Manual of Petroleum Measurement Standards Chapter 6—Metering Assemblies

Section 2—Loading Rack Metering Systems

THIRD EDITION, FEBRUARY 2004 REAFFIRMED, JULY 2016

Manual of Petroleum Measurement Standards Chapter 6—Metering Assemblies

Section 2—Loading Rack Metering Systems

Measurement Coordination

THIRD EDITION, FEBRUARY 2004 REAFFIRMED, JULY 2016

SPECIAL NOTES

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Copyright ©2004 American Petroleum Institute

FOREWORD

This standard covers the selection, installation and operation of loading rack metering sys- tems. API publications may be used by anyone desiring to do so. Every effort has been made by the Institute to assure the accuracy and reliability of the data contained in them; however, the Institute makes no representation, warranty, or guarantee in connection with this publica- tion and hereby expressly disclaims any liability or responsibility for loss or damage result- ing from its use or for the violation of any federal, state, or municipal regulation with which this publication may conflict.

Suggested revisions are invited and should be submitted to the standardization manager, American Petroleum Institute, 1220 L Street, N.W., Washington, D.C. 20005.

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1. Loading Rack Metering System Installation 1

2. Top Loading 2

3. Bottom Loading 2

4. Load Rack Accessories 3

5. Valves 3

6. Loading Rack Shock 4

1. METERS 4

   1. Displacement Meters 4

   2. Turbine Meters 4

   3. Coriolis Meters 5

   4. Electrical Installation 5

   5. Flow Rates 5

   6. Pressure Drops 5

   7. Sizing of Meter 5

   8. Back Pressure Control 6

2. BLENDING 7

   1. Sequential Blending 7

   2. Ratio Blending 7

   3. Design Considerations 9

3. ADDITIVES 11

   1. Location of Injection Point 11

   2. Additive Meters 11

   3. Calibration of Additive Injection 11

   4. Multiple Additives 11

   5. Additive Accounting 12

4. METER PROVING 12

   1. Methods 12

   2. Proving Conditions 13

   3. Proving of Blending Systems 13

   4. Density of Product 14

5. ELECTRONIC PRESET 14

   1. Operations 14

   2. Fall Back Flow Rate 14

   3. Meter Factor Linearization 14

   4. Security 14

      v

      Page

6. TEMPERATURE 15

   1. Electronic Temperature Devices 15

   2. Location of Temperature Sensor 15

   3. Temperature Correction 15

   4. Calibration/Verification of Temperature Devices 16

7. PRESSURE 16

   1. Location of Pressure Measuring Device 16

   2. Calibration 16

   3. Tolerance 16

   4. Use of Calculations 16

8. GROUNDING SYSTEMS 17

9. OVERFILL PROTECTION SYSTEMS 17

10. SEALING 17

11. TERMINAL AUTOMATION SYSTEM 17

    1. Card Systems 17

    2. Calculations 17

    3. Security 17

    4. Bill of Lading Printers 17

12. LPG 18

    1. Back Pressure 18

    2. Odorization 18

Figures

1. Installation Diagram—Metered Tank Truck Loading Rack (Top Loading) 2

2. Installation Diagram—Metered Tank Truck Loading Rack (Bottom Loading) . . . 3

3. Typical Displacement Meter Loading Rack Configuration 5

4. Typical Turbine Meter Loading Rack Configuration 6

5. Typical Coriolis Meter Loading Rack Configuration 6

6. Typical Splash Sequential Blending 7

7. Typical Automated Sequential Blending 8

8. Typical Wild Stream Blender, Off Rack/On Rack 8

9. Ratio Blending—Off Rack Header Blending 9

10. Typical Automatic Multi-product On Rack Ratio Blending 10

VI

Chapter 6—Metering Assemblies Section 2—Loading Rack Metering Systems

1. Introduction

   This standard serves as a guide in the selection, installation and operation of loading rack metering systems for petroleum products, including liquefied petroleum gas. This standard does not endorse or advocate the preferential use of any spe- cific type of metering system or meter.

   In general, metering system installations must meet certain fundamental requirements, including those that ensure proper meter type, size, installation and adequate protective and read- out devices (such as presets, registers [counters], strainers, relief valves, pressure and flow control valves, and air elimi- nators, where required). Descriptions of these and other sys- tem components are covered elsewhere in this standard or other API standards. Also, to ensure compliance with state laws and regulations the latest editions of NIST Handbook 44, Handbook 12, as well as specific local weights and measures requirements, should be considered.

   
   

2. Scope of Application

   This standard offers guidance on the design, selection, and operation of loading rack metering systems and associated equipment where liquid hydrocarbons are loaded into vehicle tanks.

   
   

3. Pertinent Publications

   1. REFERENCED PUBLICATIONS

      The most recent editions of the following standards, recom- mended practices, and handbooks are cited in this standard.

      API

      Manual of Petroleum Measurement Standards (MPMS) Chapter 4.2, “Pipe Provers”

      Chapter 4.4, “Tank Provers” Chapter 4.5, “Master Meters” Chapter 4.6, “Pulse Interpolation”

      Chapter 4.7, “Field-Standard Test Measures”

      Chapter 5.1, “General Considerations for Measure- ment by Meters”

      Chapter 5.2, “Measurement of Liquid Hydrocar- bons by Displacement Meter”

      Chapter 5.3, “Measurement of Liquid Hydrocarbons by Turbine Meters”

      Chapter 5.6, “Measurement of Liquid Hydrocarbons

      
      

      Chapter 9, “Density Determination” Chapter 11.1, “Physical Properties Data”

      Chapter 11.2.1, “Compressibility Factors for Hydro- carbons: 0 – 90 API Gravity Range”

      Chapter 11.2.2, “Compressibility Factors for Hydro- carbons: 0.350 – 0.637 Relative Density”

      Chapter 12.2, “Calculation of Liquid Petroleum Quantities by Turbine or Displacement Meters

      RP 1004 Bottom Loading and Vapor Recovery for MC-306 Tank Motor Vehicles

      RP 2003 Protection Against Ignitions Arising Out of Static, Lightning, and Stray Currents

      NIST1

      Handbook 12 Examination Procedure Outlines for Weighing and Measuring Devices

      Handbook 44 Specifications, Tolerances, and Other Technical Requirements for Weighing and Measuring Devices

      
      

4. Loading Rack Metering Systems

   The loading rack metering systems described in this stan- dard are those that apply to transport-type truck facilities. The rack may be of a single-product/single-meter, single- product/multi-meter, or multi-product/multi-meter design. The design of the rack should allow one meter to be proved without interfering with the other meters involved in the loading operations.

   
   

   1. LOADING RACK METERING SYSTEM INSTALLATION

Loading rack metering systems are designed to deliver accurate quantities of products into transport trucks for the subsequent delivery to remote locations. The metering config- urations may consist of single tally meters, single product meters, blend meters and additive meters. Since rack delivery meter volumes are considered in the terminal loss/gain deter- mination, the design, installation and operation of the meters is extremely important. It must be noted that the loading rack is usually the final opportunity to measure accurately, i.e., after the product leaves the loading rack, measurement errors are difficult to correct.

Each meter must be proved under conditions as close to normal as possible. This would encompass the usual delivery

by Coriolis Force-Flow Meters”

Chapter 6.6, “Pipeline Metering Systems” Chapter 7, “Temperature Determination”

1National Institute of Standards and Technology, U.S. Department of Commerce, Gaithersburg, Maryland 20899.

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