1、BSI Standards PublicationBS ISO 27891:2015Aerosol particle numberconcentration Calibration ofcondensation particle countersBS ISO 27891:2015 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of ISO 27891:2015. The UK participation in its preparation was entrusted to Tec
2、hnicalCommittee LBI/37, Particle characterization including sieving. A list 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 applic
3、ation. The British Standards Institution 2015.Published by BSI Standards Limited 2015ISBN 978 0 580 80574 5 ICS 19.120 Compliance with a British Standard cannot confer immunity from legal obligations.This British Standard was published under the authority of the Standards Policy and Strategy Committ
4、ee on 31 March 2015.Amendments/corrigenda issued since publicationDate T e x t a f f e c t e d ISO 2015Aerosol particle number concentration Calibration of condensation particle countersDensit de particules darosol talonnage de compteurs de particules darosol condensationINTERNATIONAL STANDARDISO 27
5、891First edition 2015-03-01Reference number ISO 27891:2015(E)BS ISO 27891:2015ISO 27891:2015(E)ii ISO 2015 All rights reservedCOPYRIGHT PROTECTED DOCUMENT ISO 2015All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form or by an
6、y means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below or ISOs member body in the country of the requester.ISO copyright officeCase postale 56 CH-1211 Gen
7、eva 20Tel. + 41 22 749 01 11Fax + 41 22 749 09 47E-mail copyrightiso.orgWeb www.iso.orgPublished in SwitzerlandBS ISO 27891:2015ISO 27891:2015(E)Foreword vIntroduction vi1 Scope . 12 Normative references 13 Terms and definitions . 14 Symbols 55 Calibration using reference instruments General princip
8、les . 85.1 General principles 85.2 Objectives for the calibration aerosol . 95.3 Setup overview . 95.4 Components and their requirements . 105.4.1 Primary aerosol source . 105.4.2 Charge conditioner .115.4.3 DEMC . 115.4.4 Make-up or bleed air .115.4.5 Mixing device, flow splitter and connection tub
9、ing 125.4.6 Reference instrument: FCAE or CPC 125.4.7 Other tools 145.5 Differences between FCAE and CPC as a reference instrument 146 Calibration using an FCAE as reference instrument .156.1 Overview of the setup and calibration procedure .156.2 Preparation . 186.2.1 General preparation .186.2.2 Pr
10、imary aerosol .186.2.3 Other equipment .186.2.4 DEMC . 186.2.5 FCAE. 196.2.6 Test CPC 206.2.7 Check of the complete setup . 216.3 Calibration procedure of detection efficiency . 236.3.1 General. 236.3.2 DEMC diameter adjustment 236.3.3 Primary aerosol adjustment . 236.3.4 Splitter bias measurement 2
11、46.3.5 Test CPC efficiency measurement 246.3.6 Measurement of different particle concentrations .266.3.7 Measurement of different sizes 266.3.8 Repetition of first measurement point 266.3.9 Preparation of the calibration certificate 266.4 Measurement uncertainty 266.4.1 General.266.4.2 Particle size
12、 276.4.3 Detection efficiency 276.4.4 Particle number concentration 28 ISO 2015 All rights reserved iiiContents PageBS ISO 27891:2015ISO 27891:2015(E)7 Calibration using a CPC as reference instrument 287.1 Overview of the setup and calibration procedure .287.2 Preparation . 317.2.1 General preparati
13、on .317.2.2 Primary aerosol .317.2.3 Other equipment .317.2.4 DEMC . 317.2.5 Reference CPC327.2.6 Test CPC 337.2.7 Check of the complete setup . 337.3 Calibration procedure of detection efficiency . 357.3.1 General. 357.3.2 DEMC diameter adjustment 357.3.3 Primary aerosol adjustment .367.3.4 Splitte
14、r bias measurement .367.3.5 Test CPC efficiency measurement 377.3.6 Measurement of different particle concentrations .387.3.7 Measurement of different sizes 387.3.8 Repetition of first measurement point 387.3.9 Preparation of the calibration certificate 387.4 Measurement uncertainty 387.4.1 General.
15、 387.4.2 Particle size 397.4.3 Detection efficiency 397.4.4 Particle number concentration 408 Reporting of results 40Annex A (informative) CPC performance characteristics 42Annex B (informative) Effect of particle surface properties on the CPC detection efficiency 51Annex C (informative) Example cal
16、ibration certificates .53Annex D (normative) Calculation of the CPC detection efficiency 62Annex E (informative) Traceability diagram .73Annex F (informative) Diluters 75Annex G (normative) Evaluation of the concentration bias correction factor between the inlets of the reference instrument and test
17、 CPC .78Annex H (informative) Extension of calibration range to lower concentrations .83Annex I (informative) Example of a detection efficiency measurement 90Annex J (normative) Volumetric flow rate calibration . 106Annex K (normative) Testing the charge conditioner and the DEMC at maximum particle
18、number concentration . 108Annex L (informative) A recommended data recording method when using a reference FCAE .109Annex M (informative) Uncertainty of detection efficiency due to particle size uncertainty 111Annex N (informative) Application of calibration results . 113Bibliography . 116iv ISO 201
19、5 All rights reservedContents PageBS ISO 27891:2015ISO 27891:2015(E)ForewordISO (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
20、 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. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with
21、 the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.The procedures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed fo
22、r the different types of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights
23、. ISO shall not be held responsible for identifying any or all such patent rights. Details of any patent rights identified during the development of the document will be in the Introduction and/or on the ISO list of patent declarations received (see www.iso.org/patents).Any trade name used in this d
24、ocument is information given for the convenience of users and does not constitute an endorsement.For an explanation on the meaning of ISO specific terms and expressions related to conformity assessment, as well as information about ISOs adherence to the WTO principles in the Technical Barriers to Tr
25、ade (TBT), see the following URL: Foreword Supplementary information .The committee responsible for this document is ISO/TC 24, Particle characterization including sieving, Subcommittee SC 4, Particle characterization. ISO 2015 All rights reserved vBS ISO 27891:2015ISO 27891:2015(E)IntroductionA con
26、densation particle counter (CPC) is a measuring device for the number concentration of small aerosol particles. The common principle of all different CPC types is that condensation of supersaturated vapours is used to grow ultra-fine and nanoparticles to droplets of sizes that can be detected optica
27、lly.44The counting of the droplets is performed via optical light scattering. The droplet passes through a detection area where it is illuminated by a focused light beam and a portion of the scattered light is detected with a photodetector. The frequency of this event leads, with the known volume of
28、 sampled air, to the particle number concentration. At low concentrations, the CPC counts individual particles and allows an absolute determination of particle number concentration.Commercially available CPCs employ different working fluids to generate the vapour, e.g. 1-butanol, 2-propanol, or wate
29、r. Moreover, different principles are in use to achieve the needed supersaturation in the sample air. The most common CPC uses laminar flow and diffusional heat transfer. The diffusion constant of the working fluid determines the needed heating or cooling steps to initiate condensation and hence, th
30、e principle design of a laminar flow CPC. Less common are turbulent mixing CPCs: in these CPCs, the supersaturation is achieved by turbulently mixing the sample air with a particle free gas flow saturated with the working fluid. Figure 1 shows a schematic of the probably most common CPC type with a
31、laminar flow through a heated saturator and a cooled condenser.Key1 aerosol inlet 7 droplet2 working fluid reservoir 8 light source3 heated saturator 9 illumination optics4 nanoparticle 10 receiving optics5 thermoelectric cooling and heating device 11 photodetector6 condenser 12 aerosol outletFigure
32、 1 Principle of a laminar flow CPCvi ISO 2015 All rights reservedBS ISO 27891:2015ISO 27891:2015(E)The accuracy of CPC measurements, however, depends on various influences. For example, if the flow rate had an error, the concentration would have an error. Coincidence error at very high concentration
33、, inefficient activation of particle growth at very small sizes, and losses of particles during transport from the inlet to the detection section are other possible sources of errors. For accurate measurement, the CPC shall be calibrated.“Calibration” of the CPC is usually done using a Faraday-cup a
34、erosol electrometer (FCAE) as reference instrument.3336In many cases, the purpose of the “calibration” is to determine the limit of particle detection at very small size. The FCAE has been used as the reference since the detection efficiency of the FCAE was considered to be unity at any size. The de
35、tection efficiency of a CPC is determined as the ratio of the concentration indicated by the CPC under calibration to that by the FCAE, while aerosols of singly charged, size-classified particles of the same number concentration are supplied simultaneously to both instruments.This International Stan
36、dard sets out two distinct methods of CPC calibration: the characterization of a CPC by comparison with an FCAE, which is the same as the traditional approach described above; and by comparison with a reference CPC. An FCAE that has a reputable calibration certificate, covering the relevant particle
37、 number concentrations, sizes, and composition, can be used. In the latter case, the reference CPC is one that has a reputable calibration certificate, again covering the relevant particle number concentrations, sizes, and composition. A reputable calibration certificate shall mean either one that h
38、as been produced by a laboratory accredited to ISO/IEC 17025 or an equivalent standard, where the type and range of calibration is within the laboratorys accredited scope, or a European Designated Institute or a National Metrology Institute that offers the relevant calibration service and whose meas
39、urements fulfil the requirements of ISO/IEC 17025.Two major sources of errors are known in CPC calibration: the presence of multiply charged particles and the bias of the particle concentrations between the inlet of the CPC under calibration and that of the reference instrument. Evaluation of these
40、factors and corrections for them shall be included in the calibration procedure, the methods of which are specified in this International Standard.This International Standard is aimed at users of CPCs (e.g. for environmental or vehicle emissions purposes) who have internal calibration programmes, CP
41、C manufacturers who certify and recertify the performance of their instruments, and technical laboratories who offer the calibration of CPCs as a service, which can include National Metrology Institutes who are setting up national facilities to support number concentration measurements. ISO 2015 All
42、 rights reserved viiBS ISO 27891:2015BS ISO 27891:2015Aerosol particle number concentration Calibration of condensation particle counters1 ScopeThis International Standard describes methods to determine the detection efficiency of condensation particle counters (CPCs) at particle number concentratio
43、ns ranging between 1 cm-3and 105cm-3, together with the associated measurement uncertainty. In general, the detection efficiency will depend on the particle number concentration, the particle size, and the particle composition. The particle sizes covered by the methods described in this Internationa
44、l Standard range from approximately 5 nm to 1 000 nm.The methods can therefore be used both to determine a CPC calibration factor to be applied across the range of larger particle sizes where the detection efficiency is relatively constant (the plateau efficiency), and to characterize the drop in CP
45、C detection efficiency at small particle sizes, near the lower detection limit. These parameters are described in more detail in Annex A.The methods are suitable for CPCs whose inlet flows are between approximately 0,1 l/min and 5 l/min.This International Standard describes a method for estimating t
46、he uncertainty of a CPC calibration performed according to this International Standard.2 Normative referencesThe following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For
47、undated references, the latest edition of the referenced document (including any amendments) applies.ISO 15900, Determination of particle size distribution Differential electrical mobility analysis for aerosol particles3 Terms and definitionsFor the purpose of this document, the following terms and
48、definitions apply.3.1aerosolsystem of solid or liquid particles suspended in gas3.2bipolar chargerparticle charge conditioner to attain the equilibrium, known size-dependent charge distribution by exposing aerosol particles to both positive and negative ions within the deviceNote 1 to entry: Exposin
49、g aerosol particles to an electrically neutral cloud of positive and negative gas charges with sufficiently high charge concentration and for a sufficiently long period of time leads to an equilibrium with the net charge of the aerosol nearly zero (also known as charge neutralization).INTERNATIONAL STANDARD ISO 27891:2015(E) ISO 2015 All rights reserved 1BS ISO 27891:2015ISO 27891:2015(E)3.3calibrationoperation that, under specified conditions, in a first step, establishes a relation between the quantity values with measurem
