1、Designation: D7634 10Standard Test Method forVisualizing Particulate Sizes and Morphology of ParticlesContained in Hydrogen Fuel by Microscopy1This standard is issued under the fixed designation D7634; 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 primarily intended for visualizingand measuring the sizes and morph
3、ology of particulates inhydrogen used as a fuel for fuel cell or internal combustionengine powered vehicles. This test method describes proce-dures required to obtain size and morphology data of knownquality. This test method can be applied to other gaseoussamples requiring determination of particul
4、ate sizes and mor-phology provided the users data quality objectives are satis-fied.1.2 Mention of trade names in standard does not constituteendorsement or recommendation. Other manufacturers ofequipment, software or equipment models can be used.1.3 The values stated in SI units are to be regarded
5、asstandard. No other units of measurement are included in thisstandard.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 th
6、e applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D7650 Test Method for Test Method for Sampling ofParticulate Matter in High Pressure Hydrogen used as aGaseous Fuel with an In-Stream Filter2.2 SAE Standards:3SAE TIR J2719 Hydrogen Quality Guideline f
7、or Fuel CellVehicles, April 2008SAE J6000 Compressed Hydrogen Surface Vehicle Refu-eling Connection Devices3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 constituentcomponent (or compound) found withina hydrogen fuel mixture3.1.2 contaminantimpurity that adversely affects the
8、 com-ponents within the fuel cell system or the hydrogen storagesystem3.1.3 fuel cell grade hydrogenhydrogen satisfying thespecifications in SAE TIR J2719.3.1.4 gaseous fuelmaterial to be tested, as sampled, with-out change of composition by drying or otherwise.3.1.5 HEPA FilterA high efficiency par
9、ticulate air filterwhich, by definition, removes at least 99.97% of airborneparticles 0.3m in diameter.3.1.6 SAE TIR J2719Information Report on the develop-ment of a hydrogen quality guideline for fuel cell vehicles3.2 Acronyms:3.2.1 FCVFuel Cell Vehicle3.2.2 PSAParticulate sampling adapter for samp
10、ling par-ticulate in hydrogen fuel3.2.3 HQSAHydrogen quality sampling adapter for sam-pling gaseous hydrogen fuel3.2.4 SAESociety of Automotive Engineers International3.2.5 PEMPolymer Electrolyte Membrane, also calledProton Exchange Membrane3.2.6 PEMFCproton exchange membrane fuel cells4. Summary of
11、 Test Method4.1 This procedure is for visualizing and measuring, bymicroscopy, the sizes and morphology of particulates aftercollection of particulates contained within hydrogen fuel atfueling station dispenser nozzles (Test Method D7650, SAEJ2600) or other gaseous fuel delivery system dispenser int
12、er-faces. Every precaution should be taken to avoid contamination1This 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.
13、1520/D763410.2For 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 SAE International (SAE), 400 Com
14、monwealth Dr., Warrendale,PA 15096-0001, http:/www.sae.org.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.of particulates onto the filter coming from the PSA, theanalytical system, ambient air, filter handling or other environ-menta
15、l sources.5. Significance and Use5.1 Low temperature fuel cells such as proton exchangemembrane fuel cells (PEMFCs) require high purity hydrogenfor maximum material performance and lifetime. The particu-lates in hydrogen used in FCVs and hydrogen powered internalcombustion vehicles may adversely aff
16、ect pneumatic controlcomponents, such as valves or other critical system compo-nents. The visualization of the size and morphology of particlesis an important tool for determining particle origin as well asfor devising particle formation reduction strategies.6. Interferences6.1 Particulate matter or
17、iginating in the environment orequipment will interfere with the determinations. Every pre-caution should be taken to avoid contamination of particulatesonto the filter coming from the analytical system, ambient air,filter handling, or other environmental sources.6.2 The potential effect of body moi
18、sture or oils contactingthe filters is minimized by using powder-free gloves whilehandling filters outside the glove box.7. Apparatus7.1 MicroscopeA microscopy system is necessary to havereflectance and transmittance illuminations, built-in polariza-tion system and a digital camera with an USB conne
19、ction to acomputer. The microscope is covered with a plastic cover whennot in use and placed on a table top inside a horizontal flowhood containing a HEPA filter (7.3).7.2 Mini-Clean RoomA small clean room with HEPAfilter should be used to store unused TFE-flourocarbon filters,filter holders, and sa
20、mpled filters at atmospheric moisture lessthan 30%.7.3 HEPA Filter Fitted Horizontal Flow HoodA flowhood that blows filtered air through a HEPA filter horizontally.This eliminates or reduces environmental particulates that caninterfere with microscope visualization. The air velocity mea-sured by Van
21、eometer (7.4) should be over 80 ft/minute (1.46km/hour); otherwise, an electronic air velocity meter (7.5)should alarm the operator.7.4 VaneometerThis metering device is used to measureair velocity passing through the HEPA Filter fitted HorizontalFlow Hood.7.5 Electronic Air Velocity MeterAn Electro
22、nic air veloc-ity meter is used to notify the analyst if the horizontal air flowbehind the microscope falls below approximately 80 ft perminute.7.6 HEPA VacuumA vacuum fitted with a HEPA filter isused to remove dust from the glove box or areas where filtersare stored or manipulated.8. Reagents and M
23、aterials8.1 FilterA 47 mm diameter polytetrafluoroethylene filter(PTFE Membrane Disc Filters) is used. An example of asuitable filter is a Pall TF-200 47mm 0.2 m (P/N 66143) witha pore size of 0.2 m. One side of this type filter is composedof polytetrafluoroethylene (PTFE) and the reverse side iscom
24、posed of polypropylene. Installed in the filter holder, thePTFE side should face the hydrogen fuel stream. The polypro-pylene side of the filter is generally shinier than the PTFE side,which is dull when viewed under a bright light. Whenexamining, visualizing, handling, and weighing filters, the sid
25、efacing the gas stream and collecting particulates must alwaysface up. Before visualizing a filter by microscopy, examine itcarefully to ensure the filter is not damaged and record thecondition and appearance of the filter. Filters are always storedin a small particulate free plastic container in a
26、mini clean room(7.2) when not in use.9. Test Specimens and Test Units9.1 Test specimensParticulate.9.2 Test unitsm.10. Preparation of Apparatus10.1 MicroscopeThe microscope, when not in use, mustbe covered with particulate free plastic and remain in aHorizontal Flow Hood (7.3) fitted with a HEPA Fil
27、ter. Thesurface of the hood must be cleaned using a HEPA filter fittedvacuum (7.6) before visualization activity and the flow in thehood is turned on at least an hour before this activity.11. Conditioning11.1 Filter ConditioningNew filters are stored in theiroriginal packaging and the filters ready
28、for visualization arestored in a mini-clean room as described in 7.2.12. Procedure12.1 Always clean horizontal flow hood HEPAfilter air inletsurfaces using a HEPA Vacuum before handling filters.12.2 Clean the surface area around microscope with a HEPAvacuum before performing visualizations.12.3 Remo
29、ve the plastic microscope covering inside theHEPA filter fitted horizontal flow hood. Place a Vaneometers(7.4) on one side of the microscope and an electronic airvelocity meter (7.5) on the other side to ensure the air linearvelocity is greater than 80ft/min.12.4 Transfer filters stored in a plastic
30、 container from themini clean room to the hood and adjacent to the microscope.12.5 Use plastic tweezers to remove a filter from the plasticcontainer and place it onto a clean glass surface under themicroscopes objective lens. The glass is placed on a stage,which can be moved in different directions
31、so that differentportions of filter can be visualized.12.6 Adjust the coaxial coarse and fine adjustments to focusthe surface of filter. Use the lowest magnification and move thestage to locate particulates on the polytetrafluoroethylene filter.12.7 Use a higher magnification, reflectance polarizing
32、 lightor transmittance illumination as needed to get the best visual-ization of particulates on the filter. The images of the particu-lates are taken by a digital camera interfaced to the microscope.12.8 The digital image is input into Adobe Acrobat4,orsimilar, software. The grid measurement tool of
33、AdobeAcrobat4Trademarked by Adobe Systems Incorporated.D7634 102is used to measure the size of the particulate. Select a scaleratio such that the length of 1.00 mm microscope calibrationgrid provided by microscope manufacturer to 1 mm, as shownin Fig. 1 which is an example of measurement of the size
34、s ofparticulates by Adobe Acrobat software. The scale ratio asshown in Fig. 1 of the Adobe Acrobat measurement tool is setso as the microscope calibration grid (1.00 mm total length) tobe 1 mm. We found the distance between grids on polytet-rafluoroethylene filters is close to 1 mm. After measuremen
35、t,one can use “Export Measurement Makeup to Excel” tool todownload all the measurements to an Excel5file for dataprocess.12.9 Use the largest diameter or measurement of the particleto associate a size to that particle. Particle size and any otherobservations, such as, pinholes, are recorded and subm
36、ittedwith the final report.13. Report13.1 Report particulate sizes, and any other observations orcomments. Include images of particulates and their size mea-surement in the final report. However, there are several casesencountered in the particulate sizes analyses, which should bereported accordingl
37、y as described below.13.2 A few particulates on filterIn this case, all theparticulates images with their sizes should be reported with anexample given in Fig. 2. However, if the transmission micro-scope cannot give clear image of the particulate, the reflectivepolarized light microscope should be u
38、sed to give clear imageand particulate size. An example is shown in Fig. 3 and Fig. 4,in which the image of particulate is taken by a transmission andpolarized light reflective microscope, respectively. The polar-ized light reflective microscopic image apparently showsclearer image of the particulat
39、e.13.3 Pinhole on filterPolytetrafluoroethylene filter is ingeneral not damaged; however, occasionally particulates withmetallic nature, such as the one shown in Fig. 4, can penetratethe filter with pinholes left behind. Most of pinholes usuallylocate close to the center of the filter. In case pinho
40、les aredetected, the sizes and images of pinholes should be reported.An example of pinhole image and size is shown in Fig. 5.13.4 A lot of 100m or smaller particulates at the center offilterMost of 100m or smaller particulates usually locate atthe centric circle on the filter of approximate 8mm OD.
41、In thiscase, all the sizes of the particulates within this circle should bemeasured and their sizes downloaded into an Excel file, inwhich the particulate sizes are rearranged from small to largesizes. The number of particulates found in the different rangesof particulate sizes should be reported al
42、ong with the images ofthe centric center on the filter containing most of smallparticulates. A portion of images of the centric circle on thefilter with many 100m or smaller particulates is shown as anexample in Fig. 6.Any particulates found outside the 8 mm ODcentric circle on filter should be repo
43、rted as in 13.2.5Trademarked by Microsoft Corporation.FIG. 1 An Example of Particulate Size MeasurementD7634 10313.5 Overlapped particulates at the center of filter In thiscase, the image of overlapped particulate should be reportedwith the overall dimension. An example is given in Fig. 7,inwhich th
44、e dimension of the overlapped particulates is approxi-mately 3.55 by 3.06 mm. Any particulates found outside theoverlapped particulates should be reported as in 13.2.13.6 A lot of pinholes at the center of filterAll thepinholes usually locate with 8mm OD centric circle on thefilter. The image of the
45、 centric center on the filter containingmost of the pinholes pointed by arrows should be reported. Aportion of images of the centric circle on the filter with manypinholes is shown as an example in Fig. 8. The sizes ofpinholes may not necessary measured as long as their sizes canbe estimated by the
46、sizes of nearby particulates. Any particu-lates found in this case should be reported as in 13.2.14. Precision and BiasNOTE 1Statements of precision and bias for this test method will beprovided as a result of interlaboratory testing which will be performedwithin 5 years.14.1 RepeatabilityThe differ
47、ence between successive testresults obtained by the same operator with the same apparatusunder constant operating conditions on identical test materials.14.1.1 Repeatability1% full scale for successive identicalsamples.FIG. 2 Particulate Images with Size of 0.29FIG. 3 Particulate Images by Transmiss
48、ion MicroscopeFIG. 4 Particulate Image by Polarized Light Reflective MicroscopeD7634 10414.2 ReproducibilityThe difference between two singleand independent results obtained by different operators work-ing in different laboratories on identical test materials.14.2.1 Reproducibility data to added wit
49、hin 5 years ofmethod approval.14.3 BiasA statement of bias will be developed throughinter-laboratory testing by the responsible study group.15. Keywords15.1 image; microscope; particulate sizeFIG. 5 Pinhole Images and SizesFIG. 6 Many Particulates Found at Center of FilterFIG. 7 Overlapped Particulates Found at Center of FilterD7634 105ADDITIONAL READINGASTM Standards2(1) D4150 Terminology Relating to Gaseous Fuels(2) D7651 Test Method for Gravimetric Measurement of ParticulateConcentration of Hydrogen FuelISO Standards6(3) ISO/TR 15916
