ASTM_D_4928_-_12.pdf

Designation:D492812Manual of Petroleum Measurement Standards(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 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 determination 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 can 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 standardcommercially 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 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 for 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 Method 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 Practice 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 isanalyzed 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 primary 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 Karl 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,Liquid Fuels,and Lubricants and the API Committee onPetroleum Measurement and is the direct responsibility of Subcommittee D02.02/COMQ on Hydrocarbon 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 ASTM 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 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 standardCopyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 endpoint detector and the titration is terminated.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 achieve 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 depend