Manual of Petroleum Measurement Standards Chapter 22—Testing Protocol

Section 2—Differential Pressure Flow

Measurement Devices

SECOND EDITION, APRIL 2017

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Contents

Page

1. Scope 1

   1. General 1

   2. Differential Pressure or Head-type Flow Meters 1

2. Normative References 5

3. Terms and Definitions 5

4. Field of Application 9

5. Parameter Variations Affecting Device Performance 9

   1. Flowing Conditions 9

   2. Meter Pipe Conditions 10

   3. Meter Conditions 10

6. Mandatory Tests 11

   1. Test Conditions 11

   2. Required Piping Conditions Upstream and Downstream of the Meter 13

   3. Test Results 13

   4. Baseline Testing 13

   5. Non-ideal Condition Testing (Installation Effects Testing) 14

   6. Testing the Gas Expansion Factor for Compressible Fluids 16

   7. Special Installation Tests 16

   8. Testing Procedure 17

7. Test and Calibration Facility Requirements 19

   1. Test Facility Audit Process 19

   2. In-house Calibration Facility Verification Process 19

   3. Test Facility Qualification 20

   4. Validity/Precision of Test Facility Results 20

   5. Test and Calibration Facility Uncertainty 21

8. Uncertainty and Statistical Significance Analysis and Calculation 21

   1. Test Facility and Calibration Facility Uncertainty 21

   2. Meter Uncertainty 21

   3. Determination of Statistical Significance 22

9. Test Report 23

   1. General 23

   2. Test Facility Information 23

   3. Calibration Facility Information 23

   4. Meter Information 24

   5. Description of the Full Test Matrix and Results 24

   6. Sample Meter Test Reporting Form 25

Annex A (normative) Test Matrices for Section 6 27

Annex B (normative) Uncertainty Estimate 33

Annex C (informative) Dimensional Parameters for Prototype Testing 38

Annex D (informative) Interpolation of Uncertainty for Intermediate Area Ratios and Line Diameters 39

Bibliography 42

Figures

1. Concentric Orifice Flow Meter 1

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   Contents

   Page

2. Eccentric and Segmental Orifice Flow Meters 2

3. Quadrant-edge and Conical Orifice Plates 2

4. Venturi Flow Meter 2

5. Flow Nozzle 3

6. Cone Meter 3

7. Dall Tube Low-loss Meter 3

8. Wedge Meter 4

9. Pitot-static Tube Meter 4

10. Multi-port Averaging Pitot 4

Introduction

This document defines a testing and reporting protocol for flow measurement devices based on the detection of a pressure differential that is created by the device in a flowing stream. The overall objectives of this testing protocol are to facilitate the introduction of new technologies, provide a standard method for validating manufacturer's performance specifications, and define the minimum requirements needed to determine relative performance characteristics of differential pressure metering devices under a standardized testing protocol. This protocol applies to both liquids and gases.

This protocol achieves these objectives by testing representative meters provided by the manufacturer in order to:

• Quantify the discharge coefficient uncertainty and the meter's sensitivity to flow profile over a range of Reynolds numbers, sizes, area ratios, upstream and downstream piping installations, and differential pressure to static pressure ratios;

  
  

• Test the gas expansion factor equation provided by the manufacturer and the manufacturer's method of determining the individual discharge coefficient for each meter to determine if they are statistically similar;

  
  

• Report the results of the testing and disclose any results that are not statistically similar as discovered during the testing process.

Performance characteristics such as discharge coefficient uncertainty, installation effects, the gas expansion factor equation, and the method of determining the discharge coefficient, can be performed as a type test under this protocol. For these characteristics, the results obtained from the tests described in this protocol can be applied to all meters of the same design that are used within the limits of the parameters tested under this protocol (e.g. size, area ratio, Reynolds number, differential pressure to static pressure ratio).

This is not a type-testing protocol for those meters that use a standard discharge coefficient equation for all meters of the same model, size, and area ratio. This standard requires the discharge coefficient or discharge coefficient equation to be determined for each individual meter. Quantifying the uncertainty of a standard discharge coefficient equation based on the statistical variation of dimensions in the manufacturing process is beyond the scope of this protocol. This protocol assumes that the influence of dimensional variation is quantified by individually testing each meter to determine its discharge coefficient under baseline conditions.

Examples of flow meters covered in this standard include, but are not limited to, orifice plates, Venturis, nozzles, cone-type meters, wedge meters, and multiport averaging Pitot tubes. However, this protocol does not cover differential devices for which an API standard has been published (the flange-tapped orifice plate per API MPMS Ch. 14.3, for example).

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Chapter 22—Testing Protocol

Section 2—Differential Pressure Flow Measurement Devices

1. Scope

   1. General

      The testing protocol is limited to single-phase Newtonian fluid flow, and no consideration is given to pulsation effects. Further revisions of this document may include the testing of such meters in wet gas or multi-phase service and the effects of pulsation. This standard does not address testing protocols of those devices that operate on the principle of critical or choked flow condition of fluids.

      
      

      The testing protocol covers any flow meter operating on the principle of a local change in flow velocity caused by the meter geometry, giving a corresponding change of pressure between two reference locations. There are several types of differential pressure meters available to industry. It is the purpose of this standard to illustrate the range of applications of each meter design and not to endorse any specific meter. The basic principle of operation of the flow measuring devices follows the physical laws relating to the conservation of energy and mass for the fluid flows through the device.

      
      

      Any API MPMS document addressing a specific type or design of differential pressure flow measuring device will supersede the requirements of this document for that type or design. An example of such standards are all parts of API MPMS, Chapter 14.3, Concentric, Square-Edged Orifice Meters.

      
      

   2. Differential Pressure or Head-type Flow Meters

The operating principle of a differential pressure flow meter is based on two physical laws - the conservation of energy and conservation of mass, where changes in flow cross-sectional area and/or flow path produce a differential pressure, which is a function of the flow velocity, fluid path, and fluid properties.

This testing protocol applies to all types of differential-pressure meters. The examples presented below illustrate some of the applicable meter designs; however, this protocol is not limited to these meter types.

Figure 1—Concentric Orifice Flow Meter

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2 API MPMS CHAPTER 22.2—TESTING PROTOCOL

Figure 2—Eccentric and Segmental Orifice Flow Meters

Figure 3—Quadrant-edge and Conical Orifice Plates

Figure 4—Venturi Flow Meter