1、Designation:D437700(Reapproved 2011)Manual of Petroleum Measurement Standards(MPMS),Chapter 10.7Designation:356/99Standard Test Method forWater in Crude Oils by Potentiometric Karl Fischer Titration1This standard is issued under the fixed designation D4377;the number immediately following the design
2、ation 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 agencie
3、s of the U.S.Department of Defense.1.Scope1.1 This test method covers the determination of water inthe range from 0.02 to 2%in crude oils.Mercaptan and sulfide(Sor H2S)sulfur are known to interfere with this test method(see Section 5).1.2 This test method is intended for use with standard KarlFische
4、r reagent or pyridine-free Karl Fischer reagents.1.3 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.4 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility o
5、f the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.Specific precau-tionary statements are given in Section 7.2.Referenced Documents2.1 ASTM Standards:2D1193 Specification for Reagent WaterD4006 Tes
6、t Method for Water in Crude Oil by DistillationD4057 Practice for Manual Sampling of Petroleum andPetroleum ProductsD4177 Practice for Automatic Sampling of Petroleum andPetroleum ProductsE203 Test Method for Water Using Volumetric Karl FischerTitration2.2 API Standards:3MPMS Chapter 8.1 Manual Samp
7、ling of Petroleum andPetroleum Products(ASTM Practice D4057)MPMS Chapter 8.2 Automatic Sampling of Petroleum andPetroleum Products(ASTM Practice D4177)MPMS Chapter 10.2 Determination of Water in Crude Oil byDistillation(ASTM Test Method D4006)3.Summary of Test Method3.1 After homogenizing the crude
8、oil with a mixer,analiquot of the crude,in a mixed solvent,is titrated to anelectrometric end-point using Karl Fischer reagent.4.Significance and Use4.1 A knowledge of the water content of crude oil isimportant in the refining,purchase,sale,or transfer of crudeoils.5.Interferences5.1 A number of sub
9、stances and class of compounds asso-ciated with condensation or oxidation-reduction reactions in-terfere in the determination of water by Karl Fischer.In crudeoils,the most common interferences are mercaptans andsulfides.At levels of less than 500 g/g(ppm)(as sulfur)theinterference from these compou
10、nds is insignificant.For moreinformation on substances that interfere in the determination ofwater using the(Karl Fischer reagent)titration method see TestMethod E203.6.Apparatus6.1 Karl Fischer Apparatus,using electrometric end-point.A suggested assembly of the apparatus is described in AnnexA2.1Th
11、is 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 a
12、pproved June 1,2011.Published August 2011.Originallyapproved in 1984.Last previous edition approved in 2006 as D437700(2006).DOI:10.1520/D4377-00R11.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards
13、volume information,refer to the standards Document Summary page onthe ASTM website.3Published as Manual of Petroleum Measurement Standards.Available fromAmerican Petroleum Institute(API),1220 L.St.,NW,Washington,DC 20005-4070,http:/api-ec.api.org.Copyright ASTM International,100 Barr Harbor Drive,PO
14、 Box C700,West Conshohocken,PA 19428-2959.United States1 6.1.1 Presently there is available on the market commercialKarl Fischer titration assemblies,some of which automaticallystop the titration at the end-point.Instructions for operation ofthese devices are provided by the manufacturer and notdesc
15、ribed herein.This test method is not intended for use withcoulometric Karl Fischer titrators.6.2 Mixer,to homogenize the crude sample.6.2.1 Non-Aerating,High-Speed,Shear Mixer,4capable ofmeeting the homogenization efficiency test described in AnnexA1.The sample size is limited to that suggested by t
16、hemanufacturer for the size of the probe.6.3 Syringes:6.3.1 Samples and base liquid are most easily added to thetitration vessel by means of accurate glass syringes with LUERfittings and hypodermic needles of suitable length.The boresof the needles used should be kept as small as possible,butlarge enough to avoid problems arising from back pressure/blocking whilst sampling.Suggested syringe sizes are asfollows:6.3.1.1 Syringe,10 L,with a needle long enough to dipbelow the surface of the base sol
