BS-ISO-13319-2007.pdf

BRITISH STANDARD BS ISO 13319:2007 Determination of particle size distributions Electrical sensing zone method ICS 19.120 ? Licensed Copy: London South Bank University, London South Bank University, Fri Oct 05 02:27:12 GMT+00:00 2007, Uncontrolled Copy, (c) BSI BS ISO 13319:2007 This British Standard was published under the authority of the Standards Policy and Strategy Committee on 28 September 2007 © BSI 2007 ISBN 978 0 580 55238 0 National foreword This British Standard is the UK implementation of ISO 13319:2007. It supersedes BS ISO 13319:2000 which is withdrawn. The UK participation in its preparation was entrusted to Technical Committee LBI/37, Sieves, screens and particle sizing. 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 application. Compliance with a British Standard cannot confer immunity from legal obligations. Amendments issued since publication Amd. No. DateComments Licensed Copy: London South Bank University, London South Bank University, Fri Oct 05 02:27:12 GMT+00:00 2007, Uncontrolled Copy, (c) BSI Reference number ISO 13319:2007(E) INTERNATIONAL STANDARD ISO 13319 Second edition 2007-07-01 Determination of particle size distributions Electrical sensing zone method Détermination des répartitions granulométriques Méthode de la zone de détection électrique BS ISO 13319:2007 Licensed Copy: London South Bank University, London South Bank University, Fri Oct 05 02:27:12 GMT+00:00 2007, Uncontrolled Copy, (c) BSI ii Licensed Copy: London South Bank University, London South Bank University, Fri Oct 05 02:27:12 GMT+00:00 2007, Uncontrolled Copy, (c) BSI iii Contents Page Foreword iv 1 Scope 1 2 Normative references1 3 Terms and definitions .1 4 Symbols2 5 Principle3 6 General operation4 6.1 Response4 6.2 Size limits .4 6.3 Effect of coincident particle passage4 6.4 Dead time5 7 Repeatability of counts .6 8 Operational procedures 6 8.1 Instrument location6 8.2 Linearity of the aperture/amplifier system6 8.3 Linearity of the counting system .7 8.4 Choice of electrolyte solution 7 8.5 Preparation of electrolyte solution 7 8.6 Recommended sampling, sample splitting, sample preparation and dispersion 8 8.7 Choice of aperture(s) and analysis volume(s)9 8.8 Clearing an aperture blockage.10 8.9 Stability of dispersion .10 8.10 Calibration11 9 Analysis 11 10 Calculation of results 12 11 Instrument qualification12 11.1 General12 11.2 Report .12 Annex A (informative) Calibration for the measurement of porous and conductive particles .13 Annex B (informative) Technique using two (or more) apertures16 Annex C (informative) Chi-squared test of the correctness of instrument operation or sample preparation.18 Annex D (informative) Table of materials and electrolyte solutions20 Annex E (informative) Mass integration method30 Annex F (informative) Calibration and control of frequently used apertures.36 Bibliography37 BS ISO 13319:2007 Licensed Copy: London South Bank University, London South Bank University, Fri Oct 05 02:27:12 GMT+00:00 2007, Uncontrolled Copy, (c) BSI iv Foreword 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 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 the International Electrotechnical 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 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 rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 13319 was prepared by Technical Committee ISO/TC 24, Sieves, sieving, and other sizing methods, Subcommittee SC 4, Sizing by methods other than sieving. This second edition cancels and replaces the first edition (ISO 13319:2000), which has been technically revised. BS ISO 13319:2007 Licensed Copy: London South Bank University, London South Bank University, Fri Oct 05 02:27:12 GMT+00:00 2007, Uncontrolled Copy, (c) BSI 1 Determination of particle size distributions Electrical sensing zone method 1 Scope This International Standard gives guidance on the measurement of the size distribution of particles dispersed in an electrolyte solution using the electrical sensing zone method. The method measures pulse heights and their relationship to particle volumes or diameters, and it reports in the range from approximately 0,4 µm to approximately 1 200 µm. It does not address the specific requirements of the measurement of specific materials. However, guidance on the measurements of conducting materials such as porous materials and metal powders is given. 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 referenced document (including any amendments) applies. ISO 787-10, General methods of test for pigments and extenders Part 10: Determination of density Pyknometer method ISO 9276-2:2001, Representation of results of particle size analysis Part 2: Calculation of average particle sizes/diameters and moments from particle size distributions 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 dead time time during which the electronics are not able to detect particles due to the signal processing of a previous pulse 3.2 aperture small-diameter hole through which suspension is drawn 3.3 sensing zone volume of electrolyte solution within, and around, the aperture in which a particle is detected 3.3 sampling volume volume of suspension that is analysed 3.4 channel size interval BS ISO 13319:2007 Licensed Copy: London South Bank University, London South Bank University, Fri Oct 05 02:27:12 GMT+00:00 2007, Uncontrolled Copy, (c) BSI 2 3.5 envelope size external size of a particle as seen in a microscope 3.6 envelope volume volume of the envelope given by the three-dimensional boundary of the particle to the surrounding medium 4 Symbols For the purposes of this document, the following symbols apply. p A amplitude of the most frequent pulse x A amplitude of the electrical pulse generated by an arbitrary particle p d modal diameter of a certified particle size reference material d mean particle diameter of a size interval or channel L d particle diameter at the lower boundary of a size interval or channel U d particle diameter at the upper boundary of a size interval or channel D aperture diameter d K calibration constant of diameter dK mean calibration constant of diameter ad K arbitrary calibration constant of diameter m mass of sample i N number of counts in a size interval i T V volume of electrolyte solution in which a mass, m, is dispersed m V analysis volume i V arithmetic mean volume for a particular size interval i i V volume of the particle obtained from a threshold or channel boundary x diameter of a sphere with volume equivalent to that of the particle 501090 ,xxx values of x corresponding to the 50 %, 10 % and 90 % points of the cumulative percent undersize distributions mass of the particles per volume of the electrolyte displaced d K standard deviation of mean calibration constant BS ISO 13319:2007 Licensed Copy: London South Bank University, London South Bank University, Fri Oct 05 02:27:12 GMT+00:00 2007, Uncontrolled Copy, (c) BSI 3 5 Principle A dilute suspension of particles dispersed in an electrolyte solution is stirred to provide a homogeneous mixture and is drawn through an aperture in an insulating wall. A current applied across two electrodes, placed on each side of the aperture, enables the particles to be sensed by the electrical impedance changes as they pass through the aperture. The particle pulses thus generated are amplified and counted, and the pulse height is analysed. After employing a calibration factor, a distribution of the number of particles against the volume-equivalent diameter is obtained. This distribution is usually converted to percentage by mass versus particle size, where the size parameter is expressed as the diameter of a sphere of volume and density equal to that of the particle. See Figure 1. Key 1 volumetric metering device 2 valve 3 pulse amplifier 4 oscilloscope pulse display 5 counting circuit 6 pulse-height analyser 7 output 8 stirred suspension of particles in electrolyte solution 9 aperture 10 counter start/stop triggered by the volumetric device 11 electrodes Figure 1 Diagram illustrating the principle of the electrical sensing zone method BS ISO 13319:2007 Licensed Copy: London South Bank University, London South Bank University, Fri Oct 05 02:27:12 GMT+00:00 2007, Uncontrolled Copy, (c) BSI 4 6 General operation 6.1 Response The response (i.e. the electrical pulse generated when a particle passes through the aperture) has been found both experimentally and theoretically to be proportional to the particle volume if the particles are spherical 1-3.This has also been shown to be true for particles of other shapes; however, the constant of proportionality (i.e. the instruments calibration constant) may be different 4. In general, particles should have a low conductivity with respect to the electrolyte solution, but particles with high conductivity can be measured e.g. metals 5, carbon 6, silicon and many types of cells and organisms, such as blood cells 7, 8. For porous particles, the response may vary with the porosity 9, 10. Recommendations for the measurement of conducting particles and porous particles are given in Annex A. As the response is proportional to the volume of particles, the pulse amplitude provides a relative scale of particle volumes. By calibration, this scale may be converted to spherical diameter. The calibration constant based on diameter may be calculated by Equation (1): p 3 p d d K A = (1) The size, x, of any particle can be calculated by Equation (2): 3 dx xKA= (2) 6.2 Size limits The lower size limit of the electrical sensing zone method is generally considered to be restricted only by thermal and electronic noise. It is normally stated to be about 0,6 µm but, under favourable conditions, 0,4 µm is possible. There is no theoretical upper size limit, and for particles having a density similar to that of the electrolyte solution, the largest aperture available (normally 2 000 µm) may be used. The practical upper size limit is about 1 200 µm, limited by particle density. In order to increase the possibility of keeping the particles in homogeneous suspension, the viscosity and the density of the electrolyte solution may be increased, for example by addition of glycerol or sucrose. The homogeneity may be checked by repeated analyses at a range of stirrer speeds. The results of this should be compared to establish the lowest speed at which recovery of the largest particles is maintained. The size range for a single aperture is related to the aperture diameter, D. The response has been found to depend linearly in volume on D, within about 5 % under optimum conditions, over a range from 0,015 D to 0,8 D (i.e. 1,5 µm to 80 µm for a 100 µm aperture) although the aperture may become prone to blockage at particle sizes below the maximum size where the particles are non-spherical. In practice, the limitation of thermal and electronic noise and the physical limitation of non-spherical particles passing through the aperture usually restricts the operating range to 2 % to 60 % of the aperture size. This size range can be extended by using two or more apertures (see Annex B). In practice, this procedure can be avoided by the careful selection of the diameter of one aperture, to achieve an acceptable range. 6.3 Effect of coincident particle passage Ideal data would result if particles traversed the aperture singly, when each particle would produce a single pulse. When two or more particles arrive in the sensing zone together, the resulting pulse will be complex. Either a single large pulse will be obtained, resulting in a loss of count and effectively registering a single larger particle, or the count will be correct but the reported size of each will be increased, or some particles will not be counted. These effects will distort the size distribution obtained but can be minimized by using low concentrations. Table 1 shows counts per millilitre for the coincidence probability to be 5 %. BS ISO 13319:2007 Licensed Copy: London South Bank University, London South Bank University, Fri Oct 05 02:27:12 GMT+00:00 2007, Uncontrolled Copy, (c) BSI 5 Table 1 Counts for 5 % coincidence probability for typical aperture diameters Aperture diameter D µm Analysis volume a Vm ml Count for 5 % coincidence b N 1 000 2 80 560 2 455 400 2 1 250 280 2 3 645 200 2 10 000 140 2 29 150 100 0,5 20 000 70 0,5 58 500 50 0,05 16 000 30 0,05 74 000 20 0,05 250 000 a For other sampling volumes, use pro rata values. b Calculated using the equation N= 10 3 410 m V D × Counts per millilitre should always be less than these quoted values. Since particle size distributions should not be a function of concentration, the effect of coincidence can be tested by obtaining a distribution at one concentration and comparing it with that obtained when the concentration is halved. In such a test, repeat such dilutions until the reduction in count in a channel with the largest number decreases in proportion to the dilution. This should always be done when analysing very narrow size distributions, as this is where the effect of coincidence is most noticeable. 6.4 Dead time In instruments using digital pulse processing routines, to analyse the signal it is scanned at high frequency. Information on pulse parameters, such as maximum pulse height, maximum pulse width, mid-pulse height, mid-pulse width and pulse area, is stored for subsequent analysis. In this case, analog-to-digital conversion of the pulse with storage of the size value for the pulse is not performed in real time and dead time losses are avoid