1、 Reference number ISO 14488:2007(E) ISO 2007INTERNATIONAL STANDARD ISO 14488 First edition 2007-12-15 Particulate materials Sampling and sample splitting for the determination of particulate properties Matriaux particulaires chantillonnage et division des chantillons pour la caractrisation des propr
2、its particulaires ISO 14488:2007(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 unless the typefaces which are embedded are licensed to and installed on the computer performing the
3、 editing. In downloading this file, parties accept therein the responsibility of not infringing Adobes licensing policy. The ISO Central Secretariat accepts no liability in this area. Adobe is a trademark of Adobe Systems Incorporated. Details of the software products used to create this PDF file ca
4、n be found in the General Info relative to the file; the PDF-creation parameters were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In the unlikely event that a problem relating to it is found, please inform the Central Secretaria
5、t at the address given below. COPYRIGHT PROTECTED DOCUMENT ISO 2007 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing fr
6、om either ISO at the address below or ISOs member body in the country of the requester. ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ii ISO 2007 All rights reservedISO 14488:2007(E
7、) ISO 2007 All rights reserved iii Contents Page Foreword iv Introduction v 1 Scope . 1 2 Normative references . 1 3 Terms and definitions. 1 4 Abbreviations and symbols. 2 5 Principles of sampling and sample splitting .3 5.1 General. 3 5.2 Fundamental error 4 5.3 Total error/number of samples or in
8、crements. 7 6 Sampling plan . 9 7 General procedures 10 7.1 Safety precautions 10 7.2 Primary sampling 10 7.3 Sample handling . 11 7.4 Sample containers 11 7.5 Marking of sample containers . 12 8 Sample division techniques 12 8.1 General. 12 8.2 Spinning riffler 13 8.3 Static riffle divider. 13 8.4
9、Coning and quartering . 14 8.5 Increment division method 15 8.6 Scoop sampling 16 8.7 Sampling from paste 16 8.8 Suspension sampling. 16 9 Validation. 18 Annex A (informative) Calculation of variances at different stages in the sampling sequence 19 Annex B (informative) Estimation of sampling errors
10、 and minimum mass of sample . 23 Bibliography . 30 ISO 14488:2007(E) iv ISO 2007 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
11、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 wo
12、rk. 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 Inte
13、rnational 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 t
14、he 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 14488 was prepared by Technical Committee ISO/TC 24, Sieves, sieving and other sizing methods, Subcommittee SC 4, Sizing by methods other than sievin
15、g. ISO 14488:2007(E) ISO 2007 All rights reserved v Introduction The characterization of particle properties like size, form and specific surface area requires very careful sampling and sample splitting practices to be followed. The distributions of the values of such properties are related to the n
16、umber of particles, which cannot be increased as in sampling for chemical analysis. Deviations from statistical values occur due to the presence of particles of different sizes and shapes for each component in a powder obtained from a sampled mass of powder. INTERNATIONAL STANDARD ISO 14488:2007(E)
17、ISO 2007 All rights reserved 1 Particulate materials Sampling and sample splitting for the determination of particulate properties 1 Scope This International Standard specifies methods for obtaining a test sample from a defined bulk of particulate material (powder, paste, suspension or dust) that ca
18、n be considered to be representative of that bulk with a defined confidence level. It is particularly relevant to the measurement of particle size, size distribution and surface area. 2 Normative references The following referenced documents are indispensable for the application of this document. Fo
19、r dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 3165, Sampling of chemical products for industrial use Safety in sampling ISO 6206, Chemical products for industrial use Sampling Vocabula
20、ry ISO 9276-2, Representation of results of particle size analysis Part 2: Calculation of average particle sizes/diameters and moments from particle size distributions ISO 14887, Sample preparation Dispersing procedures for powders in liquids 3 Terms and definitions For the purposes of this document
21、 the terms and definitions given in ISO 6206 and the following apply. 3.1 bias systematic difference between true (or accepted) value and measured value 3.2 “critical” size class specific size class, whose sampling error, in its fractional mass, has a significant influence upon the product properti
22、es 3.3 error difference between a measured value and the true value, which may have a random or a systematic nature 3.4 gross sample primary sample, composed of several sample increments 3.5 grab sample sample that has not been taken under well-defined conditions ISO 14488:2007(E) 2 ISO 2007 All rig
23、hts reserved3.6 primary sample sample (single or composed) taken from a defined bulk product 3.7 representative sample sample that has the same properties as a defined batch of material and represents the bulk material, within a defined confidence limit 3.8 sample part of a defined bulk product take
24、n for the purpose of characterization 3.9 sample increment single sample, taken from any of a defined set of locations in a bulk product or at any of a defined set of times from a production/transportation line, to be mixed with other increments to form a gross sample 3.10 sampling sequence sequence
25、 of sampling, sample division and combination steps that result in a test sample for a defined bulk product 3.11 spot sample sample, taken at a defined location or production time, from a batch of material 3.12 test sample sample that is entirely used for a property characterization 4 Abbreviations
26、and symbols For the purposes of this document, the following abbreviations and symbols apply. CV coefficient of variation, i.e. standard deviation relative to the corresponding mean value, expressed as fraction or percentage 12 , F standard F-distribution value with 1and 2degrees of freedom FE funda
27、mental error MMD mass median diameter n total number of particles in sample or sample increment n 0number of particles in a defined size class n minnumber of particles in a sample or sample increment required to obtain a defined maximum deviation maxwith a defined level of confidence n MMDrequired n
28、umber of particles in a sample to meet the stated error of the MMD n rtotal number of particles in the log-normal particle size distribution required to reach a maximum coefficient of variation of 3,16 % in x 90N number of measured samples N rnumber of samples required to obtain a defined maximum de
29、viation max , with a defined level of confidence, between the estimated and the true mean value of a property of interest ISO 14488:2007(E) ISO 2007 All rights reserved 3 Q 0 (x i ) cumulative number-based particle size distribution Q 3 (x i ) cumulative volume- or mass-based particle size distribut
30、ion r dimensionality (type of quantity) of a distribution: r = 0: number; r = 1: length; r = 2: area; r = 3: volume or mass SD standard deviation s yestimate of standard deviation of y, coming from measurements t Students t-factor for statistical significance, which depends on the confidence level t
31、aken and the number of degrees of freedom (N 1) (to be taken from statistical tables) Var variance x particle size x 55 percentile size of the particles x 9595 percentile size of the particles x iparticle size corresponding to percentile i y value of any property of interest of the particulate mater
32、ial, e.g. specific size, shape, surface area y mean value of y z ccritical z-value related to a defined confidence level according to the standard normal distribution (to be taken from statistical tables) max defined maximum level of deviation at defined confidence level (half-width of the stated co
33、nfidence interval) granulometric factor, related to the width of the particle size distribution, expressed by the ratio x 95 /x 5of the undersize particle size distribution; 0,25 for wide particle size distribution with x 95 /x 5 4; 0,5 for 2 x 95 /x 5 4; 0,75 for 1 x 95 /x 5 2; and 1 for x 95 /x 5
34、1 density of particles in kg/m 3 standard deviation; square root of variance (theoretical value) ggeometric standard deviation of the log-normal particle size distribution Pfundamental error (standard deviation) of mass fraction of particles smaller than or equal to x i , i.e. Q 3 (x i ) 5 Principle
35、s of sampling and sample splitting 5.1 General Particulate materials consist of discrete particles, each having its own properties such as size, shape, surface area, density and/or composition. Sometimes, the material is well mixed and the properties show only random variations with respect to locat
36、ion in the bulk and/or time of production. More often, however, segregation occurs due to the free-flowing behaviour of the material and/or fluctuations in the production process. This can result in a systematic deviation between the mean properties at different locations and at different times. For
37、 representative sampling, each of the particles in a bulk product must have the same probability of being sampled, in their proportions. For well-mixed materials, a single sample of adequate quantity may suffice. For most materials, some degree of segregation is to be expected. Then, several sample
38、increments must be taken from different locations or at different production times. These are either analysed as such or combined into one primary sample. In most cases, there is no recipe for representative sampling. The quality of the ISO 14488:2007(E) 4 ISO 2007 All rights reservedsampling proced
39、ure can only be assessed by measurement. Often, the primary sample collected in this way is too large for characterization of the required property. Then, sample splitting is necessary until the required quantity for the test is obtained. The total error of sampling and sample splitting consists of
40、two parts: the fundamental error and the segregation error. The fundamental error is related to the discrete nature of particles given their different properties. It is a statistical error, related to the random variations of the properties with respect to location. It represents the lower limit of
41、the total sampling error. This error depends on the amount (number, mass) of sample taken. The segregation error is related to the degree of segregation, or the degree of “de-mixing” of particles according to their size, shape and density. It cannot be predicted, but only assessed by measurement of
42、samples taken at different locations in the bulk and at different times of production. These measurements provide an estimation of the segregation error (see 5.3). Given the complex behaviour of particulate materials, it is required that the complete procedure for sampling and sample splitting be de
43、scribed in a sampling plan (see Clause 6). 5.2 Fundamental error 5.2.1 Number distributions Q 0 (x) For number-based size distributions, the fundamental error expressed as the variance Var or squared standard deviation of a fraction Q 0 (x i ) at any point x i can be calculated using the mathematics
44、 of binomial distributions1, 6 : VarQ 0 (x i ) = Q0,i 2= Q 0 (x i )1 Q 0 (x i )/n (1) If the number of particles in a size class or above a certain size is very small in comparison to the total number of particles taken into account for a measurement, then Poisson statistics may be used for estimati
45、ng the variance or the standard deviation: Var(n 0 ) = (n 0 ) 2= n 0(2) For example, for the number of particles larger than x 90 , it can be seen that n 0= 1 Q 0 (x 90 )n (3) and, since Q 0 (x 90 ) = 0,9 or almost 1, Equations (1) and (3) give approximately the same answers. If the fundamental erro
46、r is the only error, the minimum number of particles n minrequired to obtain a defined maximum deviation maxwith a defined confidence can be derived from: max= z c Q0,i= z c00m i n () 1 () / ii Qx Qxn (4) or n min= Q 0 (x i )1 Q 0 (x i ) z c 2 / max 2(5) where z cis the critical z-value related to t
47、he defined confidence level according to the standard normal distribution and may be obtained from statistical tables. The standard deviation of x ican be calculated from Q0,ithrough multiplication by the reciprocal value of the slope of the cumulative size distribution at point x i : xi= Q0,idx i /
48、dQ 0 (x i ) (6) ISO 14488:2007(E) ISO 2007 All rights reserved 5 The coefficient of variation of x ican be calculated from this standard deviation by multiplication by 100 and division by x i : CV xi= 100 xi /x i(7) 5.2.2 Volume- or mass-based distributions Q 3 (x) For volume- or mass-based size dis
49、tributions, the general calculation of the fundamental error is not simple. One way is to use a spreadsheet programme (e.g. Excel) to convert the measured volume-based size distribution of a typical sample into the corresponding number distribution. The conversion principles and equations given in ISO 9276-2 shall be used. This estimation of the minimum amount of sample in view of a stated minimum fundamental error shall always be the fi
