1、BS ISO15900:2009ICS 19.120NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBRITISH STANDARDDeterminationof particle sizedistribution Differential electricalmobility analysis foraerosol particlesThis British Standardwas published under theauthority of the StandardsPolicy and Stra
2、tegyCommittee on 30 June2009. BSI 2009ISBN 978 0 580 59614 8Amendments/corrigenda issued since publicationDate CommentsBS ISO 15900:2009National forewordThis British Standard is the UK implementation of ISO 15900:2009.The UK participation in its preparation was entrusted to TechnicalCommittee LBI/37
3、, Particle characterization including sieving.A list of organizations represented on this committee can be obtained onrequest to its secretary.This publication does not purport to include all the necessary provisionsof a contract. Users are responsible for its correct application.Compliance with a B
4、ritish Standard cannot confer immunityfrom legal obligations.BS ISO 15900:2009Reference numberISO 15900:2009(E)ISO 2009INTERNATIONAL STANDARD ISO15900First edition2009-05-15Determination of particle size distribution Differential electrical mobility analysis for aerosol particles Dtermination de la
5、distribution granulomtrique Analyse de mobilit lectrique diffrentielle pour les particules darosol BS ISO 15900:2009ISO 15900:2009(E) PDF disclaimer This PDF file may contain embedded typefaces. In accordance with Adobes licensing policy, this file may be printed or viewed but shall not be edited un
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10、htiso.org Web www.iso.org Published in Switzerland ii ISO 2009 All rights reservedBS ISO 15900:2009ISO 15900:2009(E) ISO 2009 All rights reserved iiiContents Page Foreword iv Introduction v 1 Scope . 1 2 Terms and definitions. 1 3 Symbols . 4 4 General principle. 5 4.1 Particle size classification w
11、ith the DEMC. 5 4.2 Relationship between electrical mobility and particle size 6 4.3 Measurement and data inversion 7 4.4 Transfer function of the DEMC 8 4.5 The charge distribution function. 8 5 System and apparatus 9 5.1 General configuration. 9 5.2 Components 10 6 Measurement procedures 11 6.1 Se
12、tup and preparation of the instrument .11 6.2 Pre-measurement checks 14 6.3 Measurement. 14 6.4 Maintenance 15 7 Periodic tests and calibrations 16 7.1 Overview 16 7.2 Leak test 16 7.3 Zero tests. 17 7.4 Flow meter calibration 17 7.5 Voltage calibration 17 7.6 Particle charge conditioner integrity t
13、est. 18 7.7 Calibration for size measurement . 18 7.8 Size resolution test. 19 7.9 Number concentration calibration 20 8 Reporting of results 20 Annex A (informative) Particle charge conditioners and charge distributions . 21 Annex B (informative) Particle detectors. 29 Annex C (informative) Slip co
14、rrection factor. 33 Annex D (informative) Data inversion 37 Annex E (informative) Cylindrical DEMC . 43 Annex F (informative) Size calibration of a DMAS with step-wise voltage change using particle size standards . 49 Annex G (informative) Uncertainty . 52 Bibliography . 55 BS ISO 15900:2009ISO 1590
15、0:2009(E) iv ISO 2009 All rights reservedForeword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member b
16、ody interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electro
17、technical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with 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
18、by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval 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 r
19、ights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 15900 was prepared by Technical Committee ISO/TC 24, Particle characterization including sieving, Subcommittee SC 4, Particle characterization. BS ISO 15900:2009ISO 15900:2009(E) ISO 2009 All rights reserved
20、vIntroduction Differential electrical mobility classification and analysis of airborne particles has been widely used to measure a variety of aerosol particles ranging from nanometre-size to micrometre-size in the gas phase. In addition, the electrical mobility classification of charged particles ca
21、n be used to generate mono-disperse particles of known size for calibration of other instruments. One notable feature of these techniques is that they are based on simple physical principles. The techniques have become important in many fields of aerosol science and technology, e.g. aerosol instrume
22、ntation, production of materials from aerosols, contamination control in the semiconductor industry, atmospheric aerosol science, characterization of engineered nanoparticles, and so on. However, in order to use electrical mobility classification and analysis correctly, several issues, such as the s
23、lip correction factor, the ion-aerosol attachment coefficients, the size-dependent charge distribution on aerosol particles and the method used for inversion of the measured mobility distribution to the aerosol size distribution, need due caution. There is, therefore, a need to establish an Internat
24、ional Standard for the use of differential electrical mobility analysis for classifying aerosol particles. Its purpose is to provide a methodology for adequate quality control in particle size and number concentration measurement with this method. BS ISO 15900:2009BS ISO 15900:2009INTERNATIONAL STAN
25、DARD ISO 15900:2009(E) ISO 2009 All rights reserved 1Determination of particle size distribution Differential electrical mobility analysis for aerosol particles 1 Scope This International Standard provides guidelines on the determination of aerosol particle size distribution by means of the analysis
26、 of electrical mobility of aerosol particles. This measurement is usually called “differential electrical mobility analysis for aerosol particles”. This analytical method is applicable to particle size measurements ranging from approximately 1 nm to 1 m. This International Standard does not address
27、the specific instrument design or the specific requirements of particle size distribution measurements for different applications, but includes the calculation method of uncertainty. In this International Standard, the complete system for carrying out differential electrical mobility analysis is ref
28、erred to as DMAS (differential mobility analysing system), while the element within this system that classifies the particles according to their electrical mobility is referred to as DEMC (differential electrical mobility classifier). NOTE For differential electrical mobility measurements relating t
29、o Road Vehicle applications, please refer to relevant national and international standards. ISO Technical Committee TC 22, Road vehicles, is responsible for developing International Standards relating to road vehicles, components and measurements. 2 Terms and definitions For the purposes of this doc
30、ument, the following terms and definitions apply. 2.1 aerosol system of solid or liquid particles suspended in gas 2.2 attachment coefficient attachment probability of ions and aerosol particles 2.3 bipolar charger device to attain the equilibrium steady state of charging by exposing aerosol particl
31、es to both positive and negative ions within the device 2.4 charge neutralization process that leaves the aerosol particles with a distribution of charges that is in equilibrium and makes the net charge of the aerosol nearly zero, which is usually achieved by exposing aerosol particles to an electri
32、cally neutral cloud of positive and negative gas charges 2.5 condensation particle counter CPC instrument that measures the particle number concentration of an aerosol NOTE 1 The sizes of particles detected are usually smaller than several hundred nanometres and larger than a few nanometres. BS ISO
33、15900:2009ISO 15900:2009(E) 2 ISO 2009 All rights reservedNOTE 2 A CPC is one possible detector for use with a DEMC. NOTE 3 In some cases, a condensation particle counter may be called a condensation nucleus counter (CNC). 2.6 critical mobility instrument parameter of a DEMC that defines the electri
34、cal mobility of aerosol particles that exit the DEMC in aerosol form, which may be defined by the geometry, aerosol and sheath air flow rates, and electrical field intensity NOTE Particles larger or smaller than the critical mobility migrate to an electrode or exit with the excess flow and do not ex
35、it from the DEMC in aerosol form. 2.7 differential electrical mobility classifier DEMC classifier that is able to select aerosol particles according to their electrical mobility and pass them to its exit NOTE A DEMC classifies aerosol particles by balancing the electrical force on each particle with
36、 its aerodynamic drag force in an electrical field. Classified particles are in a narrow range of electrical mobility determined by the operating conditions and physical dimensions of the DEMC, while they can have different sizes due to difference in the number of charges that they have. 2.8 differe
37、ntial mobility analysing system DMAS system to measure the size distribution of submicrometre aerosol particles consisting of a DEMC, flow meters, a particle detector, interconnecting plumbing, a computer and suitable software 2.9 electrical mobility mobility of a charged particle in an electrical f
38、ield NOTE Electrical mobility can be defined as the migration velocity dependent on the strength of the electrical field, the mechanical mobility and the number of charges per particle. 2.10 electrometer device that measures electrical current ranging from about 1 femtoampere (fA) to about 10 picoam
39、peres (pA) 2.11 equilibrium charge distribution charging condition for aerosol particles that is stable after exposure to bipolar ions for a sufficiently long period of time NOTE Bipolar ions are positive and negative ions which are produced by either a radioactive source or a corona discharge. 2.12
40、 Faraday-cup aerosol electrometer FCAE electrometer designed for the measurement of electrical charges carried by aerosol particles NOTE A Faraday-cup aerosol electrometer consists of an electrically conducting and electrically grounded cup as a guard to cover the sensing element that includes aeros
41、ol filtering media to capture charged aerosol particles, an electrical connection between the sensing element and an electrometer circuit, and a flow meter. BS ISO 15900:2009ISO 15900:2009(E) ISO 2009 All rights reserved 32.13 Knudsen number Kn ISO ratio of gas molecular mean free path to the radius
42、 of the particle, which is an indicator of free molecular flow versus continuum gas flow 2.14 laminar flow gas flow with no temporally or spatially irregular activity or turbulent eddy flow 2.15 migration velocity steady-state velocity of a charged airborne particle within an externally applied elec
43、tric field 2.16 particle charge conditioner device used to establish a known size-dependent charge distribution on the sampled aerosol of an unknown charging state, which is either a bipolar or unipolar charger 2.17 Peclet number Pe ISO dimensionless number representing the ratio of a particles conv
44、ective to diffusive transport 2.18 Reynolds number Re ISO dimensionless number expressed as the ratio of the inertial force to the viscous force; for example, applied to an aerosol particle or a tube carrying aerosol particles 2.19 slip correction Scdimensionless factor that is used to correct the d
45、rag force acting on a particle for non-continuum effects that become important when the particle size is comparable to or smaller than the mean free path of the gas molecules 2.20 space charge net charge spatially distributed in a gas 2.21 Stokes drag drag force acting on a particle that is moving r
46、elative to a continuum fluid in the creeping flow (low Reynolds number) limit 2.22 system transfer function transfer function defined as the ratio of the particle concentration at the particle concentration measurement detector of a DMAS to the particle concentration at the inlet of the DMAS, which
47、is normally expressed as a function of electrical mobility 2.23 transfer function ratio of particle concentration at the outlet of a DEMC to the particle concentration at the inlet of the DEMC, which is normally expressed as a function of electrical mobility BS ISO 15900:2009ISO 15900:2009(E) 4 ISO
48、2009 All rights reserved2.24 unipolar charger device to attain a steady-state charge distribution of aerosol particles by exposing them to either positive or negative ions within the device 3 Symbols For the purposes of this document, the following symbols are applied. Symbol Quantity SI Unit A, B,
49、C elements of the slip correction factor defined in Equation (2) dimensionless CNnumber concentration of an aerosol m3c thermal velocity of an ion or molecule m s1D diffusion coefficient of a particle or an ion in air m2s3d aerosol particle diameter m E electric field strength in a DEMC V m1 relative error e elementary charge = 1,602 177 1019C Kn Knudsen number k Boltzmann constant = 1,381 1023J K1L effective active length of a DEMC, approximated by the axial distance between the midpoint of the aerosol entrance and t
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