects on the prover steel are determined from standard equations, using the appropriate coefficients for the prover material of construction. Then the meter factors for the individual proving runs are calculated as shown in Equation 3-9.

(Eq. 3-9)

where

ρp = fluid density under flowing conditions at the prover

Section 9, page 119, provides additional information on proving calculations. Proving form B-1, page 176 (Appendix B), can be used to record data, and shows the calculation steps.

Repeatability(%)MFMAX MFMIN–

MFMIN

------------------------------------------* 100=

MFm

BPV* Ctsp* Cpsp* ρp

Meter Factor

K–Factor---------------------------------------

-------------------------------------------------------=



Figure 3-4. Mass proving with a density meter. Requirements for using a density meter

at the prover for proving a Coriolis meter configured for mass measurement.

Using a Density Meter at the

Prover

This example is a variant of the procedure described above for minimum mass proving requirements. It applies when the density cannot be determined from pressure and temperature measurements at the prover. Figure 3-4 illustrates the equipment requirement for this scenario. Components have been added to the minimum mass proving system to accommodate the following circumstances:

1. The density at the prover cannot be determined from pressure and temperature measurements.

2. The density of the fluid cannot be held constant (within ±0.0002 g/cc) during the proving pass or run, requiring an average density to be determined.



Proving Equipment

Additional components of this mass metering/proving system, beyond those shown in Figure 3-3, page 23, include:

• A density meter at the prover (a small Coriolis meter installed at the prover can be used to provide density measurement)

• A density proving system for the density meter

• An optional density averager, if the fluid density does not remain constant during the proving pass or run

• An optional bypass loop, which includes valves V1, V2, and V3. The bypass allows flow to be diverted around the meter to allow meter zeroing. This is required for applications in which the flow through the pipeline cannot be stopped.

All of these components may not be required. Add only those items that are needed for the particular application.

Proving Procedure

The additional steps involved in proving a meter configured for mass measurement

V1

V2 V3

V4

V5

V6V7

V8

V9V10

V11

Flow Sensor

Prover loop

Coriolis meter

Pulse counter

Pressure

Temperature

Prover detectors

Transmitter

Bypass loop (optional)

Density averager (optional)

Density sampler

Density meter


Proving Procedure s: Conventi onal and Smal l Volume ProversMeter Configured For Mass Measurement3

using a density meter at the prover, beyond those described beginning on page 23, are described below:

1. If the fluid is expansive, closing a single valve downstream of the meter may result in reverse flow through the meter.

This would result in an incorrect zero value being determined. Therefore, the meter may have to be blocked in by closing both valves V2 and V3, which are depicted in Figure 3-4, page 25.


3. The density meter must be enabled.

4. Prior to proving the Coriolis meter, the density meter’s density factor (DF) must be determined. This is accomplished by opening valves V7, V10, and V9. Valve V11 is used to generate sufficient pressure drop to obtain a representative fluid sample in the density loop. Care should be taken to ensure that flashing or cavitation does not result from dropping the pressure. Fluid is circulated through the density meter and density sampling container until the temperature at both locations has stabilized and the two temperatures agree to within 0.2°C. (Figure 3-4 does not show the details of the density proving equipment. Refer to Section 11.4, page 146, for a complete description of this process.) Once conditions have stabilized, a density sample is collected and the density meter’s density reading is recorded simultaneously. This process is repeated two to three times, to ensure the density factor is repeatable.

5. After the density factor has been determined, the system is returned to normal operation by opening valve V8 and closing valves V10 and V9. For safety reasons valve V8 would need to be opened before closing valves V10 and V9. Valve V11 is still used to generate sufficient pressure drop to obtain a representative fluid sample in the density loop.

6. While the meter is being proved, the density reading from the density meter is recorded along with the other proving data.

7. If the optional density averager is used, it must be enabled. The density averager is connected to the prover detectors and the density meter’s density measurement output. The prover detectors trigger the averager to average the density meter’s density measurement during the proving run. The average density is recorded at the end of the proving pass or run.


As discussed for minimum mass proving, the repeatability value is calculated by using the meter factor, not the meter pulses (as shown in Equation 3-8, page 24). An additional calculation is also performed: the determination of the density meter’s density factor, as shown in Equation 3-10.

(Eq. 3-10)

The density of the fluid at the prover (ρp) is obtained from the density meter reading. This will either be obtained from the density meter or the density averager, if required. The Ctsp and Cpsp correction factors for the effects on the prover steel are determined from standard equations, using the appropriate coefficients for the prover material of construction. The meter factors for the individual proving runs are then calculated as shown in Equation 3-11.

(Eq. 3-11)

Section 9, page 119, provides additional information on proving calculations. Proving form B-1, page 176 (Appendix B), can be used to record data, and shows the calculation steps. Density proving form C-1, page 186 (Appendix C), is used for determining the density meter’s density factor. Although form C-1 specifies that it is for proving the Coriolis meter density, it is applicable to any density meter.

DFDensity from Density Sample

Density Meter Reading-------------------------------------------------------------------------------=

MFm

BPV * Ctsp* Cpsp* DF * ρp

Meter Pulses

K–Factor-----------------------------------

-----------------------------------------------------------------------=



Using the Coriolis Meter

Density Measurement

There are significant advantages to using the Coriolis meter’s density measurement instead of using a density meter at the prover:

1. The cost of the proving system is reduced because an additional density meter is not required.

2. Maintenance is reduced because one less instrument is used in the system.

3. The Coriolis meter samples the entire fluid stream, which eliminates problems associated with sampling systems that are required with most density meters.

The disadvantage of using this system is that the density measurement is not located at the prover. If the conditions at the prover and Coriolis meter are not similar, additional pressure and temperature measurements at the meter will be required to correct the density measurement to prover conditions.

Figure 3-5, page 28, illustrates the equipment requirement for using the Coriolis meter’s density measurement to prove a Coriolis meter configured for mass measurement. The system includes an optional bypass loop to allow meter zeroing. Components have been added to the minimum mass proving system, shown in Figure 3-3, page 23, to accommodate the following special circumstances:

1. The density at the prover cannot be determined from pressure and temperature measurements.

2. The density of the fluid cannot be held constant while the meter is being proved, requiring an average density to be determined.



Figure 3-5, page 28, illustrates a density proving system that is installed parallel to the Coriolis meter. An in-series density proving system can also be used. The advantages and disadvantages of series and parallel density proving systems are discussed in detail in Section 11.4, page 146.

Proving Equipment

Additional components of this mass metering/proving system, beyond those shown in Figure 3-3, page 23, include:

• A density proving system for the Coriolis meter

• An optional density averager, if the fluid density does not remain constant during the proving

• An optional bypass loop, which includes valves V1, V2, and V3. The bypass allows flow to be diverted around the meter to allow meter zeroing. This is required for applications in which the flow through the pipeline cannot be stopped.

• Optional Cplm determination from pressure measured at the meter, to correct the measured fluid volume to standard pressure

• Optional Ctlm determination from temperature measured at the meter, to correct the measured fluid volume to standard temperature

• Optional Cplp determination from pressure measured at the prover, to correct the fluid volume to standard pressure

• Optional Ctlp determination from temperature measured at the prover, to correct the fluid volume to standard temperature

All of the components may not be required. Add only those items that are needed for the particular application.

Proving Procedure

The additional steps involved in proving a meter configured for mass measurement using the Coriolis meter’s density measurement, beyond those described beginning on page 23, are described below:


Proving Procedure s: Conventi onal and Smal l Volume ProversMeter Configured For Mass Measurement3

Figure 3-5. Mass proving using Coriolis density. Requirements for using a Coriolis

meter density measurement for proving a Coriolis meter configured for mass measurement.

1. If the fluid is expansive, closing a single valve downstream of the meter may result in reverse flow through the meter. This would result in an incorrect zero value being determined. Therefore, the meter may have to be blocked in by closing both valves V2 and V3, which are depicted in Figure 3-5.


3. Prior to proving the meter, the Coriolis meter’s density factor (DF) must be determined. This is accomplished by opening valves V7 and V8. Valve V3, V4, or V6 is used to generate sufficient pressure drop to obtain a representative fluid sample in the density loop. Fluid is circulated through the density sampling loop until the temperature at the density sample loop and the Coriolis meter has stabilized and the two temperatures agree to within 0.2°F. (Figure 3-5 does not show the details of the density proving equipment. Refer to Section 11.4, page 146, for a complete description of

this process.) Once conditions have stabilized, a density sample is collected and the Coriolis meter’s density reading is recorded simultaneously. This process is repeated two to three times to ensure the density factor is repeatable.

4. After the density factor has been determined, the system is returned to normal operation by closing valves V7 and V8. Valves V3, V4, and V6 are fully opened.

5. While the meter is being proved, the density reading from the Coriolis meter is recorded along with the other proving data.

6. If the optional density averager is used, it must be enabled. The density averager is connected to the prover detectors, and the Coriolis meter’s density measurement output. The prover detectors trigger the averager to average the Coriolis meter’s density measurement during the proving run. The average density is recorded at the end of the proving run.

7. In addition to recording the pressure and temperature at the prover, it may be necessary to record pressure and temperature at the Coriolis meter.

V1

V2V7 V8

V5

V4 V6

V3Flow

Sensor

Prover loop

Coriolis meter

Pulse counter

Pressure

TemperatureProver

detectors

Transmitter

Bypass loop (optional)

Density averager (optional)

Pressure andtemperature

(optional)

Density sampling loop (optional)




As discussed for minimum mass proving, the repeatability is calculated by using the meter factor, not the meter pulses (as shown in Equation 3-8, page 24). The Coriolis meter’s density factor is determined from Equation 3-12.

(Eq. 3-12)

The meter factors for the individual proving runs are then calculated using Equation 3-11, page 26, the same equation that was used for the density meter at the prover. The Coriolis meter’s density reading and density factor are used in this equation. Equation 3-11 can be used as long as the process conditions at the Coriolis meter and the prover are the same. If this is not the case, the density at the Coriolis meter must be converted to the prover conditions by using Equation 3-13.

(Eq. 3-13)

Temperature and pressure measurements at the Coriolis meter are used to determine the Ctlm and Cplm correction factors shown in Equation 3-13. The Ctl and Cpl correction factors are determined from API MPMS look-up tables, or from API equation 2540 and compressibility equations. Section 9, page 119, provides a more detailed discussion of proving calculations.

Proving form B-1, page 176 (Appendix B), can be used to record data, and shows the calculation steps. Density proving form C-1, page 186 (Appendix C), is used to determine the density factor, and form C-2, page 187, is used to convert the Coriolis meter density to prover conditions as shown in Equation 3-13.

Proving in Volume Units/

Measuring in Mass Units

Another alternative for performing the proving using the Coriolis meter’s density measurement is to configure the meter for volume measurement during the proving process, then return the configuration to mass measurement for normal measurement. The advantages of this approach are:

1. Established volume proving procedures can be used (as described in Section 3.1, page 17).

2. If the fluid density varies during the proving, a separate density averager is not required. The volume measurement obtained from the Coriolis meter will integrate any density variations, because the meter is continuously sampling the process fluid density.

The disadvantages of this approach are:

1. The meter configuration parameters must be accessed, and the meter must be changed from mass to volume measurement during proving, and back to mass measurement after proving.

2. To ensure the product inventory is not compromised during the proving, the meter’s K-factor (pulse scaling factor) must be checked, and perhaps adjusted, to make sure the number of pulses output while in the volume measurement mode are essentially the same as the number of pulses that would be output while in the mass measurement mode. Alternately, the K-factor in the accounting system would have to be changed to match the value obtained from the meter when it is configured for volume measurement, and then changed back to the original value when it is returned to mass measurement.

Proving Equipment

The equipment required is the same as shown in Figure 3-5, page 28, except the density averager is entirely eliminated.

Proving Procedure

The additional steps involved in proving a meter configured for mass measurement by using its pulse output to indicate volume, beyond those described in Section 3.1, page 17, are described below:

1. Prior to proving the meter, the Coriolis meter’s density factor (DF) must be determined (Step 3, page 28).

2. Before the proving is initiated, the Coriolis meter pulse output must be reconfigured to volume measurement using a Rosemount® HART®

DFDensity from Density Sample

Coriolis Meter Density Reading-------------------------------------------------------------------------------------=

ρp ρm* Ctlp* Cplp

Ctlm* Cplm

----------------------------=


Proving Procedures: Conventional and Small Volume ProversTransfer Standard Proving3

Communicator or the Micro Motion ProLink® software program.

3. The K-factor (pulse scaling factor) must be checked. Adjustments to this value or the inventory calculation may be required to ensure that the inventory measurement remains correct during the proving.

4. The meter is proved as a volume meter as described in Section 3.1, page 17.

5. The meter is returned to the mass measurement configuration once the proving is completed.


Because the meter is configured for volume measurement during the proving process, the repeatability calculation can be based on the number of pulses measured, as shown in

Equation 3-5, page 20. The meter’s density factor is determined from Equation 3-12, page 29. The volume meter factor is calculated from either Equation 3-6, page 20, or Equation 3-7, page 22, whichever is appropriate. The mass meter factor is then determined by multiplying the Coriolis meter’s density factor by the volume meter factor as shown in Equation 3-14.

(Eq. 3-14)

Proving form A-1, page 166 (Appendix A), is used to obtain the volume meter factor (MFv), and form C-1, page 186 (Appendix C), is used to obtain the density factor (DF). The calculation shown in Equation 3-14 can be added to the bottom of form A-1.

3.3 Transfer Standard Proving

When using small volume provers or undersized conventional provers, there may be difficulties in obtaining good repeatability, due to a mismatch between the prover size and the Coriolis meter’s response time. When the proving is initiated, there is usually a drop in flow rate. If the prover prerun is too short, the Coriolis meter pulse output may not represent the actual flow rate before the pulse accumulation begins. This will result in an error in the meter factor that is determined.

The fundamental measurement of a Coriolis meter is time based, and depends on the frequency of vibration of the flow tubes. The longer the proving time, the more measurement samples that are made, resulting in a more precise measurement. If the proving run is too short, the Coriolis meter will inherently perform fewer measurements, resulting in poorer repeatability. In some applications the prover is too small for the Coriolis meter, and cannot be used to provide accurate, repeatable proving results. This occurs most commonly when a small-volume prover is used to prove a relatively large Coriolis meter.

If a larger prover is not available, a transfer standard proving method can be employed. The transfer standard method uses a meter with a very fast response time, such as a turbine meter, to prove the Coriolis meter. The turbine meter is first proved against the prover, then the Coriolis meter is proved against the turbine meter. Since there is no fixed prover volume limiting the proving time, the Coriolis meter and turbine meter measurements can be compared for one minute or more. This provides a longer time base for the Coriolis meter to perform measurements, resulting in improved repeatability.

It is important to distinguish transfer standard proving from master meter proving. Master meter proving typically utilizes a “master” meter that has been calibrated in a laboratory setting. The master meter is brought out to the field, and is used as the reference to determine a meter factor for the test meter. Therefore, the master meter’s meter factor has not been established under actual operating conditions. Master meter proving has uncertainty associated with the effect of the actual operating conditions on the master meter’s calibration.

MFm MFv* DF=

Proving Procedures: Conventional and Small Volume ProversTransfer Standard Proving 3


Figure 3-6. Transfer standard proving configuration. Requirements for using transfer

standard for proving Coriolis meter.

For transfer standard proving, the meter factor for the transfer standard meter is determined at actual operating conditions, against the prover. Then the transfer standard meter is used immediately to determine the meter factor for the Coriolis meter. For transfer standard proving, the uncertainty associated with changing process conditions is eliminated.

Proving Equipment

Figure 3-6, page 31, illustrates the equipment requirement for performing a transfer standard proving. This method can be used for a Coriolis meter configured for volume or mass measurement. Only the minimum equipment requirement is shown, additional items such as bypass loops, density meters and density averagers are not included; however, these components may be required. Refer to Section 3.1, page 17, and Section 3.2, page 22, for additional equipment requirements. The unique items required for a transfer standard proving are:

1. A fast response turbine meter

2. A two-channel pulse counter, with a push button or some other means to activate the accumulation of pulses from both the turbine meter and Coriolis meter simultaneously

Proving Procedure

The additional steps involved in performing a transfer standard proving, beyond those described Section 3.1, page 17, and Section 3.2, page 22, are presented below:

1. Prior to proving the Coriolis meter, the turbine meter must first be proved. The procedures described in Section 3.1, page 17, should be followed to prove the turbine meter. A volume meter factor (MFv) is determined for the turbine meter. It is important that the turbine meter be proved at the same flow rate as the Coriolis meter. Any changes in the flow rate may affect the turbine meter’s meter factor.

2. The Coriolis meter is then proved against the turbine meter, by activating the two-channel pulse counter to accumulate pulses from both meters. The proving duration should be between one and two minutes.

3. The pressure, temperature and flow rate are recorded while the meter is being proved. Additionally, pressure and temperature measurement at the Coriolis meter may be required if the conditions at the Coriolis meter and the turbine meter are not relatively the same.

4. A series of three to five proving runs are performed.

V2

V3V1

Flow Sensor

Prover loop

Coriolis meter

2-channel pulse counter

Pressure

Temperature

Prover detectors

Transmitter

Turbinemeter

32 Proving Micro Motion Coriolis Flowmeters

Proving Procedures: Conventional and Small Volume ProversTransfer Standard Proving3


The proving calculations will depend on whether the Coriolis meter is configured for mass or volume measurement.

Volume Measurement

Since the proving volume is not constant with this method, but depends on the proving time, repeatability cannot be based on the pulses accumulated per proving run. The repeatability must be based on the meter factor, as shown in Equation 3-8, page 24. The meter factor is calculated from Equation 3-15.

(Eq. 3-15)

However, if the temperature and pressure at the Coriolis meter and turbine meter are sufficiently different, liquid temperature and pressure correction factors will be required. These factors would be applied in the same fashion as for provers, as shown in Equation 3-7, page 22.

Proving form A-1, page 166 (Appendix A), can be used to determine the transfer standard meter’s meter factor. Then, proving form A-4, page 169, is used to determine the Coriolis meter’s meter factor.

Mass Measurement

As with the other proving methods for a Coriolis meter configured for mass measurement, the repeatability must be based on the meter factor, as shown in Equation 3-8, page 24. The meter factor is calculated as shown in Equation 3-16.

(Eq. 3-16)

The density at the transfer standard (ρp) is determined either by calculation from pressure and temperature, from a density meter at the prover, or from the Coriolis meter’s density measurement. If a density meter or the Coriolis meter are used to determine density, a density factor will need to be determined, as shown by Equation 3-10, page 26, or Equation 3-12, page 29. If the Coriolis meter is used, then Equation 3-13, page 29, may be needed to correct to the conditions at the turbine.

Proving form A-1, page 166 (Appendix A), can be used to determine the transfer standard meter’s meter factor. If required, density proving form C-1, page 186 (Appendix C), is used to determine the density factor, and form C-2, page 187, is used to convert the density at the Coriolis meter to the transfer standard conditions. Then proving form B-4, page 179 (Appendix B), is used to determine the Coriolis meter’s meter factor.

MFv

Turbine Meter Pulses

Turbine K–Factor---------------------------------------------------------------

* MFturbine

Coriolis Meter Pulses

Coriolis K–Factor----------------------------------------------------------------

---------------------------------------------------------------------------------------------------=

MFm

Turbine Meter Pulses

Turbine K–Factor-----------------------------------------------------------------

* MFturbine* ρp* DF

Coriolis Meter Pulses

Coriolis K–Factor----------------------------------------------------------------

------------------------------------------------------------------------------------------------------------------------------=


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A Proving Forms for Volume Measurement

Form A-1 Coriolis Meter Volume vs. Conventional Pipe Prove . . . . 166Form A-2 Coriolis Meter Volume vs. Small Volume Prover. . . . . . . . 167Form A-3 Coriolis Meter Volume vs. Volumetric Tank Prover . . . . . 168Form A-4 Coriolis Meter Volume vs. Volumetric Master Meter . . . . 169Form A-5 Coriolis Meter Volume vs. Coriolis Master Meter Mass . . 170Form A-6 Coriolis Meter Volume vs. Gravimetric Tank Prover . . . . 171

Table A-1 Proving conversion factors. . . . . . . . . . . . . . . . . . . . . . . . . . 172Table A-2 Buoyancy correction factors . . . . . . . . . . . . . . . . . . . . . . . . 172


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A Proving Forms for Volume Measurement

This appendix contains forms that can be used for proving the Coriolis meter’s volume measurement. The forms use the units of lbs, gallons and g/cc. Table A-1 provides conversion factors, for use in developing forms with other units of measure.

Form A-6 shows the required calculations when proving the Coriolis meter volume against a weigh scale, and Form A-5 shows the calculation for proving the Coriolis meter volume against a master Coriolis meter measuring mass. These option were not covered in the primary text because they are not typical proving scenarios. When using weigh scales, a buoyancy correction must be applied. Buoyancy factors are presented in Table A-2.

Proving Forms for Volume Measurement A


Form A-1. Coriolis Meter Volume vs. Conventional Pipe Prover

Company Date

Base Prover Volume (BPV) gal Meter Model No.

Meter K-Factor pulse/gal Meter Serial No.

Flow Rate gal/min Meter Tag No.

Density g/cc Current Meter Factor (MFcurrent)

Average Meter Zero Reading (optional)

Run Number: 1 2 3 4 5

Meter Pulses

Temperature at Prover (°F)

Ctsp

Ctlp

Pressure at Prover (psig)

Cpsp

Cplp

Temperature at Meter (°F)

Ctlm

Pressure at Meter (psig)

Cplm

Prover Volume (gal)= BPV * Ctsp * Cpsp * Ctlp * Cplp

Meter Volume (gal)= (Pulses/K-Factor) * Ctlm * Cplm

Meter Factor= Prover Volume/Meter Volume

MFproving= (average of above meter factors)Repeatability= (Pulsesmax – Pulsesmin) * 100 / Pulsesmin

For Version 3 RFT9739 transmittersNew Volume Meter Factor Register Value= MFcurrent * MFproving

%



Form A-2. Coriolis Meter Volume vs. Small Volume Prover

Company Date



Flowe Rate gal/min Meter Tag No.

Density g/cc Current Meter Factor (MFcurrent)

Passes per Run Average Meter Zero Reading (optional)


Avg Meter Interpolated Pulses

Avg Temperature at Prover (°F)

Avg Ctsp

Avg Ctlp

Avg Pressure at Prover (psig)

Avg Cpsp

Avg Cplp

Avg Temperature at Meter (°F)

Avg Ctlm

Avg Pressure at Meter (psig)

Avg Cplm

Avg Prover Volume (gal)= BPV * Ctsp * Cpsp * Ctlp * Cplp

Avg Meter Volume (gal)= (Pulses/K-Factor) * Ctlm * Cplm

Avg Meter Facto r= Prover Volume/Meter Volume

MFproving= (average of above meter factors)Repeatability= (Pulsesmax – Pulsesmin) * 100 / Pulsesmin


%



Form A-3. Coriolis Meter Volume vs. Volumetric Tank Prover

Company Date




Density g/cc Current Meter Factor (MFcurrent )



Total Meter Pulses

Prover Fill Time (sec)

Temperature at Prover (°F)

Ctsp

Ctlp

Pressure at Prover (psig)

Cpsp

Cplp


Ctlm


Cplm

Prover Volume (gal)= BPV * Ctsp * Cpsp * Ctlp * Cplp

Meter Volume (gal)= (Pulses / K-Factor) * Ctlm * Cplm or= Totalizer Display Value * Ctlm * Cplm

Meter Factor= Prover Volume / Meter Volume

MFproving= (average of above meter factors)Repeatability= (MFmax – MFmin) * 100 /MFmin


%



Form A-4. Coriolis Meter Volume vs. Volumetric Master Meter

Company Date

Master Meter K-Factor pulse/gal Meter Model No.




Master Meter Factor (MFmaster ) Average Meter Zero Reading (optional)


Master Total Pulses

Meter Total Pulses

Test Time

Temperature at Master (°F)

Ctlp

Pressure at Master (psig)

Cplp


Ctlm


Cplm

Master Volume (gal)= (Meter Pulses / Meter K-Factor) *

Ctlp * Cplp * MFmaster

Meter Volume (gal)= (Meter Pulses / Meter K-Factor) *

Ctlm * Cplm

Meter Factor= Master Volume / Meter Volume

MFproving= (average of above meter factors)Repeatability= (MFmax – MFmin) * 100 / MFmin


%



Form A-5. Coriolis Meter Volume vs. Coriolis Master Meter Mass

Company Date

Master Meter K-Factor pulse/lb Meter Model No.




Master Meter Factor (MFmaster ) Average Meter Zero Reading (optional)


Master Total Pulses

Meter Total Pulses

Meter Density (g/cc)

Test Time (sec)

Master Mass (lb)= MFmaster * Master Pulses/Master

K-Factor

Meter Volume (gal)= Meter Pulses / Meter K-Factor

Meter Mass (lb)= Meter Volume * Density *

8.3454

Meter Factor= Master Mass/Meter Mass



%



Form A-6. Coriolis Meter Volume vs. Gravimetric Tank Prover

Company Date

Target Test Quantity lb Meter Model No.

Weigh Scale Resolution lb Meter Serial No.

Meter K-Factor pulse/gal Meter Tag No.

Flow Rate gal/min Current Meter Factor (MFcurrent )



Weigh Scale Total

Meter Total Pulses

Fill Time (sec)

Meter Density (g/cc)

Buoyancy Factorsee Table A-2, page 172

Corrected Scale Mass (lb)= Scale Total * Buoyancy Factor

Meter Volume (gal)= Pulses / K-Factor or= Totalizer Display Value

Meter Mass (lb)= Meter Volume * Density * 8.3454

Meter Factor= Corr.Scale Mass / Meter Mass



%



.

Table A-1. Proving conversion factors.

Measurement Units

Mass Volume Density* Conversion Factor

lb gallons g/cc lb/gal = 8.3454 * g/cc

lb barrels g/cc lb/bbl = 350.51 * g/cc

lb cubic feet g/cc lb/ft3 = 62.428 * g/cc

kg cubic meters g/cc kg/m3 = 1000 * g/cc

kg liters kg/m³ kg/liter = 0.001 * kg/m³

*If the density measurement unit is Relative Density (Specific Gravity), the following relationships can be substituted into the conversion factors above.

Relative to water at 60°F and 14.696 psia:g/cc=SG * 0.999012k/m³=SG * 999.012

Relative to water at 15°C and 101.325 kPa:g/cc=SG * 0.999098k/m³=SG * 999.098

Table A-2. Buoyancy correction factors.

Density, kg/m3 Density, g/cc Correction Factor2000 2.0 1.00051900 1.9 1.00051800 1.8 1.00051700 1.7 1.00061600 1.6 1.00071500 1.5 1.00071400 1.4 1.00071300 1.3 1.00081200 1.2 1.00091100 1.1 1.00091000 1.0 1.0011900 0.9 1.0012800 0.8 1.0014700 0.7 1.0016600 0.6 1.0019500 0.5 1.0023


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F Mass Flow Measurement

F.1 Coriolis Meter Mass Flow Measurement

A Coriolis meter consists of two primary components: a sensor and a transmitter. The sensor consists of a flow tube assembly, encased in a housing and installed in the process pipeline. The transmitter is an electronics assembly that is connected to the sensor with a cable, which permits it to be located remotely from the sensor. The sensor and transmitter are both required for flow measurement.

The transmitter provides energy to oscillate the sensor flow tubes. The sensor reacts to the Coriolis forces produced by the fluid flowing through the oscillating flow tubes. Flow detectors (pickoffs) mounted on the flow tubes produce electrical signals, which are received and processed by the transmitter. Finally, the transmitter produces output signals that represent the mass flow

rate of the fluid flowing through the sensor tubes.

The primary components of a typical Coriolis sensor are presented in Figure F-1. The flow tubes are vibrated in opposition to one another, at their natural frequency. This motion is shown in Figure F-2, page 208, which represents a simplistic model of a Coriolis meter. The transmitter provides alternating current to the drive coil, which is mounted on one of the flow tubes, generating an alternating magnetic field in the coil. The alternating magnetic field causes the fixed magnet mounted on the other tube to be alternately repelled and attracted, forcing the tubes first away from and then toward one another in a sinusoidal manner.

When fluid flows through the vibrating sensor flow tubes, a Coriolis force is produced. The Coriolis force causes

Figure F-1. Components of a Coriolis flow sensor. Shown is an ELITE® CMF300 sensor.

Pickoff coil andmagnet

Drive coil and magnet

Flow tubes

Pickoff coil and magnet

Mass Flow MeasurementCoriolis Meter Mass Flow MeasurementF


Figure F-2. Simplified model of an operating Coriolis sensor. Vibration of flow tubes,

and signals from pickoffs, are represented.

the inlet and outlet legs of the sensor flow tube to be deflected in opposite directions. As the mass flow rate through the oscillating tubes increases, the relative offset in position from one leg of the tube to the other increases. The amount of flow tube deflection caused by the Coriolis force is measured by the pickoffs, which are placed on the inlet and outlet legs of the sensor flow tubes. The pickoffs are comprised of a coil, mounted on one flow tube, and a magnet, mounted on the other flow tube. The pickoffs produce a sinusoidal voltage signal, which represents the motion of the flow tube.

Figure F-3 is a block diagram that shows the signal processing by the transmitter to produce a mass flow measurement. The transmitter is comprised of three main parts: the signal interface to the sensor, the signal processing section, and the outputs to external devices. The primary interfaces

between the transmitter and the sensor are the drive coil, pickoffs, and the RTD (which is used for flow tube temperature measurement). The transmitter processes the sine wave signals from the pickoffs (see Figure F-2), and determines the time difference (∆t) between the movement of the inlet and outlet flow tube legs. This time difference is directly proportional to the mass flow rate of fluid through the flow tubes. If fluid is not flowing, there is no time difference between the two pickoff signals.

Mathematically, the mass flow rate measurement can be expressed simply as Equation F-1. This equation is idealized, and does not take into consideration any effects of temperature or pressure on the sensor.

(Eq. F-1)

1f

∆tFd

Fd

Sensor Model

Inlet pickoff

Drive coil

Outlet pickoff

No flow

Flow

Flow Tubes Pickoff Signals

Inlet and outletpickoff signals

Inletpickoffsignal

Outlet pickoff signal

m·

Kcal

∆t( )=

Mass Flow MeasurementCoriolis Meter Mass Flow Measurement F


Figure F-3. RFT9739 signal processing block diagram.

where

= Mass flow rate (g/s)Kcal = Meter calibration constant (g/s/µs)∆t = Time difference between pickoff signals (µs)

Taking into account the effects of temperature and pressure on the sensor and meter zeroing, Equation F-1 can be modified. The equation used for determining the mass flow rate of the fluid flowing through the meter is shown as Equation F-2.

(Eq. F-2)

where

∆tflow = Time difference under flowing conditions (µs)∆tzero = Time difference under no-flow conditions (µs)KT = Temperature coefficient for flow (% /100°C)T = Measured flow tube temperature (°C)KP = Pressure coefficient for flow (% /psig)Pmeas = Measured pressure under flowing conditions (psig)Pcal = Pressure during calibration (psig) — factory calibration at 20

psig

Sensor Transmitter

Interface Signal processing Outputs

Drive coil

Inletpickoff

Outletpickof

Flow tube temperature

External pressure (optional)

Drive control

Signal amplifier

Signal amplifier

Tempera-ture

amplifier

Analogor

HART

Precision oscillator

Counter

Pickoff comparator

A/D converter

A/D converter

Frequency

Analog (4-20 mA)

RS-485/RS-232

Alarm

ρ

M

T

P(optiona

Qq

m·

Microprocessor

m·

m·

Kcal

∆tflow

∆tzero

–( ) * 1 KT * 0.0001 * T–( ) * 1 K

P * 0.01 Pmeas

Pcal

–( )+[ ]=

Mass Flow MeasurementInfluences on Coriolis Meter Mass Flow AccuracyF


The values ∆tzero, KT and T (obtained from the sensor RTD), are always used in the mass flow rate computation. The pressure components of Equation F-2, page 209 (KP , Pmeas and Pcal), are used only for specific sensors and applications that warrant pressure compensation. Key parameters of Equation F-2 are discussed below.

Calibration constant, Kcal — The calibration constant is a factor that is used for converting the time difference measured between the two pickoff signals to units of mass flow rate. The value of the calibration constant is determined when the meter is calibrated. The unit of measure is grams per second flow per microsecond of time difference (g/s/µs). The larger the sensor, the larger the value of this factor. The factor is different for each individual sensor.

Meter zero, tzero — The zero value represents the baseline offset between the sensor pickoffs under no-flow conditions, determined by zeroing the Coriolis meter at startup. (Refer to Appendix E, page 195, for information about zeroing the meter.)

Temperature coefficient, KT — The temperature coefficient compensates for the influence of tube temperature on the elasticity of the sensor flow tube material. As temperature increases, the tube becomes more elastic. As temperature decreases, the tube becomes stiffer. Under conditions of constant mass flow rate, increasing the temperature of the flow tube will cause it to deflect a greater amount, which would be interpreted as an increase in the mass flow rate. The temperature signal from the RTD mounted on the flow tube is used by the transmitter to correct for the effect of temperature variations. The value of the temperature coefficient is different for different flow tube materials. For 316L stainless steel the temperature coefficient is

approximately 4.26% per 100°C change in temperature, and for Hastelloy® C-22 it is approximately 2.79% per 100°C change in temperature. The actual temperature coefficient for a particular sensor is found in the last three digits of the sensor’s calibration factor, which is stamped on the serial number tag attached to the sensor.

Pressure coefficient, KP — The pressure coefficient compensates for the influence of fluid pressure on the stiffness of the flow tube. As pressure increases, the flow tube becomes stiffer, making it more difficult to be deflected. Under conditions of constant mass flow rate, increasing the pressure inside the flow tube will cause it to deflect less, which would be interpreted as a decrease in the mass flow rate. The pressure measurement from an external pressure transducer can be input to the transmitter, where it is used in the calculation of the mass flow rate. (Pressure input is shown in the lower functional blocks in Figure F-3, page 209.) The need for pressure correction is dependent on the sensor size and model. Pressure correction is generally required only for 2-inch and larger sensors, and for Model DL sensors. The value of the correction coefficient varies from one sensor size to the next. Table F-1 lists pressure coefficients for Micro Motion flow sensors that are affected by pressure.

F.2 Influences on Coriolis Meter Mass Flow Accuracy

The Coriolis force depends only on the mass flow rate of the fluid, and is independent of changes in fluid properties. However, the deformation of the sensor flow tubes in response to the Coriolis force is influenced

by the process conditions to which the tubes are subjected. Each sensor model behaves somewhat differently when fluid properties change.

Table F-1. Pressure coefficients for flow.

SensorModel

Coefficient*,KP

D300 and DL200D600 and DL100CMF100CMF200CMF300

0.0090.0050.00020.00080.0006

*Percent offset per psi pressure

Mass Flow MeasurementInfluences on Coriolis Meter Mass Flow Accuracy F


Changes in fluid properties usually affect the flexibility (stiffness) of the oscillating tube and/or the zero flow offset between the sensor pickoffs. As indicated by Equation F-2, page 209, temperature and pressure are the primary influence factors on mass flow measurement. Additional factors that may affect performance of the meter include:

• Entrained gas in the fluid• External vibration• Erosive properties of the fluid• Coating/plugging of the flow tubes

The descriptions of these influences presented in the following sections are based on the current understanding of the sensor dynamics. These explanations are likely to be expanded in the future, as more research is conducted and subtleties of the meters’ operation are better understood.

Influences on Tube Stiffness

Variations in temperature and pressure will change the flexibility or stiffness of the oscillating tube. Assuming a constant mass flow rate, a change in temperature or pressure will change the stiffness of the tube, which will cause the relative offset between the two sides of the oscillating tube to vary. This will lead to a change in the ∆t between the pickoffs. Since the mass flow rate has not

changed, there will be a measurement error. The effects of temperature and pressure are systematic and can be characterized and compensated for, to minimize or eliminate their influence on the accuracy of the meter. The magnitude of these influences will vary from one sensor design to another, and depends on tube material, wall thickness, and geometric design.

Temperature

The effect of temperature on the elastic properties of the tube material was discussed briefly on page 210. As temperature increase the tube will become more elastic, which increases the generated ∆t — even when the mass flow rate has not changed. The magnitude of the temperature influence on elasticity depends primarily upon the material of construction of the flow tube.

The effects of temperature on the mass flow rate measurement is a linear effect, and can be readily characterized. Figure F-4 illustrates the effect of temperature on the meter’s flow rate measurement for stainless steel and Hastelloy sensors with no temperature compensation.

All Micro Motion meters provide continuous compensation for temperature effect, using the RTD mounted on the sensor flow tube.

Figure F-4. Temperature effect on mass flow rate measurement — if there were no

temperature compensation. Automatic temperature compensation is standard for all meters.

-0.5

0

0.5

1

1.5

2

2.5

30 40 50 60 70 80 90 100 110 120

316L

Hastelloy C-22

Temperature (°F)

Mas

s flo

w r

ate

erro

r (%

)



Pressure

The effect of pressure on the sensor is a combination of several different mechanisms. An increase in pressure causes an increase in the flow tube hoop stress (acting perpendicular to the tube wall). This results in a stiffening of the flow tube, which reduces the generated ∆t — even when the mass flow rate has not changed. However, the effect of pressure on the sensor is complicated by the tube geometry.

In bent-tube designs, the fluid pressure generates significant forces normal to the tube walls (along the axis of the tubing). This axial force acts to offset the hoop stress on the flow tube. The flow tube wall thickness, diameter, geometry, and material of construction determine the magnitude of the pressure influence on the sensor. Smaller sensor sizes exhibit a negligible pressure effect on meter accuracy.

However, the effect becomes more pronounced with increasing sensor size. Figure F-5 illustrates the magnitude of the pressure effect on D600 and CMF300 sensors calibrated at 20 psig.

If a particular sensor is sensitive to pressure, a correction method similar to the temperature correction for material elasticity can be employed: a pressure transducer is mounted in the pipeline as close to the meter as possible, and a pressure correction factor is entered into the transmitter. The transmitter then automatically compensates for pressure.

Table F-1, page 210, lists pressure compensation coefficients to correct the mass flow rate measurement of sensors that are affected by pressure. Only Model D300, D600, DL100, and DL200 sensors are significantly impacted by pressure. The effect on ELITE CMF100, CMF200, and CMF300 sensors is an order of magnitude less than for the Model D sensors.

Figures F-6a, page 213, and F-6b, page 214, show the components required for on-line pressure compensation for a flowmeter. The pressure transducer must provide either a 4-20 mA or HART output for use with the RFT9739 transmitter. (The RFT9712, CEQ 6079 transmitter is capable only of reading pressure from a HART Bell 202 output.)

Figure F-5. Pressure effect on mass flow rate measurement — no pressure

compensation.

-0.5

-0.4

-0.3

-0.2

-0.1

0

0.1

0.2

0 20 40 60 80 100

CMF300

D600

Pressure (psig)

Mas

s flo

w r

ate

erro

r (%

)



Figure F-6a. RFT9739 wiring connections for pressure compensation with HART

(digital) communications

If a HART output is used, the pressure measurement is brought in as a multidrop connection on the RFT9739 primary variable (PV) analog output, as shown in Figure F-6a. The PV output will be driven to 4 mA in this case, and cannot be used as a process variable output. The multidrop connection provides the pressure measurement from the pressure transducer using HART communication for polling. It is important to configure both the pressure transducer and the RFT9739 with unique (non-zero) communication “addresses” to allow communication.

If a 4-20 mA pressure signal input is used, the wiring will be connected as illustrated in Figure F-6b, page 214. Using a direct 4-20 mA input is preferable to the HART polling method described above, because it is easier to wire, provides faster response time, and

does not disable the RFT9739 PV output. In the 4-20 mA input configuration, the RFT9739 provides DC power to the pressure transmitter, eliminating the need for an external power supply.

An alternative to on-line compensation is to determine a new meter flow calibration factor at the operating process fluid pressure. This method is only acceptable if the process pressure remains fairly constant (±10 psi for D300 and D600 sensors, ±100 psi for CMF200 and CMF300 sensors, ±300 psi for CMF100 sensors).

The best recommendation for minimizing pressure influences is to use a sensor that is least affected by pressure. Therefore, CMF200 and CMF300 sensors are preferred over D300 sensors.

D30 Z30

CN2

P

P

24 VDC

24 VDC

Flow

Flow

RFT9739 rack-mount

RFT9739 field-mount

Pressure transmitter SMART only (1151 or 3051)

Pressure transmitter SMART only (1151 or 3051)

250Ω ±5% 0.5W

250Ω ±5% 0.5W

250Ω ±5% 0.5W

250Ω ±5%0.5W

Power supply

Power supply



Figure F-6b. RFT9739 wiring connections for pressure compensation with analog

input.

Meter Zero Influences

As part of the normal startup procedure for a Coriolis meter, the baseline offset between the pickoff sensors under no-flow conditions is determined. This process is called zeroing the meter. The zero value that is determined (∆tzero) is subtracted from all subsequent time difference measurements (∆tflow). The remaining ∆t represents the true mass flow rate. This calculation is presented in Equation F-2, page 209. (For additional information about meter zeroing, see Appendix E, page 195.)

Zero Stability or Zero Uncertainty

The zero stability specification for the meter represents the range of “stored zero” (∆tzero) values that would be obtained from zeroing

the meter a number of times in succession under constant process conditions.

The variation in ∆tzero values is the result of limitations in the transmitter’s ability to sample and precisely measure the small signal levels from the pickoffs at zero flow. The meter’s zero stability, or zero uncertainty, represents the maximum anticipated variation in the meter’s stored zero, for a stable set of process and installation conditions. It does not describe an actual zero error, because it is likely that a more accurate zero value could be obtained.

The effect of zero stability on the accuracy of the meter can be understood by examining Equation F-3, which is the nominal uncertainty equation for Coriolis meters.

Z6

Z20

CN2

P

P

Flow

Flow

RFT9739 rack-mount

RFT9739 field-mount

Pressure transmitter

Pressure transmitter

4-20 mA terminals

4-20 mA terminals



(Eq. F-3)

where

Base Uncertainty = Accuracy of sensor, expressed as a percentage, determined from individual sensor specifications (±0.10% for ELITE sensors, ±0.15% for Model D sensors)

Zero Stability = Determined from individual sensor specificationsMass Flow Rate = Operating flow rate

From Equation F-3, it can be seen that a decrease in the mass flow rate will result in an increase in the magnitude of the zero stability component in the nominal uncertainty equation. This relationship is illustrated in Figure F-7, which represents the nominal uncertainty boundaries for a Coriolis meter.

It is important to understand that the boundaries shown in Figure F-7 represent the uncertainty in the meter’s measurement, assuming that a “normal” zero value has been captured by the transmitter. The illustrated boundaries do not represent a signature curve for Coriolis meters. If the meter is zeroed perfectly, the transmitter will capture the “true zero” value, and the meter calibration will fall within the base uncertainty (±0.10% or ±0.15%) from the sensor’s specified maximum flow rate down to a flow rate of zero. However, a zero offset will skew the nominal meter uncertainty, as described below.

Combined Effect of Zero Stability and Zero Offset

The zero offset is the difference between the “stored zero” value and the “true zero” value. Generally, this difference is very small. However, a large zero offset could occur if the meter is zeroed when (1) there is actually a small amount of fluid flowing through the sensor, (2) the sensor or transmitter is removed and reinstalled without rezeroing, or (3) pipeline stresses are applied to the sensor.

The amount of zero offset can be determined by halting flow through the meter completely, and reading the meter’s mass flow rate indication (as described in Section E.3, page 198). Once the amount of zero offset has been determined, the measurement error can be calculated using Equation F-4, page 216.

Figure F-7. Meter uncertainty versus flow rate for ELITE® sensors.

Nominal Uncertainty (%) Base Uncertainty (%) Zero Stability

Mass Flow Rate---------------------------------------------- * 100+

±=

-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1

0 10 20 30 40 50 60 70 80 90 100

Nom

inal

met

er u

ncer

tain

ty (

%)

Nominal full-scale flow rate (%)



(Eq. F-4)

The impact of a hypothetical large zero offset on meter accuracy is illustrated in Figure F-8, which presents measurement error and uncertainty. This graph illustrates the error that would result if the meter zero was offset by +0.1% of the meter’s nominal full-scale flow rate. The zero offset error points shown in Figure F-8 were determined by calculating the zero offset using Equation F-4. The uncertainty limits were then determined from Equation F-3, page 215.

Zero offset errors can be eliminated by rezeroing the meter, which would cause the curve presented in Figure F-8 to return to the nominal uncertainty curve presented in Figure F-7, page 215. In order to obtain an accurate zero, it is imperative that there be no fluid flow through the sensor. Furthermore, if the sensor mounting is changed or the sensor or transmitter is removed, repaired, serviced, or otherwise altered, the meter must be rezeroed. (For information about rezeroing, see Appendix E, page 195.) A less predictable cause of a zero offset is a change in flow tube temperature, which is discussed below.

Temperature Effect On Zero Offset

A change in temperature away from the temperature at which the meter was zeroed can result in the “true zero” drifting away from the “stored zero” value. The magnitude of the drift and the direction of the drift varies from one sensor to the next.

The exact mechanism by which temperature affects the meter zero is not fully understood. It is likely that temperature variations change the stresses in the flow tubes. These changes in stress levels can result in slight variations in the location of the pickoff detectors relative to one another, which is interpreted as flow and results in a change in the meter’s “true zero” value.

Testing has been conducted on sensors to characterize the relationship between zero offset and temperature. As a result, typical uncertainty limits have been established. Micro Motion’s uncertainty specification for the effect of temperature on the meter zero is presented in Table F-2.

Figure F-8. Zero offset error and uncertainty for an ELITE® sensor

— based on an assumed zero offset of +0.1% of nominal full-scale flow.

Zero Offset Error (%)Average Meter Reading at No Flow

Typical Operating Flow Rate------------------------------------------------------------------------------------------------------- * 100=

-0.5

0

0.5

1

1.5

2

2.5

0 20 40 60 80 100

Zer

o of

fset

err

or (

%)

Nominal full-scale flow rate (%)

Zero offset errorUncertainty limit

•

–



Table F-2 also lists the meter base uncertainty and zero stability values, and can be used to compute the total meter uncertainty for varying operating temperatures. The total uncertainty for the meter’s mass flow measurement is determined using Equation F-5 and the values in Table F-2.

(Eq. F-5)

where

A = Base uncertainty, %B = Zero stability, lb/minC = Zero offset uncertainty for the effect of temperature on the

meter zero, lb/min/ °CToperating = Operating process fluid temperature, °CTzero = Temperature at which the meter was zeroed, °C

It should be kept in mind that Equation F-5 describes the maximum uncertainty for all sensors. Not every sensor will exhibit this amount of error. The higher the operating flow rate, the less impact a zero offset will have. For applications that require a larger turndown, ELITE meters should be selected because they have lower zero offset uncertainty versus temperature than Model D meters.

Any zero offset error is eliminated by rezeroing the meter at the new process

temperature. Temperature-related zero offset errors will be minimized by rezeroing the meter. The need for rezeroing will depend upon the characteristics of the sensor, the amount of temperature variation and the operating flow rates. Assessing the need for rezeroing is described in Appendix E, page 195.

Legal trade requirements prohibit rezeroing the meter, unless the meter calibration is recertified. Such applications generally have steady process conditions (temperature, pressure, product composition) and, therefore, typically do not require rezeroing.

Other Influences

The following sections discuss other process variables and installation conditions that might affect the accuracy of the meter. These influences are not well defined, and the magnitude of their impact will vary greatly from one application to the next.

Table F-2. Zero uncertainty specifications.

[A] [B] [C]

SensorModel

Nominal Full-ScaleFlow Rate(lb/min)

Base Uncertainty(%)

ZeroStability(lb/min)

Zero Offset Uncertaintyfor Temperature Effect*(lb/min/ °C)

CMF100 500 ±0.10 ±0.025 ±0.00125CMF200 1600 ±0.10 ±0.08 ±0.016CMF300 5000 ±0.10 ±0.25 ±0.05D600 25,000 ±0.15 ±2.5 ±0.5

*Worst-case zero offset due to process fluid temperature change away from the zeroing temperature.

Total Uncertainty (%) AB

2C* T

operatingT

zero –( )2

+

Operating Mass Flow Rate-------------------------------------------------------------------------------------------*100+

±=



Entrained Gas/Slugs of Gas

Mixtures of gas and liquid in the sensor can be a significant problem. The combination of gas and liquid dampens the vibration of the sensor flow tubes, which requires the drive circuitry to output more energy to keep the tubes vibrating. Due to intrinsic safety limitations, the amount of current that can be supplied to vibrate the tubes is limited. A point can be reached where the tubes will no longer vibrate at the design amplitude, even though the maximum power is being applied to the driver. This is called drive saturation.

Once drive saturation occurs, the measurement accuracy of the meter will begin to degrade. Significant measurement errors will occur as the tube amplitude decreases. At some point, the tube vibration will drop below a measurable level. Once this occurs, the meter is no longer capable of making a measurement.

The meter drive gain reading can be used for determining whether drive saturation is occurring. The drive gain should normally be between 3 and 4 volts DC. If it exceeds 13 volts DC, severe drive saturation has occurred.

A sensor’s sensitivity to entrained gas is difficult to determine, because it is dependent on so many variables:

• Sensor size and model• Fluid viscosity• Fluid flow rate• Fluid surface tension• Characteristics of gas (bubble size, well

mixed, stratified, etc.)• Fluid pressure

Larger sensors have a lower tolerance for entrained gas than smaller meters, because the fluid has a greater influence on the overall mass of the system (tube and fluid) as the tube size increases. In general, fluids with higher surface tension will tend to create a more uniform dispersion of any entrained gas in the fluid, creating more of an emulsion. The sensor will perform better in these types of applications than in those where the gas easily breaks out and accumulates.

Performance ranges for a sensor’s ability to handle entrained gas, based on tests performed with air and water, are: measurement errors will start to occur at approximately 1 to 3 percent gas by volume, and the flow tube will stop vibrating at 5 to 15 percent gas by volume. Entrained gas causes the meter reading to be low until the meter reaches the drive saturation point, at which time the output becomes unpredictable. The transmitter’s slug flow cutoff function can be used to force the meter output to indicate zero flow and a fault condition when entrained gas or slugs of gas interfere with the meter measurement. The transmitter will automatically indicate an error condition when the drive becomes saturated.

Vibration

Because Coriolis sensors operate by vibrating the flow tubes, a common misconception is that they will not function properly in an environment that is subject to vibration. Actually, sensors are often installed where they are exposed to external vibrations, yet they provide excellent performance.

Sensors are designed to withstand vibrational amplitudes associated with good pipeline practices. However, it is advisable to install adequate vibration isolation for a Coriolis sensor in an environment where piping and other process equipment have experienced vibration-related failures. In severely vibrating pipelines, the sensor can be isolated from the vibration with flexible piping and vibration isolating pipe supports, as illustrated in Figure F-9, page 219.

Vibration testing has revealed that the introduction of random vibration can increase the variation in the meter’s flow measurement indication. This does not affect the flow measurement accuracy, but will result in a degradation in repeatability as the run time is decreased. For proving applications this can result in unacceptable repeatability. The shorter the batch the worse the repeatability will become.

It also has been found that measurement errors could occur if the sensor is subjected to external vibrations at or near the vibration frequency of the oscillating tubes or one of



Figure F-9. Mounting for sensor vibration isolation. Sensor, sensor connections, and

connected piping are isolated, as a unit, from the pipeline and ground. Vibration cannot

transfer to sensor.

the harmonics of this frequency. The susceptibility of the sensor to vibration will vary from one design to another. Table F-3 presents typical operating frequencies for ELITE and Model D600 sensors. It is uncommon to find a pipeline that transmits enough vibrational energy at the operating frequency of the sensor to affect the performance of the meter. However, in the event that the pipeline frequency affects the operation of the meter, it might be possible to apply rigid clamps to the piping to change the frequency being transmitted down the pipeline.

Another vibration-related problem is encountered when multiple sensors are installed in the same pipeline. Sensors of the

same size and model operate at very similar frequencies. The sensors can transmit enough vibrational energy through the pipeline to excite one another, which in some cases can lead to measurement errors. This problem, known as cross-talk, is fairly common with Model D sensors, but has been minimized with ELITE sensors. Cross-talk will usually manifest itself as an increased variation in the meter’s flow measurement outputs. This will usually show up as poor repeatability when the meter is proved. It is easily diagnosed by disconnecting power from one of the meters, and proving the other and vice-versa. If proving repeatability becomes acceptable, this indicates that there is a cross-talk problem.

Structural mounting supports

Load-bearing vibration isolators (such as Lord sandwich mounts)

Vibration isolation with flex hose or elastomeric coupling

Table F-3. Typical sensor operating frequencies.

Sensor Tube Frequencies (Hz)

Sensor Model ρρρρ = 0.0012 g/cc ρρρρ = 0.8 g/cc ρρρρ = 0.998 g/cc

CMF025 159 139 135CMF050 157 135 131CMF100 130 110 106CMF200 87 76 73CMF300 87 76 73D600 55 41 39



In order to prevent cross-talk from occurring, precautions should be taken to vibrationally isolate sensors from one another. As stated previously, this is generally only required for Model D sensors. Figure F-9 illustrates how to provide vibration isolation. Flexible hose, or an elastomeric bellows like those used for thermal expansion joints, can be used to isolate the sensor from the piping. Load-bearing mounts, such as Lord Industrial Products sandwich mounts, can be used to isolate the sensor from any transmission through the pipe mounts.

Generally, only one mode of transmission needs to be isolated: either piping or mounting. However, there have been cases where both modes have required isolation. The objective of applying vibration isolation is to attenuate the transmission frequency. It is important to properly apply the vibration isolating components to accomplish this task.

An alternative approach is to obtain sensors which have sufficiently different natural frequencies that minimize cross-talk. Contact the factory and request information on Custom Engineering Quotation (CEQ) 7146300 for additional details to determine if this approach is suitable for your application.

Density

Variations in the density of the process fluid cause the mass of the flow tube/fluid system to change, which can alter the mass balance of the sensor. The sensors have been designed to minimize the influence of changing fluid mass, through geometric design and mass balancing of the sensor tubes. Therefore, the impact of varying fluid density on meter accuracy is negligible.

Changes in the fluid density can cause the “true zero” of the meter to change slightly, creating a small zero offset. The mechanism that causes this zero offset is not well understood, but it is likely caused when the variation in mass loading produces a change in sensor stresses. If the fluid density varies significantly, it might be necessary to rezero the meter. Use the information presented in Appendix E, page 195, to evaluate whether or not rezeroing is required.

Viscosity

Very little documented information is available on the effect of fluid viscosity on the accuracy of Coriolis meters. Although viscosity influences have been reported, no documented test data have been produced to confirm these claims. Coriolis meters are currently used on a wide variety of viscous products and exhibit excellent accuracy. It has not been established if fluid viscosity has any influence on the calibration factor or the zero offset.

A report on testing conducted with different fluid viscosities, which showed no accuracy shifts, is available. Refer to the following document: “The ELITE Mass Flowmeter, Model CMF300,” TNO report E 2620 T 93, published by WIB, October 1993, Index #3.6.

Flow Profile

Limited testing has been conducted on the influence of flow profile variations on the accuracy of Coriolis meters. Calibration tests have been conducted at a number of different test facilities, all with different piping arrangements, and no significant variation in meter performance from one facility to the next has been observed. Test meters have also been used on a wide variety of fluids ranging from laminar to turbulent flow with no apparent impact on performance.

The following paper provides test data on Coriolis meters with a variety of upstream piping configurations: “The Effect of Swirl on Coriolis Meters,” Proceedings of the 1995 North Sea Workshop.

Coating/Plugging

Some process fluids have a tendency to coat the flow tubes or harden inside the flow tubes. In some instances, the sensor flow tubes will actually become plugged, preventing flow through the sensor. This condition usually results when the sensor flow tube diameter is much smaller than the diameter of the process piping. The ratio of tube surface area to fluid volume increases as the tube diameter decreases. Therefore, in smaller diameter flow tubes, the fluid will be exposed to a greater surface area, which assists heat loss and product solidification. For a process fluid that has a tendency to



solidify, a sensor should be selected that has a flow tube inner diameter that is as close as possible to the inner diameter of the process piping.

In the event of plugging, dual-tube sensors can be particularly troublesome to unplug because one of the flow tubes will often become clear while the other tube remains plugged. When this condition occurs, the flow rate through the system will be significantly diminished due to the reduced flow path through the sensor. However, even when one of the tubes is plugged, the meter will usually measure flow properly, as long as the plugged tube remains full of process fluid and the density of the fluid in both tubes remains the same. A Model DL sensor, which has a single, double-loop flow tube, would be preferred in this case. The DL sensor’s single flow tube can be cleaned more readily than a dual tube meter.

Heat tracing can be employed to maintain a constant fluid temperature and prevent solidification in the meter. Alternatively, a routine cleaning procedure can be followed, in which the flow tubes are filled with a suitable solvent that removes any coating inside the sensor flow tubes. Buildup of coatings or tube plugging will cause the pressure drop through the meter to increase. A system to monitor pressure drop through the meter can be used to establish cleaning requirements.

Coatings generally will not affect the accuracy of the meter, unless the density of the coating material is significantly different from the density of the process fluid. If the coating density is different from the process fluid density, the mass balance of the tube can become affected, which will lead to measurement errors. Also, depending on the properties of the coating, the tube vibration may be dampened, preventing the tubes from vibrating in a normal fashion. This can also lead to measurement errors.

Erosion

Coriolis meters can be used to measure solid/liquid mixtures that contain extremely abrasive solids. However, caution must be exercised to avoid erosion of the sensor flow tubes. Erosion reduces the flow tube wall

thickness, which affects the sensor’s response to the Coriolis forces and leads to calibration shifts. Severe erosion can result in failure of the flow tube.

In order to minimize the effects of erosion, the fluid velocity inside the flow tubes should be kept below 10 feet per second when measuring abrasive materials. Select flow tubes with the largest inner diameter that is practical for the measurement application. Also, select sensors that have the most gradual bends in their flow tubes. Sharp bends are prime sites for tube erosion.

Corrosion

The vibration of the sensor flow tubes results in alternating stresses continuously being applied to the tubes. The presence of these alternating stresses makes Coriolis sensors susceptible to corrosion-fatigue failure.

A Coriolis sensor could fail in an environment that would not be predicted from general corrosion data. An example of this is a stainless steel flow tube exposed to a process fluid that contains free halogen ions. Halogen ions cause a breakdown of the protective oxide layer of stainless steels and cause pits to form. In an environment where there were no alternating stresses or very low stresses, the halogen ions would not cause a tube failure. However, if the vibration of the tube results in local stress levels that exceed the fatigue limit of a pitted material, a crack will initiate at a pit. Once a crack has begun, it quickly widens and causes failure of the flow tube. This phenomenon is known as stress-corrosion cracking. In this type of corrosion, additional wall thickness is of little benefit and will not greatly extend the life of the flow tube.

For additional resistance to corrosion, ELITE sensors are available with flow tubes of Hastelloy C-22. Consult the Micro Motion Corrosion Guide, your sales representative, or the factory for questions about material suitability.

Velocity of Sound

Velocity of sound influences are related to the localized compression and decompression of fluid at the surface of the flow tube as the tube vibrates back and forth.



It has been determined that, for vibrating tube density meters operating at high frequencies (greater than 500 Hz), the tube vibration can cause localized changes in the fluid density at the tube wall, changing the vibrating frequency of the tube.

This phenomenon should not impact the mass flow measurement, which depends on deflection of the tubes resulting from the Coriolis forces, not on the frequency of

vibration of the tubes. Additionally, Micro Motion meters operate at low tube frequency (less than 160 Hz).

Specific testing for velocity of sound influences has not been conducted. However, WIB report E2620 T93, “The ELITE Mass Flow Meter, Model CMF300,” showed no changes in accuracy between water, gasoline and propane.


Ap

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J Proving Equipment Manufacturers

Small Volume Provers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253Conventional Pipe Provers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253Proving Pulse Counters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253Proving Computers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253Flow Computers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253Pressure Transmitters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253Temperature Transmitters. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 254Pycnometers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 254Density Averager. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 254Prover Calibration Services. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 254Proving Services . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 254Structural Pipe Clamps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 254Vibration Isolation Products . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 254


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J Proving Equipment Manufacturers

Companies that manufacture proving-related equipment, and provide proving services, are listed in this appendix. This is not a complete listing of all companies that provide proving equipment and services, other suppliers are generally available.

This appendix does not provide endorsement or recommendation by Micro Motion Inc. of any of the suppliers listed herein. The purpose of this appendix is to provide general information for locating equipment and service providers.

Small Volume Provers

Calibron Systems Inc.Scottsdale, Arizona602-991-3550

Fisher-Rosemount PetroleumHouston, Texas281-240-0701

Conventional Pipe Provers

En-Fab Inc.Houston, Texas713-225-4913

Linco Electromatic Inc.Midland, Texas915-694-9644

Meter Check Inc.Moore, Oklahoma405-790-0778

Sulton CompanyTulsa, Oklahoma918-446-1611

Winco Metric PMI Corp.Tulsa, Oklahoma918-445-1141

Proving Pulse Counters

Control Instruments Inc.Houston, Texas713-667-5067


Winco Metric PMI Corp.Tulsa, Oklahoma918-445-1141

Proving Computers

Calibron Systems Inc.Scottsdale, Arizona602-991-3550

Fisher-Rosemount PetroleumHouston, Texas281-240-0701

Omni Flow ComputersStafford, Texas713-240-6161

Flow Computers

DFMStafford, Texas281-565-1118

Omni Flow ComputersStafford, Texas713-240-6161

Spectra Tek UK Ltd.Swinton Grange, MaltonNorth Yorkshire, England(01653) 600542

Pressure Transmitters

Rosemount Inc.Eden Prairie, Minnesota800-903-3728

Proving Equipment Manufacturers J


Temperature Transmitters

Rosemount Inc.Eden Prairie, Minnesota800-903-3728

Pycnometers

Arcco Instrument Company Inc.Riverside, California909-788-2823

Measurement Products Inc.Houston, Texas713-686-5783

Density Averager


(Not a standard product. Available as a special modification of the Linco Electromatic temperature averager.)

Prover Calibration Services

SGS RedwoodDeerpark, Texas281-479-1848

Proving Services

Coastal Flow MeasurementHouston, Texas281-282-0622

Liquid Meter Calibration Inc.Sand Springs, Oklahoma918-245-4129

Louisiana Meter ServiceLake Charles, Louisiana318-478-7736

Mass Flow TechnologyBaytown, Texas281-427-7284

Meter Check Inc.Moore, Oklahoma405-790-0778

Meter Proving ServiceMidland, Texas915-561-5812

Southern Petroleum Laboratories – SPLCarencro, Louisiana318-896-3055Houston, Texas713-660-0901

Sulton CompanyTulsa, Oklahoma918-446-1611

Structural Pipe Clamps

Stauff CorporationWaldwick, New Jersey201-444-7800

Vibration Isolation Products

Korfund DynamicsBloomingdale, NJ973-838-1780

Lord Mechanical ProductsErie, Pennsylvania814-868-5424


Index

Page numbers in bold indicate illustrations.

AAccuracy. See also Damping factor, proving accuracy; Installation; Meter factor; Response time, proving accuracyAPI

correction factorsmass 29volume 22

density measurement 141insulation requirements 153mass meter factor 142parallel installation 150pycnometer 148

meter installationproving connections 42

proving calculationsmass meter factor 122repeatability 123

proving devicespipe prover size 90small volume prover 101uncertainty

Coriolis master meter 116pipe prover 87, 88small volume prover 96, 97transfer standard meter 108, 109volumetric tank prover 81, 82

volume measurement 18

BBPV xxiii

conventional provers 20pipe prover 86small volume provers

proving calculations 20proving devices 94

volume meter factor 121volumetric tank proving 80

CCalibration xxii

density 141, 227accuracy influences

flow rate 232

pressure 231temperature 229

calibration factors 158, 160digital communications 143field proving 159

output trim 146proving procedure 154

flow direction 202mass flow

accuracy influencespressure 213temperature 217viscosity 220zero stability 215

calibration constant 209, 210temperature coefficient 210

calibration factor xxioutput signals 45

digital communications 46proving calculations

inventory 128, 129, 130meter factor uncertainty 126

proving concepts 9proving devices 71

density 65gravimetric tank

scale accuracy 75master meters 104temperature 63transfer standard

master meter 30uncertainty

Coriolis master meter 115gravimetric tank 74transfer standard 108volumetric tank 80

troubleshootingdensity factor offset 160flow rate 136, 161flow tube coating 137, 161meter factor 136meter recommendations 133

volume flow rate accuracy 243Communications. See HART Communicator; HART protocol; ProLink software program; Modbus protocol

Index


Conversion factordensity 156, 187proving 172, 182time units 52volume measurement 18

Coriolis sensor 208

components 225corrosion 221, 236crosstalk 135orientation 41pipe stresses 39vibration 233

Correction factor 147, 230buoyancy 172, 182

meter factor calculation 73uncertainty 74, 126

computingproving computer feature 62

density measurement 64, 122density proving 148liquid

meter factor calculationconventional pipe prover 86Coriolis master meters 114small volume prover 95volumetric master meters 107volumetric tank proving 80

uncertaintyconventional pipe proving 88Coriolis master meter 116meter factor 126small volume prover 97volumetric meter 109volumetric tank proving 82

mass meter 159mass meter factor 94meter 9pressure 212, 229

meter factor calculation 20, 22proving computer features 62volume measurement 17, 18, 32

prover steel 26proving calculations

density 26, 29mass flow 24, 122

steelpipe prover 87small volume prover 96uncertainty 126volumetric tank proving 81

temperaturemeter factor calculation 22, 24volume measurement 17

temperature and pressure measurements 29thermal expansion 18, 20turbine meter 32volume meter factor 121

Custody transferanalog output 48density 74meter proving 9meter selection 35proving 5RFT9739 46volumetric tank proving 78

Custody transfer measurement 4, 11, 122meter recommendations 133time between provings 12

DDamping factor 134

number of proving runs 103prover size 100proving accuracy 55recommendations

conventional pipe prover 90, 91Coriolis master meters 118gravimetric tank proving 78small volume prover 103, 104volumetric master meters 111volumetric tank proving 84

repeatability 103response time

output signals 53pipe prover 89small volume prover 99troubleshooting 136

troubleshooting 135, 159zero reading 198

Density averagermanufacturers 254proving procedures

density meter 25transfer standard 31volume 29

troubleshooting 135Density factor xxiii, 141

calculating 156correcting density reading 146, 158density measurement device 64density proving calculation 155determining mass meter factor 122, 123field proving 147flow tube changes 161inventory calculations 128laboratory analysis 147mass measurement 22, 32meter factor calculation 142offset 160proving calculations 29proving density device 65proving procedure 154

Coriolis meter density 28density meter 26volume 30

Index1


Density meter 4API standard 153calibration 65density measurement device 64field proving 146, 147fluid flow rate 136, 161in-line 22mass measurement 25–27, 32mass meter factor 122meter proving 141proving calculations 29proving computer feature 61proving equipment 31recommendation 142series density installation 149velocity of sound 222, 237

Density samplingcontainer 26installation 153line 147, 150, 152loop 153

density proving installations 149density proving procedure 154inlet valve 152parallel density installation 150proving procedure 28

method 125system 22tubing 153

EElectronic transmitter 3ELITE sensor

Coriolis sensors 4corrosion 221crosstalk 134custody transfer 35density measurement 142, 225

density measurement device 65density measurement recommendations 159mass flow measurement 207

meter density accuracy 229–236meter recommendations 133operating frequencies 219pressure effect 243pressure influences 212, 213repeatability specification 125

FFlow detectors. See Pickoff detectorsFlow measurement

analog output 48custody transfer 9, 35damping 54mass measurement 22meter factor calculation 113

meter outputs 46operating pressure 160pressure effect 243proving 10, 17recommendations 133, 159reproducibility 158response time 53small volume prover 93troubleshooting 136

Flow rateeffect on density 232

effect on volume 242

fluidCoriolis master meter 118density factor offset 161effects of damping 55entrained gas 218, 233maximum volume proving 24meter density accuracy 232minimizing external influences 42minimum volume proving 20reproducibility 136required number of passes 247small volume prover 92volumetric flow rate accuracy 243volumetric master meter 111

massanalog output 48Coriolis meters 3, 4density measurement 225digital information 46frequency output 49inventory calculations 129mass flow measurement 207–212meter density accuracy 228meter zero 56meter zero influences 214pressure effect 243volume measurement 17volumetric flow rate 45volumetric flow rate accuracy 241zero uncertainty 215zeroing 197–199, 203

operatingexpected 107maximum xxi, 53nominal 202normal 11procedures 105prover size recommendations 90required number of runs 123

pressure effect on mass 212

proving 5, 10rezeroing 200–201sensor installation 133tank proving ramp-up/ramp-down 76

temperature effect 217troubleshooting 136

Index


variation 56zero offset error 199zeroing influences 215

Flow tube xxi, 3coating 228, 235corrosion 221, 236density 45, 220density measurement 225erosion 235fluid flow rate 232mass flow accuracy 211mass flow measurement 207–210meter sampling 99orientation 40pressure 228, 229, 230process fluids 220sensor mounting 39system mass 226temperature 226, 228, 241transfer standard 30troubleshooting 135–137velocity of sound 236, 237vibration 218, 233zero offset 216

Frequency totalizing device 62, 121, 123Full-scale flow xxi

density factor offset 161maximum 56, 133meter factor reproducibility 136meter zero influences 216

HHART Communicator

. See also HART protocol; ProLink software program

analog density 145analog output 48analog output trim 145Bell 202 48density measurement 65, 143digital output 46frequency/pulse output 53K-factor 52low-flow cutoff 56meter information 57meter zeroing 197proving summary 134troubleshooting 159volume measurement 29

HART protocolcommunication configuration 143mA outputs 213, 230, 231multidrop network

Bell 202 48, 144RS-485 47, 144

IInstallation

accuracy 217Coriolis master meter 112custody transfer 35density measurement devices 141density proving 148, 149density sampling 153parallel density proving 150pay and check meters 14proving in new installation 11sensor 133sensor mounting 39slipstream 136small volume prover 91vertical pipeline 40zero uncertainty 214

ISO 9000quality audit 10time between provings 12

ISO 9000 verification 111, 134

KK-factor xxi, 45

field adjustment procedure 53frequency totalizers 62meter mass 123meter volume measurement 121modifying 129number of passes per run 249prover size 90proving calculations 29proving procedure 30pulse output 107, 113, 114pulse scaling factor determination 52

MmA outputs. See OutputsMass measurement 4, 17, 116

Coriolis meter configuration 113, 114density measurement device 64meter configuration 22–32

volumetric master meters 106–108meter configured for mass 124meter proving 141proving recommendations 134repeatability 135

Measurementdensity 3

analog output 48conventional pipe prover uncertainty 88Coriolis master meter uncertainty 114–

116Coriolis master meters 113correction 158custody transfer 35digital output 46

Index1


flow rate measurement 241fluid flow rate 136, 161inventory calculations 129mass measurement 22, 27, 32mass meter factor 122, 123measurement devices 64meter proving 10pressure 136, 243proving devices 65proving equipment 25, 151proving instruments 61proving procedure 26, 27, 28recommendations 159reproducibility 158required equipment 79RFT9739 transmitter 133small volume prover uncertainty 97small volume provers 94volume measurement 29, 71, 72volumetric flow rate 4, 45volumetric master meter uncertainty 109volumetric tank proving uncertainty 81,

82density measurement 225–237density proving 141–148inventory 129

analog output 48custody transfer 35density proving installations 150frequency output 49output recommendations 46transfer standard proving 30transmitter outputs and configuration

134mass 79, 85–87, 122prover volume 4, 71volumetric proving 18volumetric proving requirements 20volumetric tank proving 79

Meter factor xxiaccuracy

Coriolis master meter 111, 112erosion 90, 100prover prerun 99tank volume 83

average 102, 108calculations

conventional pipe prover 85Coriolis master meter 113density measurement 26gravimetric tank proving 73laboratory analysis 147maximum volume proving 22meter proving 10minimum mass proving 24minimum volume proving 20small volume prover 94transfer standard proving 29

volumetric master meters 107, 110volumetric tank proving 79

calibration 137damping

pipe prover 91proving accuracy 55small volume prover 104troubleshooting 136

density measurement 65error 30flow rate 56, 247

flow tube changes 137, 161inventory calculations 128–130mass xxiii, 122–123, 142

Coriolis master meter 113mass measurement 30meter proving 141volumetric master meters 107

number of proving passespredicting 247–250small volume prover 102–103

pressure measurement 63process conditions 12prover prerun 89proving frequency 11registers 158repeatability 123, 124

number of proving runs 90, 101volume measurement 32

reproducibility 126, 136rezeroing 200temperature measurement 63time between provings 12transfer standard meter 104trend chart 12, 127troubleshooting 135uncertainty 125volume xxiii

conventional pipe prover 86Coriolis master meter 114density measurement 31mass measurement 30small volume prover 95volumetric master meters 107

zeroing 202Meter inventory 40, 129Meter zeroing xxii

Coriolis master meter 202density measurement 27influences 214installation recommendations 40mass flow measurement 209maximum volume proving 21meter proving 11minimum mass proving 25output signals 56proving 201proving concepts 11

Index


reproducibility 136trend charts 12

Modbus protocolcommunication configuration 47, 143multidrop network

RS-485 144Model D sensor 210

accuracy 215custody transfer 35density accuracy 65flow rate effect 232number of proving passes 247, 248

operating frequencies 219, 234plugging 221pressure effect

density measurement 229–231mass flow accuracy 212volume measurement 243

proving passes 102recommendations 133, 142, 159sensor orientation impact 233vibration isolation 235

NNIST

density proving 151, 152pipe prover 84pipe prover uncertainty 86proving versus calibration 9small volume prover 92small volume prover uncertainty 95, 96volumetric tank proving uncertainty 80

OOperating conditions xxii, 30

Coriolis master meterprocess fluid conditions 117proving devices 111

Coriolis master meter uncertainty 114custody transfer 10gravimetric tank proving 76pipe prover 84process conditions 12proving 9repeatability 77volumetric master meters 104, 106–108volumetric tank proving 83

Output 45–57analog 45, 46, 48

Bell 202 48density measurement devices 65density proving 144interfacing with 49output trim 145

Bell 202 47density proving 144mass flow accuracy 212

density xxii, 143density measurement 26, 28digital 46frequency 51, 89

accumulating pulses 110, 117accuracy 89, 98K-factor 129prover prerun 99pulse scaling factor determination 52repeatability

gravimetric tank proving 77pipe prover 90small volume prover 103volumetric tank proving 83

response time 54frequency/pulse 45, 49

low-flow cutoff 56recommendations 46troubleshooting 53

HART 230, 231meter 35, 218pulse 30, 113

inventory calculations 129measuring in mass units 29meter factor calculation

Coriolis master meter 113pipe proving 85small volume prover 94, 95volumetric master meters and

transfer standards 107volumetric tank proving 79

minimum mass proving 23minimum volume proving 20proving systems 45

pulse measuring in mass units 29repeatable 110, 117RS-485 47, 143transmitter 134

PPickoff

detectors xxi, 53Coriolis meters 3density measurement 225, 227low-flow cutoff 56mass flow measurement 207, 208prover plenum pressure 99response time 53zero offset influences 216

sensors xxii, 208

calibration constant 210external influences 42flow calibration 129mass flow accuracy 211response time 53

signals xxiicalibration constant 210flow calibration factor 45

Index1


mass flow measurement 208, 209meter zero influences 214zeroing 197

Pressurecoefficient 210, 230compensation

custody transfer 35density accuracy 229–231density measurement 142density measurement device 65mass flow accuracy 212–214mass flow measurement 210meter recommendations 133recommendations 159volumetric flow rate accuracy 243

effectdensity 18, 229

mass flow 212, 212

prover volume 23sensor 229volume 242, 243

tube stiffness 211Process conditions xxii, 3

accuracy 210analog output 48, 144calibration 9, 160Coriolis meter proving 110, 112density 142density measurement

hydrometer 146pipe prover 85small volume prover 94volumetric tank proving 79

density measurement device 64density proving installations 148laboratory analysis 147long run times 110, 117mass measurement 22mass meter factor 122master meter proving 106meter proving 12proving calculations 29repeatability 90, 103reproducibility 126, 136rezeroing 200, 217stability 124temperature 151transfer standard proving 31troubleshooting 160uncertainty 108volume measurement 18volume meter factor 121zero offset 199zero stability 214

ProLink software program. See also HART Communicatorcalibration 158communication configuration 46–48, 52, 143connecting to transmitter 145

density measurementdensity device 65digital output 46, 143

density proving 151meter information 47, 57meter zeroing 197troubleshooting with 135using for simulation 53volume measurement 30

Protocol. See HART protocol; Modbus protocolProver

detectorsdensity averaging device 65density measurement 28mass measurement 23, 26optical 94, 95pulse interpolation 93volume measurement

minimum volume proving 19prerun xxii, 89

accumulating pulses 89damping 55, 91prover size recommendations 100small volume prover 98, 99transfer standard proving 30troubleshooting 135

stationaryconventional pipe prover 85minimum mass proving 23minimum volume proving 19, 20proving computer 61

volumebase xxiii

meter factor calculation 80, 86, 94volume meter factor 121

Coriolis meters 5correction factors

conventional pipe prover 88Coriolis master meter 116meter factor uncertainty 126small volume prover 97volumetric tank proving 82volumetric transfer standard 109

damping 55density measurement 141detector switch 89, 98K-factor 45mass measurement 22mass meter factor 122minimum mass proving 23minimum volume proving 19pipe prover 85pressure measurement device 63process conditions 124size 90, 100small volume prover 91, 92, 93transfer standard proving 30volume measurement 18volumetric tank proving 79

Index


Provingdensity 149, 150, 155

calculations 155density measurement 146, 147density proving installations 149procedure 154recommendations 159

pass xxii, 94conventional prover 25, 26predicting 247–250small volume prover 25, 26, 94

accumulating pulses 99Coriolis meter passes 102number of passes/runs 101pulse output for volume 95

reportform 157sample 157

run xxii. See also Proving, passaccumulating pulses 110, 117average meter factors 102

damping factor 111, 118density averaging device 65density factor calculation 156density meter at the prover 26determining process fluid density 64equipment 62flow rate 56introduction 4inventory calculations 128mass meter factor 123proving calculations 22, 29, 94, 124proving computers 61proving procedure

density measurement 28mass measurement 24transfer standard proving 31volume measurement 20

pulse output 45pipe prover 89small volume prover 95, 98

recommendations 134, 160repeatability 125, 249repeatable output 117temperature 90, 124transfer standard proving 30uncertainty 115volume meter factor 121volumetric master meters and transfer

standards 106Proving device

custody transfer 4density 61, 65flow rate 71in-line 71meter factor uncertainty 125proving connections 42volume meter factor 121

volumetric xxii, 17mass meter factor 122meter factor calculation 85, 94proving recommendations 134volume meter factor 121

Proving method 71, 104mass meter measurement 115meter factor uncertainty 126number of proving runs 123tank 17

conventional pipe prover 84Coriolis master meter 113damping factor recommendation 90volumetric master meters 106

traceability 71transfer standard 30uncertainty 127volume meter measurement 117

Proving processlaboratory analysis 147proving 9proving computer 61volume measurement 18, 29, 30

Proving technique 35Coriolis master meter 113reproducibility 128volumetric master meter 106

Pycnometer xxiii, 148, 152, 153calibration 161density factor 156, 158, 160density measurement 64density proving

density measurement 154density proving calculations 155density proving device 65density proving installations 148, 150density sampling loop 151repeatability 160

RRepeatability 123–125

Coriolis master meter 118cross-talk 219custody transfer 5damping factor 91, 136density averaging device 65density measurement 142flow rate 247

gravimetric tank proving 77leakage 98mass measurement

Coriolis density 29density meter at the prover 26proving calculations 24volume units 30

meter factor 102, 102

number of proving passes 247, 248, 249number of proving runs 90

Index1


poor with leakage 89pressure devices 152prover size 90, 101proving 248proving computer 61proving recommendations 134proving runs 156pulse accumulation 98–99small volume prover 103trend charts 12troubleshooting 135, 160vibration 218volume measurement 20, 22, 32volumetric master meters 111volumetric tank proving 83

Reproducibility 126, 127density factors 158meter factors 136

Response timeanalog density 145Coriolis master meter 111, 136, 160damping factor

prerun duration 56, 89, 99reproducibility 136tank proving 90

digital density 144flow measurement 53pressure measurement 213, 231proving accuracy 55transfer standard proving 30troubleshooting 135

Rezeroing 56analog output 48error 199–201frequency 197installation recommendations 40mass flow accuracy 220reproducibility 136sensor installation 133trend charts 12zero offset 215–217

RFT9712 transmitter 35density measurement 142inventory calculations 129k-factor 52low flow cut-off 56number of proving passes 102pressure 212volume measurement 18

RFT9739 transmitteraccess to meter information 57block diagram

density 227

mass flow 209

Coriolis flowmeter 3custody transfer 35, 46damping 54density 151density measurement 65

fluid flow rate 136, 232, 243frequency schematic

decreased/limited voltage 50

open collector 50

standard 50

inventory calculations 128K-factor 52local access terminals 57

low-flow cutoff 56meter measurement 129pressure compensation 212, 213, 214

pressure effectdensity factor offset 161density measurement 229, 231troubleshooting 136

recommendationsdensity measurement 142–146meter 133summary 159

viewing zero reading 198volume measurement 18zeroing 197

RTD xxiconventional pipe prover 85density measurement 227, 228flow rate accuracy 241meter mass flow accuracy 208, 210, 211small volume prover 94temperature measurement device 63volumetric tank proving 79

SSampling systems 4, 27, 142Sensor. See Coriolis sensor; ELITE sensor; Model D sensor; Pickoff sensors

TTemperature

accuracy 241coefficient 210correction coefficient 226effect

density 18, 228

mass flow 211prover volume 19volume 242

zero offset 216Transfer standard proving 30–32, 104–111

Coriolis master meter 111equipment configuration 31

volumetric master meter 105

number of passes per run 248techniques 104uncertainty 108volumetric master meters 105, 106

transfer standard proving 30

Index


Trend chart 12, 126, 128

flow calibrations factors 130meter factor 127, 127

meter performance 134, 160reproducibility 158rezeroing 133sample proving 13

Troubleshooting 131–137, 159–161analog output 146frequency/pulse output 53

VVolume

meter factor 121, 128, 159Volumetric flow rate 242

accuracy 243analog output 48custody transfer 4digital information 46frequency output 49measurement 241output signals 45turbine meters 105volume measurement 17, 18

Volumetric meter 105mass measurement 4

proving methods 17pulse output 114volume measurement 18

ZZero

offset xxii, 200, 216

determination 200error 199guidelines 202mass flow accuracy 215, 216

density influence 220temperature effect 217

proving 201proving guidelines 11trend charts 12viewing 198volumetric flow rate accuracy 243

stability xxii, 35, 215guidelines 202meter mass flow accuracy 214, 217uncertainty 115

uncertainty xxii, 202, 217

zeroing xxiiZero uncertainty 214Zeroing. See Meter zeroing; Meter factor; Zero

recycled paper

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MIcromotion Proving Coriolis

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