1、Designation: D7833 12Standard Test Method forDetermination of Hydrocarbons and Non-HydrocarbonGases in Gaseous Mixtures by Gas Chromatography1This standard is issued under the fixed designation D7833; the number immediately following the designation indicates the year oforiginal adoption or, in the
2、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 is intended to quantitatively determinethe non-condensed hydrocarbon ga
3、ses with carbon numbersfrom C1to C5+ and non-hydrocarbon gases, such as H2,CO2,O2,N2, and CO, in gaseous samples. This test method is acompanion standard test method to Test Method D1945 andPractice D1946 differing in that it incorporates use of capillarycolumns instead of packed columns and allows
4、other techno-logical differences.1.2 Hydrogen sulfide can be detected but may not beaccurately determined by this procedure due to loss in samplecontainers or sample lines and possible reactions unless specialprecautions are taken.1.3 Non-hydrocarbon gases have a lower detection limit inthe concentr
5、ation range of 0.03 to 100 mole percent using athermal conductivity detector (TCD) and C1to C6hydrocar-bons have a lower detection limit in the range of 0.005 to 100mole percent using a flame ionization detector (FID); using aTCD may increase the lower detection limit to approximately0.03 mole perce
6、nt.1.3.1 Hydrocarbon detection limits can be reduced with theuse of pre-concentration techniques and/or cryogenic trapping.1.4 This test method does not fully determine individualhydrocarbons heavier than benzene, which are grouped to-gether as C7+ When detailed analysis is not required thecompounds
7、 with carbon number greater than C5may begrouped as either C6+, or C7+. Accurate analysis of C5+components depends on proper vaporization of these com-pounds during sampling at process unit sources as well as inthe sample introduction into the analyzer in the laboratory.1.5 Water vapor may interfere
8、 with the C6+ analysis if aTCD detector is used.1.6 Helium and argon may interfere with the determinationof hydrogen and oxygen respectively. Depending on theanalyzer used, pentenes, if present, may either be separated orgrouped with the C6+ components.1.7 The values stated in SI units are to be reg
9、arded asstandard.1.8 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 us
10、e.2. Referenced Documents2.1 ASTM Standards:2D1945 Test Method for Analysis of Natural Gas by GasChromatographyD1946 Practice for Analysis of Reformed Gas by GasChromatographyD3588 Practice for Calculating Heat Value, CompressibilityFactor, and Relative Density of Gaseous FuelsE355 Practice for Gas
11、Chromatography Terms and Relation-shipsE1510 Practice for Installing Fused Silica Open TubularCapillary Columns in Gas ChromatographsF307 Practice for Sampling Pressurized Gas for Gas Analy-sis2.2 ASTM Publication:ASTM DS 4B, 1991 Physical Constants of Hydrocarbon andNon-Hydrocarbon Compounds3. Term
12、inology3.1 Terminology related to the practice of gas chromatog-raphy can be found in Practice E355.3.2 Definitions:3.2.1 sample seta collection of samples taken from thesame source or at similar component composition and concen-trations.1This test method is under the jurisdiction ofASTM Committee D
13、03 on GaseousFuels and is the direct responsibility of Subcommittee D03.07 on Analysis ofChemical Composition of Gaseous Fuels.Current edition approved Nov. 1, 2012. Published December 2012. DOI:10.1520/D7833-12.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Cus
14、tomer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States14. Summary of Test Method4.1 Compon
15、ents in a representative sample are physicallyseparated by gas chromatography (GC) and compared tocalibration data obtained under identical operating conditionsfrom a reference standard mixture of known composition. Thenumerous heavy-end components of a sample can be groupedinto irregular peaks by r
16、eversing the direction of the carrier gasthrough the column at such time as to group the heavy endseither as C5and heavier, C6and heavier, or C7and heavier oralternatively elute them in the non-backflushed mode andsummed accordingly. The composition of the sample is calcu-lated by comparing the peak
17、 areas with the correspondingvalues obtained with the reference standard.5. Significance and Use5.1 The hydrocarbon component distribution of gaseousmixtures is often required for end-use sale of this material.Applications such as chemical feedstock or fuel require precisecompositional data to ensur
18、e uniform quality. Trace amounts ofsome hydrocarbon impurities in these materials can haveadverse effects on their use and processing. Certain regulationsmay require use of such method.5.2 The component distribution data of gaseous mixturescan be used to calculate physical properties such as relativ
19、edensity, vapor pressure, and heating value calculations found inPractice D3588. Precision and accuracy of compositional datais extremely important when this data is used to calculatevarious properties of petroleum products.6. Apparatus6.1 Gas Chromatograph (GC)This method allows the useof most gas
20、chromatographic analyzers designed for gasanalysis. Generally, any gas chromatographic instrument witha linear temperature programmable column oven or adequatetemperature control to provide the required separation ofgaseous compounds being analyzed may be used. The tem-perature control must be capab
21、le of obtaining retention timerepeatability within 5% of the retention time for each compo-nent throughout the scope of this analysis for hydrocarbon andnon-hydrocarbon gas analyses.6.1.1 DetectorThe type and number of detectors em-ployed is dependent on gas analyzer model and vendor used.Detectors
22、that can be used include, but are not limited to FID,TCD, AED (Atomic Emission Detector), HID (Helium Ioniza-tion Detector), and MS(Mass Spectrometer). Many systems usea 3 detector system:(1) One FID (Flame Ionization Detector) for the determi-nation of the hydrocarbon gases for the compounds listed
23、 inTable 1,(2) One TCD (Thermal Conductivity Detector) dedicatedto the determination of hydrogen utilizing nitrogen or argon asa carrier gas, and(3) One TCD for the determination of all other requirednon-hydrocarbon gases using helium as the carrier gas.6.1.2 A TCD may also be used for the analysis
24、of thehydrocarbon gases (replacing the FID) when high sensitivity (5 vol%.NOTE 1When helium is not expected to be present in samples theresolution of hydrogen from helium is not critical.6.5 Non-Hydrocarbon and Light Hydrocarbon Gas Analysis(Except Hydrogen) (Thermal Conductivity Detector)A 10-port
25、gas sampling valve in combination with a 6-port switchingvalve or equivalent is used with helium or hydrogen carrier toanalyze for CO2,O2,N2, CH4, C2H6, and CO and in somecases H2S. Any column or multiple columns may be used aslong as the desired components are well separated.ATCD mayalso be used fo
26、r the analysis of the hydrocarbon gases(replacing the FID) when high sensitivity (5 vol%.6.6 Hydrocarbon Gas Analysis (Flame IonizationDetector)A 6-port gas-sampling valve in combination with a6-port pre-column switching valve (backflush) for the C6+or3Silcosteel is a trademarked of SilcoTek, 112 Be
27、nner Circle, Bellefonte, PA16823.4Sulfinert is a trademarked of Restek Corporation 110 Benner Circle Bellefonte,PA 16823.NOTE 1For the hydrocarbon analysis, the Al2O3PLOT was used.FIG. 3 Example Chromatogram of Hydrocarbons from System Configuration in Fig. 1D7833 124C7+ hydrocarbons is typically us
28、ed. These valves shall becontained in a heated enclosure and operated at a sufficientlyhigh temperature, and within the limits of the valve operatingtemperature as specified by manufacturer, to prevent conden-sation of the C6+ components in the sample. The use of a fritor packed-screen type filter a
29、head of the sample introductionport is recommended with use of PLOT columns. The gas-sampling valve shall provide a repeatability of at least 6 2%relative to the sample volume introduction for major com-pounds present at 5 vol%.6.7 Column Series/Reversal Switching ValveIf desired, amulti-port valve
30、may be used to provide the C5olefin/C6+orC7+ determination for this analysis. Other switching valveconfigurations may be used to allow the elution of the gaseouscompounds. Consult instrument manufacturer for optimumconfiguration.NOTE 2If a dimethylsilicone capillary column or equivalent is usedfor t
31、he hydrocarbon analysis, then the capillary column may be used in theforeflush mode (no-backflush) until all of the hydrocarbons have elutedusing temperature programming or equivalent.6.8 Gas ControlsThe gas chromatograph shall be pro-vided with suitable facilities for delivery and control of carrie
32、rgases and detector gases. This will consist of the appropriategas supply, down-stream regulators, and supply tubing as wellas the mass or pressure controls for the precise regulation of theinstrument operation.NOTE 3Most gas chromatograph suppliers will provide these devicesor recommend the proper
33、suppliers. Ensure that the analyzer when heatedand in-use does not run out of carrier gases. In addition, running out ofcarrier gas will require flushing out any air introduced into the sample inletsystem, column and/or detector.6.9 ColumnsCondition all columns used according to themanufacturers sug
34、gestions prior to putting the system inservice.6.10 Analytical Column for Hydrocarbon AnalysisA rec-ommended analytical column for the hydrocarbon analysis inFig. 1 is a 50 m 0.53 mm (I.D.) deactivated alumina (Al2O3)porous layer open tubular (PLOT) column used with a FIDdetector for lowest detectio
35、n limits. Relative retention order forthe alumina PLOT column is dependent upon the deactivationmethod for the column and moisture content. WarningSpecifically test the alumina PLOT column to ensure that thecolumn does not adsorb propadiene, methyl acetylene, andbutadiene when such compounds need to
36、 be determined. Thiscondition can exist depending upon the degree of columndeactivation.6.10.1 Routine re-conditioning of the alumina PLOT col-umn may be required to maintain column performance. It isrecommended that a standby method be used when the systemis idle to maintain the PLOT column at a te
37、mperature of at least130C or as recommended by the manufacturer.6.10.2 Alternatively, any column or combination of col-umns that provides the appropriate component C1-C5separa-tions may be used.6.11 Pre-column for Hydrocarbon Gas AnalysisWhenusing the alumina PLOT column, if an initial backflush of
38、theC5+/C6+ components through the use of the sequence reversal/backflush valve is desired, a second column is required. Anypre-column that provides separation between the componentsof interest and the composite heavier components may be used.Choices may include lengths of column such as a 10 to 30 m
39、section of 0.53 mm (I.D.) 3-m film thickness dimethylpolysiloxane ora9to15cmsection of the same columnmaterial as the analytical column or any pre-column thatprovides the desired retention of pentenes, hexanes, andheavier components. This pre-column acts to keep the heaviercomponents away from the a
40、nalytical alumina PLOT columnand to backflush the heavier components as a composite peakto the detector for quantification. If analysis of individualC6-C7components is required, extend the backflush valve timeuntil the desired components have eluted and prior to back-flushing the remaining heavier c
41、ompounds.6.12 Analytical Columns for Hydrogen AnalysisGenerallyhydrogen analysis consists of a pre-column to remove most ofthe hydrocarbons, H2S and CO2and a Molecular Sieve 5A orequivalent for separation of hydrogen from oxygen and nitro-gen. Follow vendors recommendations.6.13 Analytical Columns f
42、or Other Non-HydrocarbonGasesGenerally a series-bypass two-valve configuration isused, consisting of porous polymer-molecular sieve 5Aor 13Xcombination. Follow vendors recommendations.7. Reagents and Materials7.1 All chemicals are reagent grade unless specifiedotherwise, and all water used is distil
43、led or deionized.WarningHydrogen sulfide contained in calibration stan-dards may be flammable and harmful or fatal if ingested orinhaled. Calibration standards or samples containing hydrogensulfide should be handled in well ventilated locations awayfrom sparks and flames.7.2 Carrier GasesFor carrier
44、 gases, it is strongly recom-mended to install commercial active oxygen scrubbers andwater dryers, such as molecular sieves, ahead of the instrumentto protect the chromatographic columns. Follow supplierinstructions in the use of such gas purifiers and replace asnecessary.7.2.1 Chromatographic Grade
45、 Hydrogen, 99.995% mini-mum purity, 5 vol%. Failure tocompare may result from lack of injection splitter (if used)linearity or use of a standard that has not been maintainedaccording to the standard manufacturers recommendations. Itis necessary to compare calculated results to the certifiedvalues fo
46、r a known standard before accepting the calibration.10. Sampling10.1 Sampling at the sample source, the use of appropriatesample containers that are stored and transported properly, andintroduction into a chromatograph must be done in a mannerthat ensures that a representative sample is being analyz
47、ed. SeePractice F307 for the recommended procedures. Lack ofprecision and accuracy in using this method can most often beattributed to improper sampling, sample containment, orsample introduction procedures.10.2 Higher boiling components such as C5+ may condenseduring sampling of the process unit if
48、 the sample vessel is notat the same or greater temperature as the sample stream. ThisD7833 127will result in an inaccurate collection of sample components.Arepresentative sample must be collected to obtain valid results.Please reference API MPMS 14.1 for additional information.10.3 It is recommende
49、d that samples be equilibrated in thelaboratory at 6.7 to 10C (20 to 50F) above the sourcetemperature of the field sampling. If the hydrocarbon dew pointof the sample is known to be lower than the lowest temperatureto which the sample has been exposed, it is not necessary toheat the sample.10.4 Connections from the sample container to the sampleinlet of the instrument should be made with stainless steel orwith short pieces of TFE-fluorocarbon or inert tubing coatedwith Silcosteel3or Sulfinert4. Copper, vinyl, or rubber connec-tions are not acceptable. H
