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1、| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | BRITISH STANDARD BS ISO 13319:2000 ICS 19.
2、120 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW Determination of particle size distributions Electrical sensing zone method Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 26 04:22:18 GMT+00:00 2006, Uncontrolled Copy, (c) BSI This British Standard, having been prepare
3、d under the direction of the Sector Committee for Materials and Chemicals, was published under the authority of the Standards Committee and comes into effect on 15 June 2000 BSI 06-2000 ISBN 0 580 34916 0 BS ISO 13319:2000 Amendments issued since publication Amd. No.DateComments National foreword Th
4、is British Standard reproduces verbatim ISO 13319:2000 and implements it as the UK national standard. It supersedes BS 3406-5:1983 which is withdrawn. The UK participation in its preparation was entrusted by Technical Committee LBI/37, Sieves, screens and particle sizing, to Subcommittee LBI/37/4, S
5、izing by methods other than sieving, which has the responsibility to: aid enquirers to understand the text; present to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed; monitor related international and
6、European developments and promulgate them in the UK. A list of organizations represented on this subcommittee can be obtained on request to its secretary. This British Standard is one of a series implementing ISO standards prepared by international committee ISO/TC 24/SC 4, some of which will replac
7、e parts of BS 3406. Attention is drawn to parts of BS 3406 still current at the time of publication of this British Standard. Cross-references The British Standards which implement international publications referred to in this document may be found in the BSI Standards Catalogue under the section e
8、ntitled International Standards Correspondence Index, or by using the Find facility of the BSI Standards Electronic Catalogue. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Complian
9、ce with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, the ISO title page, pages ii to iv, pages 1 to 30, an inside back cover and a back cover. The BSI copyright notice displayed in this do
10、cument indicates when the document was last issued. Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 26 04:22:18 GMT+00:00 2006, Uncontrolled Copy, (c) BSI Reference number ISO 13319:2000(E) INTERNATIONAL STANDARD ISO 13319 First edition 2000-04-01 Determination of particle size distributions Ele
11、ctrical sensing zone method Dtermination des rpartitions granulomtriques Mthodes de la zone de dtection lectrique Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 26 04:22:18 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ISO 13319:2000(E) ii? Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 26 04
12、:22:18 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ISO 13319:2000(E) ?iii Contents?Page Foreword.iv 1?Scope 1 2?Terms and definitions .1 3?Symbols1 4?Principle2 5?General operation3 6?Operational procedures 4 7?Calculation of results 10 8?Analysis11 9?Validation11 Annex A (informative) Table of mater
13、ials and electrolyte solutions12 Annex B (informative) Technique using two (or more) sensors 23 Annex C (informative) Example of calibration by mass integration 25 Annex D (informative) Calibration and control of frequently used orifices 27 Annex E (informative) Data sheet28 Bibliography30 Licensed
14、Copy: sheffieldun sheffieldun, na, Sun Nov 26 04:22:18 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ISO 13319:2000(E) iv? Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International St
15、andards 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
16、 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 3. Draft International Standards adopte
17、d 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 International Standard may be the sub
18、ject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. International Standard 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. Annexes A to E of
19、this International Standard are for information only. Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 26 04:22:18 GMT+00:00 2006, Uncontrolled Copy, (c) BSI INTERNATIONAL STANDARD?ISO 13319:2000(E) ?1 Determination of particle size distributions Electrical sensing zone method 1?Scope This Intern
20、ational Standard gives guidance on the measurement of the size distributions of particles dispersed in an electrolyte solution using the electrical sensing zone method. It does not address the specific requirements of the particle size measurement of specific materials. The method described in this
21、International Standard measures particle volumes and reports in the range about from 0,6 ?m to 1 600 ?m. 2?Terms and definitions For the purposes of this International Standard, the following terms and definitions apply. 2.1 dead time time during which the electronics are not able to detect particle
22、s due to the signal processing of a previous particle 2.2 orifice small-diameter hole through which suspension is drawn 2.3 sensing zone volume of electrolyte solution within, and around, the orifice in which a particle is detected 2.4 sampling volume volume of suspension that is analysed 3?Symbols
23、D?orifice diameter, in ?m Kdcalibration constant of diameter Kdcalibration constant of mean diameter ? Kd standard deviation of mean calibration constant m?mass of sample in beaker, in g VTvolume of electrolyte solution in which m is dispersed, in ml Vmanalysis volume, in ml ?Ninumber of counts in a
24、 size interval i ?mass of the particles per volume of the electrolyte it displaces, in g?ml?1 Viarithmetic mean volume for a particular size interval i, in ml Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 26 04:22:18 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ISO 13319:2000(E) 2? Vivolume of t
25、he particle obtained from the threshold, or channel boundary and instrument units; without an arbitrary calibration to particle diameter (i.e. Vi= tIA, where t = threshold level, I = current through aperture and A = attenuation factor), in ml x?diameter of a sphere with volume equivalent to that of
26、the particle, in ?m x50, x10, x90the values of x corresponding to the 50 %, 10 % and 90 % percentile points of the cumulative per cent undersize distributions, in ?m 4Principle The response, i.e. the electrical pulse generated when a particle passes through the orifice, has been found both experimen
27、tally and theoretically to be proportional to the particle volume (see Bibliography). A dilute suspension of particles dispersed in an electrolyte solution is stirred to provide a homogeneous mixture and is drawn through a small orifice, or aperture, in an insulating wall. A current applied across t
28、wo electrodes, placed on each side of the orifice, enables the particles to be sensed by the electrical impedance changes as they pass through the orifice. The particle-generated pulses are amplified and counted and the pulse height is analysed. After employing a calibration factor, a distribution o
29、f 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?
30、Volumetric metering device?6?Output 2?Valve?7?Pulse-height analyser 3?Pulse amplifier?8?Stirred suspension of particles in electrolyte solution 4?Oscilloscope pulse display?9?Aperture 5?Counting circuit?10?Counter start/stop Figure 1 Diagram illustrating the principle of the electrical sensing zone
31、method Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 26 04:22:18 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ISO 13319:2000(E) ?3 5?General operation 5.1? Response If the particles are spherical, the electrical response is proportional to the volume of the particles. This has also been shown to
32、 be true for particles of other shapes; however, the constant of proportionality (i.e. the instruments calibration constant) may be different. In general, particles should have a low conductivity with respect to the electrolyte solution, but conducting particles can be measured. 5.2? Size limits The
33、 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 ?m, but under favourable conditions a lower limit is possible. There is no theoretical upper limit, and for particles having a
34、density similar to that of the electrolyte solution, the largest orifice available (normally 2 000 ?m) may be used. When the particle density is high, the upper size limit is reached when the particles can no longer be kept in homogeneous suspension. In this case, the viscosity and/or the density of
35、 the electrolyte solution has to be increased, for example by the addition of glycerol or sucrose. The size range for a single orifice sensor is proportional to the orifice diameter, D. The response has been found to depend linearly on D over a range from 0,015 D to 0,80 D (i.e. 1,5 ?m to 80 ?m for
36、a 100 ?m orifice), although the orifice may become prone to blockage at levels greater than 0,60 D. This range can be extended by using two or more sensors (see annex B) but in practice this procedure can be avoided by the careful selection of the diameter of one sensor, to achieve an acceptable ran
37、ge. The response of the instrument is dependent on the effective electrical resistance of the particle, which is usually high. The measurement of conducting particles (e.g. metals, carbon, silicon and many types of cells and organisms, such as blood cells) requires more time to implement. The partic
38、les can become electrically translucent (i.e. give a smaller electrical pulse than their volume indicates) if a voltage, typically of 10 V to 15 V or more, is applied between the electrodes. To obtain acceptable results, a distribution is obtained under normal conditions. The analysis is then repeat
39、ed using half the current and twice the gain (1/attenuation). The distributions should be the same. If they are not, the procedure should be repeated using an even lower current. 5.3? Effect of coincident particle passage Ideal data would result if particles traversed the orifice singly, when each p
40、article 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
41、 the reported size of each will be increased, or some particles will not be counted. These effects will distort the particle distribution obtained but can be minimized by using low concentrations. Table 1 shows counts per millilitre for the coincidence to be 5 % (i.e. approximately only one particle
42、 in twenty is affected). 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 whe
43、n 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
44、 noticeable. 5.4? Dead time In some modern instruments, pulse-height analysis routines are used to process the data. Since it takes a finite time to process each pulse, it is possible that the analyser may not count particles for a given time after receiving a pulse. This means that, for a relativel
45、y high count rate, a significant proportion of the counts may be lost. Since dead time is not a function of the pulse height, the loss will be proportional to the counts in each channel and will not affect the size distribution. However, if concentration is to be reported or the mass integration met
46、hod of calibration (see 6.11.3) is to be used, the effect can be kept to a minimum by using dilute suspensions (e.g. at 5 % coincidence) and setting up the instrument so that the pulses in the lowest channels are not counted. This is Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 26 04:22:18 GM
47、T+00:00 2006, Uncontrolled Copy, (c) BSI ISO 13319:2000(E) 4? done by first obtaining a count distribution and observing the number of counts per channel. A typical result is shown in Figure 2. By restricting the counts in the lowest channel to that shown by A, the dead time will be minimized. In no
48、rmal operation, this dead time will not cause any distortion of the size distribution since all particles will have the same chance of not being counted, provided that a large number of particles, at least 100 000, are counted. However dead time will affect the accuracy of the mass integration metho
49、d of calibration (see 6.11.3), when there will be an apparent loss of mass. Counts at channels below A are noise counts. True particle counts are at the higher channels Figure 2 Typical results 5.5? Repeatability of counts It has been shown that, in a correctly performed analysis, the number of counts in each channel is a random variable which follows Poissons law. This means that the standard deviation of a number of counts N approximates toN. Thus, in a series of replicate runs the number of counts in a channel, Ni,1, Ni,2, Ni,3, etc., which yield a mean coun