ISO 9276-4:2001 粒子サイズ分析の結果の表現—パート4：分類プロセスの特性評価 | ページ 2

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 3.

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 part of ISO 9276 may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights.

International Standard ISO 9276-4 was prepared by Technical Committee ISO/TC 24, Sieves, sieving and other sizing methods, Subcommittee SC 4, Sizing by methods other than sieving.

ISO 9276 consists of the following parts, under the general title Representation of results of particle size analysis:

• Part 1: Graphical representation
• Part 2: Calculation of average particle sizes/diameters and moments from particle size distributions
• Part 3: Fitting of an experimental cumulative curve to a reference model
• Part 4: Characterization of a classification process
• Part 5: Validation of calculations relating to particle size analyses using the logarithmic normal probability distribution

Annex A of this part of ISO 9276 is for information only.

Introduction

In classification processes used in particle size analysis, such as occurring in impactors, sieves, etc., the mass of the supply or feed material, m_s, or its number, n_s, of particles, the particle size distribution of which is described by its density distribution, q_{r ,s}( x ), is separated into at least one fine fraction of mass, m_f, or number, n_f, and of density distribution, q_{r ,f}( x ) and a coarse fraction of mass, m_c, or number, n_c, and a density distribution, q_{r ,c}( x ). The type of quantity chosen in the analysis is described by the subscript, r , the supply or feed material and the fine and coarse fractions by the additional subscripts: s; f and c respectively. See Figure 1.

Figure 1 — Fractions and distributions produced in a one step classification process

For the characterization of processes with more than one coarse fraction, e.g. cascade impactors, s, f and c can be replaced by numbers 0, 1 and 2. In this case e.g. number 3 describes a second coarse fraction containing larger particles than fraction 2.

It is assumed that the size, x , of a particle is described by the diameter of a sphere. Depending on the problem, the particle size, x , may also represent an equivalent diameter of a particle of any other shape.

1 Scope

The main object of this part of ISO 9276 is to provide the mathematical background for the characterization of a classification process. This part of ISO 9276 is not limited to an application in particle size analysis, the same procedure may be used for the characterization of a technical classification process (e.g. air classification, centrifugal classification) or a separation process (e.g. gas or hydrocyclones).

In clause 3 the characterization of a classification process is described under the presupposition that the density distribution curves describing the feed material and the fractions, as well as the overall mass balance, are free from errors. In clause 4 the influence of systematic errors on the efficiency of a classification process is described. The effect of stochastic errors in the characterization of a classification process is described in annex A.

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