Testing Results of KN 95 Respirators.docx
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TestingResultsofKN95Respirators
TestingResultsofKN95RespiratorsAccordingtoGB2626-2006
FinalReport
Submittedto:
TheOfficeofAttorneyGeneralofCanada(AGC)
Submittedby:
ShawnChen
VirginiaCommonwealthUniversity
February14,2022
1ExecutiveSummary
ThisreportprovidestheparticleremovalefficienciesoftestedKN95respiratorsfromall23lotsreceivedfromtheOfficeofAttorneyGeneralofCanada,including202004BF(Bag22A),20200412(Bag2),202004NW(Bag22B),20200422(Bag14),20200408(Bag1),20042015A03(Bag5),20042015A07(Bag7),20200420(Bag10),20200420(Bag11),20200423X(Bag17),20200424(Bag18),20200424X(Bag19),20200429X(Bag20),CY-20200421-1(Bag23),T202004(Bag25),20200420(Bag12),20200422(Bag15),20200423(Bag16),20200430X(Bag21),20042015A01(Bag3),20042015A02(Bag4),20042015A05(Bag6)and20200420(Bag9).ThetestingprocedureswerevigorouslybasedontheStandardOperatingProcedure(SOP)pursuanttotheChinesestandardGB2626-2006(Respiratoryprotectiveequipment-Non-poweredair-purifyingparticlerespirator).Amongstthe345randomlypickedandtestedKN95respirators(15respirators×23lots),122ofthempassedthe95%efficiencyrequirement.Onlylot20200423Xoutof23havingall15respiratorspassed95%efficiencyrequirement.
2Objective
ThistechnicalreportaimstoprovidethefiltrationefficiencymeasurementresultsofKN95masksprovidedbytheAttorneyGeneralofCanada,AGC.
3Procedures
ToobtainreliableandrepresentativeresultsfortheparticleremovalefficiencyoftestedKN95respirators,theSOPwasfollowed.
3.1Visualappearanceinspection
Allthetestedrespiratorswerecheckedintermsoftheirappearance.AppendixA(Visualinspectionform)attachedtothisdocumentsummarizestheinspectionresultsofallthetestedsamples.
3.2Respiratorsamplelabelingandstorage
Therespiratorslabelledwith1-5arereferredtopretreatedsamplesforeachLot,andtherespiratorslabelledwith6-15arenon-pretreatedsamples.
∙LabellinginformationofallrespiratorsprovidedbyAGCwasfollowedandappliedthroughwholetestingprocesses.
∙Everyrespiratorwasstoredinanindividualzipperbagwithairtightandhaditslabelwrittenoutsidethebagwithapermanentmarker.
∙Alllabelledrespiratorswerestoredinanenvironment-controlledcabinetwithatemperatureof20±2℃andrelativehumidity(RH)of40±10%beforethepretreatment(refertoSOP3.1-3.6)andefficiencytest(refertoSOP4.1-4.3).
3.3Pretreatmentbeforefiltrationefficiencytesting
Respirators1-5fromeachLotwerepretreatedwiththeproceduresaccordingtoSOP3.1-3.5.AppendixB(Pretreatmentform)oftheSOPwasusedtorecordthetimeandconditionforallthepretreatedsamples.
∙Briefly,5randomlyselectedsampleswerefirstlypretreatedwithtemperatureandRHat38±2.5℃and85±5%,respectively,for24±1hours.Thenthetreatedsampleswererecoveredtoroomtemperaturefor4hoursbeforeconductingthesecondpretreatment.
∙Thesecondpretreatmentwastoplacethe5samplesunderRH<30%and70±3℃intheVWRforcedairovenforanother24±1hours.Thetreatedsampleswererecoveredtoroomtemperatureagainfor4hoursbeforeconductingthethirdpretreatment.
∙Thethirdpretreatmentwastoconditionthe5samplesunder-30±3℃intheSummitVT65freezerforanother24±1hours.Thetreatedsampleswererecoveredtoroomtemperatureagainfor4hoursbeforeconductingtheefficiencytests.
3.4Filtrationefficiencytesting
TheefficiencytestingwasconductedaccordingtotheSOP4.1–4.4.Beforethetest,theproceduresasfollowswerecarriedout:
∙Thescanningmobilityparticlesizer(SMPS,model3936,TSIInc.,Shoreview,MN)formonitoringthesizedistributionofchallengingparticlesandtheDusttrak(model8530,TSIInc.,Shoreview,MN)fordeterminingthefiltrationefficiencywerefirstcalibratedaccordingtothemanualsfromTSI.
∙1~3wt.%NaClsolutionwerepreparedfortheatomizertogenerateNaClparticleswithacountmediandiameter(CMD)of0.075±0.020μmandageometricstandarddeviation(σg)lessthan1.86.TheCMDandσgwasmonitoredbytheSMPSeverydaybeforetesting.
∙TheleaktestswereperformedbyusingsecondmethodprovidedbySOP4.4.5,i.e.,theCPCmeasurement,beforeeachsample’sefficiencytest.
∙Beforedeterminingthefiltrationefficiencyoftherespirator,thefiltrationefficiencytestwithoutplacingtherespirator(i.e.,ηwithout,namedlossefficiency)wasalsoconductedtoensuretherewasnegligibleparticletransportlossandleakinthefilterholder.
4ResultsandDiscussions
4.1Instrumentationcalibration
4.1.1SMPScalibration
TheSMPSwascalibratedbyutilizingstandardsize3070A(70±3nm)nanospheresfromFisherScientifictoconfirmtheSMPSbeingabletomeasureaccuratesizedistributionofthechallengingparticles.ArepresentativecalibrationresultsareshowninFig.1.TheCMDandσgofthedistributionis71.8nmand1.09,respectively,indicatingthesizingaccuracyoftheSMPSisreliable.
Figure1.Sizedistributionof70nmnanospheresmeasuredbytheSMPS.
4.1.2Dusttrakcalibration
TheDusttrakcalibrationhereinvolveszerocalibration,flowcalibrationandphotometriccalibrationfactor(PCF)calibration.ZerocalibrationwasperformedbyplacingaHEPAfilterattheinletwhentheinstrumentwasfirstused.Flowcalibrationwasconductedusingaprimarybubbleflowmetertoconfirmtheflowrateofthepump(3L/min).Photometriccalibrationfactor(PCF)calibrationwasdeterminedwithNaClparticleswithaCMDof0.075±0.020μmandaσglessthan1.86.Fig.2showsthesizedistributionoftheaerosolizedNaClparticlesusedtochallengetheafterfilterinDusttrak.TheflowcalibrationresultsshowedthattheflowrateoftheDusttrakwas3.0±0.03L/min.Thephotometriccalibrationfactorwasfoundtobe0.15.
Figure2.SizedistributionofNaClparticlesusedtocalibratetheDusttrak.
4.2Sizedistributionoftheaerosolforchallengingtherespirators
AccordingtoSOP4.3.1,thesizedistributionoftheaerosolforchallengingtherespiratorsshouldbemonitoredeverydaybeforetheefficiencytesttomakesurethegeneratedNaClparticlesarewithaCMDof0.075±0.020μmandaσglessthan1.86.Herein,arepresentativesizedistributionforthechallengingparticlesisshowninFig.3forreference.
Figure3.SizedistributionofNaClparticlesusedtochallengetheKN95respirators.
4.3Leaktestresults
AsdescribedinSection3.4inthisreport,theleaktestswereconductedbyusingCPCtoconfirmnoleakoccurringwhenperformingtheefficiencytest.ArepresentativeresultofleaktestisshowninFig.4forreference.Asseen,thereisalmostnoparticledetectedforbothupstreamanddownstreammeasurement,whichdemonstratesthatthereisanegligibleleakbeforeconductingthefollowingefficiencytests.Theexistingparticleswithverylowconcentrationmaybefromtheductwallofthesetupbuttheywillnotaffecttheefficiencymeasurementastheconcentrationofchallengeparticleisintheorderof1x106.
Figure4.UpstreamanddownstreamnumberconcentrationofparticlesmeasuredbytheCPC.
4.4Lossefficiencytestresults
ThelossefficiencytestresultswereobtainedbyfollowingtheSOP4.5.Allthelossefficiencieswerecontrolledaslowaspossible,suchaswith<1%.Fig.5showsarepresentativelossefficiency(ηwithout)resultforthereference.Thelossefficiencyshownherewas0.96%.Thissmallamountofdifferenceofparticleconcentrationintheupstreamanddownstreamofthesamplingprobe(lossefficiency)shouldbeduethetransportlossofsmallparticleslessthan20nm.Tobenoted,thereallossforthemajorchallengeparticles,i.e.,75nm,shouldbemuchlowerandnegligible.
Figure5.UpstreamanddownstreamnumberconcentrationofparticlesmeasuredbytheCPC.
4.5Filtrationefficiencytestresults
TheefficiencytestresultswereobtainedbyfollowingtheSOP4.5.Table1summarizesthepassrateoftestedrespiratorsfromdifferentlots(total23lots).Itisobservedtherewasnoclearinfluenceofpretreatmentontheefficiencytestresult.Thedetailedefficiency,pressuredrop,andotherrelateddataoftestedrespiratorsaresummarizedinAppendixC1~C23:
Lot202004BF(Bag22A)inC1;Lot20200412(Bag2)inC2;Lot202004NW(Bag22B)inC3;Lot20200422(Bag14)inC4;Lot20200408(Bag1)inC5;Lot20042015A03(Bag5)inC6;Lot20042015A07(Bag7)inC7;Lot20200420(Bag10)inC8;Lot20200420(Bag11)inC9;Lot20200423X(Bag17)inC10;Lot20200424(Bag18)inC11;Lot20200424X(Bag19)inC12;Lot20200429X(Bag20)inC13;LotCY-20200421-1(Bag23)inC14;LotT202004(Bag25)inC15;Lot20200420(Bag12)inC16,Lot20200422(Bag15)inC17,Lot20200423(Bag16)inC18,Lot20200430X(Bag21)inC19,Lot20042015A01(Bag3)inC20,Lot20042015A02(Bag4)inC21,Lot20042015A05(Bag6)inC22andLot20200420(Bag9)inC23.
Table1.Summaryofthepassratioofrespiratorsfromdifferentlots.
BagNo.
Lot
Passratio
Datain
22A
202004BF
3/15
AppendixA1
2
20200412
3/15
AppendixA2
22B
202004NW
3/15
AppendixA3
14
20200422
6/15
AppendixA4
1
20200408
6/15
AppendixA5
5
20042015A03
0/15
AppendixA6
7
20042015A07
0/15
AppendixA7
10
20200420
11/15
AppendixA8
11
20200420
0/15
AppendixA9
17
20200423X
15/15
AppendixA10
18
20200424
9/15
AppendixA11
19
20200424X
14/15
AppendixA12
20
20200429X
8/15
AppendixA13
23
CY-20200421-1
0/15
AppendixA14
25
T202004
9/15
AppendixA15
12
20200420
10/15
AppendixA16
15
20200422
9/15
AppendixA17
16
20200423
8/15
AppendixA18
21
20200430X
7/15
AppendixA19
3
20042015A01