ASTM_D_6350_-_14.pdf

Designation:D635014Standard Test Method forMercury Sampling and Analysis in Natural Gas by AtomicFluorescence Spectroscopy1This standard is issued under the fixed designation D6350;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.1.Scope1.1 This test method covers the determination of totalmercury in natural gas streams down to 0.001 g/m3.Itincludes procedures to both obtaining a representative sampleand the atomic fluorescence detection of the analyte.Thisprocedure can be applied for both organic and inorganicmercury compounds.1.2 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.2.1 Exception:Inch-pound units are used in Sections 5.1.2and 7.3 when discussing pressure regulator usage.1.3 Warning:Mercury has been designated by many regu-latory agencies as a hazardous material that can cause seriousmedical issues.Mercury,or its vapor,has been demonstrated tobe hazardous to health and corrosive to materials.Cautionshould be taken when handling mercury and mercury contain-ing products.See the applicable product Safety Data Sheet(SDS)for additional information.Users should be aware thatselling mercury and/or mercury containing products into yourstate or country may be prohibited by law.1.4 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 its use.2.Referenced Documents2.1 ASTM Standards:2D5954 Test Method for Mercury Sampling and Measure-ment in Natural Gas by Atomic Absorption Spectroscopy2.2 ISO Standard3ISO 6978 Determination of Mercury in Natural Gas3.Summary of Test Method3.1 Mercury from the gaseous stream is absorbed andpreconcentrated onto a gold-coated silica sand trap.Theanalyte is desorbed by raising the temperature of the trap,anda flow of inert gas carries the mercury atoms into the cellassembly of an atomic fluorescence spectrophotometer.Thecell is irradiated by a low pressure mercury vapor lamp at253.652 nm.Excitation of mercury atoms produces resonancefluorescence which reradiates at the excitation wavelength.Thefluorescence radiation is detected by a photomultiplier tube andis directly proportional to the amount of mercury in the cell.The concentration of the element in the original sample isobtained by comparison to freshly prepared standards,whichare analyzed by direct injection of mercury vapor into theinstrument at a specified temperature on supported gold traps.4.Significance and Use4.1 This test method can be used to determine the totalmercury concentration of a natural gas stream down to 0.001g/m3.It can be used to assess compliance with environmentalregulations,predict possible damage to gas plant equipment,and monitor the efficiency of mercury removal beds.Where L1and L2are the specimen lengths at temperatures T1and T2,respectively.is,therefore,obtained by dividing thelinear expansion per unit length by the change in temperature.4.2 The preferred sampling method for mercury collectionis on supported gold sorbent,which allows the element to betrapped and extracted from the interfering matrix of the gas.Thermal desorption of mercury is performed by raising thetemperature of the trap by means of a nichrome wire coiledaround it.4.3 The preferred sampling method for mercury collectionis on supported gold sorbent,which allows the element to betrapped and extracted from the interfering matrix of the gas.1This test method is under the jurisdiction ofASTM Committee D03 on GaseousFuels and is the direct responsibility of Subcommittee D03.05 on Determination ofSpecial Constituents of Gaseous Fuels.Current edition approved Feb.1,2014.Published February 2014.Originallyapproved in 1998.Last previous edition approved in 2003 as D6350-98(2003),which was withdrawn in July 2012 and reinstated February 2014.DOI:10.1520/D6350-14.2For 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.3Available from American National Standards Institute(ANSI),25 W.43rd St.,4th Floor,New York,NY 10036,http:/www.ansi.org.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 Thermal desorption of mercury is performed by raising thetemperature of the trap by means of a nichrome wire coiledaround it.4.4 Since AFS demonstrates lower detection limits ap-proaching 0.1 pg,this test method avoids difficulties associatedwith prolonged sampling time.Saturation of the trap wit