SIST EN ISO 7971-2:2010

SLOVENSKI STANDARD
SIST EN ISO 7971-2:2010
01-januar-2010
äLWR'RORþDQMHSURVWRUQLQVNHPDVHLPHQRYDQHKHNWROLWUVNDPDVDGHO0HWRGD
VOHGOMLYRVWL]DPHULOQHLQVWUXPHQWHJOHGHQDUHIHUHQþQLPHGQDURGQLHWDORQVNL
LQVWUXPHQW,62
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 7971-2:2009)
Getreide - Bestimmung der Schüttdichte, sogenannte Masse je Hektoliter - Teil 2:
Verfahren zur Rückverfolgbarkeit von Messgeräten mittels Referenz auf internationale
Normalgeräte (ISO 7971-2:2009)
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-
2:2009)
Ta slovenski standard je istoveten z: EN ISO 7971-2:2009
ICS:
67.060 äLWDVWURþQLFHLQSURL]YRGLL] Cereals, pulses and derived
QMLK products
SIST EN ISO 7971-2:2010 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN ISO 7971-2:2010

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SIST EN ISO 7971-2:2010


EUROPEAN STANDARD
EN ISO 7971-2

NORME EUROPÉENNE

EUROPÄISCHE NORM
August 2009
ICS 67.060
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 7971-2:2009)
Céréales - Détermination de la masse volumique, dite Getreide - Bestimmung der Schüttdichte, sogenannte
masse à l'hectolitre - Partie 2: Méthode de raccordement
Masse je Hektoliter - Teil 2: Verfahren zur
des instruments de mesure à l'étalon international (ISO Rückverfolgbarkeit von Messgeräten mittels Referenz auf
7971-2:2009) internationale Normalgeräte (ISO 7971-2:2009)
This European Standard was approved by CEN on 8 August 2009.

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 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 Centre 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, Poland, Portugal,
Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.






EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2009 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 7971-2:2009: E
worldwide for CEN national Members.

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SIST EN ISO 7971-2:2010
EN ISO 7971-2:2009 (E)
Contents Page
Foreword .3

2

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SIST EN ISO 7971-2:2010
EN ISO 7971-2:2009 (E)
Foreword
This document (EN ISO 7971-2:2009) has been prepared by Technical Committee CEN/TC 338 “Cereal and
cereal products”, the secretariat of which is held 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
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, the 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, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain,
Sweden, Switzerland and the United Kingdom.
3

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SIST EN ISO 7971-2:2010

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SIST EN ISO 7971-2:2010

INTERNATIONAL ISO
STANDARD 7971-2
Second edition
2009-08-15


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 7971-2:2009(E)
©
ISO 2009

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SIST EN ISO 7971-2:2010
ISO 7971-2:2009(E)
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ii © ISO 2009 – All rights reserved

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SIST EN ISO 7971-2:2010
ISO 7971-2:2009(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. 2
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
7.2 Traceability of the secondary standard instruments through reference to the national
standard instrument . 6
7.3 Verification of instruments in operation. 7
8 Monitoring of instrument performance . 9
9 Test reports . 9
9.1 Analysis certificate . 9
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) Some owners of certified standard measurement instruments. 18
Bibliography . 19

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SIST EN ISO 7971-2:2010
ISO 7971-2:2009(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.
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 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 document 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 Committee 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).
This edition is the second to bear the number ISO 7971-2, but the technical content is new. ISO 7971-3:2009
cancels and replaces the first edition (ISO 7971-2:1995).
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 international standard
instrument
⎯ Part 3: Routine method

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SIST EN ISO 7971-2:2010
INTERNATIONAL STANDARD ISO 7971-2:2009(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 part of ISO 7971 specifies a test method for ensuring the traceability of mass per hectolitre measuring
instruments through reference to standard measurement instruments. The mass per hectolitre or bulk density
is of commercial importance for grain cereals. Several types of instruments with varying performances exist
for measuring it.
This part of ISO 7971 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 referenced documents are indispensable for the application 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, 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.
3.1
bulk density
“mass 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 Bulk density is expressed in kilograms per hectolitre of grains as received.
[ISO 7971-1:2009]
3.2
traceability
〈cereals〉 establishment of a relationship between the usual measuring instrument and the international
standard instrument via a chain
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SIST EN ISO 7971-2:2010
ISO 7971-2:2009(E)
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
[1]
[ISO 3534-2:2006 , 2.3.1]
NOTE The analysis values are plotted on the ordinate against the date (day or hour) of carrying out the measurement
on the abscissa.
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 informative list 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 10 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.
Verify and adjust these secondary standard instruments every 2 years in accordance with 7.2.
4.4 Routine measuring instrument
This term designates any mass per hectolitre measuring instrument used in commercial transactions.
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SIST EN ISO 7971-2:2010
ISO 7971-2:2009(E)
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) according to the provisions specified in 7.3.
The frequency of this traceability operation is 1 year.
5 Principle
This part of ISO 7971 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.
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.
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SIST EN ISO 7971-2:2010
ISO 7971-2:2009(E)
The correction made to the instrument ensures a slope and an intercept which are not significantly different
from 1 and 0 at the 5 % threshold [see Equations (A.8), (A.9), and (A.10), A.7.3 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 and an intercept which are not significantly different
from 1 and 0 at the 5 % threshold [see Equations (A.8), (A.9), and (A.10), A.7.3 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 between the highest and the lowest value, ∆ρ , measured on each control sample (see 7.3.4),
i
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, ∆ρ ,
i,2−m
(see 7.3.4), shall not exceed 0,3 kg/hl for mass per hectolitre under 70 kg/hl and 0,4 kg/hl for mass per
hectolitre greater than or equal to 70 kg/hl.
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 (3.3). 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.
7.1.2 Preparation of the test samples
Select three test samples of common wheat and/or durum wheat and three test samples of barley having the
following characteristics:
a) for wheat (common or durum), one test sample with a mass per hectolitre in each of the following ranges:
72 kg/hl to 76 kg/hl, 75 kg/hl to 79 kg/hl, and 78 kg/hl to 82 kg/hl;
b) for barley, one test sample with a mass per hectolitre in each of the following ranges: 60 kg/hl to 64 kg/hl,
65 kg/hl to 69 kg/hl, and 70 kg/hl to 74 kg/hl;
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SIST EN ISO 7971-2:2010
ISO 7971-2:2009(E)
c) a minimum difference between two successive test samples of at least 2 kg/hl;
d) an approximate mass of 30 kg, packed in correctly identified, rigid, airtight containers;
e) a moisture content (mass fraction) between 9 % and 14 % (as determined by ISO 712);
f) 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.
Dispatch the six test samples prepared in this manner to an owner of a certified standard measurement
instrument (see list in Annex B) for determination of their mass per hectolitre and of the uncertainty associated
with this quantity.
When these test samples come back, if they have to be stored prior to use, place them in ambient conditions
which do not affect their properties: temperature below 22 °C and relative humidity below 60 %. Do not store
these test samples at negative temperatures.
EXAMPLES
A set of test samples with masses per hectolitre of 73 kg/hl, 76 kg/hl, and 80 kg/hl for wheat and 60 kg/hl, 66 kg/hl, and
71 kg/hl for barley is suitable.
A set of test samples with masses per hectolitre of 73 kg/hl, 74 kg/hl, and 80 kg/hl for wheat and 60 kg/hl, 65 kg/hl, and
66 kg/hl for barley is not suitable because there is less than 2 kg/hl between two of the three test samples of each type.
A set of test samples with masses per hectolitre of 70 kg/hl, 73 kg/hl, and 76 kg/hl for wheat and 66 kg/hl, 68 kg/hl, and
70 kg/hl for barley is not suitable because the total range is not 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 conduct a mass per hectolitre measurement on each of them using the
national standard instrument or, if the test samples can be used in their entirety, measure each of them three
times. Three individual values marked ρ to ρ , where i represents the serial number of the referenced
i1 i3
sample, are thus obtained.
When equipment using a cutting edge is employed, the test sample shall not be analysed more than 50 times.
After that the test sample has to be replaced.
7.1.4 Interpretation of the results
From the unit results obtained on the control test samples, calculate the performance parameters according to
the relevant equations in Annex A.
Check that the specifications defined for the national standard instrument in 6.2 are fulfilled. If so, draw up the
national standard instrument conformity certificate.
If not, adjust the national standard instrument according to 7.1.5. In the event of it being impossible to obtain
the specifications requested in 6.2, the national standard instrument shall be repaired or declassified then
replaced by another instrument in order to re-obtain the required performances.
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SIST EN ISO 7971-2:2010
ISO 7971-2:2009(E)
The national standard instrument holder shall keep all of the data (raw and calculated) relative to this
traceability operation throughout the instrument's lifetime.
7.1.5 Adjustment of the national standard instrument
If the slope a and the intercept b calculated in 7.1.4 are outside the limits specified in 6.2, introduce into the
instrument, according to the manufacturer's recommendations, the necessary correction factors required to
theoretically bring the slope to 1 and the intercept to 0.
Then resume the operations specified in 7.1.3 and 7.1.4 in order to verify the validity of this correction.
7.2 Traceability of the secondary standard instruments through reference to the national
standard instrument
7.2.1 General description
The traceability of the secondary standards is conducted using a series of test samples referenced with the
mass per hectolitre obtained with the national standard instrument (6.2). The use of wheat and barley test
samples is recommended because of the regular shape of the grain and the 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.
7.2.2 Preparation of the test samples
Select three test samples of common wheat and/or durum wheat and three test samples of barley having the
following characteristics:
a) for wheat (common or durum), one test sample with a mass per hectolitre in each of the following ranges:
72 kg/hl to 76 kg/hl, 75 kg/hl to 79 kg/hl, and 78 kg/hl to 82 kg/hl;
b) for barley, one test sample with a mass per hectolitre in each of the following ranges: 60 kg/hl to 64 kg/hl,
65 kg/hl to 69 kg/hl, and 70 kg/hl to 74 kg/hl;
c) a minimum difference between two successive test samples of at least 2 kg/hl;
d) sufficient quantity for measurement on the national standard instrument (1,5 l to 25 l), packed in correctly
identified, rigid, airtight containers;
e) a moisture content (mass fraction) between 9 % and 14 % (as determined by ISO 712);
f) 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.
Dispatch the six thus prepared test samples to the national standard instrument holder body for determination
of their mass per hectolitre and of the uncertainty associated with this quantity.
When these test samples come back, if they have to be stored prior to use, place them in ambient conditions
which do not affect their properties: temperature below 22 °C and relative humidity below 60 %. Do not store
these test samples at negative temperatures.
NOTE See 7.1.2 for examples of suitable sets of test samples.
7.2.3 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.
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SIST EN ISO 7971-2:2010
ISO 7971-2:2009(E)
If the volume of the referenced test samples is such that they cannot be fully used in the secondary standard
instrument, constitute test portions of appropriate mass, which are representative of the initia
...