Manual of Petroleum Measurement Standards

Chapter 10—Sediment and Water

Section 4—Determination of Water and/or Sediment in Crude Oil by the Centrifuge Method (Field Procedure)

THIRD EDITION, DECEMBER 1999 REAFFIRMED, SEPTEMBER 2010

Manual of Petroleum Measurement Standards

Chapter 10—Sediment and Water

Section 4—Determination of Water and/or Sediment in Crude Oil by the Centrifuge Method (Field Procedure)

Measurement Coordination

THIRD EDITION, DECEMBER 1999 REAFFIRMED, SEPTEMBER 2010

SPECIAL NOTES

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Copyright © 1999 American Petroleum Institute

FOREWORD

The American Petroleum Institute, the (British) Institute of Petroleum (IP), and corre- sponding bodies of other nations have worked through Technical Committee 28 of the Inter- national Organization for Standardization (ISO) to produce several international standards that relate directly to the API Manual of Petroleum Measurement Standards.

Section 4 of Chapter 10 discusses the field centrifuge test method for determining water and/or sediment in crude oil. Section 4 is primarily intended for use within the United States and has not been approved by IP or ISO. This edition of Section 4 of Chapter 10 supersedes all previous editions of this standard.

Section 1 of Chapter 10 describes the determination of sediment in crude oils and fuel oils by the extraction method. Section 2 discusses the determination of water in crude oil by the distillation method. Section 3 describes the determination of sediment and water by a labora- tory centrifuge procedure.

This standard may involve hazardous materials, operations, and equipment. This standard does not purport to address all of the safety problems associated with its use. It is the respon- sibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

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 Measurement Coordination, American Petroleum Institute, 1220 L Street, N.W., Washington, D.C. 20005.

iii

1. SCOPE AND FIELD OF APPLICATION 1

2. REFERENCES 1

3. DEFINITIONS 1

4. SIGNIFICANCE AND USE 1

5. TEST SOLVENTS 2

   1. Use of Solvents 2

6. DEMULSIFIER 2

7. APPARATUS 2

   1. Centrifuge 2

   2. Centrifuge Tubes 3

   3. Preheater 3

   4. Sample Thermometer 3

8. SAMPLING 3

9. PROCEDURE—WATER AND SEDIMENT DETERMINATION 3

10. CALCULATION AND REPORTING 6

11. DETERMINATION OF SEDIMENT ONLY 6

    1. Procedure 6

12. CALCULATION AND REPORTING—SEDIMENT ONLY 7

13. PRECISION 8

14. BIAS 8

APPENDIX A—PRECAUTIONARY INFORMATION 9

APPENDIX B—DEMULSIFIERS AND WATER SATURATION OF SOLVENTS . . . 11 APPENDIX C—SPECIFICATIONS FOR CENTRIFUGE TUBES 13

APPENDIX D—PROCEDURE OUTLINE—WATER AND SEDIMENT DETERMINATION 17

APPENDIX E—PROCEDURE OUTLINE—SEDIMENT (ONLY)

DETERMINATION 19

Figures

1—Reading a 100-milliliter Centrifuge Tube 4

2—Reading a 200-Part Centrifuge Tube 5

C-1—8-inch (203-millimeter) Cone-Shaped Centrifuge Tube 13

C-2—6-inch (167-millimeter) Cone-Shaped Centrifuge Tube 14

Tables

1—Rotation Speeds Necessary to Produce a Relative Centrifugal Force

of 500 for Centrifuges of Various Diameters of Swing 3

2—Procedure for Reading a 100-milliliter Cone-Shaped Tube 4

3—Procedure for Reading a 200-Part Cone-Shaped Tube 5

4—Expression of Results 6

C-1—Minimum Graduation Requirements and Maximum Calibration Tolerances

for 8-inch (203-millimeter) Cone-Shaped Tubes 14

C-2—Minimum Graduation Requirements and Maximum Calibration Tolerances

for 6-inch (167-millimeter) Cone-Shaped Tubes 15

Chapter 10—Sediment and Water

SECTION 4—DETERMINATION OF WATER AND/OR SEDIMENT IN CRUDE OIL BY THE CENTRIFUGE METHOD (FIELD PROCEDURE)

1. Scope and Field of Application

   1. This section describes the field centrifuge method for determining both water and sediment or sediment only in crude oil. This method may not always produce the most accurate results, but it is considered the most practical method for field determination of water and/or sediment. When a higher degree of accuracy is required, the laboratory procedure described in Chapter 10.2, “Determination of Water in Crude Oil by Distillation” (ASTM D 4006), or Chapter 10.9, “Standard Test Method for Water in Crude Oils by Coulometric Karl Fischer” (ASTM D 4928), and the pro- cedure described in Chapter 10.1, “Determination of Sedi- ment in Crude Oils and Fuel Oils by the Extraction Method” (ASTM D 473) or Chapter 10.8, “Standard Test Method for Sediment in Crude Oil by Membrane Filtration” (ASTM D 4807) should be used.

      Note: Water by Distillation, and Sediment by Extraction, are consid- ered the referee methods for determining water and sediment in crude oils.

   2. The requirements of this standard may involve hazardous materials, operations, and equipment. This stan- dard does not purport to address all of the safety problems associated with its use. The user of this standard has the responsibility for establishing appropriate safety and health practices and determining the applicability of regulatory limi- tations prior to use.

      
      

2. References

   API

   Manual of Petroleum Measurement Standards

   Chapter 8, “Sampling Petroleum and Petroleum Products”

   Chapter 10, “Sediment and Water”

   ACGIH1

   Threshold Limit Values and Biological Exposure Indices for 1987 – 1988

   ASTM2

   D 473 Test Method for Sediment in Crude Oils and Fuel Oils by the Extraction Method

   D 3699 Specification for Kerosine

   
   

   1American Conference of Governmental Industrial Hygienists, 1330 Kemper Meadow Drive, Cincinnati, Ohio 45240.

   2American Society for Testing and Materials, 100 Barr Harbor Drive, West Conshohocken, Pennsylvania 19428-2959.

   1

   D 4006 Test Method for Water in Crude Oil by Distillation

   D 4057 Practice for Manual Sampling of Petro- leum and Petroleum Products

   D 4177 Method for Automatic Sampling of Petro- leum and Petroleum Products

   D 4928 Standard Test Method for Water in Crude Oils By Coulometric Karl Fischer Titration (Karl Fischer) Titration

   E 542 Practice for Calibration of Volumetric Ware

   OSHA3

   29 CFR Subpart Z, “Toxic and Hazardous Substances,” Section 1910.1000

   
   

3. Definitions

   1. sediment: A material that normally exists in crude oils as extremely fine, well dispersed solids that origi- nate in the reservoir from which the crude came, or in drilling fluids used to drill the wells, which may take the form of sand, clay, shale, or rock particles. Other sediments such as scale can be picked up from tubing, pipe, tanks, and other production and transportation equipment. Sediment, as defined in this standard, must have a density greater than water and will not float at test conditions.

   2. demulsifier-stock solution: A mixture of demulsifier and solvent in a fixed ratio (e.g. 25% – 75%) which is added to the test solvent to form a solution to cause a clear and distinct separation between the oil and water inter- face.

   3. solvent-solution: A mixture of any one of the approved solvents and a demulsifier, or a demulsifier-stock solution which is used as a diluent to help the separation of water and sediment from the sample being tested.

   4. solvent: Any one of the approved liquids capa- ble of dissolving or dispersing the water and sediment in the sample being tested.

      
      

4. Significance and Use

A determination of water and/or sediment content is required to accurately determine the net volumes of crude oil

3Occupational Safety and Health Administration, U.S. Department of Labor. The Code of Federal Regulations is available from the Government Printing Office, Washington, D.C. 20402.