ASTM_D_4323_-_21.pdf

Designation:D432321Standard Test Method forHydrogen Sulfide in the Atmosphere by Rate of Change ofReflectance1This standard is issued under the fixed designation D4323;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 automatic continuous deter-mination of hydrogen sulfide(H2S)in the atmosphere or ingaseous samples in the range from one part per billion byvolume(1 ppb/v)to 3000 ppb/v.Information obtained may beused for air-pollution studies,fence-line monitoring,and othersource emission monitoring.1.2 The range may be extended by appropriate dilutiontechniques or by equipment modification.1.3 The values stated in SI units are to be regarded asstandard.The values given in parentheses are mathematicalconversions to inch-pound units that are provided for informa-tion only and are not considered standard.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,health,and environmental practices and deter-mine the applicability of regulatory limitations prior to use.(See Section 9 for specific safety precautionary statements.)1.5 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade(TBT)Committee.2.Referenced Documents2.1 ASTM Standards:2D1193 Specification for Reagent WaterD1356 Terminology Relating to Sampling and Analysis ofAtmospheresD2420 Test Method for Hydrogen Sulfide in LiquefiedPetroleum(LP)Gases(Lead Acetate Method)D2725 Test Method for Hydrogen Sulfide in Natural Gas(Methylene Blue Method)(Withdrawn 1996)3D3609 Practice for Calibration Techniques Using Perme-ation TubesD4084 Test Method for Analysis of Hydrogen Sulfide inGaseous Fuels(Lead Acetate Reaction Rate Method)D4323 Test Method for Hydrogen Sulfide in theAtmosphereby Rate of Change of ReflectanceD6299 Practice for Applying Statistical Quality Assuranceand Control Charting Techniques to Evaluate AnalyticalMeasurement System PerformanceD6792 Practice for Quality Management Systems in Petro-leum Products,Liquid Fuels,and Lubricants TestingLaboratories3.Terminology3.1 DefinitionsFor definitions of terms used in this testmethod,refer to Terminology D1356.4.Summary of Test Method4.1 Hydrogen sulfide is determined by reaction of H2S withlead acetate-impregnated paper tape and by comparing areading of an unknown sample with that of a known standardusing differential colorimetric detection.Detection of the rateof change of reflectance provides measurement in ppb/v rangeswith an analysis time appropriate for the application.(See Fig.1.)Sample gas is passed through a flowmeter and a humidifier;then across lead acetate-treated paper tape.Aconstant humidityis required for a constant reaction rate of H2S with lead acetate.H2S reacts with lead acetate to form a brown stain on the paper.The resultant change in reflectance is detected by a photondetection system.The rate of change of reflectance is propor-tional to H2S concentration.The analyzer is composed of anoptical system,a photon detection system,a signal differentia-tion system of first order,and a signal output system.1This test method is under the jurisdiction of ASTM Committee D22 on AirQuality and is the direct responsibility of Subcommittee D22.03 on AmbientAtmospheres and Source Emissions.Current edition approved Nov.1,2021.Published May 2022.Originallyapproved in 1984.Last previous edition approved in 2015 as D4323 15.DOI:10.1520/D4323-21.2For 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.3The last approved version of this historical standard is referenced onwww.astm.org.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade(TBT)Committee.15.Significance and Use5.1 Hydrogen sulfide is an odorous substance which isoffensive even at low concentrations in the atmosphere andtoxic at higher levels.It may be a product of biologicalprocesses in the absence of oxygen,as may occur in municipallandfills.It is emitted from geotherm