1、BS EN ISO7971-3:2009ICS 67.060NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBRITISH STANDARDCereals Determination of bulkdensity, called massper hectolitrePart 3: Routine method (ISO7971-3:2009)This British Standardwas published underthe authority of theStandards Policy andSt
2、rategy Committee on 30November 2009. BSI 2009ISBN 978 0 580 58450 3Amendments/corrigenda issued since publicationDate CommentsBS EN ISO 7971-3:2009National forewordThis British Standard is the UK implementation of EN ISO 7971-3:2009.It supersedes BS 4317-32:1996 which is withdrawn.The UK participati
3、on in its preparation was entrusted to TechnicalCommittee AW/4, Cereals and pulses.A list of organizations represented on this committee can be obtained onrequest to its secretary.This publication does not purport to include all the necessary provisionsof a contract. Users are responsible for its co
4、rrect application.Compliance with a British Standard cannot confer immunityfrom legal obligations.EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN ISO 7971-3 August 2009 ICS 67.060 English Version Cereals - Determination of bulk density, called mass per hectolitre - Part 3: Routine method (ISO 7
5、971-3:2009) Crales - Dtermination de la masse volumique, dite masse lhectolitre - Partie 3: Mthode pratique (ISO 7971-3:2009) Getreide - Bestimmung der Schttdichte, sogenannte Masse je Hektoliter - Teil 3: Routineverfahren (ISO 7971-3:2009) This European Standard was approved by CEN on 8 August 2009
6、. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on
7、 application to the CEN Management Centre or to any CEN member. This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the CEN Management Ce
8、ntre has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Pol
9、and, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG Management Centre: Avenue Marnix 17, B-1000 Brussels 2009 CEN All rights of exploitation in any form and by
10、any means reserved worldwide for CEN national Members. Ref. No. EN ISO 7971-3:2009: EBS EN ISO 7971-3:2009EN ISO 7971-3:2009 (E) 3 Foreword This document (EN ISO 7971-3:2009) has been prepared by Technical Committee CEN/TC 338 “Cereal and cereal products”, the secretariat of which is held by AFNOR,
11、in collaboration with Technical Committee ISO/TC 34 “Food products“. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by February 2010, and conflicting national standards shall be withdrawn at the lat
12、est by February 2010. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN and/or CENELEC shall not be held responsible for identifying any or all such patent rights. According to the CEN/CENELEC Internal Regulations, the national
13、standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Polan
14、d, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom. BS EN ISO 7971-3:2009ISO 7971-3:2009(E) ISO 2009 All rights reserved iiiContents Page Foreword iv 1 Scope . 1 2 Normative references . 1 3 Terms and definitions. 1 4 Principle. 1 5 Apparatus 2 6 Procedure 2
15、6.1 General. 2 6.2 Hand-operated instruments. 2 6.3 Automatic instruments. 3 6.4 Expression of results . 3 7 Precision 3 7.1 Interlaboratory test . 3 7.2 Repeatability 3 7.3 Reproducibility 3 7.4 Comparison of two groups of measurements in one laboratory. 4 7.5 Comparison of two groups of measuremen
16、ts in two laboratories 4 7.6 Uncertainty 4 8 Test report . 5 Annex A (informative) Description of dimensions and use of KERN apparatus . 6 Annex B (informative) Description of dimensions and use of NILEMA LITRE apparatus 10 Annex C (informative) Results of interlaboratory tests 12 Bibliography . 14
17、BS EN ISO 7971-3:2009ISO 7971-3:2009(E) iv ISO 2009 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 carried out through ISO techn
18、ical 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
19、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 International Standards. Draft In
20、ternational 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 document
21、may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 7971 (all parts) was prepared by the European Committee for Standardization (CEN) Technical Committee CEN/TC 338, Cereal and cereal products, in collaboration with Technical Comm
22、ittee ISO/TC 34, Food products, Subcommittee SC 4, Cereals and pulses, in accordance with the Agreement on technical cooperation between ISO and CEN (Vienna Agreement). The first edition of ISO 7971-3 cancels and replaces the first edition of ISO 7971-2:1995, which has been technically revised. ISO
23、7971 consists of the following parts, under the general title Cereals Determination of bulk density, called mass per hectolitre: Part 1: Reference method Part 2: Method of traceability for measuring instruments through reference to the international standard instrument Part 3: Routine method BS EN I
24、SO 7971-3:2009INTERNATIONAL STANDARD ISO 7971-3:2009(E) ISO 2009 All rights reserved 1Cereals Determination of bulk density, called mass per hectolitre Part 3: Routine method 1 Scope This part of ISO 7971 specifies a routine method for the determination of bulk density, called “mass per hectolitre”
25、of cereals as grain using manual or automatic, mechanical, electric or electronic mass per hectolitre measuring instruments. NOTE Further details of the measuring instruments are specified in ISO 7971-2:2009, 6.4. 2 Normative references The following referenced documents are indispensable for the ap
26、plication 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 7971-2, Cereals Determination of bulk density, called mass per hectolitre Part 2: Method of traceability for
27、 measuring instruments through reference to the international standard instrument 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 bulk density “mass per hectolitre” cereals ratio of the mass of a cereal to the volume it occupies after being p
28、oured into a container under well-defined conditions NOTE 1 Bulk density is expressed in kilograms per hectolitre of grains as received. NOTE 2 The bulk density, as defined in this part of ISO 7971, is different from “packing density” or “intrinsic density” of cereals. ISO 7971-1:2009 4 Principle Th
29、e mass per hectolitre of a cereal is obtained from the mass of a volume of cereal determined under controlled sample filling and flow conditions. BS EN ISO 7971-3:2009ISO 7971-3:2009(E) 2 ISO 2009 All rights reservedThe mass per hectolitre can be affected by: a) space between the grains, which depen
30、ds on the grain size and shape; b) density of the grains. 5 Apparatus 5.1 General requirement for bulk density apparatus. Any apparatus (5.2 and 5.3) shall be verified according to ISO 7971-2 and shall fulfil the performance demands specified therein. 5.2 Hand-operated measuring instrument. Apparatu
31、s consisting of a filling hopper, a measuring container and the accessories necessary for their use. The manner in which the grain is poured into the measuring container and the way in which it packs into the container can cause the measurements taken by the various instruments to vary and lead to m
32、easurement errors. To minimize such variations, special attention should be given to ensuring that the design of the instruments and their size, material and shape are appropriate. NOTE Annexes A and B of this part of ISO 7971 contain examples of technical specifications of two hand-operated instrum
33、ents with a capacity of 1 l. 5.3 Automatic measuring instrument. This category includes various types of devices, some of which can be used on their own or combined with an infrared analyser. The measurement is based on the application of equations to allow the correcting of the bias and/or the drif
34、ts monitored. It does not include manual weighing. The numeric value of the hectolitre mass is directly displayed. 5.4 Analytical balance, capable of being read to the nearest 0,1 g or 0,01 g depending on the volume of the container (see 6.2). 6 Procedure 6.1 General The measurements shall be taken
35、using grain from which large impurities (straw, stones, husks, etc.) have been discarded, taking environmental conditions into consideration to ensure that there is no difference in temperature between the grain and the room in which the test is performed. Determine the bulk density in duplicate. Fo
36、r all the devices and for every sample, it is advisable to perform the two measurements on two different grain test portions. NOTE Repeating the measurement on the same grain test portion changes the friction coefficient which therefore makes it easier for the grains to slide; they are then more tig
37、htly packed, which increases the value of the bulk density. 6.2 Hand-operated instruments Check that the various components of the instrument are clean and that they are working properly. Make sure that equipment is placed on a firm, flat base, after using a spirit level to check that the base is ho
38、rizontal. Take great care to avoid any impact during filling. If the apparatus is jolted, cancel the test and start again. BS EN ISO 7971-3:2009ISO 7971-3:2009(E) ISO 2009 All rights reserved 3Each type of apparatus is different; use each according to the manufacturers instructions. When using the a
39、nalytical balance (5.4), weigh to the nearest 1 g for a 1 l container or the nearest 0,1 g for apparatus with a container of smaller volume. 6.3 Automatic instruments As the operations to be performed prior to the actual measurement differ according to the type of equipment used, reference to the ma
40、nufacturers instructions is recommended. Ensure that the instrument is placed on a horizontal surface in a room protected from extreme temperatures, humidity, dust and vibrations. Take particular care to: a) select the correct cereal to be measured to ensure that the right calibration is used; b) us
41、e the volume of cereals recommended for the device in question; c) empty the collector drawer between samples. 6.4 Expression of results Take the arithmetic mean of the two determinations as the result if the repeatability conditions are met. Express the result to the nearest 0,1 kg/hl. 7 Precision
42、7.1 Interlaboratory test Details of an interlaboratory test on the precision of the method are summarized in Annex C. The values derived from this interlaboratory test cannot be applied to other bulk density ranges and matrices than those given. 7.2 Repeatability The absolute difference between two
43、independent single test results, obtained using the same method on identical test material in the same laboratory by the same operator using the same equipment within a short interval of time, shall not in more that 5 % of cases be greater than the repeatability limit r = 0,4 for products whose mass
44、 per hectolitre is between 67,5 kg/hl and 84,5 kg/hl (see Tables C.1, C.2, and Figure C.1). 7.3 Reproducibility The absolute difference between two single test results, obtained using the same method on identical test material in different laboratories with different operators using different equipm
45、ent, shall not in more that 5 % of cases be greater than the reproducibility limit R = 1,2 for products whose mass per hectolitre is between 67,5 kg/hl and 84,5 kg/hl (see Tables C.1, C.2, and Figure C.1). BS EN ISO 7971-3:2009ISO 7971-3:2009(E) 4 ISO 2009 All rights reserved7.4 Comparison of two gr
46、oups of measurements in one laboratory Critical difference, CDr, is the difference between two averaged values obtained from two test results under repeatability conditions. As the result is a mean of two values (see 6.1), the comparison of two bulk densities shall be made with critical difference.
47、The critical difference, CDr, between two averaged values obtained from two test results under repeatability conditions is given by: 1211 1CD 2,8 2,8 1,98 0,2322 2rr r rsssnn=+= i.e. 0,2 kg/hl, after rounding, where sris the standard deviation of repeatability; n1and n2 are the number of test result
48、s corresponding to each averaged value (here, n1= n2= 2). 7.5 Comparison of two groups of measurements in two laboratories The critical difference, CDR, between two averaged values obtained in two different laboratories from two test results under repeatability conditions is given by: 22 2 2r1211CD
49、2,8 1 2,8 0,5 1,1822RR Rrss s snn=i.e. 1,2 kg/hl, after rounding, where sris the standard deviation of repeatability; sRis the standard deviation of reproducibility; n1and n2 are the number of test results corresponding to each of the averaged values (here n1= n2= 2). 7.6 Uncertainty Uncertainty, Ue, is a parameter representing the distribution of the values which may reasonably be attributed to the result. This uncertainty is given by a statistical distribution of the results from the interlaboratory test and
