Manual of Petroleum Measurement Standards Chapter 4—Proving Systems

Section 1—Introduction

THIRD EDITION, FEBRUARY 2005 REAFFIRMED, JUNE 2014

Manual of Petroleum Measurement Standards Chapter 4—Proving Systems

Section 1—Introduction

Measurement Coordination

THIRD EDITION, FEBRUARY 2005 REAFFIRMED, JUNE 2014

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Copyright ©2005 American Petroleum Institute

FOREWORD

Chapter 4 of the Manual of Petroleum Measurement Standards was prepared as a guide for the design, installation, calibration, and operation of meter-proving systems commonly used by the majority of petroleum operators. The devices and practices covered in this chap- ter may not be applicable to all liquid hydrocarbons under all operating conditions. Other types of proving devices that are not covered in this chapter may be appropriate for use if agreed on by the parties involved.

The information contained in this edition of Chapter 4 supersedes the information contained in the previous edition (First Edition, May 1978), which is no longer in print. It also supersedes the information on proving systems contained in API Std 1101 Measurement of Petroleum Liq- uid Hydrocarbons by Positive Displacement Meter (First Edition, 1960); API Std 2531 Mechanical Displacement Meter Provers; API Std 2533 Metering Viscous Hydrocarbons; and API Std 2534 Measurement of Liquid Hydrocarbons by Turbine-Meter Systems, which are no longer in print.

This publication is primarily intended for use in the United States and is related to the standards, specifications, and procedures of the National Institute of Standards and Technol- ogy (NIST). When the information provided herein is used in other countries, the specifica- tions and procedures of the appropriate national standards organizations may apply. Where appropriate, other test codes and procedures for checking pressure and electrical equipment may be used.

For the purposes of business transactions, limits on error or measurement tolerance are usually set by law, regulation, or mutual agreement between contracting parties. This publi- cation is not intended to set tolerances for such purposes; it is intended only to describe methods by which acceptable approaches to any desired accuracy can be achieved.

Chapter 4 now contains the following sections: Section 1—“Introduction”

Section 2—“Displacement Provers” Section 4—“Tank Provers”

Section 5—“Master-Meter Provers” Section 6—“Pulse Interpolation”

Section 7—“Field-Standard Test Measures” Section 8—“Operation of Proving Systems” Section 9—“Calibration of Provers”

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 publication and hereby expressly disclaims any liability or responsibility for loss or damage resulting 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.

iii

1. General Considerations 3

2. Objectives 3

3. Procedures 3

4. Accuracy 3

1. TYPES OF PROVERS 3

   1. Displacement Provers 3

   2. Tank Provers 4

   3. Master Meter Provers 4

2. CALIBRATION OF PROVERS 4

Tables

1. General Liquid Metering Hierarchy Levels 2

2. Uncertainty Indices for General Liquid Metering Hierarchy 2

3. Hypothetical Uncertainty Limits in General Liquid Metering Hierarchy 2

v

Manual of Petroleum Measurement Standards Chapter 4—Proving Systems

SECTION 1—INTRODUCTION

1. Scope

   Section 1 is a general introduction to the subject of prov- ing. The requirements in Chapter 4 are based on customary practices that evolved for crude oils and products covered by API MPMS Ch. 11.1. The prover and meter uncertainties should be appropriate for the measured fluids and should be agreeable to the parties involved.

   
   

2. Referenced Publications

   Several documents served as references and as a resource of information in the revision of this standard.

   
   

   Manual of Petroleum Measurement Standards

   Chapter 1—“Vocabulary” Chapter 4—“Proving Systems” Chapter 5—“Metering”

   Chapter 7—“Temperature Determination” Chapter 11.1—“Physical Properties Data”

   Chapter 12—“Calculation of Petroleum Quantities”

   Chapter 13—“Statistical Aspects of Measuring and Sampling”

   
   

3. Definition of Terms

   Terms used in this chapter are defined in 3.1 through 3.9.

   1. calibration: The procedure used to determine the vol- ume of a prover.

   2. meter proof: The multiple passes or round trips of the displacer in a prover for purposes of determining a meter factor.

   3. meter prover: An open or closed vessel of known volume that is used as a volumetric reference standard for the calibration of meters in liquid petroleum service. Such prov- ers are designed, fabricated, and operated within the recom- mendations of Chapter 4.

   4. meter pulse: A single electrical pulse generated by flow induced effects in the meter. The flow induced effects are normally caused by movement of physical elements within the meter’s primary flow element but may be caused by other flow induced effects that are proportional to flow rate. The pulses produced by the meter shall not be multiplied to

      increase the number of pulses to conform to the requirements of Chapter 4.

   5. prover pass: One movement of the displacer between the detectors in a prover.

   6. prover round trip: The forward and reverse passes in a bi-directional prover.

   7. proving: The procedure used to determine a meter factor.

   8. standard conditions: 60°F and atmospheric pres- sure.

      
      

4. Liquid Metering Hierarchies

   1. OVERVIEW OF HIERARCHY

Liquid metering systems designed and operated in con- formance with API’s Manual of Petroleum Measurement Standards typically have one or more of the following levels of hierarchy as shown in Table 1.

Level 1.

Primary standards involve mass, volume, and/or density stan- dards developed and/or maintained by National Institute of Standards and Technology (NIST) and/or other national labo- ratories to calibrate secondary working standards.

Level 2.

Secondary working standards include mass, volume, den- sity, and/or weighing systems maintained by NIST and/or other national laboratories to calibrate field transfer standards conforming to Chapter 4.7. Secondary working standards may also be maintained by state and other certified metrology laboratories to calibrate field transfer standards.

These additional secondary working standards, however, increase uncertainty in the final custody transfer quantities.

Level 3.

Field transfer standards conforming to Chapter 4.7 are devices used to calibrate meter provers conforming to Chap- ters 4.2, 4.3, and 4.4.

Level 4.

Meter provers conforming to Chapter 4 are used to deter- mine meter factors that correct the indicated volumes of meters.

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