1、BRITISH STANDARD BS 5551-2.9: 1991 ISO 8634:1991 Fertilizers Part 2: Sampling Section 2.9 Sampling plan for the evaluation of a large delivery of solid fertilizerBS5551-2.9:1991 This British Standard, having been prepared under the directionof the Chemicals Standards Policy Committee, waspublished u
2、nder the authorityof the Standards Boardand comes into effect on 29November1991 BSI 10-1999 The following BSI references relate to the work on this standard: Committee reference CIC/37 Draft for comment 89/51540 DC ISBN 0 580 20196 1 Committees responsible for this BritishStandard The preparation of
3、 this British Standard was entrusted by the Chemicals Standards Policy Committee (CIC/-) to Technical Committee CIC/37, upon which the following bodies were represented: Association for Consumer Research (ACRE) Association for Public Analysts British Aggregate Construction Materials Industries Briti
4、sh Coal Corporation Chemical Industries Association Department of Trade and Industry (Laboratory of the Government Chemist) Fertiliser Manufacturers Association Ltd. Institute of Trading Standards Administration Ministry of Agriculture, Fisheries and Food Ministry of Defence Amendments issued since
5、publication Amd. No. Date CommentsBS5551-2.9:1991 BSI 10-1999 i Contents Page Committees responsible Inside front cover National foreword ii 1 Scope 1 2 Normative references 1 3 Definitions 1 4 Symbols 1 5 General plan of application 2 6 Determination of the number of increments N and number of anal
6、yses N 2 7 Sampling 3 8 Sampling report 5 9 Analyses of the reduced aggregate samples 5 10 Conclusions 5 Annex A (normative) Statistical data 7 Annex B (informative) Bibliography 9 Table 1 3 Table 2 3 Table 3 3 Table 4 6 Table A.1 Values of the standardized normal variable u as a function of P 7 Tab
7、le A.2 Values of the ratio (1 a 2 )/a 2as a function of N 8 Publication(s) referred to Inside back coverBS5551-2.9:1991 ii BSI 10-1999 National foreword This Section of BS5551 has been prepared under the direction of the Chemicals Standards Policy Committee. For some years the UnitedKingdom has part
8、icipated in the standardization of methods of sampling fertilizers through Subcommittee2, Sampling, of Technical Committee 134, Fertilizers and soil conditioners, of the International Organization for Standardization (ISO). As international agreement is reached on the methods, it is proposed to publ
9、ish them as Sections of BS5551. BS 5551 is published in four Parts, each Part being subdivided into Sections and, where appropriate, Subsections. The four Parts are: Part 1: Terminology and labelling; Part 2: Sampling; Part 3: Physical properties; Part 4: Chemical analysis. This Section of Part 2 is
10、 identical with ISO 8634:1991 “Solid fertilizers Sampling plan for the evaluation of a large delivery”. 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. Compliance with a British Stand
11、ard does not of itself confer immunity from legal obligations. Cross-references International Standard Corresponding British Standard BS 5551 Fertilizers ISO 5306:1983 Section 2.2:1984 Presentation of sampling reports (Identical) ISO/TR 7553:1987 Section 2.7:1988 Recommendations for minimum mass of
12、increment of a solid fertilizer to be taken to be representative of the total sampling unit (Identical) ISO 7742:1988 Section 2.5:1989 Method for reduction of samples of solid fertilizers (Identical) ISO 8358:1991 Section 2.8:1991 Methods for preparation of samples of solid fertilizer for chemical a
13、nd physical analysis (Identical) Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages 1 to 10, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated i
14、n the amendment table on the inside front cover.BS5551-2.9:1991 BSI 10-1999 1 1 Scope This International Standard specifies a method for sampling a delivery of more than250t of fertilizer and, after analysis of the sample or samples, presents rules for assessing whether the delivery can be accepted
15、by a buyer, allowing for given reselling risks under given local legal conditions (or if he wishes to guarantee to the final buyer a given mean assay with a given risk). The weighing of the bags or lots, the date limit for sampling, etc., which are of necessity involved in the definitive evaluation
16、of the delivery, are not dealt with in this International Standard. This sampling plan is applicable to a large delivery of fertilizer supplied to a third party for resale under his own responsibility, in small lots, each of which would be subject to legislation. By “large amount” is understood, for
17、 example, a full boat-load (5000t, 10000t or more) corresponding to a relatively long period of manufacture, but the plan may be used for any delivery of250t or more. 2 Normative references The following standards contain provisions which, through reference in this text, constitute provisions of thi
18、s International Standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent editions of the standards indicated
19、 below. Members of IEC and ISO maintain registers of currently valid International Standards. ISO 5306:1983, Fertilizers Presentation of sampling reports. ISO/TR 7553:1987, Fertilizers Sampling Minimum mass of increment to be taken to be representative of the total sampling unit. ISO 7742:1988, Soli
20、d fertilizers Reduction of samples. ISO 8358:1991, Solid fertilizers Preparation of samples for chemical and physical analysis. 3 Definitions For the purposes of this International Standard, the following definitions apply. These definitions are taken from ISO 8157/Add.1. ISO8157 contains additional
21、 definitions relating to the sampling of fertilizers. 3.1 lot; sample portion the total quantity of material, assumed to have the same characteristics, to be sampled using a particular sampling plan 3.2 delivery a quantity of material transferred at one time 3.3 sampling unit a defined quantity of m
22、aterial having a boundary which may be physical, for example a container, or hypothetical, for example a particular time or time interval in the case of a flow of material 3.4 increment a representative quantity of material taken from a sampling unit 3.5 aggregate sample a combination of all increme
23、nts from the lot NOTE 1In this International Standard, all the increments are grouped in equal numbers to form aggregate samples. 3.6 reduced sample a representative part of the aggregate sample obtained by a process of reduction in such a manner that the mass approximates to that of the final (labo
24、ratory) samples 3.7 final sample a representative part of the reduced sample or, where no intermediate reduction is required, of the aggregate sample 4 Symbols The following symbols appear in this International Standard and have the meanings assigned to them below. N Number of sampling units to be s
25、elected during the sampling of the delivery. (Increments.) N Number of analyses to be carried out on the N increments during the inspection of the delivery. N R Number of sampling units contained in the smallest lot presented for resale. k Number of increments to be combined into each aggregate samp
26、le for analysis. n Number of sampling units which will be mandatorily selected during the official sampling of a lot of N Rsampling units. s Estimate of with the aid of N analyses, where is the standard deviation between the sampling units in the delivery. k BS5551-2.9:1991 2 BSI 10-1999 5 General p
27、lan of application The application of this International Standard involves a certain number of successive operations, which are described in clause6 to clause8. 5.1 Determinations prior to sampling Determination of the number of sampling units N to be sampled and determination of the number of analy
28、ses N to be carried out(see clause6). 5.2 Sampling a) Designation and separation of the sampling units resulting in increments: fertilizer in bags (see7.1.2); fertilizer in bulk (see7.2.2). b) Increments from the sampling units: fertilizer in bags (see7.1.3); fertilizer in bulk (see7.2.3). c) Prepar
29、ation of N aggregate samples by grouping N increments k by k (see7.1.4). d) Preparation by mixing and corresponding reduction of the N aggregate samples into N reduced samples for laboratory testing (see7.1.4). e) Drawing up the sampling report (see clause8). 5.3 Analyses 5.4 Conclusions 6 Determina
30、tion of the number of increments N and number of analysesN Assign numerical values to the following parameters: n, r a , r r , and Refer to Table A.1 to find the corresponding values of the reduced normal variables:and Calculate the values of N and N as a function of these values, using either the c
31、omplete procedure given in6.1 or the simplified procedure given in6.2. The simplified calculation may be used without excessive error as long asN is greater than5. NOTE 2The derivations of formulae used below are to be found in ISO/TR5307 together with typical values of N and N. i Analytical result
32、obtained on the sample of rank i. Estimate of the mean value of the delivery with the aid of the N analyses. L Official inspection limit value which depends on the declared value (D). It may be equal to D or less than D by a prescribed tolerance which may depend on the size of the lot sold. r a Prob
33、ability that the mean value of n sampling units is lower than the official limit value (L), just acceptable by the importer. r r Probability that the mean value of n sampling units is lower than the official limit value (L), just unacceptable by the importer. Probability of rejection of a delivery o
34、f just acceptable quality (sellers or producers risk). Probability of acceptance of a delivery of just unacceptable quality (importers or consumers risk). Value of the standardized normal variable such that Pr equals r a . Value of the standardized normal variable such that Pr equals r r . Value of
35、the standardized normal variable such that Pr equals . Value of the standardized normal variable such that Pr equals . K Calculation coefficient which is dependent on n, the risk levels and and the probability levels r aand r r . a Constant factor dependent on N which represents the uncertainty asso
36、ciated with the estimate of the standard deviation. Non-centrality parameter. t 0 Value of the non-central Student ratio corresponding to the level of probability for a non-centrality parameter equal to . B 0 Limit value of the estimate calculated from t 0 . A, B Calculation intermediates used durin
37、g the estimation of the lot after analysis. F Calculation intermediate used to facilitate the calculation of k and N. i u 1 r a uu 1 r a u 1 r r uu 1 r r u 1 uu 1 u 1 uu 1 Nu 1 r n u 1 r a , u 1 r r , u 1 u 1 BS5551-2.9:1991 BSI 10-1999 3 6.1 Calculation of N and N by the complete procedure To deter
38、mine the minimum value of N, calculate Using Table A.2, determine the value of N such that the ratio corresponding to this value of N is just less than calculated above. Take N 0to be this particular value of N; this is the smallest possible value for N. Leaving (1 a 2 )/a 2undetermined, calculate t
39、he expression With the aid of Table A.2, determine the values of for N = N 0 , N 0+ 1, N 0+ 2, etc. and calculate for each of these values of N the corresponding values of F and hence of k, where k is the whole part of and thus N, where N = kN. Stop when a value N is obtained for which the correspon
40、ding value of F is less than this value N. Let this value be N m . Transfer all the results to Table 1. Table 1 With the aid of Table 1, all possible pairs of N and N can be obtained. For practical application, these pairs of N and N may be given in a simplified table (Table 2). Table 2 6.2 Calculat
41、ion of N and N by the simplified procedure Use the formula where and prepare Table 3, noting that N = N/k and therefore that the value of N multiples of k immediately above the calculated figure must be chosen. Table 3 7 Sampling 7.1 Products in bags This is the general case for products packaged in
42、 small units of mass between10kg and 100kg. A bag usually weighs50kg. 7.1.1 Sampling unit In this case, the sampling unit is a bag. 7.1.2 Designation of bags from which increments are taken The designation of the bags is made at random, for example by numbering the bags1, 2, 3, etc. and using a tabl
43、e of random numbers. 7.1.3 Increments Take one increment per bag chosen, i.e. a total of N increments. Because of the more or less granular nature of solid fertilizers, the masses sampled or handled cannot be reduced indefinitely without losing all representativity. N F k N N 0 N 0+ 1 N 0+ 2N 0+ F N
44、 -1 + 1 a 2 a 2 - N N k N N 1 Z 1 /1 Z 1 2 Z 2 /2 Z 2 3 Z 3 /3 Z 3 4 Z 4 /4 Z 4 5 Z 5 /5 Z 5BS5551-2.9:1991 4 BSI 10-1999 Each increment or divided fraction shall comply with two essential rules. It shall a) contain a sufficient number of grains; b) not favour the sampling of any type of grain or an
45、y particular locality (equiprobability of selection). Condition b) is very exacting as regards the choice of sampling tool, which should be known to have no bias with the type of fertilizer sampled. In case of doubt, preliminary tests on a closely related synthetic mixture are essential. The use of
46、a tool which deals with the complete sampling unit is generally preferable (riffle, cone sample divider, automatic rotary sample divider, etc.) as long as it does not give rise to elutriation phenomena (separating out of the fine particles, centrifuging of the coarse particles, etc.). If the samplin
47、g and division operations are performed on the complete sample unit from which the increment is taken, or on the sample for division, mathematical rules can be used to link the precision obtained with the granulometry and reduced size obtained. It should be noted that all these comments concern all
48、stages of handling of the product sampled, from each increment to the test portion for analysis. The requirements for the minimum mass at each stage of the procedure are set out fully in ISO/TR7553. Place these increments individually in clean, watertight and sealable containers and number them1, 2,
49、 3, etc. 7.1.4 Aggregate samples and reduced aggregate samples Group the increments k by k so as to obtain N aggregate samples (k = N/N). Prepare N clean containers which can be hermetically sealed. Place the increments numbered 1 to k in the first container and the increments numbered from (k + 1) to 2k, etc. in the second container. Mix, as thoroughly as possible, each of the aggregate sample
