1、BSI Standards PublicationWB11885_BSI_StandardCovs_2013_AW.indd 1 15/05/2013 15:06Measurement and characterization of particles by acoustic methodsPart 3: Guidelines for non-linear theoryBS ISO 20998-3:2017 ISO 2017Measurement and characterization of particles by acoustic methods Part 3: Guidelines f
2、or non-linear theoryMesurage et caractrisation des particules par des mthodes acoustiques Partie 3: Lignes directrices pour la thorie non linaireINTERNATIONAL STANDARDISO20998-3First edition2017-04Reference numberISO 20998-3:2017(E)National forewordThis British Standard is the UK implementation of I
3、SO 20998-3:2017.The UK participation in its preparation was entrusted to Technical Committee 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 nece
4、ssary provisions of a contract. Users are responsible for its correct application. The British Standards Institution 2017 Published by BSI Standards Limited 2017ISBN 978 0 580 89639 2ICS 19.120Compliance with a British Standard cannot confer immunity from legal obligations.This British Standard was
5、published under the authority of the Standards Policy and Strategy Committee on 30 June 2017.Amendments/corrigenda issued since publicationDate Text affectedBRITISH STANDARDBS ISO 20998-3:2017 ISO 2017Measurement and characterization of particles by acoustic methods Part 3: Guidelines for non-linear
6、 theoryMesurage et caractrisation des particules par des mthodes acoustiques Partie 3: Lignes directrices pour la thorie non linaireINTERNATIONAL STANDARDISO20998-3First edition2017-04Reference numberISO 20998-3:2017(E)BS ISO 20998-3:2017ISO 20998-3:2017(E)ii ISO 2017 All rights reservedCOPYRIGHT PR
7、OTECTED DOCUMENT ISO 2017, Published in SwitzerlandAll rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without pr
8、ior 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 officeCh. de Blandonnet 8 CP 401CH-1214 Vernier, Geneva, SwitzerlandTel. +41 22 749 01 11Fax +41 22 749 09 47copyrightiso.orgwww.iso.orgBS ISO 20
9、998-3:2017ISO 20998-3:2017(E)Foreword ivIntroduction v1 Scope . 12 Normative references 13 Terms and definitions . 14 Symbols and abbreviated terms . 15 Limits of applicability of linear theory 35.1 Multiple scattering . 35.2 Concentration considerations 35.3 Steric repulsion . 66 Measurement issues
10、 in concentrated systems 76.1 General . 76.2 Path length limitation 76.3 High attenuation 76.4 Increased viscosity 76.5 Change in velocity 76.6 Change in pulse shape 86.7 Homogeneity . 87 Nonlinear attenuation 88 Determination of particle size 88.1 Calculation 88.2 Limits of application. 99 Instrume
11、nt qualification 99.1 Calibration 99.2 Precision . 99.2.1 Reference materials . 99.2.2 Repeatability . 99.2.3 Reproducibility 99.3 Accuracy 99.3.1 Qualification procedure . 99.3.2 Reference materials 109.3.3 Instrument preparation 109.3.4 Accuracy test 109.3.5 Qualification acceptance criteria 1010
12、Reporting of results 10Annex A (informative) Theories of attenuation in concentrated systems 11Annex B (informative) Practical example of PSD measurement (coupled phase model) 14Bibliography .22 ISO 2017 All rights reserved iiiContents PageBS ISO 20998-3:2017ISO 20998-3:2017(E)ForewordISO (the Inter
13、national 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 body interested in a subject for which a technical committee has
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15、andardization.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 for the different types of ISO documents should be noted. This document was drafted in accor
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17、ils 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 document is information given for the convenience of users and does not constitute an
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19、owing URL: www .iso .org/ iso/ foreword .html .This document was prepared by Technical Committee ISO/TC 24, Particle characterization including sieving, Subcommittee SC 4, Particle characterization.A list of all the parts in the ISO 20998 series can be found on the ISO websiteiv ISO 2017 All rights
20、reservedBS ISO 20998-3:2017ISO 20998-3:2017(E)IntroductionUltrasonic spectroscopy is widely used to measure particle size distribution (PSD) in colloids, dispersions, and emulsions1234. The basic concept is to measure the frequency-dependent attenuation and/or velocity of the ultrasound as it passes
21、 through the sample. This attenuation includes contributions due to scattering or absorption by particles in the sample, and the size distribution and concentration of dispersed material determines the attenuation spectrum567. Once this connection is established by empirical observation or by theore
22、tical calculations, one can estimate the PSD from the ultrasonic data. Ultrasonic techniques are useful for dynamic online measurements in concentrated slurries and emulsions. Traditionally, such measurements have been made offline in a quality control lab, and constraints imposed by the instrumenta
23、tion have required the use of diluted samples. By making in-process ultrasonic measurements at full concentration, one does not risk altering the dispersion state of the sample. In addition, dynamic processes (such as flocculation, dispersion, and comminution) can be observed directly in real time 8
24、. This data can be used in process control schemes to improve both the manufacturing process and the product performance. ISO 2017 All rights reserved vBS ISO 20998-3:2017BS ISO 20998-3:2017Measurement and characterization of particles by acoustic methods Part 3: Guidelines for non-linear theory1 Sc
25、opeThis document gives guidelines for ultrasonic attenuation spectroscopy methods for determining the size distributions of one or more material phases dispersed in a liquid at high concentrations, where the ultrasonic attenuation spectrum is not a linear function of the particle volume fraction. In
26、 this regime, particle-particle interactions are not negligible. This document is applicable to colloids, dispersions, slurries, and emulsions. The typical particle size for such analysis ranges from 10 nm to 3 mm, although particles outside this range have also been successfully measured. Measureme
27、nts can be made for concentrations of the dispersed phase ranging from about 5 % by volume to over 50 % by volume, depending on the density contrast between the continuous and the dispersed phases, the particle size, and the frequency range9 10. These ultrasonic methods can be used to monitor dynami
28、c changes in the size distribution, including agglomeration or flocculation.2 Normative referencesThe following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For u
29、ndated references, the latest edition of the referenced document (including any amendments) applies.ISO 14488:2007, Particulate materials Sampling and sample splitting for the determination of particulate propertiesISO 20998-1:2006, Measurement and characterization of particles by acoustic methods P
30、art 1: Concepts and procedures in ultrasonic attenuation spectroscopyISO 20998-2:2013, Measurement and characterization of particles by acoustic methods Part 2: Guidelines for linear theory3 Terms and definitionsFor the purposes of this document, the terms and definitions given in ISO 20998-1 and IS
31、O 20998-2 apply.ISO and IEC maintain terminological databases for use in standardization at the following addresses: ISO Online browsing platform: available at h t t p :/ www .iso .org/ obp IEC Electropedia: available at h t t p :/ www .electropedia .org/ 4 Symbols and abbreviated termsFor the purpo
32、ses of this document, the following symbols and abbreviated terms apply.INTERNATIONAL STANDARD ISO 20998-3:2017(E) ISO 2017 All rights reserved 1BS ISO 20998-3:2017ISO 20998-3:2017(E)a particle radiusc, c speed of sound in the liquid and particle, respectivelyCPspecific heat at constant pressureCV c
33、oefficient of variation (ratio of the standard deviation to the mean value)d average distance between adjacent particlesdB decibele base of the natural logarithmECAH Epstein-Carhart-Allegra-Hawley (theory)f frequencyG real part of the effective coupling parameter Si the imaginary numberk complex wav
34、enumberM radius of shell in core-shell modelPSD particle size distributionR imaginary part of the effective coupling parameter SS complex number representing the effective coupling between fluid and particleSNR ratio of signal level to noise levelx particle diameterx10the 10th percentile of the cumu
35、lative PSDx50median size (50th percentile)x90the 90th percentile of the cumulative PSD attenuation spectrum, compressibility of the liquid and particle, respectivelymean compressibility of the slurryTthermal wave skin depthVviscous wave skin depth viscosity of the liquid thermal conductivity, densit
36、y of the liquid and particle, respectivelymean density of the slurry* mean density at the complementary concentration (1-)2 ISO 2017 All rights reservedBS ISO 20998-3:2017ISO 20998-3:2017(E) volume concentration of the dispersed phasemmaximum volume concentration of the dispersed phase (maximum pack
37、ing)NLconcentration at which the skin depth becomes equal to the interparticle distance angular frequency (i.e. 2 times the frequency)5 Limits of applicability of linear theory5.1 Multiple scatteringThe interaction of a plane compressional sound wave with a particle generates three waves propagating
38、 outward: 1) a compressional wave; 2) a thermal wave; and 3) a viscous (transverse) wave. The thermal and viscous waves propagate only a short distance (of the order of 0,5 m in water at 1 MHz) through the liquid. In the linear model (discussed in ISO 20998-2), attenuation is directly proportional t
39、o particle volume concentration since only the forward compressional wave is considered as propagating beyond the region of a single isolated particle, and the effect of multiple particles is determined by the average superposition of their scattered fields. However in the nonlinear model, the wave
40、arriving at any particle is a combination of the incident wave together with all waves scattered by other particles. The resulting total scattered wave field is therefore a result of scattering of the incident wave by all particles and the rescattering (or multiple scattering) of already-scattered w
41、aves. All three wave modes (produced by scattering at a particle) contribute to the wave field at neighbouring particles, and can therefore be scattered by these neighbours, thereby producing compressional scattered waves as well as other modes. This effect creates a nonlinear concentration dependen
42、ce of attenuation.NOTE Multiple scattering depends on the configuration and aperture of the transducers as well as on the type of excitation signal, e.g. pulse, tone-burst, quasi-continuous, or continuous20.Multiple scattering models have largely considered only the multiple scattering of the compre
43、ssional wave mode, neglecting the contribution of scattered thermal and shear waves to the wave field which is incident at a particle11121314. The second-order concentration effects obtained from these multiple scattering models are significant only where there is a substantial density difference be
44、tween the phases. In many systems, the nonlinear effects due solely to compressional wave multiple scattering are small, and they can be modelled using the multiple scattering models mentioned above. Substantial nonlinear effects arise primarily because of the contributions of scattered thermal and
45、shear waves to the incident field at any particle.5.2 Concentration considerationsThe distances over which thermal and viscous waves decrease by a factor of (1/e) are known as the thermal and viscous skin depths, respectively, which are calculated by Formulae (1) and (2). The skin depths for water a
46、re shown as a function of frequency in Figure 1.T=2CP(1)V=2(2) ISO 2017 All rights reserved 3BS ISO 20998-3:2017ISO 20998-3:2017(E)Key skin depth (m)f frequency (MHz)Vviscous wave skin depthTthermal wave skin depthFigure 1 Skin depth for viscous (dashed line) and thermal (solid line) waves in water
47、at 20 CAt high concentrations, the interparticle spacing may become small enough that the particles can no longer be considered to be completely isolated. This effect is compounded at low frequencies, where the skin depths calculated in Formulae (1) and (2) are longer. The thermal and shear waves pr
48、oduced by scattering at a particle contribute significantly to the wavefield at a neighbouring particle, being rescattered to produce compressional waves (and other modes). For practical purposes, the breakdown of linear theory (or nonlinear compressional models) occurs when the viscous or thermal w
49、aves from adjacent particles overlap significantly. Quantifying the overlap in simple terms is difficult, but a standard approach is to determine the concentration when the interparticle distance is less than or equal to the skin depth. Since the viscous layer has greater thickness in most liquids, the onset of multiple scattering occurs when the interparticle distance d equals the viscous skin depth.For a suspension of monosized spheres, the interparticle distance d i
