1、Designation: D 4323 84 (Reapproved 2003)Standard Test Method forHydrogen Sulfide in the Atmosphere by Rate of Change ofReflectance1This standard is issued under the fixed designation D 4323; the number immediately following the designation indicates the year oforiginal adoption or, in the case of re
2、vision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) 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
3、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 and to monitor for emissionsources.1.2 The range may be extended by appropriate dilutiontechniques or by equipment modification.1.3 This
4、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. (See 6.2, 6.3, and6.4 f
5、or specific safety precautionary statements.)2. Referenced Documents2.1 ASTM Standards:2D 1193 Specification for Reagent WaterD 2420 Test Method for Hydrogen Sulfide In LiquefiedPetroleum (LP) Gases (Lead Acetate Method)D 2725 Test Method for Hydrogen Sulfide in Natural Gas(Methylene Blue Method)33.
6、 Summary of Test Method3.1 Hydrogen sulfide is determined by use of the reaction ofH2S with lead acetate-impregnated paper tape. Detection of therate of change of reflectance provides measurement in ppb/vranges with an approximate 3-min analysis cycle time. (SeeFig. 1.) Sample gas is passed through
7、a flowmeter and ahumidifier; then across lead acetate-treated paper tape. Aconstant humidity is required for a constant reaction rate ofH2S with lead acetate. The resultant change in reflectance isdetected by a photocell. The rate of change of reflectance isproportional to H2S concentration.4. Signi
8、ficance and Use4.1 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 municipalgarbage landfills. It is emitted from geothermal sources
9、, occursin oil and gas, and may be emitted from industrial processes.Measurement is required for air pollution studies, for pollutioncontrol, and for plume characterization. Equipment describedis suitable for fixed site or for mobile monitoring.5. Apparatus4,55.1 Rate-of-Reaction H2S AnalyzerSample
10、is passedacross a lead acetate-treated surface causing a reflectancechange. Hydrogen sulfide is determined by measuring the rateof change of reflectance resulting from darkening when leadsulfide is formed. Equipment consists of a small flowmeter,humidifier, sensing surface exposure chamber, optical
11、system,and electronic system. (See Fig. 2.) A complete analysis inabout 1 min results from use of the rate of change of colorrather than magnitude of cumulative color development. Theelectronic system provides an output that is proportional to thederivative of the photocell signal, caused by reflect
12、ancechange, and this rate measurement is a measure of H2Sconcentration. A new section of sensing material is drawn intothe sensing chamber at approximately 3-min intervals toprovide a new independent measurement.5.2 RecorderA method of recording the electronic signalis required. This may take any fo
13、rm that is suitable for therecord required. A typical system recorder will accept a rangefrom 0 to 10 V from an output impedance of 1000 V(maximum). An attenuator or amplifier (usually incorporatedinto the recorder) may be used for other sensor signal levels. A1This test method is under the jurisdic
14、tion of ASTM Committee D22 on AirQuality and is the direct responsibility of Subcommittee D22.03 on AmbientAtmospheres and Source Emissions.Current edition approved April 10, 2003. Published June 2003. Originallyapproved in 1984. Last previous edition approved in 1997 as D 4323 - 84 (1997)e1.2For re
15、ferenced 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.3Withdrawn4The sole source of supply of the apparatus described in 5
16、.1, 5.3, and 6.3 knownto the committee at this time is HoustonAtlas, Inc., 22001 N. Park Dr., Houston, TX77339-3809. If you are aware of alternate suppliers, please provide this informationto ASTM Headquarters. Your comments will receive careful consideration at ameeting of the responsible technical
17、 committee1, which you may attend.5Kimbell, C. L. and Drudhel, H. V., “Trace Sulphur Determination in PetroleumFractions,” Analytical Chemistry, Vol 50, 1978, p 26.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.chart speed of 1 cm/m
18、in is suitable for short term analyses. Achart speed of 1 to 5 cm/h is preferable for long-term sampling.Electronic processing, such as integrators, may be added whenconcentration averages over an interval of time are desirable.5.3 Reference Gas Preparation:5.3.1 MixingA calibrated 10-L cylinder hav
19、ing a movablepiston for use in making volumetric mixtures of gases in theppb/v range may be used. Materials of construction must beinert to H2S and not lead to a deterioration of prepared samples.A cylinder of acrylic lubricated with silicone grease and usinga silicone O-ring has been found to be su
20、itable. Concentrationremains stable to within 1 % over a 1-h period.5.3.2 Hypodermic SyringeGas-tight syringes of 10 and50-l capacity. A side port is convenient for purging. AvoidLuer tip syringes made of plated brass as H2S reacts with brass.Other convenient small volume measurement devices such as
21、 amicrolitre valve may be used.5.3.3 PumpA sample pump capable of providing 500mL/min flow at approximately 35 kPa 5 psi. The pumpwetted parts must be inert to H2S and not lead to a deteriorationof the sample.6. Reagent and Materials6.1 Purity of ReagentsReagent grade chemicals shall beused in all t
22、ests. Unless otherwise noted, all reagents shallconform to the specifications of the Committee on AnalyticalReagents of the American Chemical Society, where suchspecifications are available.66.2 Acetic Acid Solution (50 mL/L)Dilute 50 mL ofglacial acetic acid (CH3COOH), reagent grade, to make 1 L of
23、solution using Type III water prepared as described in Speci-fication D 1193. Caution: Concentrated acetic acid fumes arean irritant and can cause damage to skin and mucus membrane.Handle carefully to avoid injury.6.3 Sensing TapePrepare sensing tape as described in TestMethod D 2420 or use commerci
24、al sensing tape4that has beenprepared in a similar manner. Keep sensing tape in a sealedcontainer to prevent exposure to ambient H2S. Caution: Leadacetate is a cumulate poison; wash hands after handling and donot breathe any dust containing lead acetate.6.4 Hydrogen Sulfide (99.5 %)Commercially avai
25、lableH2S has been found not to be sufficiently pure. Purity certifi-cation is recommended or a commercially available H2Sgenerator may be used. Caution: Hydrogen sulfide is toxic atlevels above 10 000 ppb/v. Use only under an appropriatefume hood. Use protective glasses if liquid H2S in cylinders is
26、6Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For suggestions on the testing of reagents notlisted by the American Chemical Society, see Analar Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacope
27、iaand National Formulary, U.S. Pharmaceutical Convention, Inc. (USPC), Rockville,MD.FIG. 1 Rate of Change of Reflectance Type H2S Readout SystemD 4323 84 (2003)2handled. Sense of smell may be lost on exposure to H2S and isunreliable as a warning of danger. (See Appendix X1.1 andX1.2 on Interferences
28、.)6.5 Dilution GasA gas similar to the gas to be sampled,H2S-free. Mixture can be prepared using the 10-L cylinderdescribed in 5.3.1.7. Sampling7.1 Sample lines and containers must not absorb sampleH2S. Suitable materials are fluorocarbon resins, aluminum,borosilicate glass, and suitable inactive ac
29、rylic. Stainless steel(Type 316) may be used when required by regulations but isnot preferred.7.2 Avoid materials containing copper or having petroleumlubricant coatings.FIG. 2 Flow System for Gas Sample and for Calibration ReferenceTABLE 1 RepeatabilityFull Scale Rangeppm/vPiston Cylinder Reference
30、(Manual)Deviation,ppm/vPPM Generator Reference(Automatic) Deviation,ppm/v1.0 0.014 0.0170.1 0.002 0.002TABLE 2 ReproducibilityFull Scale Rangeppm/vPiston Cylinder Reference(Manual)Deviation,ppm/vPPM Generator Reference(Automatic) Deviation,ppm/v1.0 0.050 0.1410 0.006 0.008D 4323 84 (2003)38. Calibra
31、tion and Standardization8.1 Reference StandardReference standards are preparedby volumetric measurement at the time the reference materialis to be used. This minimizes deterioration of the sample. Thepermeation tube method or compressed gas cylinders certifiedas to concentration by the manufacturer
32、may be used as areference standard. Small volumes of pure H2S are measuredusing a gas-tight syringe. Dilution gas is measured using a10-L graduated cylinder having a movable piston. As a syringeneedle has appreciable volume, H2S can escape by diffusionfrom the needle tip. Therefore, a smooth fast wo
33、rk routine mustbe established to prevent delays and loss of sample.8.2 CalibrationTo prepare 1000 ppb/v sample add 10 Lof H2S to make a 10-L sample carrier mixture using the 10-Lacrylic cylinder described in 5.3.1. To calculate microlitres ofH2S required in a 10-L mixture, use the following equation
34、:p 5 ppb/v 3 1022(1)where: p = microlitres of pollutant used. Prepare a referencestandard of a concentration slightly higher than may beanticipated in the sample. Purge the 10-L cylinder withH2S-free carrier gas. Purge the microlitre syringe with H2S.Gradually fill the 10-L cylinder with carrier gas
35、 as the syringeis adjusted for the proper quantity of H2S. Insert the syringequickly into the cylinder septum and inject the aliquot of H2Sinto the flowing carrier gas. Turn off the carrier gas when 10 Lare obtained. Withdraw the syringe quickly after injection toprevent residual H2S in the needle t
36、ip from diffusing into theflowing gas. The reference standard is now pumped into theanalyzer to calibrate it. For samples less than 1000 ppb/v,secondary volumetric dilution will be required. For 500 ppb/vsamples, exhaust a cylinder filled with 10 L of 1000 ppb/v gasto 5 L, then fill again to 10 L wi
37、th diluent gas.9. Procedure9.1 Turn the analyzer power on, install sensing tape, and add5 % acetic acid by volume in water to the bubbler (3 % byweight barium acetate solution may be used to remove SO2).Turn on H2S-free carrier gas having a composition as near aspossible to the sample composition by
38、 pumping or from apressurized source at a constant rate of 300 mL/min flow63 %. This flow must be held constant during all testing.After30 min, adjust the analyzer zero. Record this as the recorderblank reading, b,in9.4.9.2 Calibrate the analyzer with a freshly prepared referencesample of the concen
39、tration expected in the unknown, as notedin 8.2. Adjust flow rate to 300 mL/min 6 3 % and record theanalyzer reading, r,in9.4.9.3 Connect the sample to the analyzer to adjust flow rate at300 mL/min 6 3 %. Record the analyzer reading, u,in9.4.9.4 Calculate the concentration of the unknown sample asfo
40、llows:x 5 c u 2 b!/r 2 b! (2)where:x = concentration of sample under test, ppb/v,b = blank analyzer reading, percent of scale,u = unknown sample analyzer reading, as received, per-cent of scale,r = reference standard analyzer reading, percent of scale,andc = concentration of reference standard, ppb/
41、v.10. Report10.1 Report the results in ppb/v or apply the appropriateconversion if other units are required. The procedure isself-compensating for temperature and pressure. If data aredesired in weight units of milligrams per cubic metre (mg/m3),apply the following equation:ppb/v 3 1.395 3 10235 mg/
42、m3(3)NOTE 1This equation is based on the ideal gas density computed bydividing molecular weights by molar volume at 25C and 760 mm Hg101.3 kPa. Weight is weight of H2S.11. Precision and Bias11.1 The information in this section is derived from datacollected by ASTM Committees D-2 and D-22 using a sim
43、ilartype analyzer.11.1.1 RepeatabilityAt the 95 % confidence level thedifference due to test error obtained between two results fromthe same sample at the same laboratory should be consideredsuspect if greater than shown in Table 1.11.1.2 ReproducibilityAt the 95 % confidence level thedifference due
44、 to test error obtained between two results fromthe same sample from different laboratories should be consid-ered suspect if greater than shown in Table 2.11.1.3 The precision studies were conducted by six labora-tories. There were twelve samples associated with the piston-cylinder and nine samples
45、associated with the ppm generatormethods of sample preparations.11.1.4 Hydrogen Sulfide ReferenceReference sampleswere prepared from a compressed gas cylinder containing anominal 99 % nitrogen, and 1 % H2S by volume. At the end ofthe testing the concentration was measured by the MethyleneBlue Method
46、 at 0.92 % H2S by volume. Bias of preparedsamples depend on reagent purity and care in sample prepara-tion. Test Method D 2725 (Methylene Blue Method) may beused to check prepared samples above 16 ppm 23 mg/cm3.12. Keywords12.1 atmospheres; hydrogen sulfide; tape samplerD 4323 84 (2003)4APPENDIX(Non
47、mandatory Information)X1. INTERFERENCESX1.1 In applications of this method, high levels of somecompounds can result in instrument response. Methyl mercap-tan, when 1000 times the H2S concentration can affect responseequal to H2S response. Arsine, phosphine, and free sulfur havebeen reported as causi
48、ng response. The operator should takerequired precautions if the above materials are expected to bepresent in the sample.X1.2 In the event SO2may be present, a solution of bariumacetate may be substituted for the acetic acid solution to scrubout the SO2component without removing H2S. Use 3 % byweigh
49、t barium acetate in deionized water.7Hydrogen sulfideand SO2react spontaneously and prepared samples cannot bestored more than a few minutes.ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committ
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