1、Designation: F 25/F 25M 09Standard Test Method forSizing and Counting Airborne Particulate Contamination inCleanrooms and Other Dust-Controlled Areas1This standard is issued under the fixed designation F 25/F 25M; the number immediately following the designation indicates the yearof original adoptio
2、n or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval.A superscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers counting and sizing airborneparticulate matter 5 m
3、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 be exact equiv
4、alents; 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 of the user of
5、 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 Clean RoomsUsin
6、g Instruments Capable of Detecting Single Sub-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 Document:SAE Abstra
7、ctARP-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 singu-lar direction of flow and may or may not contain uniformve
8、locities 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 pressure, the d
9、ownstream 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 requirements of a cle
10、anroom or cleanzone.3.1.5 fiberparticle having an aspect (length-to-width) ra-tio of 10 or more.3.1.6 macroparticleparticle with an equivalent diametergreater than 5 m.3.1.7 M descriptormeasured or specified concentration ofmacroparticles per cubic metre of air, expressed in terms of theequivalent d
11、iameter that is characteristic of 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).
12、M descriptors cannot be used to define airborne particu-late cleanliness classes, but they may be quoted independentlyor in conjunction with airborne particulate cleanliness classes.1This test method is under the jurisdiction of ASTM Committee E21 on SpaceSimulation and Applications of Space Technol
13、ogy and is the direct responsibility ofSubcommittee E21.05 on Contamination.Current edition approved April 1, 2009. Published April 2009. Originallyapproved in 1963. Last previous edition approved in 2004 as F 25 04.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM
14、 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:/www.ansi.org.4Available from In
15、stitute 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 15096-0001, http:/www.sae.org.1Copyrig
16、ht ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.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 equipment, materials, or personnel present
17、.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 specified manner, with the specified numberof
18、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 theaid of a vacuum. The number of sampling p
19、oints 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 techniquesof particle sizing and counting.5. Appa
20、ratus5.1 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 0.08 mm. Pressure drop across the filter used
21、 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 orifice.5.7 Flowmeter, calibrated and having
22、 a capacity in excess of10 L/min.5.8 Glass Microscope Slides, 50 mm by 75 mm, or 47-mmplastic disposable petri dishes.5.9 Binocular Microscope, (Fig. 1) with ocular-objectivecombinations to obtain 40 to 453 and 90 to 1503 magnifica-tions. Latter objective shall have numerical aperture of 0.15min.5.1
23、0 Normal Counter,10(2 gang) or equivalent.5.11 Microscope Lamp, 6 V, 5 A, high-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.6The sole source of supply of the apparatus known to the committee at this timeis 47 mm S
24、tainless Steel, Millipore XX5004710, available from Millipore Corpo-ration, 290 Concord Rd., Billerica, MA 01821. 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 responsi
25、bletechnical committee,1which you may attend.7The sole 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 supp
26、liers, please provide this information to ASTM InternationalHeadquarters. 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 (
27、5 orifices including 10 L/min), XX5000000, available fromMillipore 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 therespo
28、nsible technical committee,1which you may attend.9The 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 i
29、nformation to ASTM International Headquarters. Your comments willreceive careful consideration at a meeting of the responsible technical committee,1which you may attend.10The sole source of supply of the apparatus known to the committee at this timeis the Veeder-Root counter, available from Veeder-R
30、oot, 6th Ave. MechanicalStage; Triple Nosepiece; Ocular-Objective Combination to Obtain40 to 453 and 90 to 1503 MagnificationFIG. 2 Typical Air Sampling-Filtration ApparatusF 25/F 25M 0926. Sampling Apparatus6.1 The airborne particles shall be collected, with the aid ofa vacuum source, on a membrane
31、 filter of 960-mm2effectivefiltering area.6.2 The apparatus 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 t
32、o the sampler and either aflowmeter to measure flow 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 spe
33、cified flow rate for the orifice depends oncritical 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,
34、 including the orifice, to ensure thatit is free of 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
35、.2 The filter surface may be vertical or horizontal 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 ad
36、ditional information onisokinetic sampling.7.2.2 For 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 wi
37、th location and time.7.2.2.2 IEST G-CC1003 recommends 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 ad
38、justed for specific condi-tions.7.3.2 The number of 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 b
39、y the customer. The sample points may beselected for 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
40、 B may be used:NL5 =A (1)where:NL= minimum number of sampling locations (rounded upto a 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
41、direction of the airflow.7.5.2 The nature of the operations 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.8.2 Often by reason of the total flow, the allowable pressuredrop
42、, or the physical dimensions of the system (as for examplean air conditioning air duct), it is impracticable to sample theentire flow.8.3 Because of the low viscosity of gas, moving gas streamspresent several special sampling problems, which may disturbthe results unless care is taken.8.4 To collect
43、 a representative sample of particulate con-tamination from a ducted air stream, insert a probe (as shownin Fig. 4) coupled to the sampling apparatus described in 5.1,5.2, and 5.3.8.5 Achieving accurate isokinetic sampling requires that thegas linear velocity at the probe opening match that in the d
44、uct.Equal velocities may be achieved by a proper ratio between theprobe opening and the limiting orifice dimensions, for ex-ample:flow in duct L/min!duct cross2sectional area5sampling rate L/min!probe opening area(2)8.6 Failure to match the probe and duct velocities will causea distortion of results
45、 favoring either large particles if the probevelocity lower than duct velocity or small particles if the probevelocity higher than duct velocity.FIG. 3 Typical Aerosol Monitor Sampling SystemF 25/F 25M 0938.7 Fig. 5 shows an open-type holder installed in a duct.Some large particles are diverted from
46、 the filter by airflowaround the filter holder. Most small particles are diverted.8.8 Probes shall have thin walls, sharp edges, as large aninside diameter as is practicable, but with a minimum insidediameter of 6.4 mm (0.25 in.).8.8.1 Practice F50 provides some guidelines for sampleprobe tubing.8.8
47、.1.1 Sample transit tubes should be configured so that theflow Reynolds number is maintained in the range 5000 to25 000.8.8.1.2 For particles in the size range 0.1 m to approxi-mately 2 m in diameter and a flow rate of 30 L/min (1ft3/min), a transit tube up to 30 m long can be used.8.8.1.3 For parti
48、cles in the size range approximately 2 to 10m, a maximum transit tube length of 3 m can be used.8.8.1.4 If a flexible transit tube is to be used, then no radiusof curvature below 150 mm shall be used.8.8.2 Tubing diameter, length, and bend radius shall beselected to maximize the transport of particl
49、es of the maximumsize to be measured.8.9 Probes shall head directly up stream.8.10 Sampling rate and probe dimensions shall be carefullyadjusted to match duct and probe air velocities.9. Preparation of Apparatus9.1 Before sampling, remove dirt and dust from the filterholder by washing in a free-rinsing detergent, ketone-freeisopropyl alcohol, submicron-filtered reagent grade petroleumether (boiling range 30 to 60C) or trichloromonofluo-romethane or trichlorotrifluoroethane.9.2 The clean laboratory equipment used for counting andsizing the collected
