1、Designation: F2299/F2299M 03 (Reapproved 2010)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.2. Referenced Documents2.1 ASTM Standards:2D1356 Terminology Relating to Sampling and Analysis ofAtmospheresD1777 Test Method for Thickness of Textile MaterialsD2905 Practice
7、for Statements on Number of Specimens forTextiles3D3776 Test Methods for Mass Per Unit Area (Weight) ofFabricE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodF50 Practice for Continuous Sizing and Counting of Air-borne Particles in Dust-ControlledAreas
8、and Clean RoomsUsing Instruments Capable of Detecting Single Sub-Micrometre and Larger ParticlesF328 Practice for Calibration of an Airborne ParticleCounter Using Monodisperse Spherical Particles3F778 Methods for Gas Flow Resistance Testing of FiltrationMediaF1471 Test Method for Air Cleaning Perfor
9、mance of aHigh-Efficiency Particulate Air Filter SystemF1494 Terminology Relating to Protective ClothingF2053 Guide for Documenting the Results of AirborneParticle Penetration Testing of Protective Clothing Materi-als3. Terminology3.1 Definitions:3.1.1 aerosol, na suspension of a liquid or solid par
10、ticlesin 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 than 102particles/cm3.3.1.2 isokinetic sampling, na condition where
11、 the velocityof the airflow entering the sampling nozzle is the same as thevelocity of the airflow passing around the sampling nozzle.3.1.3 monodispersion, nscattering of discrete particles inan airflow where the size is centralized about a specific particlesize.3.1.3.1 DiscussionIn this test method
12、, the monodispersedparticle 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, ref
13、er to Terminology F1494.4. Summary of Test Method4.1 Filtered and dried air is passed through an atomizer toproduce an aerosol containing suspended latex spheres.1This test method is under the jurisdiction ofASTM Committee F23 on PersonalProtective Clothing and Equipment and is the direct responsibi
14、lity of SubcommitteeF23.40 on Biological.Current edition approved June 1, 2010. Published July 2010. Originally approvedin 2003. Last previous edition approved in 2003 as F2299 - 03. DOI: 10.1520/F2299_F2299M-03R10.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM
15、Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Withdrawn. The last approved version of this historical standard is referencedon www.astm.org.1Copyright ASTM International, 100 Barr Harbor Driv
16、e, PO Box C700, West Conshohocken, PA 19428-2959, United States.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 stable, neutralized, and driedaerosol of latex spheres to be used in the efficien
17、cy 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 aerosolconcentrations in a controlled airflow chamber.5.2 This test method provides specific
18、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 mask materials.5.2.2 This test method does not establish a comprehensivecharacteri
19、zation 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.5.3.1 The design of the medical face mask and the integrityof the seal of the medic
20、al 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.5.4.1 In general, clothing design is a significant factor,which must be considered in
21、 addition to the penetration ofpenetration of particulates.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 975.46.2 Equipment:6.2.1 Clean, dry compressed air supply,6.2.2 HEPA filter
22、s (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 detectors,6.2.10 Air blower (optional for negative pressure system),and
23、6.2.11 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 aerosol by passing the atom-izing air supply sequentially through a silica
24、-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 generator through pressure regulatorsof 67 kPa 61 psi accuracy. For th
25、rottling 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 and relative humidity at the exhaust portof the test chamber. To avoid
26、 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 constant over the sampling time ofthe efficiency test, maintain the main te
27、st 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 108particles/m3.The suspension reservoir must be large enough to sustain
28、 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 theatomizing of suspended uniform latex spheres from dilutewater suspen
29、sions. One liter quantities of these suspensionscan be made by diluting the 10 % by volume solids of theuniform latex spheres at 1000 to 1 or greater dilution ratios indeionized, filtered distilled water.NOTE 1The suspensions havea3to6month usable life. Idealsuspension dilutions are a function of th
30、e 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 established so that dilution ratios are onthe order of 1000:1 to 10 000:1.5Other aeroso
31、ls 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 availableparticles.7.3 Aerosol NeutralizerThis procedure recommends theuse of an aer
32、osol 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 aradioactive decay ionizer. The desired Boltzmanns chargeequilibrium for the aerosol has been described.6Typically, anionizing f
33、lux 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 Aerosol Dilution and Humidity ControlPrior to injec-tion or dispersion of the initial aerosol
34、concentration into the4Symposium 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. 439-443.6Liu, B. Y. H. and Piu, D. Y. H., “Electr
35、ical Neutralization ofAerosols,” AerosolScience, Vol 5, 1974, pp. 465-472.F2299/F2299M 03 (2010)2main 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 hold the relativ
36、e 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:FIG. 1 Schematic of Test MethodF2299/F2299M 03 (2010)37.5.1 The material specimen holder and test section shall
37、bea continuous straight walled vessel, 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
38、size. Choose the specimen size to ensure 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
39、 1 m3/min approximately 0.035 to 35 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 p
40、ressure (compressed air) or a negativepressure (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 H
41、igh Efficiency Particulate Aerosol (HEPA)type filter (99.97 % efficiency on 0.3 m aerosol) upstream ofthe systems airflow measurement. Size the HEPA type filter toprovide adequate system collection of the exhausting testaerosol.7.7 Pressure Drop Measurement:7.7.1 Use static pressure taps that are fl
42、ush 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, there shallbe no measurable pressure loss between the inlet-side andoutlet-side pressure taps. Use a pressure-measuring instrumentcapable of b
43、eing read to 60.025 cm of water gauge to makethis determination.7.8 Aerosol Sample Extraction and TransportUse geo-metrically and kinematically identical centerline probes toextract representative aerosols from the inlet and outlet sides ofthe material specimen test section. Use probes that have ara
44、dius 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. Locate the upstreamFIG. 2 AtomizerFIG. 3 Collision AtomizerF2299/F2299M 03 (2010)4probe 8 duct diameters (minimum) downstream of the aerosolinj
45、ection 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, diffusionand inertia for the aerosol particle size range of the test method,use th
46、e 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-ing formula:Re# 5rgVD1g(1)where:rg= gas density (kg/m3),V = gas velocity (m/s),
47、D1= inside diameter of sampling lines (m), andg= gas viscosity (kg/m-s).7.8.2 Limit horizontal sampling line length to less than 100cm and the total sample transport line to less than 2 m.7.8.3 Maintain all radius of curvatures to greater than 12cm.NOTE 4Isokinetic aerosol sampling is recommended to
48、 minimizeprobe inlet losses. However, in those cases where isokinetic conditionscannot be met, it is recommended that the operation of these probes be610 % of isokinetic or that the particle Stokes Number at the probe inletbe held to less than 1.0 in order to minimize inertial losses at the probeinl
49、et. It is also recommended that the Reynolds Number of the sampleflow lines be held to less than 2000. The Stokes Number is calculatedusing the following formula:St# 5Dp2rpVC9gDn(2)where:Dp= particle diameter (m),rp= particle density (kg/m),V = velocity of approach (m/s),g= gas viscosity (kg/m - s),Dn= diameter of sampling nozzle (m), andC = Cunningham correction factor, which for particleslarger than 1.0 3 10-6m (1 m) is assumed to be 1.0.NOTE 5Recommended sampling flow rates for extraction of themounting volume are to be less than 10 % of the t
