C z e c h  M e t r o l o g y  I n s t i t u t e  
Okružní 31,  638 00  
Brno  
 
1. ------IND- 2010 0780 CZ - EN- ------ 20101224 --- --- PROJET 
 
The Czech Metrology Institute (CMI), as the competent local body for stipulating metrological and 
technical requirements for a specified measuring device and for the stipulation of test method s for type 
approval and for verification of a specified measuring device pursuant to Section 14(1) of Act No. 
505/1990 Coll., on Metrology, as amended, and pursuant to provisions of Section 172 et seq. of Act 
No. 500/2004 Coll., the Administrative Code, as  amended (hereinafter the "AC"), has on 30 July 2010 
commenced ex officio proceedings pursuant to Section 46 of the AC, and based on su pporting doc u-
ments issues this:  
 
I. 
M E A S U R E  O F  A  G E N E R A L  N A T U R E  
number: 0111 -OOP -C015 -10 
reference no. 0313/008/10/Pos.,  
publication date: 11 October 2010  
 
stipulating metrological and technical requirements for specified measuring devices, 
including test methods for verifying specified measuring devices:  
"laboratory Brix meters with increments of 0.2 k g • hl-1" 
 
1   Basic definitions  
For the purposes of this measure of a general nature, terminology and definitions contained in the 
VIM1) and the following apply:  
1.1   hydrometer with constant mass : a measuring device with constant mass whose depth of imm er-
sion in the measured liquid determines its density or concentration of one of its comp onents  
NOTE   The hydrometer may or may not include a thermometer.  
1.2   laboratory Brix meter with increments of 0.2 kg • hl-1: a glass hydrometer with constant mass 
intended for the measurement of the content by weight of sugars in grape juices under laboratory co n-
ditions  
2   Metrological requirements  
2.1   Stipulated service conditions  
The Brix meter must meet metrological requirements for service temperature range specified by the 
manufacturer. If the manufacturer does not specify this, a service temperature range of 0 °C to 30  °C 
applies.  
                                                      
1)   International Vocabulary of Metrology - Basic and General Concepts and Associated Terms (VIM).  Measure of a General Nature No . 0111 -OOP -C015-10 
2 The reference temperature for testing Brix meters is 15  °C, reference pressure is normal atmo spheric 
pressure.  
2.2   Measurement interval  
The measurement interval of a laboratory Brix meter for measuring content by weight between 0% 
and 25% is specified by the manufacturer. If it is not specified by the manufacturer, a measurement 
interval from 10  kg · hl-1 to 30  kg · hl-1 applies, with increments of 0.2  kg · hl-1. 
If the laboratory Brix meter includes a thermometer, its measuremen t interval must correspond to the 
service temperatures specified in Article 2.1.  
2.3   Maximum permissible error  
2.3.1     Maximum permissible Brix meter error  
The maximum permissible error of a laboratory Brix meter is ±  0.2 kg · hl-1. 
2.3.2    Maximum perm issible thermometer error  
The maximum permissible error of a thermometer that is part of a laboratory Brix meter is ±  0.5 °C. 
3   Technical requirements  
3.1   Brix meter design  
A laboratory Brix meter is composed of a glass tube, which may have a built -in thermometer, and 
whose lower portion contains a conical or hemispherical weight. Connected to the upper part is a c y-
lindrical stem that is sealed at its upper end.  
The entire outside surface of the Brix meter must be symmetrical around its main axis. A cir cular 
cross -section must not exhibit any sudden changes, and transitions of all parts of the Brix meter must 
be smooth and rounded.  
The taper ratio of the stem must not exceed 0.1 mm per 100 mm. The maximum permissible deviation 
from circularity of any ste m cross -section along the entire length of the scale is 0.10 mm.  
Total Brix meter length must not exceed 400 mm.  
No part of the Brix meter may contain any unattached material.  
3.2   Brix meter graduated scale  
A Brix meter may have only one graduated scale , which must fit tightly against the inside wall of the 
Brix meter casing, must not exhibit unevenness and must not be helically twisted. The grad uated scale 
of the Brix meter must not have been damaged by flame during sealing of the stem.  
The graduated sc ale markings must be perpendicular to the axis of the Brix meter, parallel to each 
other, and clear. All Brix meter graduated scale markings must have the same thickness, which must 
be no more than 0.2 mm.  
If Brix meter graduated scale markings have differ ing lengths, then the length of short markings must 
be at least one fifth of the circumference of the stem, medium markings at least one third of the ci r-
cumference of the stem, and long markings at least half of the circumference of the stem. All grad u-
ated scale markings must be right -aligned along one imaginary perpendicular line.  
The total length of the measurement interval's graduated scale must be (145 ± 10)  mm. 
The highest graduated scale marking on the Brix meter must be at least 15 mm below the top o f the 
stem, and the lowest marking at least 5 mm above the location where the stem widens to meet the cy l-
inder.  
Brix meters are calibrated to be read at the upper part of the meniscus.  Measure of a General Nature No . 0111 -OOP -C016-10 
3 To check that the Brix meter graduated scale is correctly located in th e stem, the stem surface must 
have a verification line that aligns with the highest numbered mark on the graduated scale.  
The mutual positioning of the Brix meter graduated scale and thermometer must be such that the va l-
ues of both graduated scales can be read without turning the Brix meter, and the right ends of the Brix 
meter graduated scale lines must pass behind the profile of the stem.  
3.3   Brix meter thermometer  
The capillary must be capable of withstanding an upper temperature limit of +50  °C or the  upper limit 
of the upper measurement limit of the thermometer's graduated scale in accordance with  Article 2.2 
plus 10  °C, whichever is greater.  
The divisions of the thermometer's graduated scale must be 0.5 C.  
The total length of the thermometer's gradua ted scale must be at least 60 mm.  
To check that the thermometer's graduated scale is attached correctly, a verification line is placed on 
the backside of the cylinder at the location of the reference temperature marking during Brix meter 
assessment.  
3.4   Working position of the Brix meter  
The Brix meter must float in liquid with its vertical axis perpendicular to the surface. The deviation of 
the Brix meter's axis to the side from vertical when looking at the Brix meter's graduated scale must 
not be greate r than 1º 30´.  
When meeting the previous requirement, stability must also be maintained, where the Brix meter is 
deflected to the opposite side and then must return to its original position.  
3.5   Material  
The glass used in the manufacture of Brix meters m ust be transparent, colourless and must permit easy 
reading of the graduated scale.  
4 Markings  
4.1   Markings on the measuring device  
A laboratory Brix meter must be legibly and permanently marked with the following information:  
– the manufacturer's name or mark,  
– measuring device type,  
– serial number and date of manufacture,  
– unit of measurement (kg  · hl-1); 
– reference temperature (15  °C); 
– the type of liquid for which the Brix meter is intended, e.g. grape juice,  
– how to read data (read at upper edge of meniscus) , 
– type approval mark.  
4.2   Verification mark  
The verification mark is etched onto the backside of the body of the Brix meter below the stem a t-
tachment location.  
5   Type approval  Measure of a General Nature No . 0111 -OOP -C015-10 
4 5.1   In general  
The type approval process for the measuring device includes  the following tests:  
a) external inspection,  
b) shape and dimension check,  
c) test for stability and that the axis of the stem of the Brix meter is perpendicular to the su rface 
of the liquid in which it is floating,  
d) Brix meter accuracy test,  
e) thermometer accuracy t est. 
5.2   External inspection  
The following is assessed during an external inspection:  
a) that prescribed tec hnical documentation is complete, including the user manual,  
b) that metrological and technical characteristics specified by the manufacturer in documen tation 
conform to requirements of this regulation listed in sections 2 and 3,  
c) the appearance and completeness of information in accordance with  prescribed technical 
document ation. 
5.3   Brix meter shape and dimension check  
The shape and surface of the Brix  meter must not exhibit any sudden changes and transitions.  
The deviation from circularity and the taper of the Brix meter stem are checked at each marked point 
of the Brix meter's graduated scale with a micrometer to an accuracy of ±  0.01 mm, and the devi ation 
from circularity of any stem cross -section must not exceed values listed in Article 3.1.  
The total length of the Brix meter is measured with a length measurement device with an accuracy of 
± 0.5 mm. 
The prescribed dimensions of the Brix meter's gradu ated scale markings are checked with a length 
measurement device to an accuracy of 0.01 mm.  
5.4   Functional tests  
5.4.1    Assessment solutions  
The assessment liquid is a solution of 96% vol. sulphuric acid and 80% vol. finely refined alcohol. 
Prior to tes ting, solutions must be tempered to laboratory temperature with a maximum deviation of 
± 5 °C from the reference temperature, and temperature changes during measurement must not exceed 
± 0.5 °C · h-1. 
5.4.2    Test for stability and to ensure that the axis of the stem of the Brix meter is perpendicular 
to the su rface of the liquid in which it is floating  
The perpendicularity of the stem axis is tested by submerging the Brix meter into a suitable a ssessment 
liquid up to the lower edge of the Brix meter's grad uated scale. Using an angle template placed behind 
the Brix meter, the deviation of the Brix meter's stem from vertical is dete rmined. The projection of 
the outline of the stem is observed from a distance of at least 250 mm.  
The subsequent stability test i s performed by tilting the Brix meter opposite to its stem's lean angle.  
This test must meet the requirements of Article 3.4.  
 Measure of a General Nature No . 0111 -OOP -C016-10 
5 5.4.3    Brix meter accuracy test  
Prior to the test, the Brix meter and all necessary aids must be thoroughly degreased by dipping  into 
chromic sulphuric acid for at least 30 minutes, rinsing with running water and rinsing with di stilled 
water.  
Accuracy is tested by comparing measured values of the tested Brix meter against the values of a re f-
erence Brix meter in assessment liquids f or the given Brix meter measurement interval in accordance 
with Article 5.4.1.  
Measurement is performed at least three times for at least five points of the graduated scale.  
During the test, it is important to ensure that the Brix meter and thermometer (th at is part of the test 
bath) are at least 10 mm apart and away from the walls of the container with the assessment liquid.  
After the test, both the reference and tested Brix meters are rinsed with distilled water.  
The measurement error at each point of the  graduated scale must not exceed the maximum permissible 
error in accordance with  Article 2.3.1.  
5.4.4    Brix meter thermometer accuracy test  
The accuracy of the thermometer (that is part of the Brix meter) is tested by comparing measured va l-
ues of the tes ted thermometer with values of a reference thermometer, for at least three points of the 
scale: at the Brix meter's reference temperature and at both endpoints of the thermometer's scale.  
The measurement error at each point of the graduated scale must not exceed the maximum permissible 
error in accordance with  Article 2.3.2.  
6   Initial verification  
6.1   In general  
The following is performed during initial verification:  
a) external inspection,  
b) shape and dimension check,  
c) test for stability and to ensure that t he axis of the stem of the Brix meter is perpendicular to the 
surface of the liquid in which it is floating,  
d) Brix meter accuracy test,  
e) thermometer accuracy test.  
6.2   Visual inspection  
The following is assessed during visual inspection of laboratory Brix meters:  
a) that the measuring device is the same as the approved type;  
b) appearance (including description) and condition of the measuring device.  
6.3   Brix meter shape and dimension check  
Shape and dimensions of the Brix meter are checked in accordance with  Article 5.3.  
 Measure of a General Nature No . 0111 -OOP -C015-10 
6 6.4   Functional tests  
6.4.1    Test for stability and to ensure that the axis of the stem of the Brix meter is perpendicular 
to the su rface of the liquid in which it is floating  
The test for stability and to ensure that the axis of the stem of  the Brix meter is perpendicular to the 
surface of the liquid in which it is floating is performed in accordance with  Article 5.4.2.  
6.4.2    Brix meter accuracy test  
The Brix meter accuracy test is performed in accordance with  Article 5.4.3.  
6.4.3    Brix m eter thermometer accuracy test  
The accuracy test of the thermometer as part of the Brix meter is performed in accordance with  Article 
5.4.4.  
7   Subsequent verification  
These measuring devices are not subject to subsequent verification.  
8   Notified standa rds 
To specify metrological and technical requirements for measuring devices and to specify verific ation 
test methods stemming from this measure of a general nature, the CMI notifies Czech technical sta n-
dards, other technical standards or technical documen ts of international or foreign organizations or 
other technical documents containing detailed technical requirements (hereinafter "notified sta n-
dards"). The CMI shall publish a list of these notified standards, with their assignation to relevant 
measures, along with the measure of a general nature, in a manner available to the public (on the we b-
site www.cmi.cz).  
Compliance with notified standards or parts thereof is considered to be, to the extent and under the 
conditions stipulated by a measure of a genera l nature, to be compliance with those requirements 
stipulated by this measure to which these standards or parts thereof apply.  
 
 
 
I II. 
J U S T I F I C A T I O N  
The CMI issues, towards the implementation of Section 24c of Act No. 505/1990 Coll., on metrol ogy, 
as amended, this measure of a general nature, stipulating metrological and technical requirements for 
specified measuring devices and test methods for verification of these specified measuring devices.  
In Decree No. 345/2002 Coll., specif ying measurin g devices for mandatory verification and measuring 
devices subject to type approval, as amended, the annex "List of Specified Measuring Device Types" 
classifies "laboratory Brix meters with increments of 0.2 kg • hl-1" under item 7.1.4 as measuring d e-
vices  subject to type approval and verific ation. 
The CMI thus issues, towards the implementation of Section 24c of Act No. 505/1990 Coll., on m e-
trology, as amended, for the measuring device type specified as "  laboratory Brix meters with incr e-
ments of 0.2 kg • hl-1", this measure of a general nature, stipulating metrological and technical r e-
quirements for  laboratory Brix meters with increments of 0.2 kg • hl-1 and test methods for type a p-
proval and verification of these specified measuring d evices.  
 Measure of a General Nature No . 0111 -OOP -C016-10 
7  
III. 
N O T I C E  
A measure of a general nature cannot be appealed (Section 173 (2) of Act No. 500/2004 Coll., the 
Administrative Code, as amended (hereinafter the "Administrative Code").  
Pursuant to provisions of Section 172 (5) of the Administrative Code, a decision  on objections cannot 
be appealed in any manner.  
The conformance of a measure of a general nature with legislation can be assessed in review procee d-
ings pursuant to Section 94 to 96 of the Administrative Code. A participant may submit a request for a 
revie w to the administrative body that issued this measure of a general nature. If the administrative 
body does not find reasons for commencing review proceedings, it shall notify the applicant within 
thirty days of this fact along with its reasons. A decision on commencement of review proceedings 
can, in accordance with  Section 174 (2) of the Administrative Code, be issued within three years of the 
effective date of the measure of a general nature.  
 
 
 
IV. 
E F F E C T I V E  D  A T E  
This measure of a general nat ure takes effect on the fifteenth day following the day of its publication 
(Section 24d of Act No. 505/1990 Coll., on metrology, as amended).  
This measure of a general nature shall be published for a period of 15 days.