1、 g49g50g3g38g50g51g60g44g49g42g3g58g44g55g43g50g56g55g3g37g54g44g3g51g40g53g48g44g54g54g44g50g49g3g40g59g38g40g51g55g3g36g54g3g51g40g53g48g44g55g55g40g39g3g37g60g3g38g50g51g60g53g44g42g43g55g3g47g36g58centrifugal liquid sedimentation methods Part 2: Photocentrifuge methodICS 19.120Determination of p
2、article size distribution by BRITISH STANDARDBS ISO 13318-2:2007BS ISO 13318-2:2007This British Standard was published under the authority of the Standards Policy and Strategy Committee on 31 October 2007 BSI 2007ISBN 978 0 580 59625 4Amendments issued since publicationAmd. No. Date Commentscontract
3、. Users are responsible for its correct application.Compliance with a British Standard cannot confer immunity from legal obligations. National forewordThis British Standard is the UK implementation of ISO 13318-2:2007. It supersedes BS ISO 13318-2:2001 which is withdrawn.The UK participation in its
4、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 Reference numberISO 13318-2:20
5、07(E)INTERNATIONAL STANDARD ISO13318-2Second edition2007-09-15Determination of particle size distribution by centrifugal liquid sedimentation methods Part 2: Photocentrifuge method Dtermination de la distribution granulomtrique par les mthodes de sdimentation centrifuge dans un liquide Partie 2: Mth
6、ode photocentrifuge BS ISO 13318-2:2007ii iiiContents Page Foreword iv Introduction v 1 Scope . 1 2 Normative references . 1 3 Terms, definitions and symbols 1 4 Principle. 2 5 Apparatus 2 6 Sampling 6 7 Preparation 6 7.1 Sample preparation 6 7.2 Temperature 6 7.3 Dispersion . 6 8 Procedure 6 8.1 Li
7、ne-start methods 6 8.2 Homogeneous technique. 7 9 Tests in duplicate and validation 8 9.1 Tests in duplicate 8 9.2 Validation. 8 10 Calculation of results . 8 10.1 General. 8 10.2 Calculation of particle size 8 10.3 Calculation of cumulative mass percentage 8 11 Reporting of results 9 Annex A (infor
8、mative) Worked example. 11 Annex B (informative) Extinction curve, example for titanium dioxide 15 Annex C (informative) Effect of radial dilution 16 Bibliography . 17 BS ISO 13318-2:2007iv Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standa
9、rds 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 organ
10、izations, 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 i
11、n 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 %
12、 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 13318-2 was prepared by Technical Committee ISO/TC 24, Siev
13、es, sieving and other sizing methods, Subcommittee SC 4, Sizing by methods other than sieving. This second edition cancels and replaces ISO 13318-2:2001, of which it constitutes a minor revision, due to the extension of Clause 4 and 5.2, and the addition of Figure 3 and the Bibliography. ISO 13318 c
14、onsists of the following parts, under the general title Determination of particle size distribution by centrifugal liquid sedimentation methods: Part 1: General principles and guidelines Part 2: Photocentrifuge method Part 3: Centrifugal X-ray method BS ISO 13318-2:2007vIntroduction The sample suspe
15、nsion in a photocentrifuge may be contained in a cuvette or a disc. Sample concentration is determined by changes in a light signal monitored at a known radius. The cuvette photocentrifuge can only be run in the homogeneous mode whereas the disc photocentrifuge may be run in either the homogeneous o
16、r the line-start mode. Some systems permit the coarse end of the distribution to be measured in a gravitational mode and the fine end in the centrifugal mode. The use of light to determine particle size distribution requires a calibration factor to be applied as the particle size approaches the wave
17、length of the light, due to the inapplicability of the laws of geometric optics. BS ISO 13318-2:2007blank1Determination of particle size distribution by centrifugal liquid sedimentation methods Part 2: Photocentrifuge method WARNING This part of ISO 13318 may involve hazardous materials, operations
18、and equipment. This part of ISO 13318 does not purport to address all of the safety problems associated with its use. It is the responsibility of the user of this part of ISO 13318 to establish appropriate safety and health practices and determine the applicability of the regulatory limitations prio
19、r to its use. 1 Scope This part of ISO 13318 covers methods for determining the particle size distribution of particulate materials by means of centrifugal sedimentation in a liquid. Solids concentrations are determined by the transmission of a light beam. The resulting signal enables conversion to
20、a particle size distribution. The method of determining the particle size distribution described in this part of ISO 13318 is applicable to powders that can be dispersed in liquids, powders that are present in slurry form and some emulsions. Typical particle size range for analysis is from about 0,1
21、 m to 5 m. The method is applicable to powders in which all particles have the same density and comparable shapes and do not undergo chemical or physical change in the suspension liquid. It is usually necessary that the particles have a density higher than that of the liquid. 2 Normative references
22、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 13318-1, Determination of particle size distr
23、ibution by centrifugal liquid sedimentation methods Part 1: General principles and guidelines ISO 14887, Sample preparation Dispersing procedures for powders in liquids 3 Terms, definitions and symbols For the purposes of this document, the terms, definitions and symbols given in ISO 13318-1, and th
24、e following symbols, apply. D optical density Eiextinction coefficient for a particle of diameter xi F(surface) frequency undersize by surface G constant dependent upon the geometry of the system, the dimensions of the light beam and on the shape of the particles BS ISO 13318-2:20072 l transmission
25、of the emergent light beam, at the time t, after the start of sedimentation l0transmission of the emergent light beam when no particles are present M distance from rotation axis to measurement zone (mm) ninumber of particles of diameter xiin the beam R distance from rotation axis to centrifuge wall,
26、 inner disc radius (mm) S distance from rotation axis to liquid/air interface of sample (mm) x0 diameter of the smallest particle in the light beam (m) xStdiameter of the largest particle in the light beam, i.e. the Stokes diameter (m) 4 Principle A stable, finely collimated beam of light passes thr
27、ough a spinning disc or cuvette and sedimenting sample and is detected at a known radius. Light rays, typically from either a white light source (e.g. incandescent bulb) or a monochromatic coherent source (e.g. laser), pass through the suspension and are detected by a photodiode or photomultiplier.
28、The disc photocentrifuge can be operated in the line-start or homogeneous mode whereas the cuvette photocentrifuge can be operated only in the homogeneous mode. The signal of the light beam is monitored over the analysis time. The mass percentage of sample present in the beam is determined by calcul
29、ating the ratio of the light transmission signal, by use of a clear dispersing liquid, to the light transmission signal with the sample present. In the line-start mode the disc initially contains clear fill liquid to give maximum light transmission. Then the sample is injected as a thin layer on top
30、 of the spinning fill liquid and begins to settle outward radially. When the largest particles present reach the light beam the light transmission decreases, returning to the original transmission value when the smallest particle present passes through the beam. A buffer layer is usually injected ov
31、er the fill liquid to prevent suspension breaking through the interface in a phenomenon known as “streaming”. In an alternative configuration, the determination of the particle size distribution by centrifugal liquid sedimentation method can also be accomplished using a photocentrifuge containing a
32、line light source and a line sensor detector system aligned with the sample cell. In this configuration, light intensity/extinction alterations during centrifugation are measured simultaneously over the whole sedimentation zone as a function of both time and of position. From these data, the particl
33、e size distribution may be calculated either from the time course of the extinction at a freely selectable position within the sample numerical integration, ISO 13318-1:2001, Equation (11) in 4.3.3.3 or from the extinction profile along the sample at a freely selectable time (analytical integration,
34、 for details see Reference 1). 5 Apparatus 5.1 Disc photocentrifuge, with a chamber consisting of a hollow disc with an entry port coaxial with the axis of rotation (see Figure 1). Typically this is mounted vertically, or at a small angle to the vertical, on to the shaft of an electric motor with a
35、digitally variable speed typically between 500 rmin1and 15 000 rmin1. A white light source and detector assembly measures transmittance through the suspension as a function of time. The instrument can be used in either a line-start or homogeneous mode. Extinction coefficient corrections need to be a
36、pplied for the breakdown in the laws of geometric optics for both line-start and homogeneous modes. Additionally, a correction is required for radial dilution effects when the homogeneous mode is used. Software is provided with commercial equipment to convert the data directly into size distribution
37、s in the form of tables or graphs of cumulative mass percentage versus particle size. BS ISO 13318-2:200735.2 Cuvette photocentrifuge, in which the disc is replaced with a rectangular cell containing a homogeneous suspension (see Figure 2). Corrections need to be made for both radial dilution and li
38、ght scattering effects as described in ISO 13318-1. Cuvette photocentrifuges can typically be run in both the gravitational and centrifugal modes. Additionally, some systems may offer a gradient mode permitting the centrifuge to accelerate throughout the analysis in order to reduce the measurement t
39、ime. When determining particle size distribution using an apparatus containing a line light source and a line sensor detection system, transmittance is measured along the entire sedimentation zone simultaneously (see Figure 3). 5.3 Ancillary apparatus, consisting of: dispersing vessel, e.g. glass be
40、aker or bottle, of appropriate dimensions; flexible spatula; ultrasonic bath or probe, a bottle shaker or high speed mechanical stirrer capable of rotating at 500 rmin1 to 1 000 rmin1. Key 1 motor shaft 2 spin fluid 3 buffer layer 4 suspension 5 entry port 6 polymethylmethacrylate disc Figure 1 Side
41、 view of the disc of a disc photocentrifuge BS ISO 13318-2:20074 Key 1 motor 2 motor control 3 signal process 4 analogue to digital converter (ADC) 5 central processing unit (CPU) 6 date time 7 analysis parameters 8 revolutions per minute (RPM) 9 keyboard 10 printer 11 analog interface 12 computer i
42、nterface 13 photosensor revolutions per minute (RPM) 14 centrifugal cell 15 rotating disc 16 light-emitting diode (LED) 17 photocell (reference) 18 photocell (sample) 19 photocells aSynchro-signal (reference). bAnalog signal. cSynchro-signal (sample). Figure 2 Schematic diagram of a typical cuvette
43、photocentrifuge BS ISO 13318-2:20075Key X position for one selected time Y intensity 1 axis of rotation 2 incident parallel light 3 sample cell 4 centrifugal force 5 rotor 6 transmitted light 7 line detector array Figure 3 Schematic diagram of a cuvette photocentrifuge with line light source and lin
44、e detector array BS ISO 13318-2:20076 6 Sampling For sampling see ISO 13318-1. 7 Preparation 7.1 Sample preparation An analysis sample shall be prepared as described in ISO 13318-1. The volume and concentration required depends upon the volume of the centrifuge disc (or cuvette), the sensitivity of
45、the optical-electronic system and whether the line-start (disc only) or homogeneous method is to be used. In general, lower concentrations are required than for other sedimentation methods. A mass per volume concentration typically less than 0,25 % and providing an attenuation preferably in the 20 %
46、 to 30 % range compared to the spin fluid without sample is required. 7.2 Temperature The temperature of the spin fluid (line-start method) or suspension (homogeneous method) shall be determined and recorded before and after analysis in accordance with ISO 13318-1. The liquid viscosity and liquid de
47、nsity shall be recorded for the spin fluid or suspension at the temperature of the analysis. The temperature shall be maintained in accordance with ISO 13318-1. 7.3 Dispersion For dispersion see ISO 13318-1 and ISO 14887. 8 Procedure 8.1 Line-start methods 8.1.1 General The line-start method is one
48、in which a layer of sample suspension is deposited on a spinning fill liquid, i.e. all particles are considered to have started to sediment from the same initial radius. However, the sample suspension has a tendency to penetrate the surface of the spin liquid as globules of suspension which then “st
49、ream” rapidly through the spin liquid. The streaming effect is due to an uneven outward diffusion of the sample suspension. On injection of the sample suspension the particles can become concentrated by surface tension effects at the interface. This leads to a region of high density above one of lower density and causes a bulk transfer of concentrated suspension into the spin fluid. Streaming is particularly prone to happen if the sample suspension is injected directly on to the spin fluid (two-layer me
