【英文标准名称】:Ambientair.Determinationofasbestosfibres.Direct-transfertransmissionelectronmicroscopymethod
【原文标准名称】:周围环境空气.石棉纤维的测定.直接传递透射电子显微法
【标准号】:BSISO10312-1995
【标准状态】:现行
【国别】:英国
【发布日期】:1995-10-15
【实施或试行日期】:1995-10-15
【发布单位】:英国标准学会(GB-BSI)
【起草单位】:BSI
【标准类型】:()
【标准水平】:()
【中文主题词】:空气污染;空气质量;环境空气;石棉;石棉粉;石棉纤维;浓缩;耐久性;粉尘浓度;电子显微镜;显微分析
【英文主题词】:Airpollution;Airquality;Ambientair;Asbestos;Asbestosdust;Asbestosfibres;Concentration;Definitions;Dustconcentration;Electronmicroscopes;Microscopicanalysis
【摘要】:1SubstancedeterminedThisInternationalStandardspecifiesareferencemethodusingtransmissionelectronmicroscopyforthedeterminationoftheconcentrationofasbestosstructuresinambientatmospheresandincludesmeasurementofthelengths,widthsandaspectratiosoftheasbestosstructures.Themethodallowsdeter-minationofthetype(s)ofasbestosfibrespresent.Themethodcannotdiscriminatebetweenindividualfibresoftheasbestosandnon-asbestosanaloguesofthesameamphibolemineral.2TypeofsampleThemethodisdefinedforpolycarbonatecapillary-porefiltersorcelluloseester(eithermixedestersofcellu-loseorcellulosenitrate)filtersthroughwhichaknownvolumeofairhasbeendrawn.Themethodissuitablefordeterminationofasbestosinbothexteriorandbuildingatmospheres.3MeasuringrangeTherangeofconcentrationwhichcanbedeterminedis50structures/mmto7000structures/mmonthefilter.Theairconcentrationsrepresentedbythesevaluesareafunctionofthevolumeofairsampled.Thereisnolowerlimittothedimensionsofasbestosfibreswhichcanbedetected.Inpractice,microscopistsvaryintheirabilitytodetectverysmallasbestosfibres.Therefore,aminimumlengthof0,5μmhasbeendefinedastheshortestfibretobeincorporatedinthereportedresults.4LimitofdetectionThelimitofdetectiontheoreticallycanbeloweredin-definitelybyfiltrationofprogressivelylargervolumesofairandbyextendingtheexaminationofthespeci-mensintheelectronmicroscope.Inpractice,thelowestachievablelimitofdetectionforaparticularareaofTEMspecimenexaminediscontrolledbythetotalsuspendedparticulateconcentration.Fortotalsuspendedparticulateconcentrationsofap-proximately10μg/m,correspondingtoclean,ruralatmospheres,andassumingfiltrationof4000litresofair,ananalyticalsensitivityof0,5structure/Icanbeobtained,equivalenttoalimitofdetectionof1,8structure/I,ifanareaof0,195mmoftheTEMspecimensisexamined.Ifhighertotalsuspendedparticulateconcentrationsarepresent,thevolumeofairfilteredmustbereducedinordertomaintainanacceptableparticulateloadingonthefilter,leadingtoaproportionateincreaseintheanalyticalsensitivity.Wherethisisthecase,lowerlimitsofdetectioncanbeachievedbyincreasingtheareaoftheTEMspeci-mensthatisexamined.Inordertoachievelowerlimitsofdetectionforfibresandbundleslongerthan5μm,andforPCMequivalentfibres,lowermagni-ficationsarespecifiedwhichpermitmorerapidex-aminationoflargerareasoftheTEMspecimenswhentheexaminationislimitedtothesedimensionsoffi-bre.Thedirectanalyticalmethodcannotbeusedifthegeneralparticulateloadingofthesamplecollectionfilterexceedsapproximately10μg/cmoffiltersur-face,whichcorrespondstoapproximately10%cov-erageofthecollectionfilterbyparticulate.Ifthetotalsuspendedparticulateislargelyorganicmaterial,thelimitofdetectioncanbeloweredsignificantlybyusinganindirectpreparationmethod.
【中国标准分类号】:C51
【国际标准分类号】:13_040_20
【页数】:60P;A4
【正文语种】:英语