ASTM F2299-03

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation:F2299–03
Standard Test Method for
Determining the Initial Efficiency of Materials Used in
Medical Face Masks to Penetration by Particulates Using
Latex Spheres
This standard is issued under the fixed designation F2299; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope D3776 Test Methods for Mass Per Unit Area (Weight) of
Fabric
1.1 This test method establishes procedures for measuring
E691 Practice for Conducting an Interlaboratory Study to
the initial particle filtration efficiency of materials used in
Determine the Precision of a Test Method
medical facemasks using monodispersed aerosols.
F50 Practice for Continuous Sizing and Counting of Air-
1.1.1 This test method utilizes light scattering particle
borneParticlesinDust-ControlledAreasandCleanRooms
counting in the size range of 0.1 to 5.0 µm and airflow test
Using Instruments Capable of Detecting Single Sub-
velocities of 0.5 to 25 cm/s.
Micrometre and Larger Particles
1.2 The test procedure measures filtration efficiency by
F328 Practice for Calibration of an Airborne Particle
comparing the particle count in the feed stream (upstream) to
Counter Using Monodisperse Spherical Particles
that in the filtrate (downstream).
F778 MethodsforGasFlowResistanceTestingofFiltration
1.3 The values stated in SI units or in other units shall be
Media
regarded separately as standard. The values stated in each
F1471 Test Method for Air Cleaning Performance of a
system must be used independently of the other, without
High-Efficiency Particulate Air Filter System
combining values in any way.
F1494 Terminology Relating to Protective Clothing
1.4 The following precautionary caveat pertains only to the
F2053 Guide for Documenting the Results of Airborne
test methods portion, Section 10, of this specification. This
Particle Penetration Testing of Protective Clothing Materi-
standard does not purport to address all of the safety concerns,
als
if any, associated with its use. It is the responsibility of the user
of this standard to establish appropriate safety and health
3. Terminology
practices and determine the applicability of regulatory limita-
3.1 Definitions:
tions prior to use.
3.1.1 aerosol, n—a suspension of a liquid or solid particles
2. Referenced Documents in a gas with the particles being in the colloidal size range.
2 3.1.1.1 Discussion—In this test method, aerosols include
2.1 ASTM Standards:
solid particles having a diameter of 0.1 to 5 µm suspended or
D1356 Terminology Relating to Sampling and Analysis of
dispersed in an airflow at concentrations of less than 102
Atmospheres
particles/cm .
D1777 Test Method for Thickness of Textile Materials
3.1.2 isokinetic sampling, n—aconditionwherethevelocity
D2905 PracticeforStatementsonNumberofSpecimensfor
of the airflow entering the sampling nozzle is the same as the
Textiles
velocity of the airflow passing around the sampling nozzle.
3.1.3 monodispersion, n—scattering of discrete particles in
anairflowwherethesizeiscentralizedaboutaspecificparticle
This test method is under the jurisdiction of ASTM Committee F23 on
Protective Clothing and is the direct responsibility of Subcommittee F23.40 on
size.
Biological Hazards.
3.1.3.1 Discussion—In this test method, the monodispersed
Current edition approved July 10, 2003. Published September 2003. DOI:
particle distribution has a mean diameter size of the aerosol in
10.1520/F2299-03.
the 0.1 to 5 µm range, with a coefficient of variation of the
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
mean diameter of 610% or less, as certified by the manufac-
Standards volume information, refer to the standard’s Document Summary page on
turer.
the ASTM website.
3 3.2 Fordefinitionsofotherprotectiveclothing-relatedterms
Withdrawn. The last approved version of this historical standard is referenced
on www.astm.org. used in this test method, refer to Terminology F1494.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
F2299–03
4. Summary of Test Method acceptable levels of background aerosol by passing the atom-
izing air supply sequentially through a silica-gel dryer (for
4.1 Filtered and dried air is passed through an atomizer to
reductionofmoisture),amolecularsievematerial(forremoval
produce an aerosol containing suspended latex spheres.
of oil vapor) and an ultra low penetrating aerosol (better than
4.1.1 This aerosol is then passed through a charge neutral-
99.9999%efficientat0.6µm)filter.Then,supplytheairtothe
izer.
test chamber of aerosol generator through pressure regulators
4.1.2 The aerosol is then mixed and diluted with additional
of 67kPa[61psi]accuracy.Forthrottlingofthemainairflow
preconditioned air to produce a stable, neutralized, and dried
as well as other flow splitting requirements, use needle valves
aerosol of latex spheres to be used in the efficiency test.
to maintain adequate flow stability and back pressure. For
5. Significance and Use
recommended flow control measurement, see 7.6. Monitor and
recordthetemperatureandrelativehumidityattheexhaustport
5.1 Thistestmethodmeasurestheinitialfiltrationefficiency
ofthetestchamber.Toavoidinterferencefromthetestaerosol,
of materials used in medical face masks by sampling represen-
take the humidity measurement from the outlet side of the
tative volumes of the upstream and downstream latex aerosol
HEPA filter (see 7.6.2) with an in-line probe.
concentrations in a controlled airflow chamber.
7.1.1 To provide a stable, reproducible aerosol through the
5.2 This test method provides specific test techniques for
test material that remains constant over the sampling time of
both manufacturers and users to evaluate materials when
the efficiency test, maintain the main test duct and filter
exposed to aerosol particle sizes between 0.1 and 5.0 µm.
medium specimen holder in a vertical orientation to minimize
5.2.1 This test method establishes a basis of efficiency
aerosol sedimentation losses.
comparison between medical face mask materials.
7.2 Aerosol Generation:
5.2.2 This test method does not establish a comprehensive
7.2.1 The aerosol generator must be capable of a latex
characterization of the medical face mask material for a
7 8 3
sphere count concentrations output of 10 to 10 particles/m .
specific protective application.
The suspension reservoir must be large enough to sustain a
5.3 This test method does not assess the overall effective-
stabilized output greater than 1 h.Two commercially available
nessofmedicalfacemasksinpreventingtheinwardleakageof
atomizing techniques that provide these concentrations of the
harmful particles.
latex spheres are presented in Figs. 2 and 3.
5.3.1 The design of the medical face mask and the integrity
7.2.2 AsviewedinFigs.2and3,thesetechniquesutilizethe
ofthesealofthemedicalfacemasktothewearer’sfacearenot
atomizing of suspended uniform latex spheres from dilute
evaluated in this test.
water suspensions. One liter quantities of these suspensions
5.4 This test method is not suitable for evaluating materials
can be made by diluting the 10% by volume solids of the
used in protective clothing for determining their effectiveness
uniform latex spheres at 1000 to 1 or greater dilution ratios in
against particulate hazards.
deionized, filtered distilled water.
5.4.1 In general, clothing design is a significant factor,
which must be considered in addition to the penetration of
NOTE 1—The suspensions havea3to6 month usable life. Ideal
penetration of particulates.
suspension dilutions are a function of the latex particle size to the aerosol
generatordropletsize.Inordertominimizetheatomizationofdoubletsor
6. Apparatus
higher aerosol multiples in the drying process, a recommended latex
6.1 The aerosol test system incorporates the components as suspensiondilutionratiohasbeenestablishedsothatdilutionratiosareon
the order of 1000:1 to 10000:1. Other aerosols produced from these
shown in Fig. 1. A more detailed diagram of test system
atomizers can be classified into monodispersed systems but for an
components and equipment is found in STP 975.
industrially recognized standard of particle size and composition the
6.2 Equipment:
uniform latex spheres are the most reproducible and readily available
6.2.1 Clean, dry compressed air supply,
particles.
6.2.2 HEPA filters (2),
7.3 Aerosol Neutralizer—This procedure recommends the
6.2.3 Aerosol generator,
use of an aerosol charge neutralizer at the inlet of the test
6.2.4 Charge neutralizer,
system. This technique generally will ensure aerosol surface
6.2.5 Humidifier,
charge stability.The aerosol neutralizer can be in the form of a
6.2.6 Test filter holder and duct assembly,
radioactive decay ionizer. The desired Boltzmann’s charge
6.2.7 Pressure drop measuring device,
equilibrium for the aerosol has been described. Typically, an
6.2.8 Air flow rate measuring device,
3 3
ionizing flux of 10 mCi/m /s provides the required aerosol
6.2.9 Temperature and relative humidity detectors,
neutralization.
6.2.10 Air blower (optional for negative pressure system),
and
NOTE 2—A Krypton 85 source, a Polonium 210 source, or a Corona
6.2.11 Optical particle counters.
electrical discharge, A-C source have been found satisfactory for this
purpose.
7. System Preparation and Control
7.1 Totestintheaerosolparticlesizerangeof0.1to5.0µm,
itisnecessarytomaintainaverycleaninletairsupply.Achieve
Raabe, O., “The Dilution of Monodispersed Suspensions for Aerosolization,”
American Industrial Hygiene Association Journal, Vol 29, 1968, pp. 439-443.
4 6
Symposium on Gas and Liquid Filtration, ASTM STP 975, ASTM, Vol 11, Liu,B.Y.H.andPiu,D.Y.H.,“ElectricalNeutralizationofAerosols,” Aerosol
1986, pp. 141-164. Science, Vol 5, 1974, pp. 465-472.
F2299–03
FIG. 1 Schematic of Test Method
7.4 Aerosol Dilution and Humidity Control—Prior to injec- Complete the aerosol mixing a minimum of 8 duct diameters
tion or dispersion of the initial aerosol concentration into the distance before the inlet sampling probe and the material
main test chamber, dry or dilute the aerosol with make-up specimen.
airflow for the final test aerosol concentration as needed. 7.5 Material Specimen Holder:
Conduct material testing in a relative humidity range of 30 to 7.5.1 The material specimen holder and test section shall be
50% and hold the relative humidity 65% during a given test. a continuous straight walled vessel, interrupted only by the
F2299–03
FIG. 2 Atomizer
7.6.1 Use a positive pressure (compressed air) or a negative
pressure (exhaust fan or blower) system for the airflow to the
main test chamber. For the application of any of these
techniquesofairflowmeasurementandcalibration,refertothe
standardsandpracticesoftheAmericanSocietyofMechanical
Engineers.
7.6.2 Use a High Efficiency Particulate Aerosol (HEPA)
type filter (99.97% efficiency on 0.3 µm aerosol) upstream of
the systems airflow measurement. Size the HEPAtype filter to
provide adequate system collection of the exhausting test
aerosol.
7.7 Pressure Drop Measurement:
7.7.1 Use static pressure taps that are flush with the duct
walls at a distance of 1 duct diameter upstream and down-
stream of the filter medium faces.
7.7.2 Withnofiltermediuminthesampleholder,thereshall
FIG. 3 Collision Atomizer
be no measurable pressure loss between the inlet-side and
outlet-side pressure taps. Use a pressure-measuring instrument
filter medium sample throughout its length. The material
capable of being read to 60.025 cm of water gauge to make
specimen holder must provide an uninterrupted airflow, pas-
this determination.
sage without measurable peripheral air leakage. Use a 50 to
7.8 Aerosol Sample Extraction and Transport—Use geo-
150 mm [2 to 6 in.] cross-sectional diameter for the medium
metrically and kinematically identical centerline probes to
sample size. Choose the specimen size to ensure that the test
extractrepresentativeaerosolsfromtheinletandoutletsidesof
specimen is representative of the overall material and provides
the material specimen test section. Use probes that have a
enough rigidity to be self-supporting.
radius of curvature (R)of12cmor R/D (Diameter) > 20:1 and
present a cross-sectional area of less than 10% of the cross-
NOTE 3—The recommended filter medium cross sections allow face
velocities of 0.5 to 25 cm/s [approximately 1 to 50 ft/min] at flow rates of
sectional area of the test system ducting. Locate the upstream
3 3
1 L/min to 1 m /min [approximately 0.035 to 35 ft /min] to be developed
probe 8 duct diameters (minimum) downstream of the aerosol
in testing.
injection point and 2 duct diameters ahead of the material
7.5.2 Introduce the latex aerosol a minimum of 10 duct specimen. Locate the downstream probe 3 duct diameters
diametersupstreamofthematerialspecimenandatasufficient downstream of the filter medium specimen. To minimize
distance to provide thorough mixing before the upstream aerosol sampling transport line losses due to settling, diffusion
sampling probe. andinertiafortheaerosolparticlesizerangeofthetestmethod,
7.6 Airflow Metering: use the following characteristics of the sampling.
F2299–03
7.8.1 Maintain the sampling line flow in the laminar flow for aerosol particle counting. Recommended sampling times
regime; that is, the Reynolds Number must be less than 1000. are on the order of 10 to 60 s. If separate particle counters are
CalculatetheReynoldsNumberinaccordancewiththefollow- used for inlet and outlet aerosol concentrations, they must be
ing formula: calibrated for the aerosol particle size and concentration
response needed within the test system.
r VD
g 1
Re# 5 (1)
µ
g
NOTE 6—The flow rate of the respective optical particle counter must
be measured and recorded.
where:
NOTE 7—For test system changes in sampling configuration; that is,
r = gas density (kg/m ),
g
alternate upstream and downstream sampling or opening and closing the
V = gas velocity (m/s),
aerosol flow system, allow a purge time so that 25 sampling line volume
D = inside diameter of sampling lines (m), and
1 changes can occur before counting resumes. (For flow rates of 7 L/min in
µ = gas viscosity (kg/m-s).
6 mm ID samplings, the purge time will be between 10 to 15 s.)
g
7.8.2 Limit horizontal sampling line length to less than 100
8. Number of Downstream/Upstream Sampling Intervals
cm and the
...