1、Designation: D7634 10 (Reapproved 2017)Standard 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 a
2、doption 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 is primarily intended for visualizingand measuring t
3、he sizes and morphology 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 determi
4、nation of particulate 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 a
5、re to be regarded 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 practice
6、s and determine the applica-bility of regulatory limitations prior to use.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 Re
7、com-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D7650 Test Method for Sampling of Particulate Matter inHigh Pressure Hydrogen used as a Gaseous Fuel with anIn-Stream Filter2.2 SAE Standards:3SAE TIR J2719 Hyd
8、rogen Quality Guideline for Fuel CellVehicles, April 2008SAE J6000 Compressed Hydrogen Surface Vehicle Refuel-ing 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 t
9、hat adversely affects the 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 Fi
10、lterA high efficiency particulate 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
11、sampling adapter for sampling 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 membran
12、e fuel cells1This 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 April 1, 2017. Published April 2017. Originallyapproved in 2010. Last previous edition approved in 2
13、010 as D7634-10. DOI:10.1520/D763410R17.2For 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 I
14、nternational (SAE), 400 Commonwealth Dr., Warrendale,PA 15096-0001, http:/www.sae.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
15、 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.14. Summary of Test Method4.1 This procedure is for visualizing and measuring, bymic
16、roscopy, 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 inter-faces. Every precaution should be taken to avoid contaminationof pa
17、rticulates onto the filter coming from the PSA, theanalytical system, ambient air, filter handling or other environ-mental sources.5. Significance and Use5.1 Low temperature fuel cells such as proton exchangemembrane fuel cells (PEMFCs) require high purity hydrogenfor maximum material performance an
18、d lifetime. The particu-lates in hydrogen used in FCVs and hydrogen powered internalcombustion vehicles may adversely affect 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
19、 particle origin as well asfor devising particle formation reduction strategies.6. Interferences6.1 Particulate matter originating in the environment orequipment will interfere with the determinations. Every pre-caution should be taken to avoid contamination of particulatesonto the filter coming fro
20、m the analytical system, ambient air,filter handling, or other environmental sources.6.2 The potential effect of body moisture 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
21、 to havereflectance and transmittance illuminations, built-in polariza-tion system and a digital camera with an USB connection 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-Cl
22、ean RoomA small clean room with HEPAfilter should be used to store unused TFE-flourocarbon filters,filter holders, and sampled 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
23、 or reduces environmental particulates that caninterfere with microscope visualization. The air velocity mea-sured by Vaneometer (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 m
24、easureair velocity passing through the HEPA Filter fitted HorizontalFlow Hood.7.5 Electronic Air Velocity MeterAn Electronic 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
25、 a HEPA filter isused to remove dust from the glove box or areas where filtersare stored or manipulated.8. Reagents and Materials8.1 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
26、 pore size of 0.2 m. One side of this type filter is composedof polytetrafluoroethylene (PTFE) and the reverse side iscomposed 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
27、 side,which is dull when viewed under a bright light. Whenexamining, visualizing, handling, and weighing filters, the sidefacing 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 recor
28、d thecondition and appearance of the filter. Filters are always storedin a small particulate free plastic container in a 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
29、not in use, mustbe covered with particulate free plastic and remain in aHorizontal Flow Hood (7.3) fitted with a HEPA Filter. 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
30、activity.11. Conditioning11.1 Filter ConditioningNew filters are stored in theiroriginal packaging and the filters ready 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 ha
31、ndling filters.12.2 Clean the surface area around microscope with a HEPAvacuum before performing visualizations.12.3 Remove 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
32、.5) on the other side to ensure the air linearvelocity is greater than 80ft/min.12.4 Transfer filters stored in a plastic 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 glas
33、s surface under themicroscopes objective lens. The glass is placed on a stage,which can be moved in different directions so that differentportions of filter can be visualized.D7634 10 (2017)212.6 Adjust the coaxial coarse and fine adjustments to focusthe surface of filter. Use the lowest magnificati
34、on and move thestage to locate particulates on the polytetrafluoroethylene filter.12.7 Use a higher magnification, reflectance polarizing 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
35、camera interfaced to the microscope.12.8 The digital image is input into Adobe Acrobat4,orsimilar, software. The grid measurement tool ofAdobeAcrobatis used to measure the size of the particulate. Select a scaleratio such that the length of 1.00 mm microscope calibrationgrid provided by microscope m
36、anufacturer to 1 mm, as shownin Fig. 1 which is an example of measurement of the sizes 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
37、 between grids on polytetra-fluoroethylene filters is close to 1 mm. After measurement, onecan 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 partic
38、le. Particle size and any otherobservations, such as, pinholes, are recorded and submittedwith 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 c
39、asesencountered in the particulate sizes analyses, which should bereported accordingly 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
40、 clear image of the particulate, the reflectivepolarized light microscope should be used 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-iz
41、ed light reflective microscopic image apparently showsclearer image of the particulate.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 be
42、hind. Most of pinholes usuallylocate close to the center of the filter. In case pinholes 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 p
43、articulates usually locate atthe centric circle on the filter of approximate 8mm OD. 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
44、 particulates found in the different rangesof particulate sizes should be reported along 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
45、. 6.Any particulates found outside the 8 mm ODcentric circle on filter should be reported as in 13.2.4Trademarked by Adobe Systems Incorporated.5Trademarked by Microsoft Corporation.FIG. 1 An Example of Particulate Size MeasurementD7634 10 (2017)3FIG. 2 Particulate Images with Size of 0.29FIG. 3 Par
46、ticulate Images by Transmission MicroscopeFIG. 4 Particulate Image by Polarized Light Reflective MicroscopeFIG. 5 Pinhole Images and SizesD7634 10 (2017)413.5 Overlapped particulates at the center of filterIn thiscase, the image of overlapped particulate should be reportedwith the overall dimension.
47、 An example is given in Fig. 7,inwhich the 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 the pinholesusually locate with 8mm OD cent
48、ric circle on the filter. Theimage of the centric center on the filter containing most of thepinholes pointed by arrows should be reported. A portion ofimages of the centric circle on the filter with many pinholes isshown as an example in Fig. 8. The sizes of pinholes may notnecessary measured as lo
49、ng as their sizes can be estimated bythe sizes of nearby particulates. Any particulates found in thiscase 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 difference 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 ident
