C z e c h  M e t r o l o g y  I n s t i t u t e   
Circular 31, 638 00  
Brno  
 
1. ------IND- 2013 0520 CZ - EN- ------ 20130925 --- --- PROJET 
Managerial summary for the EC ( not part of this legislation ) 
Measuring instrument s for the gas flow quantity of heating gas ( either velocity or rotary piston type ) 
which are intended for use in  residential and commercial zones and light industry are placed onto the 
market and entered into service in the Czech Republic in accordance with Directive 2004/22/EC 
MID.  They are subject to national metrological regulation – validation (at specified inte rvals).  The 
subject of this notified legislation is simply the validation of measuring instrument s which have 
already been put into service.  This legalisation does not concern placement on the market or 
introduction into service  (with the exception of case s pursuant to Article 23 MID).  
The requirements imposed upon these measuring instrument s in operation are fully compatible with 
the MID and are based on EN 12261+A1 and EN 12480+A1 standards, which are harmonised 
standards for the MID.  
Some of the paramete rs specified here are properties of measuring instrument s in new condition and 
are only noted here because preserving said properties during service is merely the subject of visual 
or other inspection in the scope of validation.  
(End of managerial summary .) 
 
 
 
 
As a body with material and local competence in matters concerning the establishment of metrological 
and technical requirements for the specified measuring instrument  and the establishment of testing 
methods for type approval and validation of the s pecified measuring instrument  pursuant to Section 14 
Paragraph 1 of Act No 505/1990 Coll. on metrology, as amended (hereinafter referred to as the 
‘Metrology Act’), and pursuant to the provisions of Section 172 et seq. of Act No 500/2004 Coll., the 
Rules o f Administrative Procedure (hereinafter referred to as ‘RAP’), the Czech Metrological Institute 
(CMI) has launched ex officio an administrative proceeding pursuant to Section 46 of the RAP on 8 
July 2013, and, on the basis of the documentation, enacts the following:  
 
 
I. 
GENERAL MEASURE  
Number:  0111 -OOP -C031 -13 
Reference No  0313/002/13/Pos.,  
 
establishing metrological and technical requirements for specified measuring 
instrument s, including testing methods for validating the following specified 
measuring in strument s: 
‘instrument s for measuring the gas flow quantity of heating gas ( either velocity or 
rotary piston type ) which are intended for use in residential and commercial zones and 
light industry’  General Measure No 0111 -OOP -C031-13 
2  
This General Measure  establishes the metrological and tec hnical requirements for instruments for 
measuring the gas flow quantity of heating gas (either velocity or rotary piston type) which are intended 
for use in residential and commercial zones and light industry . This General Measure  applies to the 
validation  of said devices after they have been placed on the market or until they are introduced into 
service.  The requirements of this General Measure  are in accordance with the requirements of 
Government Regulation No 464/2005 Coll. laying down the technical requ irements for measuring 
instruments, as amended (hereinafter referred to as the ‘Government Regulation on Measuring 
Instruments’)1), and make use of the relevant requirements of harmonised standards.  
Instruments for measuring the gas flow quantity of heatin g gas ( either velocity or rotary piston type ) 
whose type was approved in accordance with the Metrology Act, as amended as of 30 October 2006, i.e. 
in its state before the implementation into the Czech legal order of Directive of the European 
Parliament and  Council 2004/22/EC, as amended, are subject during validation to the same 
metrological requirements which were decisive in their placement on the market.  
1   Basic definitions   
The terms and definitions pursuant to the VIM a VIML2 as well as the terms and  definitions specified 
in the following shall apply for the purposes of this General Measure:  
1.1 
Gas meter with rotary pistons (hereinafter referred to as a ‘rotary gas meter’)   
A volumetric gas meter in which a fixed measuring chamber is formed betwe en the walls of a 
stationary chamber and a rotary element; each rotation cycle of the element(s)  moves a defined 
volume of gas, which is comprehensively recorded and indicated on a display  device.  
1.2 
Turbine gas meter   
A velocity gas flow meter in which the d ynamic forces of the flowing gas cause the turbine wheel to 
rotate at a velocity which is the function of the volumetric flow; the number of rotations of the turbine 
wheel form the basis for indicating the volume which flowed through the turbine gas meter.  
1.3 
Ultrasound gas meter   
A velocity gas flow meter with which the measurement principle is to measure the velocity of the gas 
flowing in a pipe. This measurement principle is based on determining the time it takes for ultrasound 
signals to pass through t he flowing gas between the units for transmitting and receiving the ultrasound 
signals.  
1.4 
Vortex gas flow meter   
A velocity gas flow meter which is based on an effect in which vortices are alternately separate d on 
both sides of a non -aerodynamically shap ed obstacle which gas flows around on both sides. The 
vortices are generated at a frequency which is proportionate to the velocity of the gas flow, and thus 
the size of the flow as well. A suitable sensor picks up the frequency of the vortices  which are 
                                                   
1) This Government Regulation implements European Parliament and Council Directive 2004/22/EC of 31 
March 2004 on Measuring Instruments into Czech legislation.  
2) International Vocabulary of Metrology – Basic and general concepts and assoc iated terms (Mezinárodní 
metrologický slovník – Základní a všeobecné pojmy a přidružené termíny – VIM) and the International 
Vocabula ry of Terms in Legal Metrology (Mezinárodní slovník termínů v legální metrologii – VIML) are part of 
the technical harmonisation collection 'Terminology in the Field of Metrology’ (Terminologie v oblasti 
metrologie) which is accessible to the public at www .unmz.cz.  General Measure No 0111 -OOP -C031-13 
3 generated this way and converts them into the value of the volumetric flow in the required 
measurement units.  
1.5 
Measurement error   
A percentage value which expresses the ratio of the difference between the volume indicated by the 
gas meter and the volume w hich actually flowed through the gas meter to the actual flow volume.   
2   Metrological requirements  
The metrological requirements are based on the requirements of the Government Regulation on 
Measuring Instruments  and make use of the relevant requirements  of the harmonised standards.   
The same metrological requirements which were decisive in the gas flow meters’ placement on the 
market will be applied during the validation of said meters.  
2.1   Specified operating conditions  
2.1.1    Flow range  
The manufact urer must specify  a maximum flow Qmax and a minimum flow Qmin when placing the 
meter on the market.  
The transitional flow values Qt are specified in Table  1. 
Table 1 – Transitional flow values.  
Flow range  
Qmin : Qmax Transitional flow Qt 
 1: 20  0.20Qmax 
1: 30  0.15Qmax 
1: 50  0.10Qmax 
 1: 50  0.05Qmax 
 
2.1.2    Maximum operating pressure  
The manufacturer shall specify the gas meter’s maximum operating pressure, which must be indicated 
on the gas meter.  
2.1.3    Temperature range  
All gas meters must be cap able of meeting the requirements for the minimum ambient temperature 
range –10 °C to 40  °C.  
The minimum temperature range of heating gas is 40  °C. 
2.2   Maximum permissible error  
2.2.1    Maximum permissible error during validation  
The maximum permissible errors for rotary and velocity gas meters are generally specified in Table 2.  
Table  2 – Maximum permissible errors  
Flow  
(m3/h) Maximum permissible errors  
During validation  During use  General Measure No 0111 -OOP -C031-13 
4 Qmin 
 Q 
 Qt ±2.0 % ±4 % 
Qt 
 Q 
 Qmax ±1.0 % ±2 % 
 
Rotary and velo city gas flow meters in accuracy class 1.0 are give n the maximum permissible error  
during validation in the upper flow region Qt 
 Q 
 Qmax.  
The maximum permissible errors for household ultrasound gas meters are generally specified in Table 
3. 
 
Table 3 – Maximum permissible errors for household ultrasound gas meters  
Flow  
(m3/h) Maximum permissible errors for household ultrasound gas meters  
During validation  In use  
Qmin 
 Q 
 Qt ±3.0 % ±6 %  
Qt 
 Q 
 Qmax ±1,5 %  ±3 %  
 
Household ultrasound gas meters  in accuracy class 1. 5 are given the maximum permissible error 
during validation in the upper flow region Qt 
 Q 
 Qmax. 
With certain types of gas meters with which the national technical standards were applied during their 
approval, the maximum permissible er ror which was valid at the time of approval may differ from the 
maximum permissible error specified above; in such case, the maximum permissible error specified in 
the type approval certificate shall take precedence . 
2.2.2    Maximum permissible error durin g use  
In the case of measuring instruments which were validated while in use in accordance with Section 11 
Paragraph 4 of the Metrology Act at the request of a party whose interests may be significantly 
compromised by improper measurement, the ‘maximum per missible error during use’ specified in 
Table 2 or Table 3 in Article 2 .2.1. shall apply depending on the principle by which the gas meter was 
designed.  
For previously used measuring instruments with which the national technical standards were applied 
during their approval, the maximum permissible error shall apply at two times the maximum 
permissible error specified in the type approval certificate.  
2.3   Loss of pressure  
The manufacturer must declare the maximum loss of pressure Qmax. 
The mean loss of pre ssure for a gas meter at maximum air flow Qmax with an air density of 1.2  kg/m3 
may not exceed the manufacture’s specified values or the values specified in the type approval 
certificate.   
3   Technical requirements  
The metrological requirements are based on the requirements of the Government Regulation on 
Measuring Instruments and make use of the relevant requirements of the harmonised standards.   
The same metrological requirem ents which were decisive in the  placement of the gas flow meter on 
the market wi ll be applied during the validation of said meters.  General Measure No 0111 -OOP -C031-13 
5 3.1   Measuring instrument  design  
Rotary and velocity gas flow meters have two connection points for flanged or threaded measuring 
instrument  connections, or one coaxial connection.   
3.2   Counter  
The gas  meter must be equipped with a metrologically inspected counter (display).  
The counter must function properly under normal conditions of use throughout the typical service life 
of the gas meter being tested.   
If it is a cylindrical mechanical counter, it m ust be non -volatile and impossible to reset to zero. The 
rotation of the cylinder during the final tenth of its course, i.e. from 9 to 0, must cause the cylinder of 
the next higher digit place to move by one unit.  
With electronic counters, the number of th e next higher digit place must increase by one when any 
number changes from 9 to 0.   
It must be possible to clearly and correctly read the value indicated on the counter.   
3.3   Materials  
The components of the gas meter in the gas flow must be resistant to  the effects of the constituents of 
the gas medium in which they operate, and they must be resistant to wear and corrosion.   
3.4   Operating position  of the gas meter  
The operating position in which the gas meter is to be used must be indicated on the lab el of the gas 
meter , or it must be specified on the type approval certificate.  
3.5   Rectifier tube   
A gas meter with which the metrological properties depend on the length of the rectifier tube 
connected to the gas meter must be validated and used with th e rectifier tube specified by the 
manufacturer or on the type approval certificate.  
3.6   Software   
If the evaluation or indication unit contains software which is essential for the metrological properties, 
it must be identified and secured.  The gas meter must enable the software to be identified by simple 
means.  
3.7   Resistance to improper handling  
The gas meter must be designed so that any kind of mechanical action which is capable of affecting 
measurement accuracy will visibly and permanently damage the  measurement device or the official or 
security seals.  
3.8   Storage and transport  
Wherever possible, the connections of the gas meter  must be equipped with suitable unsealed caps or 
covers which prevent foreign matter from getting into the meter during tr ansport and storage.   
4   Measuring instrument  markings  
4.1   Every gas meter must be marked with at least the following information on the counter or on a 
separate label:  
a) identification mark or name of the manufacturer,  
b) serial number and year of productio n, General Measure No 0111 -OOP -C031-13 
6 c) maximum flow Qmax (m3/h), 
d) minimum flow Qmin (m3/h), 
e) maximum operating pressure pmax, 
f) with rotary gas meters, the rated cyclic volume value V (dm3), 
g) the impulse number value, which corresponds with the specified recorded flow volume at the 
place where th e impulse transmitter is to be used,  
h) accuracy class,  
i) any potential other marks, if stated in a binding manner, such as type number or trial 
certificate number, mark of conformity, supplementary metrological markings, etc.  
Connections for pressure and tempe rature discharge from the gas meter must be properly marked with 
the appropriate labels.  
The markings must be at a clearly visible location and must be permanent under normal conditions of 
gas meter use.  
With certain gas meters whose type was approved in a ccordance with the national technical standar ds, 
the requirement on the measuring instrument’s markings which were valid at the time the measuring 
instrument received its type approval may differ from the above -mentioned official requirement. In 
such case,  the requirements specified on the type approval certificate shall be decisive.  
4.2   Gas meter with two connections   
Gas meters with two connections must have the gas flow direction clearly and permanently marked by 
an arrow between these two connection p oints.  
4.3   Placement of official marking  
The placement of official markings is established by the type approval certificate or EC certificate of 
type testing or other document applied during the conformity assessment when placed on the market 
and into se rvice in accordance with the Government Regulation on Measuring Instruments1). 
5   Measurement device type approval  
These measuring instruments are placed on the market and into service with a conformity assessment 
in accordance with the Government Regulat ion on Measuring Instruments, meaning that they are not 
subject to type approval.   
6   Initial validation  
These measuring instruments are placed on the market and into service with a conformity assessment 
in accordance with the Government Regulation on Mea suring Instruments.   
The initial validation only applies to measuring instruments which have a certificate which was valid 
at the time of type approval with the application of the transitional provision pursuant to Section 9 of 
the Government Regulation on  Measuring Instruments. It also applies to measuring instruments after 
repairs have been conducted.  
A procedure identical to the follow -up validation pursuant to Chapter 7 is applied during the initial 
validation.  General Measure No 0111 -OOP -C031-13 
7 7   Follow -up validation  
7.1   Overview of  tests conducted   
The following tests are conducted during follow -up gas meter validations conducted after the initial 
validation and during validation pursuant to Section 11 Paragraph 4 of the Metrology Act:  
a) visual inspection,  
b) accuracy test,  
c) pressure loss  test, but only in cases where this is specified on the type approval certificate.  
7.2   Visual inspection   
The visual inspection checks whether the gas meter submitted for validation is in conformity with the 
approved type or with the measuring instrument ’s design, for which conformity was declared during 
placement on the market, and special attention must be paid to checking the correctness of the 
markings in the sense of Article 4.1.  
The durability and legibility of the markings is also inspected.  
Gas me ters which have been mechanically damage d and ones which do not conform with the 
approved type or measuring instrument design for which conformity was declared during placement 
on the market shall not be tested further.   
7.3   Function tests  
Fulfillment of  the relevant metrological and technical requirements pursuant to Chapters 2 and 3 are 
continuously monitored o ver the course of the function tests and evalu ations thereof.   
7.3.1    Requirements for test equipment  
The test equipment must be equipped with r eference calibrating devices which are suitable for testing 
the applicable gas meters and are valid in relation to metrology.  
Pressure gauges, thermometers and reference calibrating devices for volume flow must have up -to-
date metrological traceability and  must state uncertainty of calibration.  
The total uncertainty of establishing the actual measurement error of the gas meter must be at least 
three times less than the value of the maximum permissible error specified for the measuring 
instrument being teste d.  
7.3.2    Accuracy test  
Gas meters are tested at the flows specified in the following Table 4.   
Table 4 - Test flows for validation gas meters  
Gas meter flow ratio Qmax:Qmin Test flows  
20:1 and less  Qmax; 0.7Qmax; 0.4Qmax; 0.25 Qmax; 0.1Qmax; 0.05 Qmax 
Over 20:1 up to 30:1  Qmax; 0.7Qmax; 0.4Qmax; 0.25 Qmax; 0.1Qmax; 0.05 Qmax; Qmin 
Over 30:1 up to 50:1 and higher  Qmax; 0.7Qmax; 0.4Qmax; 0.25 Qmax; 0.15 Qmax; 0.05 Qmax; Qmin 
 
Previous used measuring instruments which the national technical standards were appl ied to during 
their approval will be tested at the flow rates specified in the type approval certificate.  
The calculated measurement error for individual test flow rates must meet the requirements for the 
maximum permissible error during validation specifi ed in Table 2 or 3, or, as the case may be, in the 
type approval certificate.  General Measure No 0111 -OOP -C031-13 
8 If this is specified by the manufacturer or on type approval certificates, it will be necessary to meet the 
requirements for installing the gas meter, such as the length of the s tabilising pipe before and after the 
gas meter, as well as the position of the gas meter (vertical, horizontal), during testing.  
During the accuracy test, it is necessary to inspect all devices in the gas meter which are capable of 
generating an electronic  signal commensurate to the flowing gas volume.   
7.3.3    Loss of pressure test  
The loss of pressure test is conducted in cases in which its value was specified by the manufacturer or 
is specified on the type approval certificate.  Gas meters are tested usin g air with a density of 1 .2 kg/m3 
at a maximum  flow of Qmax and the differential pressure is measured between input and output  of the 
gas meter . 
The mean loss of pressure, calculated as the mean measured maximum and minimum differential 
pressure, may not e xceed the maximum permissible loss of pressure specified by the manufacturer or 
on the type approval certificate.  
8   Declared standards  
For the purposes of specifying the metrological and technical requirements for measurement devices 
and for the purposes  of specifying testing methods during validation based on this general measure, 
the CMI declares Czech technical standards, other technical standards or technical documents of 
international or foreign organisations or other technical documents containing m ore detailed technical 
requirements (hereinafter referred to as ‘declared standards’).  The CMI announces a list of these 
notified standards assigned to the applicable measure together with the General Measure by means 
accessible to the public (at the inter net site www.cmi.cz).  
In the scope of and under the conditions established by this General Measure , compliance with these 
declared standards or compliance with portions thereof is deemed to be compliance with said 
requirements established by the measure  to which these standards (or portions thereof) apply.  
 
 
II. 
GROUND S 
The CMI is issuing this General Measure establishing metrological and technical requirements for the 
specified measuring instrument s and testing methods during the validation of said specifi ed measuring 
instrument s for the purposes of implementing Section 24c of the Metrology Act.  
Regulation No 345/2002 Coll. establishing measuring instrument s for compulsory validation and 
measuring instrument s subject to type a pproval, as amended, classifies  measuring instrument s for 
measuring the flow quantity of gas  (either velocity or rotary piston type) as measuring instrument s 
subject to validation under Item 1.3.10 c) in the Annex to the Second List of Specified Measuring 
Instruments ). 
The CMI hereby is sues this General Measure establishing metrological and technical requirements for  
the specific type of measuring instruments: ‘ instruments for measuring the gas flow quantity of 
heating gas (either velocity or rotary piston type) which are intended for us e in residential and 
commercial zones and light industry ’ and the testing methods for validating said measuring 
instruments for the purposes of implementing Section 24c of the Act on Metrology . 
This Regulation (General Measure) was notified in accordance w ith European Parliament and Council 
Directive 98/34/EC of 22 June 1998 on the procedure for the provision of information in the field of 
technical standards and regulations and rules on Information Society services, as amended by 
Directive 98/48/EC.  General Measure No 0111 -OOP -C031-13 
9  
 
III. 
LEGAL INSTRUCTIONS  
Legal remedies pursuant to Section 173 Paragraph 2 of the RAP may not be filed for General 
Measure s. 
In accordance with the provisions of Section 172 Paragraph 5 of the Rules of Administrative 
Procedure, decisions on objections may not be revoked, and appeals may not be raised against them.  
The conformity of the General Measure with the statutory regulations can be evaluated in the research 
procedure pursuant to the provisions of Section 94 to 96 of the Rules of Administrative Procedure.  The 
participant may submit a motion to conduct a research procedure to the administrative body which issued 
this General Measure . If the administrative body does not find reason to initiate a research procedure, it 
shall inform the submitter of this fact and substantiate its reasons within thirty days.  Rulings on the 
initiation of a research procedure may be issued within three years as of the entry into legal effect of the 
General Measure in accordance with the provisions of Section 174 Paragraph 2 of the  Rules of 
Administrative Procedure.  
 
 
IV. 
ENTRY INTO LEGAL EFF ECT  
This General Measure shall enter into legal effect on the fifteenth day as of the date of its 
promulgation (Section 24d of the Metrology Act).  
 
 
 
 ...…………………………..............  
 RNDr.  Pavel Kl enovský  
 General Director