Cereals - Determination of bulk density, called mass per hectolitre - Part 2: Method of traceability for measuring instruments through reference to the international standard instrument (ISO 7971-2:2019)

This document specifies a test method for ensuring the traceability of bulk density, called “mass per
hectolitre”, measuring instruments through reference to standard measurement instruments. The
mass per hectolitre is of commercial importance for grain cereals. Several types of instruments with
varying performances exist for measuring it.
This document also specifies the performances required of national standards instruments, secondary
standards instruments, and measuring instruments used in laboratories or in collection or storage silos.

Getreide - Bestimmung der Schüttdichte, sogenannte Masse je Hektoliter - Teil 2: Verfahren zur Rückverfolgbarkeit von Messgeräten mittels Referenz auf internationale Normalgeräte (ISO 7971-2:2019)

Dieses Dokument legt ein Prüfverfahren zur Sicherstellung der Rückverfolgbarkeit der für die Messung der Schüttdichte, bezeichnet als „Masse je Hektoliter“, angewendeten Geräte durch Bezugnahme auf ein Normal¬messgerät fest. Die Masse je Hektoliter ist bei Getreide von wirtschaftlicher Bedeutung. Zur Messung dieser Eigenschaft stehen verschiedene Messgeräte mit unterschiedlichem Leistungsverhalten zur Verfügung.
Dieses Dokument legt auch die Leistungsanforderungen fest, die die nationalen Normalgeräte, die sekun-dären Normalgeräte und die in Laboratorien oder in Annahme  oder Lagersilos verwendeten Messgeräte er¬füllen müssen.

Céréales - Détermination de la masse volumique, dite masse à l'hectolitre - Partie 2: Méthode de raccordement des instruments de mesure à l'étalon international (ISO 7971-2:2019)

Le présent document spécifie une méthode d'essai pour assurer le raccordement des instruments de mesure de la masse volumique, dite «masse à l'hectolitre» aux étalons. La masse à l'hectolitre présente un intérêt commercial pour les céréales en grains. Il existe plusieurs types d'instruments aux performances variables pour la mesurer.
Le présent document spécifie également les performances exigées pour les étalons nationaux et secondaires ainsi que pour les instruments de mesure utilisés dans les laboratoires ou dans les silos de collecte ou de stockage.

Žito - Določanje prostorninske mase, imenovane hektolitrska masa - 2. del: Metoda sledljivosti za merilne instrumente glede na referenčni mednarodni etalonski instrument (ISO 7971-2:2019)

Ta dokument določa preskusno metodo za zagotavljanje sledljivosti instrumentov za merjenje prostorninske mase, imenovane »hektolitrska masa«, glede na referenčne etalonske merilne instrumente. Hektolitrska masa je komercialno pomembna za žito v zrnju. Za merjenje je na voljo več vrst instrumentov z različnimi zmogljivostmi.
Ta dokument določa tudi zmogljivosti, ki se zahtevajo od nacionalnih etalonskih instrumentov, sekundarnih etalonskih instrumentov in merilnih instrumentov, ki se uporabljajo v laboratorijih ali v zbirnih oziroma skladiščnih silosih.

General Information

Status
Published
Public Enquiry End Date
04-Mar-2018
Publication Date
08-Apr-2019
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
18-Mar-2019
Due Date
23-May-2019
Completion Date
09-Apr-2019

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SIST EN ISO 7971-2:2019
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Cereals - Determination of bulk density, called mass per hectolitre - Part 2: Method of

traceability for measuring instruments through reference to the international standard

instrument (ISO 7971-2:2019)
Getreide - Bestimmung der Schüttdichte, sogenannte Masse je Hektoliter - Teil 2:

Verfahren zur Rückverfolgbarkeit von Messgeräten mittels Referenz auf internationale

Normalgeräte (ISO 7971-2:2019)

Céréales - Détermination de la masse volumique, dite masse à l'hectolitre - Partie 2:

Méthode de raccordement des instruments de mesure à l'étalon international (ISO 7971-

2:2019)
Ta slovenski standard je istoveten z: EN ISO 7971-2:2019
ICS:
67.060 äLWDVWURþQLFHLQSURL]YRGLL] Cereals, pulses and derived
QMLK products
SIST EN ISO 7971-2:2019 en

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN ISO 7971-2:2019
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SIST EN ISO 7971-2:2019
EN ISO 7971-2
EUROPEAN STANDARD
NORME EUROPÉENNE
March 2019
EUROPÄISCHE NORM
ICS 67.060 Supersedes EN ISO 7971-2:2009
English Version
Cereals - Determination of bulk density, called mass per
hectolitre - Part 2: Method of traceability for measuring
instruments through reference to the international
standard instrument (ISO 7971-2:2019)

Céréales - Détermination de la masse volumique, dite Getreide - Bestimmung der Schüttdichte, sogenannte

masse à l'hectolitre - Partie 2: Méthode de Masse je Hektoliter - Teil 2: Verfahren zur

raccordement des instruments de mesure à l'étalon Rückverfolgbarkeit von Messgeräten mittels Referenz

international (ISO 7971-2:2019) auf internationale Normalgeräte (ISO 7971-2:2019)

This European Standard was approved by CEN on 8 February 2019.

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 application to the CEN-CENELEC 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-CENELEC Management

Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,

Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,

Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,

Turkey and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels

© 2019 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 7971-2:2019 E

worldwide for CEN national Members.
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SIST EN ISO 7971-2:2019
EN ISO 7971-2:2019 (E)
Contents Page

European foreword ....................................................................................................................................................... 3

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SIST EN ISO 7971-2:2019
EN ISO 7971-2:2019 (E)
European foreword

This document (EN ISO 7971-2:2019) has been prepared by Technical Committee ISO/TC 34 "Food

products" in collaboration with Technical Committee CEN/TC 338 “Cereal and cereal products” the

secretariat of which is held by AFNOR.

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 September 2019, and conflicting national standards

shall be withdrawn at the latest by September 2019.

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. CEN shall not be held responsible for identifying any or all such patent rights.

This document supersedes EN ISO 7971-2:2009.

According to the CEN-CENELEC Internal Regulations, the national standards organizations of the

following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,

Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia,

France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta,

Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,

Turkey and the United Kingdom.
Endorsement notice

The text of ISO 7971-2:2019 has been approved by CEN as EN ISO 7971-2:2019 without any

modification.
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SIST EN ISO 7971-2:2019
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SIST EN ISO 7971-2:2019
INTERNATIONAL ISO
STANDARD 7971-2
Third edition
2019-02
Cereals — Determination of bulk
density, called mass per hectolitre —
Part 2:
Method of traceability for measuring
instruments through reference to the
international standard instrument
Céréales — Détermination de la masse volumique, dite masse à
l'hectolitre —
Partie 2: Méthode de raccordement des instruments de mesure à
l'étalon international
Reference number
ISO 7971-2:2019(E)
ISO 2019
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SIST EN ISO 7971-2:2019
ISO 7971-2:2019(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2019

All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may

be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting

on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address

below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Fax: +41 22 749 09 47
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2019 – All rights reserved
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SIST EN ISO 7971-2:2019
ISO 7971-2:2019(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Requirements .......................................................................................................................................................................................................... 2

4.1 Certified international or national standard instrument ................................................................................... 2

4.2 National standard instrument ................................................................................................................................................... 2

4.3 Secondary or internal standard instrument .................................................................................................................. 2

4.4 Routine measuring instrument ................................................................................................................................................. 3

5 Principle ........................................................................................................................................................................................................................ 3

6 Apparatus ..................................................................................................................................................................................................................... 3

7 Procedure..................................................................................................................................................................................................................... 4

7.1 Traceability of national standard instruments through reference to the certified

international or national standard instrument .......................................................................................................... 4

7.1.1 General description ....................................................................................................................................................... 4

7.1.2 Preparation of the test samples .......................................................................................................................... 5

7.1.3 Use of the referenced test samples .................................................................................................................. 5

7.1.4 Interpretation of the results .................................................................................................................................. 5

7.1.5 Adjustment of the national standard instrument ................................................................................ 6

7.2 Traceability of the secondary standard instruments through reference to the

national standard instrument .................................................................................................................................................... 6

7.2.1 General description ....................................................................................................................................................... 6

7.2.2 Preparation of the test samples .......................................................................................................................... 6

7.2.3 Use of the referenced test samples .................................................................................................................. 7

7.2.4 Interpretation of the results .................................................................................................................................. 7

7.2.5 Adjustment of the secondary standard instrument .......................................................................... 7

7.3 Verification of instruments in operation .......................................................................................................................... 7

7.3.1 General description ....................................................................................................................................................... 7

7.3.2 Preparation of the control test samples....................................................................................................... 8

7.3.3 Use of the referenced test samples .................................................................................................................. 8

7.3.4 Interpretation of the results .................................................................................................................................. 8

7.3.5 Adjustment of the instrument .............................................................................................................................. 9

8 Monitoring of instrument performance ....................................................................................................................................... 9

9 Test reports .............................................................................................................................................................................................................10

9.1 Analysis certificate ............................................................................................................................................................................10

9.2 Conformity certificate ....................................................................................................................................................................10

10 Identification of traced measuring instruments ..............................................................................................................10

Annex A (normative) Method for calculation of performance parameters of standard

instruments and of measurement instruments ................................................................................................................11

Annex B (informative) Example — Owners of certified standard measurement instruments .............22

Bibliography .............................................................................................................................................................................................................................23

© ISO 2019 – All rights reserved iii
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SIST EN ISO 7971-2:2019
ISO 7971-2:2019(E)
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.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the

different types of ISO documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/directives).

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. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www .iso .org/patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO’s adherence to the

World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see www .iso

.org/iso/foreword .html.

This document was prepared by Technical Committee ISO/TC 34, Food products, Subcommittee SC 4,

Cereals and pulses.

This third edition cancels and replaces the second edition (ISO 7971-2:2009), which has been technically

revised. The main changes compared with the previous edition are as follows:

— changes have been made to the test samples used for the traceability of measuring instruments

through reference to standard measurement instruments (review of the number, range, distribution

and characteristics of the samples);
— further details have been given on statistical tests;

— clarification has been given on the decision rules by adding a decision tree for national standard

instruments and secondary or internal standard instruments and by introducing a bias control.

A list of all parts in the ISO 7971 series can be found on the ISO website.

Any feedback or questions on this document should be directed to the user’s national standards body. A

complete listing of these bodies can be found at www .iso .org/members .html.
iv © ISO 2019 – All rights reserved
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SIST EN ISO 7971-2:2019
INTERNATIONAL STANDARD ISO 7971-2:2019(E)
Cereals — Determination of bulk density, called mass per
hectolitre —
Part 2:
Method of traceability for measuring instruments through
reference to the international standard instrument
1 Scope

This document specifies a test method for ensuring the traceability of bulk density, called “mass per

hectolitre”, measuring instruments through reference to standard measurement instruments. The

mass per hectolitre is of commercial importance for grain cereals. Several types of instruments with

varying performances exist for measuring it.

This document also specifies the performances required of national standards instruments, secondary

standards instruments, and measuring instruments used in laboratories or in collection or storage silos.

2 Normative references

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements 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 712, Cereals and cereal products — Determination of moisture content — Reference method

ISO 7971-1:2009, Cereals — Determination of bulk density, called mass per hectolitre — Part 1:

Reference method
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https: //www .iso .org/obp
— IEC Electropedia: available at http: //www .electropedia .org/
3.1
mass per hectolitre
bulk density
test weight

ratio of the mass of a cereal to the volume it occupies after being poured into a container

under defined manufacturer’s conditions

Note 1 to entry: Mass per hectolitre is expressed in kilograms per hectolitre of grains as received.

[SOURCE: ISO 7971-1:2009, 2.1, modified — In the definition, “defined manufacturer’s conditions” has

replaced “well-defined conditions”, and the Note 2 to entry has been deleted.]
© ISO 2019 – All rights reserved 1
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SIST EN ISO 7971-2:2019
ISO 7971-2:2019(E)
3.2
traceability

establishment of a relationship between the usual measuring instrument and the

international standard instrument via a chain
3.3
analysis certificate

document supplied by the international standard instrument holder body or national standard

instrument holder body containing the individual values of measurements, the mass per hectolitre

average value and its uncertainty for the test sample being analysed
3.4
conformity certificate

document, issued by the body in charge of verifying the performances of the instrument, specifying the

conformity decision for the requested use
3.5
control chart

chart on which some statistical measure of a series of samples is plotted in a particular order to steer

the process with respect to that measure and to control and reduce variation.

Note 1 to entry: The analysis values are plotted on the ordinate against the date (day or hour) of carrying out the

measurement on the abscissa.

[SOURCE: ISO 3534-2:2006, 2.3.1, modified — The two notes to entry have been replaced by a new

Note 1 to entry.]
4 Requirements
4.1 Certified international or national standard instrument

A standard measurement instrument for mass per hectolitre has a 20 l hopper and is certified by a

national or international authority. An example list of suppliers of such instruments is given in Annex B.

4.2 National standard instrument

Each country defines, on the basis of the specifications given in 6.2, the instrument designated as a

national standard instrument within the respective country.

This national standard instrument should be an instrument designated by its name (model,

manufacturer, serial number). Any other instrument of the same model as that adopted as the national

standard instrument shall not be referred to as a “national standard instrument”.

Each country defines the public or private organization responsible for the safe keeping, use, and

maintenance of this national standard instrument. This same organization ensures its traceability

through reference to a certified international or national standard instrument (4.1), according to the

provisions specified in 7.1, every ten years.

Each country shall ensure that no natural or legal person is refused access to the results of this national

standard instrument so that any manufacturer, holder, repairer, controller or user can ensure the

traceability of his own instruments through reference to the national standard instrument.

4.3 Secondary or internal standard instrument

For the purposes of inspection of instruments in operation, a body may possess an appliance specific to

this activity. This instrument shall have the required qualities, established using the national standard

instrument. It shall then constitute the reference which ensures the traceability of the instruments in

operation.
2 © ISO 2019 – All rights reserved
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SIST EN ISO 7971-2:2019
ISO 7971-2:2019(E)

Verify and adjust these secondary standard instruments every two years in accordance with 7.2.

4.4 Routine measuring instrument

This term designates any mass per hectolitre measuring instrument used in commercial transactions.

The traceability of instruments in operation and of new instruments (prior to commissioning) shall be

ensured through reference to a secondary standard instrument (4.3) or a national standard instrument

(4.2) according to the provisions specified in 7.3.

The frequency of this traceability operation is every one year for hand operated instruments and every

two years for automatic devices.
5 Principle

This document specifies a procedure for ensuring the traceability of mass per hectolitre measuring

instruments through reference to standard instruments.
The traceability principle is illustrated by Figure 1.

Figure 1 — Principle of traceability of instruments through reference to standard instruments

6 Apparatus

6.1 International standard instrument for mass per hectolitre as specified in ISO 7971-1.

© ISO 2019 – All rights reserved 3
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SIST EN ISO 7971-2:2019
ISO 7971-2:2019(E)

6.2 National standard instrument for mass per hectolitre. Manual or automatic, mechanical,

electric or electronic mass per hectolitre measuring instrument, of which the capacity of the measuring

container is at least 1 l, accepting a bias correction or a bias and slope correction.

This instrument is used according to the requirements given in 4.2 and traceability is ensured through

reference to the international standard instrument according to the procedure specified in 7.1.

The correction made to the instrument ensures a slope that is not significantly different from 1

and an intercept of bias (difference between the mean of the reference values and the mean of the

measurements produced by the instrument) that is not significantly different from 0 at the 5 %

threshold [see Formulae (A.8), (A.9) and (A.10), A.7.1.2 and A.8.2].

If the national standard instrument is a 20 l apparatus, for any correction refer to ISO 7971-1.

6.3 Secondary standard instrument for the mass per hectolitre. Manual or automatic, mechanical,

electric or electronic mass per hectolitre measuring instrument, of which the capacity of the measuring

container is at least 750 ml, accepting a bias and/or slope correction.

This instrument is used according to the requirements given in 4.3 and traceability is ensured through

reference to the national standard instrument according to the procedure specified in 7.2.

The correction made to the instrument ensures a slope that is not significantly different from 1

and an intercept of bias (difference between the mean of the reference values and the mean of the

measurements produced by the instrument) that is not significantly different from 0 at the 5 %

threshold [see Formulae (A.8), (A.9) and (A.10), A.7.1.2 and A.8.2].

6.4 Mass per hectolitre measuring instrument. Manual or automatic, mechanical, electric or

electronic, adjustable or fixed mass per hectolitre measuring instrument, associated if necessary with an

equivalence or correction table and used according to the requirements given in 4.4.

The verification of these instruments specified in 7.3 concerns both new instruments and instruments

in operation.

The amplitude, Δρ , between the highest and the lowest value, measured on each control sample (see

7.3.4), shall not exceed 0,3 kg/hl.

For each control sample, the difference between the value given by the national standard instrument or

the secondary standard instrument and the mean of the measurements carried out on the instrument,

i.e. Δρ (see 7.3.4), shall not exceed 0,4 kg/hl.
i,2–m

6.5 Divider. Manual or mechanical cone-shaped divider that can representatively reduce a 25 l volume

of grains to a volume suited to the instruments to undergo traceability.
7 Procedure

7.1 Traceability of national standard instruments through reference to the certified

international or national standard instrument
7.1.1 General description

The traceability of national standard instruments is conducted using a series of test samples referenced

with their mass per hectolitre and accompanied by their analysis certificate. The use of wheat and

barley test samples is recommended because of the regular shape of the grain and the good availability

of these species of grains. Other seeds with regular shape of grain, e.g. triticale or rye, can be used if

performance requirements are fulfilled. The use of grains with inhomogeneous shape, e.g. oats, is not

advisable.
4 © ISO 2019 – All rights reserved
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SIST EN ISO 7971-2:2019
ISO 7971-2:2019(E)
7.1.2 Preparation of the test samples

Select seven test samples of common wheat and/or durum wheat and seven test samples of barley

having the following characteristics:

a) the mass per hectolitre of one of the barley test samples shall be less than 64 kg/hl and the mass

per hectolitre of one of the (common and/or durum) wheat test samples shall be greater than or

equal to 82 kg/hl to ensure that a wide range is covered;

b) with a difference in mass per hectolitre between two successive test samples that is as regular as

possible in the range 1 kg/hl to 3 kg/hl;

c) an approximate mass of 30 kg, packed in correctly identified, rigid, airtight containers;

d) a moisture content (mass fraction) between 9 % and 14 % (as determined by ISO 712 or using a

rapid method whose measurement does not differ from the reference value by ±0,4 g water per

100 g of sample);

e) freedom from abnormal odours and from live insects, not containing any heterogeneous impurities

of a size over 10 mm and guaranteeing a residual impurity content below 2 % mass fraction of the

following: broken grain, other cereals, sprouted grain, foreign grain and inert material (such as

soil, sand, plastic and glass particles, husk, straw).

Dispatch the fourteen test samples prepared in this manner to an owner of a certified standard

measurement instrument for determination of their mass per hectolitre and of the uncertainty

associated with this quantity. Check that this uncertainty is no more than 0,30 kg/hl.

When these test samples come back, if they have to be stored prior to use, place them in controlled

conditions with temperature capped at 22 °C so as to not affect their properties. Do not store these test

samples at negative temperatures.
EXAMPLE

A set of test samples with masses per hectolitre of 71 kg/hl, 73 kg/hl, 75 kg/hl, 78 kg/hl, 81 kg/hl, 82 kg/hl

and 84 kg/hl for wheat and 63 kg/hl, 65 kg/hl, 68 kg/hl, 70 kg/hl, 73 kg/hl, 75 kg/hl and 77 kg/hl for barley is

suitable.

The wheat and barley distributions overlap, the differences between two successive test samples are in the range

1 kg/hl to 3 kg/hl, and the full range is covered.
7.1.3 Use of the referenced test samples

If the mass per hectolitre referenced test samples have been stored in a refrigerating chamber, it is

necessary to wait until their temperature has reached equilibrium with that of the premises where the

tests are being carried out before opening the containers.

If the volume of the referenced test samples is such that they cannot be fully used in the national

standard instrument, constitute test portions of appropriate mass, which are representative of the

initial test sample, using a divider.
Select three of these test portions and conduc
...

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