1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationBS EN ISO 28439:2011W o r k p l a c e a t m o s p h e r e s Characterization of ultrafine aerosols/nanoaerosols Determination of the size distribution and number concentration us
2、ing differential electrical mobility analysing systemsBS EN ISO 28439:2011 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of EN ISO 28439:2011. The UK participation in its preparation was entrusted to T e c h n i c a l Committee EH/2/2, Work place atmospheres.A list
3、of organizations represented on this committee can be obtained on request to its secretary.This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. BSI 2011 ISBN 978 0 580 60119 4 ICS 13.040.30 Compliance with a Briti
4、sh Standard cannot confer immunity from legal obligations.This British Standard was published under the authority of the Standards Policy and Strategy Committee on 30 April 2011.Amendments issued since publicationDate T e x t a f f e c t e dEUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN ISO 28
5、439 April 2011 ICS 13.040.30 English Version Workplace atmospheres - Characterization of ultrafine aerosols/nanoaerosols - Determination of the size distribution and number concentration using differential electrical mobility analysing systems (ISO 28439:2011) Air des lieux de travail - Caractrisati
6、on des arosols ultrafins/nanoarosols - Dtermination de la distribution granulomtrique et de la concentration en nombre laide de systmes danalyse diffrentielle de mobilit lectrique (ISO 28439:2011) Arbeitsplatzatmosphre - Charakterisierung ultrafeiner Aerosole/Nanoaerosole - Bestimmung der Grenvertei
7、lung und Anzahlkonzentration mit differentiellen elektrischen Mobilittsanalysesystemen (ISO 28439:2011) This European Standard was approved by CEN on 10 March 2011. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Stand
8、ard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN member. This European Standard exists in three official versions (English
9、, French, German). A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management Centre has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Bul
10、garia, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. EUROPEAN COMMITTEE FO
11、R STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG Management Centre: Avenue Marnix 17, B-1000 Brussels 2011 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN ISO 28439:2011: EBS EN ISO 28439:2011 EN ISO
12、28439:2011 (E) 3 Foreword This document (EN ISO 28439:2011) has been prepared by Technical Committee CEN/TC 137 “Assessment of workplace exposure to chemical and biological agents”, the secretariat of which is held by DIN, in collaboration with Technical Committee ISO/TC 146 “Air quality“. This Euro
13、pean Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by October 2011, and conflicting national standards shall be withdrawn at the latest by October 2011. Attention is drawn to the possibility that some of the ele
14、ments of this document may be the subject of patent rights. CEN and/or CENELEC shall not be held responsible for identifying any or all such patent rights. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this E
15、uropean Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland an
16、d the United Kingdom. BS EN ISO 28439:2011ISO 28439:2011(E) ISO 2011 All rights reserved iiiContents Page Foreword iv Introduction.v 1 Scope1 2 Normative references1 3 Terms and definitions .1 4 Symbols and abbreviated terms 2 4.1 Symbols2 4.2 Abbreviated terms.3 5 Principle .3 6 Equipment 4 6.1 Gen
17、eral .4 6.2 Sampling line .4 6.3 Pre-separator .5 6.4 Particle charge conditioner 5 6.5 DEMC 5 6.6 Aerosol particle detector 5 7 Measurement strategy 6 8 Measuring procedure6 8.1 Preparation.6 8.2 Sampling 7 9 Presentation and evaluation of data7 10 Check of DMAS performance.8 10.1 Check on particle
18、 classification.8 10.2 Check on particle number-counting efficiency 8 11 Problems and errors .8 11.1 CPC (CNC) counting efficiency8 11.2 Particles with multiple charges9 11.3 Sampling losses 9 11.4 Uncertainties10 11.5 Overloading11 11.6 Sampling of fibres .11 11.7 Humidity .11 11.8 Maintenance.11 A
19、nnex A (informative) Methods for determining exposure 12 Annex B (informative) List of manufacturers (non-comprehensive)13 Bibliography14 BS EN ISO 28439:2011ISO 28439:2011(E) iv ISO 2011 All rights reservedForeword ISO (the International Organization for Standardization) is a worldwide federation o
20、f national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. In
21、ternational organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with
22、the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval
23、 by at least 75 % of the member bodies casting a vote. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 28439 was prepared by the European Committ
24、ee for Standardization (CEN) Technical Committee CEN/TC 137, Assessment of workplace exposure to chemical and biological agents, in collaboration with Technical Committee ISO/TC 146, Air quality, Subcommittee SC 2, Workplace atmospheres, in accordance with the Agreement on technical cooperation betw
25、een ISO and CEN (Vienna Agreement). BS EN ISO 28439:2011ISO 28439:2011(E) ISO 2011 All rights reserved vIntroduction Within occupational hygiene, aerosol concentrations have been traditionally measured in terms of mass concentrations. For some ultrafine aerosols and nanoaerosols, other exposure metr
26、ics such as the number and surface area concentration are likely to become important for predicting health effects, depending on chemical and physical properties. This International Standard provides a method for determining the number concentration and size distribution of ultrafine aerosols and na
27、noaerosols at workplaces by using differential mobility analysing systems (DMASs). This can be used by occupational hygienists and researchers to measure the concentration at some workplaces. The system is generally not suitable for personal exposure measurements. BS EN ISO 28439:2011BS EN ISO 28439
28、:2011INTERNATIONAL STANDARD ISO 28439:2011(E) ISO 2011 All rights reserved 1Workplace atmospheres Characterization of ultrafine aerosols/nanoaerosols Determination of the size distribution and number concentration using differential electrical mobility analysing systems 1 Scope This International St
29、andard provides guidelines for the determination of the number concentration and size distribution of ultrafine aerosols and nanoaerosols by use of mobility particle sizers (also called differential mobility analysers). Only the particle fraction of the aerosol is considered. For ultrafine aerosols
30、and nanoaerosols, exposure metrics such as the number and surface area concentration are important. This International Standard also gives guidelines for the determination of workplace exposure to ultrafine aerosols and nanoaerosols. Specifically, the differential mobility analysing system (DMAS), n
31、ow available from several vendors, is discussed. Principles of operation, problems of sampling in the workplace environment, calibration, equipment maintenance, measurement uncertainty, and reporting of measurement results are covered. Potential problems and limitations are described, which need to
32、be addressed when limit values are fixed and compliance measurements carried out. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the
33、referenced document (including any amendments) applies. ISO/TR 27628, Workplace atmospheres Ultrafine, nanoparticle and nano-structured aerosols Inhalation exposure characterization and assessment 3 Terms and definitions For the purposes of this document, the terms and definitions given in ISO/TR 27
34、628 and the following apply. 3.1 critical electrical mobility Zcritelectrical mobility of particles that in the differential electrical mobility classifier are transferred from the sample air flow to the exiting monodisperse aerosol flow NOTE Due to the finiteness of the DEMC, the exiting monodisper
35、se flow is not strictly monodisperse, but corresponds to a range of electrical mobilities for each voltage. BS EN ISO 28439:2011ISO 28439:2011(E) 2 ISO 2011 All rights reserved3.2 particle charge equilibrium charging condition for aerosol particles that is stable after exposure to positive and negat
36、ive ions for a sufficiently long period of time NOTE 1 Bipolar ions are produced by either a radioactive source or a corona discharge. NOTE 2 The electrical charge on individual particles of an aerosol at charge equilibrium is not neutral. NOTE 3 Adapted from ISO 15900:20091, 2.11. 3.3 (equivalent)
37、particle electrical mobility diameter diameter of a sphere with the same electrical mobility as the particle in question 4 Symbols and abbreviated terms 4.1 Symbols B particle mechanical mobility s/kg C Cunningham correction factor 1 CNaerosol number concentration 1/m3d particle diameter nm dpequiva
38、lent particle electrical mobility diameter m pd average equivalent particle electrical mobility diameter m D particle diffusion coefficient m2/s e basic unit of charge (elementary charge) 1,602 177 1019C q1DEMC sample air flow rate m3/s q2DEMC filtered sheath air flow rate m3/s q3DEMC excess air flo
39、w rate m3/s q4DEMC exiting air flow rate to particle detector m3/s k Boltzmann constant 1,38 1023Nm/K L length of sampling line m n number of charges 1 p penetration through sampling line 1 t (coagulation) time s tscanscan time s T absolute temperature at which the DEMC is operated K Vvvolume of buf
40、fer vessel for the sample air flow rate m3Z electrical mobility of a charged airborne particle m2/Vs Zcritcritical electrical mobility of a charged airborne particle m2/Vs gas viscosity Pas parameter for diffusion losses 1 BS EN ISO 28439:2011ISO 28439:2011(E) ISO 2011 All rights reserved 34.2 Abbre
41、viated terms CNC condensation nuclei counter CPC condensation particle counter DEMC differential electrical mobility classifier DMAS differential mobility analysing system NOTE A DMAS is also known as a differential mobility particle sizer (DMPS) or scanning mobility particle sizer (SMPS). HEPA high
42、 efficiency particle arrestor 5 Principle The aerosol is sampled in the workplace at a position representative of the atmosphere to which a worker might be exposed. Larger particles than approximately 1 m are precipitated and the particles smaller than approximately 1 m drawn into the instrument. Af
43、ter charge conditioning, the aerosol particles are separated in the electrical field of the DEMC (see References 6 and 7) according to their electrical mobility, which is given by Equation (1). p3ZneBCBd= =(1) where Z is the electrical mobility, in metres squared per volt second, of a charged aeroso
44、l particle; n is the number of electrical charges; e is the basic unit of charge (elementary charge), 1,602 177 1019C; B is the particle mechanical mobility, in seconds per kilogram; C is the Cunningham correction factor; is the gas viscosity, in pascal seconds; dpis the equivalent particle electric
45、al mobility diameter, in metres. The critical particle electrical mobility, Zcrit, is directly related to the geometric dimensions of the DEMC. The equivalent particle electrical mobility diameter, dp, can be determined from equations provided by the instrument manufacturer. Particles of a certain s
46、ize or size interval are counted in a condensation nuclei counter (CNC) also known as a condensation particle counter (CPC) or electrometer, and the particle number concentration for each size or size interval is determined. By scanning or stepwise changing the voltage of the DEMC, a number size dis
47、tribution is obtained. The size range from 3 nm to 1 000 nm in electrical mobility diameter can be partly covered by different instruments (see Reference 8). The DEMC has the advantage that the electrical mobility diameter is approximately equivalent to the projected-area diameter of particles (defi
48、ned as the diameter of a sphere with the same projected area as the particles being sized) with compact geometries. The entire number concentration is obtained by adding or integrating all size channels. Though the composition of the sampled particles cannot be obtained, the distribution of surface
49、area and volume concentration in some instances, e.g. if the particles are known to be spherical, can be estimated from calculations provided by the manufacturer or in the literature. BS EN ISO 28439:2011ISO 28439:2011(E) 4 ISO 2011 All rights reserved6 Equipment 6.1 General A DMAS consists of different instrument sections (see Figure 1): a) pre-separator; b) particle charger or particle charge conditioner; c) differential electrical mobility classifier (DEMC), with flow control and high vol
