1、Manual of PetroleumMeasurement StandardsChapter 10.9Standard Test Method for Water in Crude Oils by Coulometric Karl Fischer TitrationTHIRD EDITION, MAY 2013Special NotesAPI publications necessarily address problems of a general nature. With respect to particular circumstances, local,state, and fede
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14、ainst liability for infringement of letters patent.Shall: As used in a standard, “shall” denotes a minimum requirement in order to conform to the specification.Should: As used in a standard, “should” denotes a recommendation or that which is advised but not required in orderto conform to the specifi
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16、ng the procedures under whichthis publication was developed should be directed in writing to the Director of Standards, American PetroleumInstitute, 1220 L Street, NW, Washington, DC 20005. Requests for permission to reproduce or translate all or any partof the material published herein should also
17、be addressed to the director.Generally, API standards are reviewed and revised, reaffirmed, or withdrawn at least every five years. A one-timeextension of up to two years may be added to this review cycle. Status of the publication can be ascertained from theAPI Standards Department, telephone (202)
18、 682-8000. A catalog of API publications and materials is publishedannually by API, 1220 L Street, NW, Washington, DC 20005.Suggested revisions are invited and should be submitted to the Standards Department, API, 1220 L Street, NW,Washington, DC 20005, standardsapi.org.iiiContentsPage1 Scope . . .
19、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Referenced Documents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
20、. . . . . . . . 13 Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Summary of Test Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
21、 . . . . . . . . . . . . . . . . . . . . . 15 Significance and Use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 Interferences . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
22、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 Apparatus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 Reagents and Materials . . . . . . . . . . . . . . .
23、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 Sampling and Test Specimens. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 310 Preparation of Apparatus . . . . . .
24、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 411 Verification of Equipment Calibration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 412 Procedure. . . . . . .
25、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 413 Calculation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
26、. . . . . . . . 414 Report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 515 Troubleshooting and Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
27、 . . . . . . . . . . . . . . . . . . . . . 516 Precision and Bias . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 517 Keywords . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
28、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6Summary of Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6Tables1 Approximate Test Specimen Size Based on Expect
29、ed Water Content . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 Precision Intervals. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5vDesignation: D4928 12Manual of Petroleum Measurement Stan
30、dards (MPMS), Chapter 10.9Standard Test Method forWater in Crude Oils by Coulometric Karl Fischer Titration1This standard is issued under the fixed designation D4928; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last
31、 revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1. Scope*1.1 This test method covers the determinatio
32、n of water inthe range from 0.02 to 5.00 mass or volume % in crude oils.Mercaptan (RSH) and sulfide (Sor H2S) as sulfur are knownto interfere with this test method, but at levels of less than500 g/g ppm(m), the interference from these compounds isinsignificant (see Section 6).1.2 This test method ca
33、n be used to determine water in the0.005 to 0.02 mass % range, but the effects of the mercaptanand sulfide interference at these levels has not been deter-mined. For the range 0.005 to 0.02 mass %, there is noprecision or bias statement.1.3 This test method is intended for use with standardcommercia
34、lly available coulometric Karl Fischer reagent.1.4 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.5 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility
35、 of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. For specificwarning statements, see Section 8.2. Referenced Documents2.1 ASTM Standards:2D1193 Specification for Reagent WaterD4057 Practice fo
36、r Manual Sampling of Petroleum andPetroleum Products (API MPMS Chapter 8.1)D4177 Practice for Automatic Sampling of Petroleum andPetroleum Products (API MPMS Chapter 8.2)D5854 Practice for Mixing and Handling of Liquid Samplesof Petroleum and Petroleum Products (API MPMS Chap-ter 8.3)E203 Test Metho
37、d for Water Using Volumetric Karl FischerTitration2.2 API Standards:3MPMS Chapter 8.1 Practice for Manual Sampling of Petro-leum and Petroleum Products (ASTM Practice D4057)MPMS Chapter 8.2 Practice for Automatic Sampling ofPetroleum and Petroleum Products (ASTM PracticeD4177)MPMS Chapter 8.3 Practi
38、ce for Mixing and Handling ofLiquid Samples of Petroleum and Petroleum Products(ASTM Practice D5854)3. Terminology3.1 The following terms are used with respect to sampling(see Section 9).3.2 Definitions of Terms Specific to This Standard:3.2.1 aliquot, na small portion of a larger sample which isana
39、lyzed and assumed to represent the whole sample.3.2.2 sample, nportion extracted from the contents of anypipe, tank, or other system, and intended to be representative ofthat system, placed in a primary sample container for analysis.3.2.3 test specimen, nthe representative sample takenfrom the prima
40、ry or intermediate sample (aliquot) container foranalysis. The entire test specimen is used in the analysis.4. Summary of Test Method4.1 After homogenizing the crude oil sample, a test speci-men of that sample is injected into the titration cell of a KarlFischer apparatus in which iodine for the Kar
41、l Fischer reactionis generated coulometrically at the anode. When all the waterhas been titrated, excess iodine is detected by an electrometric1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products and Lubricants and the API Committee on Petroleum Measure-ment and is
42、the direct responsibility of Subcommittee D02.02 /COMQ on Hydro-carbon Measurement for Custody Transfer (Joint ASTM-API).Current edition approved Dec. 1, 2012. Published April 2013. Originallyapproved in 1989. Last previous edition approved in 2011 as D492811. DOI:10.1520/D4928-12.2For referenced AS
43、TM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Published as Manual of Petroleum Standards. Available from AmericanPetroleum I
44、nstitute (API), 1220 L. St., NW, Washington, DC 20005-4070, http:/www.api.org.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1endpoint detector and the titration is term
45、inated. Based on thestoichiometry of the reaction, one mole of iodine reacts withone mole of water thus the quantity of water can be deter-mined.4.2 The precision of this test method is critically dependenton the effectiveness of the homogenization step. The accept-ability of the mixing used to achi
46、eve a homogeneous sample isdetermined by the procedure given in Practice D5854 (APIMPMS Chapter 8.3). In addition, if the test method is per-formed on a volume basis, the precision of the test method iscritically dependent on the accuracy and repeatability of thevolume injected.4.3 Two procedures ar
47、e provided for the determination ofwater in crude oils. In one procedure, a weighed test specimenis injected into the titration cell and the mass % of water isdetermined. The other procedure provides for the direct deter-mination of the volume % of water in the crude oil bymeasuring the volume of cr
48、ude oil injected into the titrationcell.5. Significance and Use5.1 The accurate analysis of a crude oil sample to determinethe water content is important in the refining, purchase, sale, ortransfer of crude oils.6. Interferences6.1 A number of substances and classes of compoundsassociated with conde
49、nsation or oxidation-reduction reactionsinterfere in the determination of water by Karl Fischer. In crudeoils, the most common interferences are mercaptans andsulfides (not total sulfur). At levels of less than 500 g/gppm(m) (as sulfur), the interference from these compounds isinsignificant. Most crude oils, including crude oils classified as“sour crude,” have mercaptan and sulfide levels of less than500 g/g ppm(m) as sulfur. For more information on sub-stances that interfere in the determination of water by KarlFischer titration method, see Test Method E203.6.2 The
