1、Designation: F25/F25M 09 (Reapproved 2015)Standard Test Method forSizing and Counting Airborne Particulate Contamination inCleanrooms and Other Dust-Controlled Areas1This standard is issued under the fixed designation F25/F25M; the number immediately following the designation indicates the year ofor
2、iginal 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 covers counting and sizing airborneparticula
3、te matter 5 m and larger (macroparticles). Thesampling areas are specifically those with contamination levelstypical of cleanrooms and dust-controlled areas.1.2 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard. The values stated ineach system may not
4、be exact equivalents; therefore, eachsystem shall be used independently of the other. Combiningvalues from the two systems may result in non-conformancewith the standard.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility
5、of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory requirements prior to use.2. Referenced Documents2.1 ASTM Standards:2F50 Practice for Continuous Sizing and Counting of Air-borne Particles in Dust-Controlled Areas and C
6、leanRooms Using Instruments Capable of Detecting SingleSub-Micrometre and Larger Particles2.2 ISO Standard:ISO 14644-1 Cleanrooms and Associated ControlledEnvironmentsPart 1: Classification of Air Cleanliness32.3 IEST Document:IEST-G-CC1003 Measurement of Airborne Macroparticles(1999)42.4 SAE Docume
7、nt:SAE Abstract ARP-743, Procedure for the Determination ofParticulate Contamination of Air in Dust-ControlledSpaces by Particle Count Method, August 196253. Terminology3.1 Definitions:3.1.1 airflow:3.1.1.1 unidirectional airflowair flow which has a singulardirection of flow and may or may not conta
8、in uniformvelocities of air flow along parallel lines.NOTE 1Formerly known as laminar airflow.3.1.1.2 non-unidirectional airflowair distribution wherethe supply air entering the room mixes with the internal air bymeans of induction.3.1.2 critical pressurefor an orifice, with a constant up-stream pre
9、ssure, the downstream pressure at which the flowwill not increase when the downstream pressure decreases.3.1.3 critical pressure ratiothe ratio of the critical pres-sure of an orifice to the entrance pressure.3.1.4 customerorganization, or the agent thereof, respon-sible for specifying the requireme
10、nts of a cleanroom or cleanzone.3.1.5 fiberparticle having an aspect (length-to-width) ratioof 10 or more.3.1.6 macroparticleparticle with an equivalent diametergreater than 5 m.1This test method is under the jurisdiction of ASTM Committee E21 on SpaceSimulation and Applications of Space Technology
11、and is the direct responsibility ofSubcommittee E21.05 on Contamination.Current edition approved Oct. 1, 2015. Published November 2015. Originallyapproved in 1963. Last previous edition approved in 2009 as F25 09. DOI:10.1520/F0025_F0025M-09R15.2For referenced ASTM standards, visit the ASTM website,
12、 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 American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/ww
13、w.ansi.org.4Available from Institute of Environmental Sciences and Technology (IEST),Arlington Place One, 2340 S. Arlington Heights Rd., Suite 100, Arlington Heights,IL 60005-4516, http:/www.iest.org.5Available from Society of Automotive Engineers (SAE), 400 CommonwealthDr., Warrendale, PA 15096-000
14、1, http:/www.sae.org.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13.1.7 M descriptormeasured or specified concentration ofmacroparticles per cubic metre of air, expressed in terms of theequivalent diameter that is characteristic of
15、 the measurementmethod used.3.1.7.1 DiscussionThe M descriptor may be regarded asan upper limit for the averages at sampling locations (or as anupper confidence limit, depending upon the number of sam-pling locations used to characterize the cleanroom or cleanzone). M descriptors cannot be used to d
16、efine airborne particu-late cleanliness classes, but they may be quoted independentlyor in conjunction with airborne particulate cleanliness classes.3.1.8 occupancy states:3.1.8.1 as-builtcondition where the installation is com-plete with all services connected and functioning but with noadditional
17、equipment, materials, or personnel present.3.1.8.2 at-restcondition where the installation is completewith equipment installed and operating in a manner agreedupon by the customer and supplier, but with no personnelpresent.3.1.8.3 operationalcondition where the installation isfunctioning in the spec
18、ified manner, with the specified numberof personnel present and working in the manner agreed upon.3.1.9 particle sizemajor projected dimension of the par-ticle.4. Summary of Test Method4.1 The test method is based on the microscopical exami-nation of particles impinged upon a membrane filter with th
19、eaid of a vacuum. The number of sampling points is propor-tional to the floor area of the enclosure to be checked. Theapparatus and facilities required are typical of a laboratory forthe study of macroparticle contamination. The operator musthave adequate basic training in microscopy and the techniq
20、uesof particle sizing and counting.5. Apparatus5.1 Filter Holder,6aerosol open type having an effectivefiltering area of 960 6 25 mm2.5.2 Adapter.75.3 Flow-Limiting Orifice,810 L/min.5.4 Membrane Filters,9black, 0.80-m mean pore size,47-mm diameter, with imprinted grid squares having sides 3.106 0.0
21、8 mm. Pressure drop across the filter used shall be nogreater than 50 torr for an air flow rate of 1 L/mincm2.5.5 Forceps, with unserrated tips.5.6 Vacuum Pump, capable of producing a pressure of 34kPa (260 torr) (vacuum of 500 torr) downstream of the orificeat a flow rate of 10 L/min through the or
22、ifice.5.7 Flowmeter, calibrated and having a capacity in excess of10 L/min.5.8 Glass Microscope Slides, 50 mm by 75 mm, or 47-mmplastic disposable petri dishes.6The sole source of supply of the apparatus known to the committee at this timeis 47 mm Stainless Steel, Millipore XX5004710, available from
23、 MilliporeCorporation, 290 Concord Rd., Billerica, MA01821. If you are aware of alternativesuppliers, please provide this information to ASTM International Headquarters.Your comments will receive careful consideration at a meeting of the responsibletechnical committee,1which you may attend.7The sole
24、 source of supply of the apparatus known to the committee at this timeis Luer slip to14 in. -38 in. ID hose Stainless Steel, XX6200004, available fromMillipore Corporation, 290 Concord Rd., Billerica, MA 01821. If you are aware ofalternative suppliers, please provide this information to ASTM Interna
25、tionalHeadquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee,1which you may attend.8The sole source of supply of the apparatus known to the committee at this timeis Limiting Orifice Set (5 orifices including 10 L/min), XX5000000, available f
26、romMillipore Corporation, 290 Concord Rd., Billerica, MA 01821. If you are aware ofalternative suppliers, please provide this information to ASTM InternationalHeadquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee,1which you may attend.9The
27、sole source of supply of the apparatus known to the committee at this timeis AABG04700, Black Grid, 0.80 m, available from Millipore Corporation, 290Concord Rd., Billerica, MA 01821. If you are aware of alternative suppliers, pleaseprovide this information to ASTM International Headquarters. Your co
28、mments willreceive careful consideration at a meeting of the responsible technical committee,1which you may attend.FIG. 1 Suitable Microscope: Inclined Binocular Body; MechanicalStage; Triple Nosepiece; Ocular-Objective Combination to Obtain40 to 45 and 90 to 150 MagnificationFIG. 2 Typical Air Samp
29、ling-Filtration ApparatusF25/F25M 09 (2015)25.9 Binocular Microscope, (Fig. 1) with ocular-objectivecombinations to obtain 40 to 45 and 90 to 150 magnifica-tions. Latter objective shall have numerical aperture of 0.15min.5.10 Normal Counter,10(2 gang) or equivalent.5.11 Microscope Lamp, 6 V, 5 A, hi
30、gh-intensity.5.12 Ocular Micrometer Scale, 5-mm linear scale with 100divisions.5.13 Stage Micrometer, standard 0.01-mm to 0.1-mm scale.6. Sampling Apparatus6.1 The airborne particles shall be collected, with the aid ofa vacuum source, on a membrane filter of 960-mm2effectivefiltering area.6.2 The ap
31、paratus specified in 5.1, 5.2, and 5.3 or equivalentshall be used.6.3 Fig. 2 is picture of a typical sampler.6.4 Fig. 3 is a drawing of a typical sampler assembly.6.5 Sampler airflow is maintained using the vacuum pump,specified in 5.6, connected to the sampler and either aflowmeter to measure flow
32、or a calibrated orifice to controlflow.6.5.1 The flow rate may be adjusted using a flowmeter andvalve downstream of the sampler with filter and other elementsinstalled.6.5.2 A calibrated orifice, 5.3, may be used to control theairflow rate. The specified flow rate for the orifice depends oncritical
33、pressure ratio of less than 0.53 for air at roomtemperature and pressure. The limiting orifice shall be cali-brated with the pump, filter holder, and filter used for this testmethod. The required flow rate is 10 6 0.5 L/min.6.6 Inspect the sampler, including the orifice, to ensure thatit is free of
34、restricting matter before each test. Clean if required.7. Sampling in a Cleanroom, Clean Zone, or otherControlled Areas7.1 Sampling Plan:7.1.1 A sampling plan shall be provided.7.1.2 ISO 14644-1 and IEST-G-CC1003 may be used asguides for the plan.7.2 The filter surface may be vertical or horizontal
35、withrespect to the floor.7.2.1 The orientation of the filter depends on airflow direc-tion for unidirectional airflow areas.7.2.1.1 Sampling in a unidirectional airflow shall be as closeto isokinetic as is possible.7.2.1.2 IEST-G-CC1003 provides additional information onisokinetic sampling.7.2.2 For
36、 nonunidirectional airflow areas, the customer mayspecify an orientation or the process being monitored in thecleanroom may indicate which orientation would be preferred.7.2.2.1 In nonunidirectional airflow, airflow directions andvelocities vary with location and time.7.2.2.2 IEST G-CC1003 recommend
37、s a sample inlet probe,with an inlet diameter of at least 20 mm, facing upward. Thiswill collect larger particles that tend to settle out of the air.7.3 The standard sample for this test method shall be 300 L(10 ft3).7.3.1 The sample size may be adjusted for specific condi-tions.7.3.2 The number of
38、particles sampled shall meet statisticalcriteria of ISO 14644-1 or other accepted statistical samplingcriteria.7.4 The sample shall be taken at waist level 0.9 to 1.0 m(36 to 40 in.) from the floor), at bench level, or at other pointsas specified by the customer. The sample points may beselected for
39、 relevance to and sensitivity of the operations beingperformed in the cleanroom.7.5 The number and location of sampling points shall be asdesignated in the sampling plan.7.5.1 The minimum number of sample locations as specifiedin ISO 14644-1, Annex B may be used:NL5 =A (1)where:NL= minimum number of
40、 sampling locations (rounded up toa whole number), andA = area of the cleanroom or clean zone in square metres.In the case of unidirectional horizontal airflow, the area Amay be considered as the cross section of the moving airperpendicular to the direction of the airflow.7.5.2 The nature of the ope
41、rations or the customer mayselect the number of sampling points.8. Sampling in a Duct or Pipe8.1 The sampling of a moving gas stream in a duct orpipeline requires isokinetic sampling.10The sole source of supply of the apparatus known to the committee at this timeis the Veeder-Root counter, available
42、 from Veeder-Root, 6th Ave. 100 divisions of the measuring eyepiece subtend1050 m, one division of the measuring eyepiece = 10.5 m.10.7.3 Place the microscope slide or petri dish containingthe specimen under the microscope. The petri dish cover mustbe removed.10.7.4 Adjust the microscope lamp intens
43、ity and direct it onthe specimen from an oblique position to obtain the maximumdefinition for sizing and counting. High intensity illuminationis a critical requirement.10.7.5 Use a magnification of approximately 45 for count-ing particles 50 m or larger and approximately 100 forparticles smaller tha
44、n 50 m. (Greater magnification may beadvantageous for examination to identify particles.)NOTE 3Analysis for particles in the 0.5-m to 5.0-m size range maybe achieved by using transmitted light techniques, after rendering thewhite filter transparent by placing the filter on immersion oil of refractiv
45、eindex 1.515. A magnification of at least 500 is required. For transmittedlight microscopy, a white filter must be used (instead of black filter) sinceonly the white filter can be rendered transparent with immersion oil. If asmaller pore size filter is used, the flowmeter and limiting orifice willre
46、quire calibration with filter holder and filter in place.10.7.6 Particles should be counted and tabulated in two sizeranges: particles greater than 50 m and particles 5 to 50 m.Particles smaller than 5 m are not to be counted by thismethod. The size of a particle is determined by its greatestproject
47、ed dimension.10.8 Method of Counting Particles:10.8.1 Adjust the microscopic focus and lamp position sothat maximum clarity of filter surface and particle definition isobtained.10.8.2 With the lower magnification (approximately 45),count the entire effective filter area for particles in the rangesla
48、rger than 50 m.10.8.3 Use a manual counter or equal for counting theparticles.10.8.4 At the higher magnification, estimate the number ofparticles in the 5-m to 50-m ranges over the effectivefiltering area by scanning one unit area.10.8.5 If the total number of particles in this range isestimated to
49、be less than 500, count the number of particles ineach size range being measured over the entire effectivefiltering area.10.8.6 A statistical analysis shall be performed on theparticle counts in each size range to determine the uncertaintiesin the measurement.10.8.7 If the total number of particles in the 5-m to 50-mranges is estimated is greater than 500, the counting procedurein 10.9 applies.10.8.8 The largest projected dimension of the particle de-termines the size category of the particle.10.8.9 Fibers may be counted separately i
