ASTM D4928-11

This document is not anASTM standard and is intended only to provide the user of anASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation:D4928–00 (Reapproved 2010) Designation:D4928–11
Designation: Manual of Petroleum Measurement Standards (MPMS), Chapter 10.9
Designation: 386/99
Standard Test Method for
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Water in Crude Oils by Coulometric Karl Fischer Titration
This standard is issued under the fixed designation D4928; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript 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 determination of water in the range from 0.02 to 5 mass or volume % in crude oils. Mercaptan
−
(RSH) and sulfide (S or H S) as sulfur are known to interfere with this test method, but at levels of less than 500µg/g (ppm),
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the interference from these compounds is insignificant (see Section 5).
1.2 This test method can be used to determine water in the 0.005 to 0.02 mass % range, but the effects of the mercaptan and
sulfide interference at these levels has not been determined.
1.3 This test method is intended for use with standard commercially available coulometric Karl Fischer reagent.
1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory
limitations prior to use. For specific hazard statements, see Section 7.
2. Referenced Documents
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2.1 ASTM Standards:
D1193 Specification for Reagent Water
D4057 Practice for Manual Sampling of Petroleum and Petroleum Products
D4177 Practice for Automatic Sampling of Petroleum and Petroleum Products
D5854 Practice for Mixing and Handling of Liquid Samples of Petroleum and Petroleum Products
E203 Test Method for Water Using Volumetric Karl Fischer Titration
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2.2 API Standards:
MPMS Chapter 8.1 Practice for Manual Sampling of Petroleum and Petroleum Products (ASTM Practice D4057)
MPMS Chapter 8.2 Practice for Automatic Sampling of Petroleum and Petroleum Products (ASTM Practice D4177)
MPMSChapter8.3 PracticeforMixingandHandlingofLiquidSamplesofPetroleumandPetroleumProducts(ASTMPractice
D5854)
3. Summary of Test Method
3.1 After homogenizing the crude oil with a mixer, an aliquot is injected into the titration vessel of a Karl Fischer apparatus
inwhichiodinefortheKarlFischerreactionisgeneratedcoulometricallyattheanode.Whenallthewaterhasbeentitrated,excess
iodineisdetectedbyanelectrometricend-pointdetectorandthetitrationisterminated.Basedonthestoichiometryofthereaction,
onemoleofiodinereactswithonemoleofwater,thusthequantityofwaterisproportionaltothetotalintegratedcurrentaccording
to Faraday’s Law.
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This test method is under the jurisdiction ofASTM Committee D02 on Petroleum Products and Lubricants and theAPI Committee on Petroleum Measurement, and is
the direct responsibility of Subcommittee D02.02.10 on Sediment and Water (API MPMS Chapter 10.0).
Current edition approved June 1, 2010.2011. Published July 2010.August 2011. Originally approved in 1989. Last previous edition approved in 20052010 as D4928–00
(2005).(2010). DOI: 10.1520/D4928-00R10.10.1520/D4928-11.
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ForreferencedASTMstandards,visittheASTMwebsite,www.astm.org,orcontactASTMCustomerServiceatservice@astm.org.For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
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Published as Manual of Petroleum Standards.Available fromAmerican Petroleum Institute (API), 1220 L. St., NW, Washington, DC 20005-4070, http://www.api.org.
*A Summary of Changes section appears at the end of this standard.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
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D4928–11
3.2 The precision of this test method is critically dependent on the effectiveness of the homogenization step. The efficiency of
the mixer used to achieve a homogeneous sample is determined by the procedure given in Practice D5854 (API MPMS Chapter
8.3).
3.3 Two procedures are provided for the determination of water in crude oils. In one procedure, a weighed aliquot of sample
isinjectedintothetitrationvesselandthemass%ofwa
...