Measurement of Liquid Hydrocarbons by Ultrasonic Flow Meters

SECOND EDITION, NOVEMBER 2011 ERRATA, FEBRUARY 2014

REAFFIRMED, MAY 2017

Measurement of Liquid Hydrocarbons by Ultrasonic Flow Meters

Measurement Coordination Department

SECOND EDITION, NOVEMBER 2011 ERRATA, FEBRUARY 2014

REAFFIRMED, MAY 2017

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Copyright © 2011 American Petroleum Institute

Foreword

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iii

1. Scope 1

   1. General 1

   2. Field of Application 1

2. Normative References 1

3. Terms and Definitions 1

4. Design Considerations 2

5. Bi-directional Flow 4

6. Selecting a Meter and Accessory Equipment 4

7. Installation 5

   1. General 5

   2. Flow Conditioning 5

   3. Valves 5

   4. Electronics 6

   5. Electrical 6

8. Meter Performance 6

9. Proving Accuracy and Repeatability 7

10. Operation and Maintenance 7

    1. System Setup 7

    2. Hardware 7

    3. Operation of Metering Systems 7

    4. Setting the UFM Response Time 7

    5. Pulse Scaling 8

    6. Methods of Controlling Correction Factor 8

    7. Zeroing the Meter 9

11. Auditing and Reporting Requirements 9

    1. General 9

    2. UFM Configuration Parameters and Settings 9

    3. Alarm, Event Logs 9

12. Diagnostics 9

13. UFM Security and Access 11

Annex A (informative) UFM Measurement Principle 12

Annex B (informative) Verification and Validation of Meter Performance 14

Annex C (informative) Manufactured Flow Pulses and Their Impact on the Proving Process 17

Annex D (informative) Reynolds Number Performance Curve 18

Bibliography 23

Figures

1. Typical Elements of a Single UFM Installation 3

2. UFM Main Components. 8

A.1 UFM Transit Time Method 13

v

1. Flow Profile and Boundary Layer 19

2. Increasing Boundary Layer Thickness with Decreasing Reynolds Number 19

3. Constant Boundary Layer Thickness with Constant Reynolds Numbers 20

4. Meter Factor vs Flowrate – 3 Oils 21

5. Meter Factor vs Reynolds Number 21

6. Meter Factor vs Reynolds Number – Characterized 22

Tables

B.1 Proving an Ultrasonic Flow Meter 15

vi

This document describes methods for the installation and operation of Ultrasonic Flow Meters (UFMs) when they are used to measure liquid hydrocarbons.

Ultrasonic meters are inferential meters that derive the liquid flow rate by measuring the transit times of high- frequency sound pulses. Transit times are measured from sound pulses traveling diagonally across the pipe, downstream with the flow and upstream against the liquid flow. The difference in these transit times is related to the average liquid flow velocity along multiple acoustic paths. Numerical calculation techniques are then used to compute the average axial liquid flow velocity and the liquid volume flow rate at line conditions through the meter. See Annex A for additional details.

vii

Measurement of Liquid Hydrocarbons by Ultrasonic Flow Meters

1. Scope

   
   

   1. General

      
      

      This document defines the application criteria for UFMs and addresses the appropriate considerations regarding the liquids to be measured. This document addresses the installation, operation, and maintenance of UFMs in liquid hydrocarbon service.

      
      

   2. Field of Application

      
      

      The field of application of this standard is the dynamic measurement of liquid hydrocarbons. While this document is specifically written for custody transfer measurement, other acceptable applications may include allocation measurement, check meter measurement, and leak detection measurement. This document only pertains to spool type, multi-path ultrasonic flow meters with permanently affixed acoustic transducer assemblies.

      
      

2. Normative References

   
   

   The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.

   
   

   API MPMS Chapter 4.5, Master-Meter Provers

   
   

   API MPMS Chapter 4.8, Operation of Proving Systems

   
   

   API MPMS Chapter 6.1, Lease Automatic Custody Transfer (LACT) Systems

   
   

   API MPMS Chapter 6.2, Loading Rack Metering Systems

   
   

   API MPMS Chapter 6.4, Metering Systems for Aviation Fueling Facilities

   
   

   API MPMS Chapter 6.5, Metering Systems for Loading and Unloading Marine Bulk Carriers

   
   

   API MPMS Chapter 6.6, Pipeline Metering Systems

   
   

   API MPMS Chapter 6.7, Metering Viscous Hydrocarbons

   
   

   API MPMS Chapter 13.1-1985, Statistical Concepts and Procedures in Measurement

   
   

   API MPMS Chapter 21.2, Electronic Liquid Volume Measurement Using Positive Displacement and Turbine Meters

   
   

3. Terms and Definitions

For the purposes of this document, the following definitions apply.

3.1

acoustic path

The path that the acoustic signals follow as they propagate through the measurement section between the acoustic transducer elements.

1