ASTM_D_3227_-_16.pdf

Designation:D322716Designation:342/00Standard Test Method for(Thiol Mercaptan)Sulfur in Gasoline,Kerosine,AviationTurbine,and Distillate Fuels(Potentiometric Method)1This standard is issued under the fixed designation D3227;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 U.S.Department of Defense.1.Scope*1.1 This test method covers the determination of mercaptansulfur in gasolines,kerosines,aviation turbine fuels,anddistillate fuels containing from 0.0003%to 0.01%by mass ofmercaptan sulfur.Organic sulfur compounds such as sulfides,disulfides,and thiophene,do not interfere.Elemental sulfur inamounts less than 0.0005%by massdoes not interfere.Hydrogen sulfide will interfere if not removed,as described in9.2.1.2 The values in acceptable SI units are to be regarded asthe standard.1.2.1 ExceptionThe values in parentheses are for informa-tion only.1.3 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 Sections 6,8,9,and Appendix X1.2.Referenced Documents2.1 ASTM Standards:2D1193 Specification for Reagent WaterD1250 Guide for Use of the Petroleum Measurement TablesD1298 Test Method for Density,Relative Density,or APIGravity of Crude Petroleum and Liquid Petroleum Prod-ucts by Hydrometer MethodD4052 Test Method for Density,Relative Density,and APIGravity of Liquids by Digital Density MeterD4057 Practice for Manual Sampling of Petroleum andPetroleum ProductsD4177 Practice for Automatic Sampling of Petroleum andPetroleum ProductsD6299 Practice for Applying Statistical Quality Assuranceand Control Charting Techniques to Evaluate AnalyticalMeasurement System Performance3.Summary of Test Method3.1 The hydrogen sulfide-free sample is dissolved in analcoholic sodium acetate titration solvent and titrated potentio-metrically with silver nitrate solution,using as an indicator thepotential between a glass reference electrode and a silver/silver-sulfide indicating electrode.Under these conditions,themercaptan sulfur is precipitated as silver mercaptide and theend point of the titration is shown by a large change in cellpotential.4.Significance and Use4.1 Mercaptan sulfur has an objectionable odor,an adverseeffect on fuel system elastomers,and is corrosive to fuelsystem components.5.Apparatus5.1 As described in 5.2 5.5;alternatively,any automatictitration system may be used that,using the same electrode pairdescribed in 5.3,is capable of performing the titration asdescribed in Section 9 and selecting the endpoint specified in11.1 with a precision that meets or is better than that given inSection 14.5.2 MeterAn electronic voltmeter,operating on an inputof less than 9 10 12A and having a sensitivity of 62 mVover a range of at least 61 V.The meter shall be electrostati-cally shielded,and the shield shall be connected to the ground.35.3 Cell System,consisting of a reference and indicatingelectrode.The reference electrode should be a sturdy,pencil-type glass electrode,having a shielded lead connected to1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products,Liquid Fuels,and Lubricantsand is the direct responsibility ofSubcommittee D02.03 on Elemental Analysis.Current edition approved Oct.1,2016.Published November 2016.Originallyapproved in 1973.Last previous edition approved in 2013 as D3227 13.DOI:10.1520/D3227-16.2For 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.3Any apparatus that will give equal or better precision is acceptable.*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 ground.The indicating electrode shall be made from a silverwire,2 mm(0.08 in.)in diameter or larger,mounted in aninsulated support.Silver billet electrodes can also be used.5.4 Buret,10 mL capacity,graduated in 0.05 mL intervals,with a tip that extends approximately 120 mm(5 in.)below thestopcock.5.5 Titration Stand,preferably built as an integral part of themeter housing and provided with supports for the electrodesand electrical stirrer,all connected to ground.No permanentchange in meter reading should be noticeable upon connectingor disconnecting the stirring motor.6.Reagents and Materials6.1 Purity of ReagentsReagent grade chemicals shall beused in all tests.Unl