1、Designation: F2299/F2299M 03 (Reapproved 2017)Standard Test Method forDetermining the Initial Efficiency of Materials Used inMedical Face Masks to Penetration by Particulates UsingLatex Spheres1This standard is issued under the fixed designation F2299/F2299M; the number immediately following the des
2、ignation indicates the yearof original adoption 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 establishes
3、procedures for measuringthe initial particle filtration efficiency of materials used inmedical facemasks using monodispersed aerosols.1.1.1 This test method utilizes light scattering particlecounting in the size range of 0.1 to 5.0 m and airflow testvelocities of 0.5 to 25 cm/s.1.2 The test procedur
4、e measures filtration efficiency bycomparing the particle count in the feed stream (upstream) tothat in the filtrate (downstream).1.3 The values stated in SI units or in other units shall beregarded separately as standard. The values stated in eachsystem must be used independently of the other, with
5、outcombining values in any way.1.4 The following precautionary caveat pertains only to thetest methods portion, Section 10, of this specification. Thisstandard does not purport to address all of the safety concerns,if any, associated with its use. It is the responsibility of the userof this standard
6、 to establish appropriate safety and healthpractices and determine the applicability of regulatory limita-tions 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 theDe
7、velopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D1356 Terminology Relating to Sampling and Analysis ofAtmospheresD1777 Test Method for Thickness of Textile M
8、aterialsD2905 Practice for Statements on Number of Specimens forTextiles (Withdrawn 2008)3D3776/D3776M Test Methods for Mass Per Unit Area(Weight) of FabricE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodF50 Practice for Continuous Sizing and Counting
9、of Air-borne Particles in Dust-Controlled Areas and CleanRooms Using Instruments Capable of Detecting SingleSub-Micrometre and Larger ParticlesF328 Practice for Calibration of an Airborne Particle Coun-ter Using Monodisperse Spherical Particles (Withdrawn2007)3F778 Methods for Gas Flow Resistance Te
10、sting of FiltrationMediaF1471 Test Method for Air Cleaning Performance of aHigh-Efficiency Particulate Air Filter SystemF1494 Terminology Relating to Protective ClothingF2053 Guide for Documenting the Results of AirborneParticle Penetration Testing of Protective Clothing Mate-rials3. Terminology3.1
11、Definitions:3.1.1 aerosol, na suspension of a liquid or solid particlesin a gas with the particles being in the colloidal size range.3.1.1.1 DiscussionIn this test method, aerosols includesolid particles having a diameter of 0.1 to 5 m suspended ordispersed in an airflow at concentrations of less th
12、an 102 par-ticlescm3.3.1.2 isokinetic sampling, na condition where the velocityof the airflow entering the sampling nozzle is the same as thevelocity of the airflow passing around the sampling nozzle.1This test method is under the jurisdiction ofASTM Committee F23 on PersonalProtective Clothing and
13、Equipment and is the direct responsibility of SubcommitteeF23.40 on Biological.Current edition approved June 1, 2017. Published June 2017. Originallyapproved in 2003. Last previous edition approved in 2010 as F2299/F2299M 03(2010). DOI: 10.1520/F2299_F2299M-03R17.2For referenced ASTM standards, visi
14、t 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.3The last approved version of this historical standard is referenced onwww.astm.org.Copyright AST
15、M 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 standardization established in the Decision on Principles for theDevelopment of International Stan
16、dards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.13.1.3 monodispersion, nscattering of discrete particles inan airflow where the size is centralized about a specific particlesize.3.1.3.1 DiscussionIn this test method, the monodisper
17、sedparticle distribution has a mean diameter size of the aerosol inthe 0.1 to 5 m range, with a coefficient of variation of themean diameter of 610 % or less, as certified by the manufac-turer.3.2 For definitions of other protective clothing-related termsused in this test method, refer to Terminolog
18、y F1494.4. Summary of Test Method4.1 Filtered and dried air is passed through an atomizer toproduce an aerosol containing suspended latex spheres.4.1.1 This aerosol is then passed through a charge neutral-izer.4.1.2 The aerosol is then mixed and diluted with additionalpreconditioned air to produce a
19、 stable, neutralized, and driedaerosol of latex spheres to be used in the efficiency test.5. Significance and Use5.1 This test method measures the initial filtration efficiencyof materials used in medical face masks by sampling represen-tative volumes of the upstream and downstream latex aerosolconc
20、entrations in a controlled airflow chamber.5.2 This test method provides specific test techniques forboth manufacturers and users to evaluate materials whenexposed to aerosol particle sizes between 0.1 and 5.0 m.5.2.1 This test method establishes a basis of efficiencycomparison between medical face
21、mask materials.5.2.2 This test method does not establish a comprehensivecharacterization of the medical face mask material for aspecific protective application.5.3 This test method does not assess the overall effective-ness of medical face masks in preventing the inward leakage ofharmful particles.5
22、.3.1 The design of the medical face mask and the integrityof the seal of the medical face mask to the wearers face are notevaluated in this test.5.4 This test method is not suitable for evaluating materialsused in protective clothing for determining their effectivenessagainst particulate hazards.5.4
23、.1 In general, clothing design is a significant factor whichmust be considered in addition to the penetration of particu-lates.6. Apparatus6.1 The aerosol test system incorporates the components asshown in Fig. 1. A more detailed diagram of test systemcomponents and equipment is found in STP 975.46.
24、2 Equipment:6.2.1 Clean, dry compressed air supply,6.2.2 HEPA filters (2),6.2.3 Aerosol generator,6.2.4 Charge neutralizer,6.2.5 Humidifier,6.2.6 Test filter holder and duct assembly,6.2.7 Pressure drop measuring device,6.2.8 Air flow rate measuring device,6.2.9 Temperature and relative humidity det
25、ectors,6.2.10 Air blower (optional for negative pressure system),and6.2.11 Optical particle counters.7. System Preparation and Control7.1 To test in the aerosol particle size range of 0.1 to 5.0 m,it is necessary to maintain a very clean inlet air supply.Achieveacceptable levels of background aeroso
26、l by passing the atom-izing air supply sequentially through a silica gel dryer (forreduction of moisture), a molecular sieve material (for removalof oil vapor), and an ultra-low penetrating aerosol (better than99.9999 % efficient at 0.6 m) filter. Then, supply the air to thetest chamber of aerosol g
27、enerator through pressure regulatorsof 67 kPa 61 psi accuracy. For throttling of the main airflowas well as other flow splitting requirements, use needle valvesto maintain adequate flow stability and back pressure. Forrecommended flow control measurement, see 7.6. Monitor andrecord the temperature a
28、nd relative humidity at the exhaust portof the test chamber. To avoid interference from the test aerosol,take the humidity measurement from the outlet side of theHEPA filter (see 7.6.2) with an in-line probe.7.1.1 To provide a stable, reproducible aerosol through thetest material that remains consta
29、nt over the sampling time ofthe efficiency test, maintain the main test duct and filtermedium specimen holder in a vertical orientation to minimizeaerosol sedimentation losses.7.2 Aerosol Generation:7.2.1 The aerosol generator must be capable of a latexsphere count concentrations output of 107to 108
30、particles/m3.The suspension reservoir must be large enough to sustain astabilized output greater than 1 h. Two commercially availableatomizing techniques that provide these concentrations of thelatex spheres are presented in Figs. 2 and 3.7.2.2 As viewed in Figs. 2 and 3, these techniques utilize th
31、eatomizing of suspended uniform latex spheres from dilutewater suspensions. One-liter quantities of these suspensionscan be made by diluting the 10 %-by-volume solids of theuniform latex spheres at 1000:1 or greater dilution ratios indeionized, filtered distilled water.NOTE 1The suspensions have a t
32、hree- to six-month usable life. Idealsuspension dilutions are a function of the latex particle size to the aerosolgenerator droplet size. In order to minimize the atomization of doublets orhigher aerosol multiples in the drying process, a recommended latexsuspension dilution ratio has been establish
33、ed so that dilution ratios are onthe order of 1000:1 to 10 000:1.5Other aerosols produced from theseatomizers can be classified into monodispersed systems, but for anindustrially recognized standard of particle size and composition, theuniform latex spheres are the most reproducible and readily avai
34、lableparticles.4Symposium on Gas and Liquid Filtration, ASTM STP 975, ASTM, Vol 11,1986, pp. 141-164.5Raabe, O., “The Dilution of Monodispersed Suspensions for Aerosolization,”American Industrial Hygiene Association Journal, Vol 29, 1968, pp. 439443.F2299/F2299M 03 (2017)27.3 Aerosol NeutralizerThis
35、 procedure recommends theuse of an aerosol charge neutralizer at the inlet of the testsystem. This technique generally will ensure aerosol surfacecharge stability. The aerosol neutralizer can be in the form of aFIG. 1 Schematic of Test MethodF2299/F2299M 03 (2017)3radioactive decay ionizer. The desi
36、red Boltzmanns chargeequilibrium for the aerosol has been described.6Typically, anionizing flux of 103mCi/m3/s provides the required aerosolneutralization.NOTE 2A Krypton 85 source, a Polonium 210 source, or a Coronaelectrical discharge, A-C source have been found satisfactory for thispurpose.7.4 Ae
37、rosol Dilution and Humidity ControlPrior to injec-tion or dispersion of the initial aerosol concentration into themain test chamber, dry or dilute the aerosol with make-upairflow for the final test aerosol concentration as needed.Conduct material testing in a relative humidity range of 30 to50 % and
38、 hold the relative humidity 65 % during a given test.Complete the aerosol mixing a minimum of 8 duct diametersdistance before the inlet sampling probe and the materialspecimen.7.5 Material Specimen Holder:7.5.1 The material specimen holder and test section shall bea continuous straight-walled vessel
39、, interrupted only by thefilter medium sample throughout its length. The materialspecimen holder must provide an uninterrupted airflow, pas-sage without measurable peripheral air leakage. Use a 50- to150-mm 2- to 6-in. cross-sectional diameter for the mediumsample size. Choose the specimen size to e
40、nsure that the testspecimen is representative of the overall material and providesenough rigidity to be self-supporting.NOTE 3The recommended filter medium cross sections allow facevelocities of 0.5 to 25 cm/s approximately 1 to 50 ft/min at flow rates of1 L/min to 1 m3/min approximately 0.035 to 35
41、 ft3/min to be developedin testing.7.5.2 Introduce the latex aerosol a minimum of 10 ductdiameters upstream of the material specimen and at a sufficientdistance to provide thorough mixing before the upstreamsampling probe.7.6 Airflow Metering:7.6.1 Use a positive pressure (compressed air) or a negat
42、ivepressure (exhaust fan or blower) system for the airflow to themain test chamber. For the application of any of thesetechniques of airflow measurement and calibration, refer to thestandards and practices of theAmerican Society of MechanicalEngineers.7.6.2 Use a high efficiency particulate aerosol
43、(HEPA)-typefilter (99.97 % efficiency on 0.3-m aerosol) upstream of thesystems airflow measurement. Size the HEPA-type filter toprovide adequate system collection of the exhausting testaerosol.6Liu, B. Y. H. and Piu, D. Y. H., “Electrical Neutralization ofAerosols,” AerosolScience, Vol 5, 1974, pp.
44、465472.FIG. 2 AtomizerFIG. 3 Collision AtomizerF2299/F2299M 03 (2017)47.7 Pressure Drop Measurement:7.7.1 Use static pressure taps that are flush with the ductwalls at a distance of 1 duct diameter upstream and down-stream of the filter medium faces.7.7.2 With no filter medium in the sample holder,
45、there shallbe no measurable pressure loss between the inlet-side andoutlet-side pressure taps. Use a pressure-measuring instrumentcapable of being read to 60.025 cm of water gauge to makethis determination.7.8 Aerosol Sample Extraction and TransportUse geo-metrically and kinematically identical cent
46、erline probes toextract representative aerosols from the inlet and outlet sides ofthe material specimen test section. Use probes that have aradius of curvature (R)of12cmorR/D (Diameter) 20:1 andpresent a cross-sectional area of less than 10 % of the cross-sectional area of the test system ducting. L
47、ocate the upstreamprobe 8 duct diameters (minimum) downstream of the aerosolinjection point and 2 duct diameters ahead of the materialspecimen. Locate the downstream probe 3 duct diametersdownstream of the filter medium specimen. To minimizeaerosol sampling transport line losses due to settling, dif
48、fusion,and inertia for the aerosol particle size range of the test method,use the following characteristics of the sampling.7.8.1 Maintain the sampling line flow in the laminar flowregime; that is, the Reynolds number must be less than 1000.Calculate the Reynolds number in accordance with the follow
49、-ing formula:Re# 5gVD1g(1)where:g= gas density (kg/m3),V = gas velocity (m/s),D1= inside diameter of sampling lines (m), andg= gas viscosity (kg/m-s).7.8.2 Limit horizontal sampling line length to less than100 cm and the total sample transport line to less than 2 m.7.8.3 Maintain all radius of curvatures to greater than12 cm.NOTE 4Isokinetic aerosol sampling is recommended to minimizeprobe inlet losses. However, in those cases where isokinetic conditionscannot be met, it is recommended that the operation of these probes be610 % of isokinetic o
