1、Designation: D7649 10Standard Test Method forDetermination of Trace Carbon Dioxide, Argon, Nitrogen,Oxygen and Water in Hydrogen Fuel by Jet Pulse Injectionand Gas Chromatography/Mass Spectrometer Analysis1This standard is issued under the fixed designation D7649; the number immediately following th
2、e 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 describ
3、es a procedure primarily for thedetermination of carbon dioxide, argon, nitrogen, oxygen andwater in high pressure fuel cell grade hydrogen by gaschromatograph/mass spectrometer (GC/MS) with injection ofsample at the same pressure as sample without pressurereduction, which is called “Jet Pulse Injec
4、tion”. The proceduresdescribed in this method were designed to measure carbondioxide at 0.5micromole per mole (ppmv), Argon 1 ppmv,nitrogen 5 ppmv and oxygen 2 ppmv and water 4 ppmv.1.2 The values stated in SI units are standard. The valuesstated in inch-pound units are for information only.1.3 The
5、mention of trade names in standard does notconstitute endorsement or recommendation for use. Othermanufacturers of equipment or equipment models can be used.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 o
6、f this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 Other Standards:SAE TIR J2719 Information Report on the Development ofa Hydrogen Quality Guideline for Fuel Cell VehiclesApril20082
7、3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 absolute pressurepressure measured with referenceto absolute zero pressure, usually expressed as kPa, mm Hg,bar or psi. All the pressures mentioned in this method areabsolute pressure.3.1.2 constituentA component (or compound) fo
8、undwithin a hydrogen fuel mixture.3.1.3 contaminantimpurity that adversely affects the com-ponents within the fuel cell system or the hydrogen storagesystem by reacting with its components. An adverse effect canbe reversible or irreversible.3.1.4 dynamic calibrationcalibration of an analytical sys-t
9、em using calibration gas standard generated by diluting knownconcentration compressed gas standards with hydrogen, asused in this method for carbon dioxide, argon, nitrogen andoxygen (7.3 and 7.4).3.1.5 extracted ion chromatogram (EIC)a GC/MS chro-matogram where a selected ion is plotted to determin
10、e thecompound(s) of interest.3.1.6 fuel cell grade hydrogenhydrogen satisfying thespecifications in SAE TIR J2719.3.1.7 hydrogen fuelhydrogen to be tested without compo-sitional change due to sample introduction, etc.3.1.8 jet pulse injectionhigh pressure hydrogen fuelsample is introduced instantane
11、ously at the same pressure intoGC/MS.3.1.9 relative humidityratio of actual pressure of existingwater vapor to maximum possible pressure of water vapor inthe atmosphere at the same temperature, expressed as apercentage.3.1.10 response factor (RF)-the amount in volume (L)of an analyte divided by the
12、EIC area of the analyte.3.1.11 static calibrationcalibration of an analytical sys-tem using standards in a matrix, state or manner different thanthe samples to be analyzed, as used in this method for waterconcentration in hydrogen.3.2 Acronyms:3.2.1 FCVfuel cell vehicle.3.2.2 PEMFCproton exchange me
13、mbrane fuel cell.4. Summary of Test Method4.1 The simultaneous analysis of carbon dioxide, argon,nitrogen, oxygen and water at 0.5 5 ppmv (micromole permole) in hydrogen fuel samples from fueling stations ischallenging due to high hydrogen fuel sample pressure andpossible contaminations from ambient
14、 air.1This test method is under the jurisdiction ofASTM Committee D03 on GaseousFuels and is the direct responsibility of Subcommittee D03.14 on Hydrogen andFuel Cells.Current edition approved Dec. 1, 2010. Published February 2011. DOI: 10.1520/D764910.2Available from SAE International (SAE), 400 Co
15、mmonwealth Dr., Warrendale,PA 15096-0001, http:/aerospace.sae.org.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.4.2 In this method, a small stainless steel loop is initiallypressurized with high pressure hydrogen standard or sample
16、without any pressure regulation or restriction (“Sample LoopPressurization”, Fig. 1). The hydrogen in the loop is thenreleased entirely as a “jet pulse” into a T-union which splitssample into a 0.25 m ID 30 m long capillary column and anelectronic flow controller (EFC) used to vent excess hydrogento
17、 the atmosphere (“Jet Pulse Injection”, Fig. 2). Less than 1%of hydrogen enters the capillary column with the remainingsample venting to atmosphere through EFC. As demonstratedin Appendix X1, the hydrogen volume “jet pulse injected” intothe capillary column is a constant volume and independent ofthe
18、 sample loop pressure when the sample loop pressure is over90 psi. Therefore, the constant hydrogen volume from stan-dards or samples is GC/MS analyzed in regardless of standardor sample pressures.4.3 Jet pulse injected volume into the capillary column isapproximate 100 L (In Appendix X1, this volum
19、e is calcu-lated to be 115L under the analytical conditions described inAppendix X1). When a 2-mL of sample loop is pressurized to200 psi, the hydrogen in the loop is (200 psi/14.7psi) 3 2mLor 27 mL. Hence, 99.5% of the hydrogen sample vents toatmosphere. This type of “Jet Pulse Injection” has been
20、foundacceptable for the analysis of high pressure hydrogen fuelsample since the hydrogen volume injected is independent ofthe pressures of hydrogen standards or samples. Consequentlyit is unnecessary to regulate standards and hydrogen samples tothe same pressure. In addition to possible trace leaks
21、or airtrapped inside, regulators are not recommended as moisture onthe regulator surface can be released into the sample resultingin a high moisture determination.4.4 A mass spectrometer provides sensitive and selectivedetection towards carbon dioxide, argon, nitrogen, oxygen andwater.5. Significanc
22、e and Use5.1 Low operating temperature fuel cells such as protonexchange membrane fuel cells (PEMFCs) require high purityhydrogen for maximum performance. The following are thereported effects (SAE TIR J2719) of the compounds deter-mined by this test method.5.2 Carbon Dioxide (CO2), acts largely as
23、a diluent, how-ever in the fuel cell environment CO2can be transformed intoCO.5.3 Water (H2O), is an inert impurity, as it does not affectthe function of a fuel cell stack; however, it provides atransport mechanism for water-soluble contaminants, such asNa+or K+. In addition, it may form ice on valv
24、e internalsurface at cold weather or react exothermally with metalhydride used as hydrogen fuel storage.5.4 Inert Gases (N2and Ar), do not normally react with afuel cell components or fuel cell system and are considereddiluents. Diluents can decrease fuel cell stack performance.5.5 Oxygen (O2), in l
25、ow concentrations is considered aninert impurity, as it does not adversely affect the function of afuel cell stack; however, it is a safety concern for vehicle onboard fuel storage as it can react violently with hydrogen togenerate water and heat.6. Apparatus6.1 Mass Spectrometer (MS)The MS can perf
26、orm masscalibration with a scanning range from m/e 15 to 650. Thebackground peak intensities of water, nitrogen, argon, oxygenand carbon dioxide in the mass spectrum of FC-43 (perfluo-rotributylamine), used for mass calibration, should be less than10% of m/e 69 to demonstrate a background acceptable
27、 for thedetermination of these analytes before beginning sample analy-sis. All analytes determined according to this method have aFIG. 1 Sample Loop PressurizationD7649 102molecular mass less than 44 amu; therefore, the mass scanningrange of m/e 15 to 50 is typically used.6.2 Data SystemAcomputer or
28、 other data recorder loadedwith appropriate software for data acquisition, data reduction,and data reporting and possessing the following capabilities isrequired:6.2.1 Graphic presentation of the total ion chromatogram(TIC) and extracted ion chromatogram (EIC).6.2.2 Digital display of chromatographi
29、c peak areas.6.2.3 Identification of peaks by retention time and massspectra.6.2.4 Calculation and use of response factors.6.2.5 External standard calculation and data presentation.6.3 Gas chromatography (GC)Chromatographic systemcapable of obtaining retention time repeatability of 0.05 min (3s) thr
30、oughout the analysis.6.3.1 Interface with MSA heated interface connecting theGC column to the MS ion source.6.3.2 GC ColumnA 0.25mm ID 30m 0.25 m film thick-ness DB-5 column has been successfully used to perform thisanalysis. Other capillary columns may be used providedchromatographic peaks do not s
31、ignificantly tail. One end of theGC column is connected to the Jet Pulse Split (6.4.5) and theother end is connected to the ion source inlet of a massspectrometer.6.3.3 Carrier GasUltra high purity hydrogen is used ascarrier gas. Use of helium carrier gas results in unacceptablebroadening of the wat
32、er chromatographic peak. An example ofwater peaks is shown in Fig. 3.6.3.4 GC InjectorAn injector port with a glass insert anda septum is connected through a116 in. OD stainless steeltubing to a jet pulse split (6.4.5) in the inlet system (6.4). Theinjector temperature is set to at 220C to ensure th
33、at all watervapor in injected ambient air are not condensed in the injector.The GC column and total split flow rate are electronically setat 1.5 and 75 mL/min, respectively. The GC total split flowincludes a GC septum purge flow of 3mL/min (Fig. 1 and Fig.2) and GC injector split flow of 72mL/min.6.
34、4 Inlet SystemA system introduces high pressuresamples or standards into GC/MS for analysis. The sample orstandard enter the inlet system through “Sample Loop Pressur-ization” (Fig. 1) and then leave the inlet system to GC/MSthrough “Jet Pulse Injection” (Fig. 2). While the inlet system isin “Sample
35、 Loop Pressurization”, the sample loop (6.4.4)ispressurized directly with hydrogen samples or calibrationstandards without pressure regulation or flow restriction. Af-terwards, a six-port sample valve (6.4.1) switches the inletsystem to “Jet Pulse Injection”, in which pressurized hydrogenin the samp
36、le loop is released instantaneously onto the GCcolumn (6.3.2) and jet pulse split (6.4.5). Since the samplepressure is high, all parts of the inlet system must be capable ofworking at pressures of 1500 psi or higher.6.4.1 Six Ports ValveThis valve is used to switch from“Sample Loop Pressurization” (
37、Fig. 1) to “Jet Pulse Injection”(Fig. 2).6.4.2 Samples and Calibration StandardsAll calibrationstandards and samples are prepared or collected in 1800 psipressure rated containers with a DOT 3A1800 label (UnitedStated Department of Transportation mandated label) affixed tothe outside surface. All ca
38、libration standards and samples areconnected to the inlet system before beginning an analyticsequence to minimize the potential for air or moisture contami-nation due to addition or replacement of standard or samplecontainers.6.4.3 Vacuum Pumpan oil vacuum pump that can pumpdown to 50 mtorr or less.
39、6.4.4 Sample Loopstainless steel tubing with116 in. ODand 2 mL inside volume. Both ends of the sample loop areconnected to a six port valve (6.4.1).FIG. 2 Jet Pulsed InjectionD7649 1036.4.5 Jet Pulse Splita T-union connects the followingthree portions.6.4.5.1 Six port valve (6.4.1)6.4.5.2 Inlet of G
40、C column (6.4.2)6.4.5.3 Inlet of an electronic flow controller (EFC) with itsoutlet to ambient air. The flow rate of this EFC is alwayselectronically set at 150mL/min to vent most of the GC injectorsplit flow (72mL/min) during “Sample Loop Pressurization”(Fig. 1) and released hydrogen from pressuriz
41、ed sample loop in“Jet Pulse Injection” (Fig. 2).6.4.6 Digital Vacuum Gaugecapable of measuring abso-lute pressure at vacuum range 0 to 12,000 milli-torr (mtorr or10-3torr). For the vacuum range from 0 to 1000 mtorr, theaccuracy is 6 10% or6 10 mtorr, whichever is larger.6.4.7 Digital Pressure Gauges
42、Two types of digital pres-sure gauges are required. A pressure gauge 0 to 1000 psig isused to measure sample and standard final pressure. Anotherdigital pressure gauge in the low and narrow pressure range,such as 0 to 2000 torr, is used to measure the pressure of puregases in initial standard prepar
43、ation.6.4.8 Pressure RegulatorA 10,000 psi pressure regulatoris used to reduce UHP hydrogen pressure to approximate 400psi for calibration standard preparation. It is also used topressurize the inlet system during method blank analysis, andduring inlet system flushing.7. Reference Standards7.1 Typic
44、al reference standards are listed in Fig. 1.Twostandards prepared in helium containing 100 ppmv O2and 100ppmv N2, are commercial available. Remaining standardslisted in Fig. 1 are prepared as per below.7.2 0.5% CO2,Ar,N2and O2in hydrogenAn evacuated1-L cylinder is connected to four pressure-regulate
45、d com-pressed gas cylinders containing reagent or UHP grade CO2,Ar, N2and O2. The system is evacuated to less than 500 mtorrwith all the regulators opened and the main cylinder valvesclosed. With the system isolated from vacuum pump, the 1-Lcylinder valve is opened and 100 torr of each target compou
46、ndfrom the compressed gas cylinders is expanded into the systemand 1-Lcylinder. The 1-Lcylinder is then pressured using UHPFIG. 3 m/e18 Extracted Ion Chromatogram of Sample Analysis with Co-Injection of Ambient AirD7649 104hydrogen to 390 psi, or 390/14.7 3 760 = 2.02 3 104torr. Theconcentration of
47、each target compound is 100 torr/(2.023104torr) = 0.5 %. This standard can be used as a co-injectionstandard (9.3.3) and further diluted to prepare a 5 ppmvstandard (7.3). The UHP hydrogen used for preparation of both0.5% (7.2) and 5 ppmv standards (7.3) are free from CO2,Ar,N2and O2by this test met
48、hod.7.3 5ppmv CO2,Ar,N2and O2in hydrogen:7.3.1 Close all the valves in Fig. 1 except leave Valves 2, 4and both valves of the cylinder labeled with “5 ppmv CO2,Ar,N2this should be close to 72 mL/min.9.2.4 Close both Valves 2 and 4 and pressurize the entiresystem with standard or sample and measure th
49、e loop pressureusing a digital high pressure gauge as depicted in Fig. 1. Forsafety reason, it is recommended that the loop pressure not beover 500 psi. For the method blank analysis using UHPhydrogen, the loop should be pressurized to approximate 400psi.9.3 Jet Pulse Injection/GC/MS Analysis (Fig. 2):9.3.1 Switch the six port valve to “Jet Pulse Injection” (Fig.2) and simultaneously start GC/MS acquisition.9.3.2 Measure the GC injector split flow rate, which shouldbe 0 mL/min since most injector split flow vents out from thejet pulse split
