1、January 2010DEUTSCHE NORM English price group 9No part of this standard may be reproduced without prior permission ofDIN Deutsches Institut fr Normung e. V., Berlin. Beuth Verlag GmbH, 10772 Berlin, Germany,has the exclusive right of sale for German Standards (DIN-Normen).ICS 67.060!$Tr“1564979www.d
2、in.deDDIN EN ISO 7971-1Cereals Determination of bulk density, called mass per hectolitre Part 1: Reference method (ISO 7971-1:2009)English version of DIN EN ISO 7971-1:2010-01Getreide Bestimmung der Schttdichte, sogenannte Masse je Hektoliter Teil 1: Referenzverfahren (ISO 7971-1:2009)Englische Fass
3、ung DIN EN ISO 7971-1:2010-01www.beuth.deDocument comprises pages13DIN EN ISO 7971-1:2010-01 National foreword This standard has been prepared by Technical Committee CEN/TC 338 “Cereal and cereal products” (Secretariat: AFNOR, France) in collaboration with Technical Committee ISO/TC 34 “Food product
4、s” (Secretariat: AFNOR, France), Subcommittee SC 4 “Cereals and pulses” (Secretariat: SAC, China) and has been published in accordance with the result of the parallel voting procedure within the scope of the Agreement on technical cooperation between ISO and CEN (Vienna Agreement) to adopt, without
5、alteration, International Standard ISO 7971-1:2009 as a European Standard. The responsible German body involved in its preparation was the Normenausschuss Lebensmittel und landwirtschaftliche Produkte (Food and Agricultural Products Standards Committee), Working Committee NA 057-05-06 AA Getreide un
6、d Getreideerzeugnisse. In addition to the legal units of measurement, this standard also uses the unit “kgf” (kilogramme-force). It is important to note that according to the German law on units in metrology, the use of the unit “kgf” is not permitted in official or business communications within Ge
7、rmany. Non-SI unit SI-unit kgf 9,806 65 N DIN EN ISO 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 internation
8、al standard instrument Part 3: Routine method 2 EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN ISO 7971-1 August 2009 ICS 67.060 English Version Cereals - Determination of bulk density, called mass per hectolitre - Part 1: Reference method (ISO 7971-1:2009) Crales - Dtermination de la masse vo
9、lumique, dite masse l hectolitre - Partie 1: Mthode de rfrence (ISO 7971-1:2009) Getreide - Bestimmung der Schttdichte, sogenannte Masse je Hektoliter - Teil 1: Referenzverfahren (ISO 7971-1:2009) This European Standard was approved by CEN on 8 August 2009. CEN members are bound to comply with the C
10、EN/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 application to the CEN Management Centre or
11、 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 Centre has the same status as the official ver
12、sions. 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, Poland, Portugal, Romania, Slovakia, Slovenia,
13、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 any means reserved worldwide for CEN nationa
14、l Members. Ref. No. EN ISO 7971-1:2009: EContents Page Foreword. Scope . 4 2 3 4 Requirements for apparatus . 4 4.1 4.2 . 6 4.3 . .7 4.4 9 5 6 7 Test reports . 10 Bibliography . 11 .31Terms and definitions. 4Principle. 4General . 4Description and operation Dimensions .Calibration and adjustmentSampl
15、ing. 9Procedure. 9Expression of results 108EN ISO 7971-1:2009 (E) DIN EN ISO 7971-1:2010-01 2. 10 9Det 6.16.2Preliminary operationsermination.Foreword This document (EN ISO 7971-1:2009) has been prepared by Technical Committee CEN/TC 338 “Cereal and cereal products”, the secretariat of which is held
16、 by AFNOR, 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
17、 at the latest 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, th
18、e national 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, No
19、rway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom. EN ISO 7971-1:2009 (E) DIN EN ISO 7971-1:2010-01 31 Scope This part of ISO 7971 specifies the reference method for the determination of bulk density, called “mass per hectolitre”, of cereals as gr
20、ain. NOTE Several routine methods are used in different countries. A routine method for the determination of bulk density, called “mass per hectolitre”, is given in ISO 7971-3. 2 Terms and definitions For the purposes of this document, the following terms and definitions apply. 2.1 bulk density “mas
21、s per hectolitre” cereals ratio of the mass of a cereal to the volume it occupies after being poured into a container under well-defined conditions NOTE 1 Bulk density is expressed in kilograms per hectolitre of grain as received. NOTE 2 The bulk density, as defined in this part of ISO 7971, is diff
22、erent from “packing density” or “intrinsic density” of cereals. 3 Principle A sample is poured in a controlled manner from a hopper into a 20 l container, which is then weighed. 4 Requirements for apparatus 4.1 General The apparatus used shall comply with the following requirements, which correspond
23、 to those in OIML R 15 2, and shall be similar to that shown in Figure 1. EN ISO 7971-1:2009 (E) DIN EN ISO 7971-1:2010-01 4Dimensions in millimetres Figure 1 Apparatus for determining bulk density of cereals (continued) EN ISO 7971-1:2009 (E) DIN EN ISO 7971-1:2010-01 5Key 1 filling hopper 11 shutt
24、er 2 truncated cone for guiding the flow of grain 12 frame of straightedge 3 straightedge counterweight 13 straightedge 4 guiding skirt for surplus grain 14 straightedge counterweight 5 guide by rail and rollers of the frame of the straightedge 15 height of flow 6 removable part of skirt allowing th
25、e measuring container to be removed 16 wedged base support of measuring container in filling position 7 measuring container, volume 20 l 17 collecting box for surplus grain 8 base support of measuring container 18 distributor 9 tapered emptying tube 19 straightedge 10 guiding collar for grain flow 2
26、0 handle of wedge for base support NOTE This figure is for information only except for the dimensions shown, which are obligatory. Figure 1 Apparatus for determining bulk density of cereals 4.2 Description and operation 4.2.1 Pre-filling container. The pre-filling measure has a nominal volume of 24
27、l. Its internal form is a right circular cylinder with height approximately equal to its diameter. 4.2.2 Filling hopper. The hopper has the shape of a truncated vertical circular cone surmounted by a cylindrical rim. Its lower part terminates in an axial tube with a slightly tapering bore, the wider
28、 end of which is at the bottom. A shutter, hinge-mounted on the tube and able to close the tube completely, controls the emptying process. The hopper receives from the pre-filling container a quantity of grain greater than the content of the measuring container. 4.2.3 Distributor. The distributor is
29、 an inverted circular mushroom-shaped element connected to the bottom end of a vertical rod positioned in the axis of the hopper. The rod lowers the distributor inside the tapered tube to an adjustable level from top to bottom to allow adjustment of the apparatus: lowering the distributor increases
30、the rate of flow of the grain, which collects in greater quantity owing to compaction in the measuring container, thus giving higher results; conversely, the results are lower when the distributor is raised. 4.2.4 Measuring container. The measuring container has a nominal volume of 20 l. Its interna
31、l form is a right circular cylinder with height approximately equal to its diameter. Its upper edge is ground flat. 4.2.5 Base support for the measuring container. A base on rails supports the container and allows it to travel underneath the hopper, in the axis of which it can be locked, or taken ou
32、t of the chassis for easy removal. 4.2.6 Protection and guiding collar for grain flow. A cylindrical collar, of the same diameter as the measuring container, is placed between the hopper and the measuring container, leaving a horizontal space between its lower edge and the upper edge of the containe
33、r to allow the passage of a straightedge. During filling, the collar, which is surmounted by a truncated cone-shaped section, protects the grain as it drops and at the end retains the surplus grain. 4.2.7 Straightedge (levelling blade). The straightedge is a flat, thin but rigid steel blade, sharpen
34、ed to the form of an open V at the front. It is fixed horizontally in a frame mounted on rollers and driven in its plane by a counterweight. EN ISO 7971-1:2009 (E) DIN EN ISO 7971-1:2010-01 6The frame guides the straightedge across the grain in the gap between the collar and the upper edge of the me
35、asuring container. The movement shall be continuous and not jerky, and the straightedge shall touch neither the collar nor the container. In its movement, the straightedge levels the grain to the level of the measuring container, thus giving a determined volume. 4.2.8 Collecting box for surplus grai
36、n. At the same time as levelling the grain, the straightedge also closes off the lower surface of the collar as it removes from the container any grain surplus to its volume. When the straightedge is drawn back, with the container removed, this surplus grain falls into a collecting box placed beneat
37、h the base of the container and towards which the grain is guided by a skirt. 4.2.9 Overall assembly. The apparatus is assembled in a rigid chassis equipped with a verticality adjustment screw; verticality is checked by means of a plumbline or a spirit-level. The hopper with its tube and distributor
38、, the collar and the measuring container shall be coaxial and positioned vertically by means of the adjustment device described above, the upper edge of the measuring container thus being horizontal. 4.2.10 Weighing device. The grain contained in the measuring container is weighed using a non-automa
39、tic balance which has been weighted to compensate for the mass of the empty container. Therefore, one single weighing gives the mass of the grain. The error of the balance shall not exceed 0,01 % of load between 10 kgf and 20 kgf or, when using weights, the sum of errors of weights shall not exceed
40、0,02 %. 4.3 Dimensions 4.3.1 Pre-filling container This shall have the following dimensions: volume to top: 24 l 0,1 l; internal diameter: 300 mm 10 mm; internal height: approximately 340 mm, adjusted to obtain the specified volume. 4.3.2 Filling hopper This shall have the following dimensions: a) t
41、op rim internal diameter: 390 mm 1 mm; height: 120 mm 2 mm; b) truncated-cone body upper internal diameter: 390 mm 1 mm; lower internal diameter: 84,5 mm 0,5 mm; height: 240 mm 1 mm; EN ISO 7971-1:2009 (E) DIN EN ISO 7971-1:2010-01 7c) emptying tube top internal diameter: 84,5 mm 0,5 mm; bottom inte
42、rnal diameter: 86,5 mm 0,5 mm; length: 80 mm 0,5 mm. 4.3.3 Distributor This shall have the following dimensions: a) diameter of the rod: 11 mm 0,2 mm; b) mushroom-shaped element diameter: 33 mm 0,2 mm; head thickness: 5 mm 0,5 mm; connecting radius to the rod: 16 mm 0,5 mm; c) distance from bottom s
43、urface of mushroom to bottom end of emptying tube: 14 mm 0,5 mm. 4.3.4 Measuring container This shall have the following dimensions: volume up to ground top: 20 l 0,01 l; internal diameter 295 mm 1 mm; internal height: approximately 292 mm, adjusted to obtain the specified volume. 4.3.5 Base support
44、 for measuring container This shall have the following dimensions: distance between bottom of inside of container and bottom end of emptying tube: 500 mm 2 mm; distance between top of container and lower surface of straightedge: 0,5 mm 0,2 mm. 4.3.6 Protection and guiding collar for grain flow This
45、shall have the following dimensions: internal diameter: 295 mm 1 mm; height: 78 mm 2 mm; distance between lower edge of collar and upper surface of straightedge: 0,5 mm 0,2 mm. 4.3.7 Straightedge (levelling blade) This shall have the following dimensions: thickness of blade: 3 mm 0,2 mm; mass of dri
46、ving counterweight: 5 kg 0,1 kg. EN ISO 7971-1:2009 (E) DIN EN ISO 7971-1:2010-01 84.3.8 Chassis A plumbline shall be provided of length at least 500 mm (or spirit-level of the same sensitivity), for checking verticality. 4.4 Calibration and adjustment 4.4.1 Calibration Calibration of the apparatus
47、(l) is carried out by comparison with a calibrated national or international measurement standard instrument1)(E). Use a wheat free from impurities, whose grains are approximately spherical, with a standard mass per hectolitre of not less than 80 kg/hl, at the same temperature and under the same con
48、dition of humidity as the atmosphere of the room where the measurement is to be made. For this purpose, spread the cereal in a thin layer and leave it for 10 h (one night) in the room where the measurement is to be made, ensuring that the relative humidity of the air does not exceed 60 %. Carry out
49、six measurements with each apparatus, using the same sample of 24 l of grain, in the following order. Before each new measurement, the grain contained in the measuring container should be well mixed with the grain that has fallen into the collecting box during the previous measurement. Measurement No. 1 2 3 4 5 6 Order of measurements E-I I-E E-I I-E E-I I-E The standard deviation of the values given by I shall not exceed 6 g. 4.4.2 Accuracy error The
