Czech Metrology Institute  
Okružní 31, 638 00 Brno  
 
1. ------IND- 2018 0334 CZ - EN- ------ 20180803 --- --- PROJET 
Executive summary for the EC (not part of this legislation)  
Water flow quantity meters —water meters that are intended for uses other than residential, 
commercial  and light industry are placed on the market and put into use in the Czech Republic as 
specified measuring instruments following type approval and initial validation pursuant to Act 
No 505/1990 on metrology, as amende d. 
The subject of this notified regulation is to lay down metrological and technical requirements for 
these measuring instruments.  This regulation also stipulates tests for type approval and verification.  
This regulation does not cover measuring instrument s placed on the market and into operation 
pursuant to Directive  2014/32/EU  (MID).  
(End of executive summary.)  
 
Contact person:  Mgr.  Tomáš 
Hendrych  
Phone:545  555 414 
 
PUBLIC DECREE  
 
As the authority with substantive and territorial jurisdiction for stipulating metrological and technical 
requirements for specified measuring instruments and stipulating test methods for type approval and 
verification of legally specified instruments pursuant to §  14(1) of Act No  505/1990, on metrology, as 
amended (herei nafter the ‘Metrology Act’), and in accordance with the provisions of §  172 et seq. of 
Act No  500/2004, the Code of Administrative Procedure (hereinafter the ‘CAP’), the Czech Metrology 
Institute (hereinafter the ‘CMI’) commenced ex officio proceedings on 22January2016 pursuant to 
§ 46 of the CAP, and, based on supporting documents, issues the following:  
 
 
I. 
DRAFT GENERAL MEASUR E 
number:  0111 -OOP -C051 -16 
 
defining metrological and technical requirements for specified measuring instruments, including 
testing methods for the type approval and verification of those instruments:  
'Water flow quantity meters —water meters that are intended for uses other than residential, 
commercial  and light industry'  
 General Measure No  0111 -OOP -C051 -16 
2 With respect to relevant EU legislation and national legislation of the Czech Republic, instruments for 
measuring water flow quantity are a type of measuring instrument that from the perspective of the 
scope of authority of this legislation is split into two groups with respect to being placed on the market 
and into circulation, as follows:  
a) water meters for residential, commercial  and light industry;  
b) water flow quantity meters for uses other than residential, commercial  and light industry.  
In the case of water meters pursuant to (a), the process for placing t hem on the market and into 
operation, including metrological requirements for meters and their test methods, are governed by 
special legislation1. 
In the case of water flow quantity meters pursuant to point  (b), this legislation stipulates metrological 
and technical requirements, and test methods applied when being placed into circulation, i.e. during 
type approval pursuant to Chapter  5 and during initial verification pursuant to Chapter  6, and test 
methods during subsequent verification pursuant to Chapter  7, performed after measuring instruments 
have been put into circulation.  
1 Basic definitions  
For the purposes of this Measure of a General Nature, terms and definitions according to VIM and 
VIML2 and the terms and definitions below apply:  
1.1 
water flow q uantity meter, water meter  
a device intended for continuous measurement, recording  and display of the volume of water that has 
flowed through the measuring transducer under measurement conditions  
1.2 
flow rate  
the ratio of the volume of water that has flowed through the water meter to the amount of time during 
which this volume flowed through the water meter; it is expressed in m3/h 
1.3 
minimum flow rate Q1 
the lowest flow rate for which the water meter is required to operate within the limits of maximu m 
permissible errors  
NOTE Minimum flow rate was formerly designated qmin or Qmin (provisions concerning Q1 therefore apply in a 
similar manner to qmin or Qmin). 
                                                      
1 Government Regulation No 120/2016 stipulating technical requirements for measuring instruments 
(hereinafter the 'Government Regulation') implementing Directive  2014/32/EU of the European Parliament 
and of the Council of 26  February  2014 on the harmonisation of the laws of the M ember States relating to 
measuring instruments (MID)  
2 TNI 01 0115 International Vocabulary of Metrology – Basic and General Concepts and Associated Terms 
(VIM) and International Vocabulary of Legal Metrology (VIML) are part of the technical harmonisation 
compendium ‘Terminology in the field of metrology’, which is publicly available at www.unmz.cz.  Draft Measure of a General Nature No  0111 -OOP -C051 -17 
3 1.4 
transient flow rate Q2 
a flow rate that lies between the permanent flow rate Q3 and the min imum flow rate Q1 and that splits 
the flow rate range into two regions, the 'lower flow rate region' and the 'upper flow rate region', each 
characterised by its own maximum permissible errors  
NOTE The transitional flow rate was formerly designated qt or Qt (provisions concerning Q2 therefore apply in a 
similar manner to qt or Qt). 
1.5 
permanent flow rate Q3 
the highest flow rate under rated operating conditions under which the water meter is required to 
operate within the limits of maximum permissible erro rs 
NOTE The permanent flow rate was formerly designated qp, Qp, qn or Qn (provisions concerning Q3 therefore 
apply in a similar manner to qp, Qp, qp or Qn). 
1.6 
overload flow rate Q4 
the maximum flow rate during which the water meter is required to operate  within the limits of 
maximum permissible errors for a short amount of time, while its metrological function remains 
preserved, when it subsequently operates within its range of rated operating conditions  
NOTE The overload flow rate was formerly designated  qs, Qs or Qmax (provisions concerning Q4 therefore also 
apply in a similar manner to qs, Qs or Qmax). 
1.7 
test flow  
average flow during a test, calculated from indications on a calibrated reference device  
1.8 
nominal diameter (DN)  
an alphanumeric designation for the size of a part of a pipe system, used for reference purposes; it 
consists of the letters DN followed by a dimensionless whole number that indirectly applies to the size 
of the opening or outer diameter of end connectors in mm  
1.9 
minimu m allowable pressure (mAP) and maximum allowable pressure (MAP)  
the minimum and maximum pressure of liquid that the water meter can resist on a permanent basis 
within the range of rated operating conditions without degrading its metrological functions.  
NOT E The minimum allowable pressure and maximum allowable pressure are the lower and upper limit of rated 
operating conditions for operating pressure.  
1.10 
minimum allowable temperature (mAT) and maximum allowable temperature (MAT)  
the minimum and maximum ope rating temperature that the water meter can resist on a permanent 
basis within the range of rated operating conditions without degrading its metrological functions  
NOTE The minimum allowable temperature and maximum allowable temperature are the lower and u pper limit 
of rated operating conditions for operating temperature.  General Measure No  0111 -OOP -C051 -16 
4 2 Metrological requirements  
The same metrological requirements which were decisive in the placement of water meters on the 
market will be applied during their verification.  
2.1 Rated operating conditions  
The operating conditions for a water meter type must be stipulated by the manufacturer.  
Range of rated operating conditions:  
a) the water temperature range must comply with at least the following conditions:  
 from 0.1  °C to 30  °C for water  meters for cold water; or  
 from 30  °C to 90  °C for water meters for hot water; or  
 the water meter can be designed to operate in both ranges;  
b) the range of relative operating water pressure is from 0.03  MPa (0.3  bar) to at least 1  MPa 
(10 bar) (for meters wi th DN ≥ 500, the maximum allowable pressure must be at least 0.6  MPa 
(6 bar));  
c) for a power supply the nominal value of AC voltage or limit values of DC voltage must be 
stipulated.  
2.2 Measuring range  
The water flow rate range must meet the following condit ions:  
 Q3 (expressed in m3/h) must be chosen from the values in Table  1. 
Table  1 – Values of Q3 expressed in  m3/h 
1.0 1.6 2.5 4.0 6.3 
10 16 25 40 63 
100 160 250 400 630 
1,000  1 600 2 500 4 000 6 300 
This list of values can be extended toward higher or lower values in the range.  
 Q3/Q1 (‘R’)  40, must be chosen from the values in Table  2. 
Table  2 – Values of the ratio Q3/Q1 (‘R’)  
40 50 63 80 100 
125 160 200 250 315 
400 500 630 800 1,000  
This list of values can be extended toward higher values in the range.  
 Q2/Q1 = 1.6; 
 Q4/Q3 = 1.25.  
2.3 Maximum permissible error  
The manufacturer of the measuring instrument must specify accuracy class  1 or accuracy class  2.If the 
accuracy class is not specified, the maximum permissible error as per 2.3.1.2 and 2.3.2.2 applies.  Draft Measure of a General Nature No  0111 -OOP -C051 -17 
5 2.3.1 Maximum permissible error in the lower region of flow rate  
2.3.1.1 Accuracy class  1 
The maximum permissible error in volume delivered during a flow rate equal to or higher than the 
minimum flow rate Q1 and up to but not including the transie nt flow rate Q2 is ±3  % for water of any 
temperature.  
2.3.1.2 Accuracy class  2 
The maximum permissible error in volume delivered during a flow rate equal to or higher than the 
minimum flow rate Q1 and up to but not including the transient flow rate Q2 is ±5  % for water of any 
temperature.  
2.3.2 Maximum permissible error in the upper region of flow rate  
2.3.2.1 Accuracy class  1 
The maximum permissible error in volume delivered during a flow rate equal to or higher than the 
transient flow rate Q2 and up to and including the overload flow rate Q4 is as follows:  
±1 % for water of temperature  30 °C; 
±2 % for water of temperature  30 °C. 
2.3.2.2 Accuracy class  2 
The maximum permissible error in volume delivered during a flow rate equal to or higher than th e 
transient flow rate Q2 and up to and including the overload flow rate Q4 is as follows:  
±2 % for water of temperature  30 °C; 
±3 % for water of temperature  30 °C. 
2.3.3 Evaluation of measuring instrument errors  
A water meter must not exploit the maximum permissible error or systematically favour either side.  
If all errors within the limits of the meter's measuring range have the same sign during this 
verification, at least one of the errors must not exceed one half of the maximum permissible error . 
2.4 Measuring instrument classification  
2.4.1 Measuring instrument pressure class  
The minimum allowable pressure (mAP) must be 0.030  MPa (0.3  bar). 
Measuring instruments are classified by a maximum allowable pressure (MAP) class that corresponds 
to values in the range MAP  6 (only for DN  500), MAP  10, MAP  16, MAP  25, and MAP  40 chosen 
by the manufacturer.  A water meter must be capable of resisting in ternal pressure according to the 
relevant pressure class and must be tested with the appropriate test.  
2.4.2 Measuring instrument temperature class  
Measuring instruments are classified by water temperature class corresponding to various ranges 
selected by the manufacturer:  
 water meters specified only by the maximum allowable temperature (MAT) as T30, T50, T70, 
T90, T130, and T180;  
 water meters specified by the minimum allowable temperature (mAT) and the maximum 
allowable temperature (MAT) as T30/90, T30/130, and T30/180.  General Measure No  0111 -OOP -C051 -16 
6 2.4.3 Classes of sensitivity of the current profile  
The water meter must be capable of resisting the effect of abnormal velocity fields caused by baffles.  
The manufacturer of the meter must specify the current profile sensitivity clas s: 
a) in front of the meter:  
 U0, U3, U5, U10, and U15 without a current rectifier;  
 U0S, U3S, U5S, and U10S with a current rectifier;  
b) past the meter:  
 D0, D3, and D5 without a current rectifier;  
 D0S and D3S with a current rectifier;  
where the value expresses the required straight length as a multiple of DN.  
Every section that modifies current, including rectifiers and/or straight sections, that is to be used, 
must be completely defined by the manufacturer and is considered auxiliary equipment connected to 
the tested meter type.  
2.4.4 Pressure drop  
The maximum pressure drop between Q1 and Q3 must not be greater than 0.063  MPa (0.63  bar). This 
value includes any filter or rectifier.  The class must be selected from among the following: P 63, P 
40, P 25, P 16, a nd P 10, where the number means the highest pressure drop in bars times a 
hundred.  
Concentric meters of any type or measurement principle must be tested together with their appropriate 
collection pipes.  
2.5 Other important metrological properties  
2.5.1 Absence of flow  
The volume indicated by the water meter must not change in the absence of either flow or of water.  
2.5.2 Backflow  
For meters designed to measure backflow, the permanent flow rate and the measurement range may be 
different in each direction.  
The manufacturer must specify whether the meter is designed to measure backflow.  If it is, the 
backflow volume must either be subtracted from the indicated volume or it must be recorded 
separately.  The maximum permissible error pursuant to Articles  2.3.1 and 2.3.2 must be met for both 
forward flow and backflow.  
Water meters that are not designed to measure backflow must either prevent backflow or must be 
capable of resisting chance backflow up to Q3 without any deterioration or changes in their 
metrologica l properties for forward flow.  
3 Technical requirements  
Technical requirements for water meters intended for use in areas other than residential, commercial  
and light industry are adopted from harmonised standards where relevant.  
The same technical require ments that were decisive in placing water meters into circulation will be 
applied during their verification.  Draft Measure of a General Nature No  0111 -OOP -C051 -17 
7 3.1 Size of the meter and overall dimensions  
The size of a water meter is designated by its nominal diameter (DN).A minimum thread size is 
established for instruments with threaded end -connections.  
3.2 Indicator  
The indicator of a water meter must facilitate easy reading, and reliable and unambiguous visualisation 
of the indicated volume.  Combined water meters may have two indicators, the sum  of which provides 
the indicated volume.  
The indicator may contain elements for testing using other methods, for example for automatic testing.  
Water volume must be indicated in cubic metres.  The ‘m3’ symbol must be shown on the numerical 
display or immediately adjacent to it.  The indication range specified in Table  3 must make it possible 
to record the indicated volume in cubic metres without crossing zero.  
Table  3 – Water meter indication ra nge 
Q3 
(m3/h) Indication range 
(minimum values)  
(m3) 
Q3 6.3 9 999 
6.3 <  Q3 63 99 999 
63 < Q3 630 999 999 
630 <  Q3 6 300 9 999 999 
Every indicator must be equipped with means of visual and clear testing when verifying the control 
element.  
The size of the verification scale interval must not exceed:  
 0.25 % of the volume that flows through in 90  minutes during the minimum flow rate Q1 for 
accuracy class  1; and  
 0.5 % of the volume that flows through in 90  minutes during the minimum flow rate Q1 for 
accuracy class  2. 
3.3 Electronic device counter  
The counter may be equipped with an interface that allows connection of other devices.  If these 
interfaces are used, the water meter's hardware and software must continue to operate properly and it 
must be impossible to influence its metrological properties.  
3.4 Auxiliary devices  
Aside from indicators, a water meter may contain auxiliary devices.  Addition of these devices, either 
temporary or permanent, must not change the meter's metrological properties.  
An auxiliary device may be used to detect activity of a flow sensor earlier displayed on the indicator.  
3.5 Software  
Software that is critical for the metrological characteristics of electronic equipment, termed legally 
relevant software, must be readily ide ntifiable and must be secured.  Easy software identification must General Measure No  0111 -OOP -C051 -16 
8 be possible.  Identification and security must be in accordance with the current version of the 
WELMEC  7.2, 20153 guide.  
3.6 Ambient conditions  
3.6.1 Climactic and physical environment  
For wat er meters that use electronic devices, climactic and physical environment classes are defined:  
 Class  B for fixed meters installed in buildings;  
 Class  O for fixed meters installed outdoors;  
 Class  M for mobile meters.  
3.6.2 Electromagnetic environment  
For wa ter meters with electronic devices intended for use in areas other than residential, commercial  
and light industry, electromagnetic environment class  E2 for an industrial environment applies.  
The water meter must be immune to electrical and electromagnetic  interference or it must respond to it 
in a defined manner, e.g. by reporting an error, inhibition of measurement, etc. It also must not emit 
unwanted electromagnetic fields.  
3.7 Power  
The manufacturer specifies how a water meter with electronic devices is  powered.  
Water meters with electronic devices must be designed so that if the external power source (AC or 
DC) fails, the volume indicated by the meter immediately prior to the fault is not lost, and remains 
accessible for at least one year.  Relevant storage in memory must take place at least once a day, or 
after every volume equivalent to 10  minutes of flow at Q3.All other properties or parameters of the 
meter must not be affected by changes in electrical power or its interruption.  
The intern al battery, if one is used, must ensure that if there is an external power failure the meter 
operates for at least one month under normal measurement conditions.  Battery lifespan must be 
marked on the meter.  
The manufacturer must prove that the specified lifespan of a non -replaceable battery guarantees proper 
operation of the meter for at least one year more than the meter's operating lifespan.  
In the case of a replaceable battery, the meter's properties and parameters must not be affected by a 
power inter ruption when the battery is being replaced.  This does not apply to measurement and 
recording of flow while the battery is being replaced.  Battery lifespan must be marked on the meter.  
3.8 Correction devices  
Water meters may be equipped with correction devi ces in order to reduce (indication) errors as much 
as possible to zero.  Such devices are always considered an integral part of the meter that must comply 
with all relevant tests and requirements.  
3.9 Materials and construction  
A water meter must be made of  materials whose strength and lifespan is appropriate to the water 
meter's purpose.  Materials must not be negatively affected by changes in water temperature within the 
operating temperature range, must be resistant to internal and external corrosion or pr otected with a 
suitable surface treatment, and at the same time all parts of the water meter that come into contact with 
                                                      
3 WELMEC  7.2, 2015:Software Guide (Measuring Instruments Directive  2014/32/EU) – publicly available at 
www.welmec.org  Draft Measure of a General Nature No  0111 -OOP -C051 -17 
9 the water that is flowing through it must be made of materials that are non -toxic, uncontaminated  and 
biologically inert.  
The water met er's indicator must be protected by a transparent window and can also be additionally 
protected by a suitable lid.  The water meter must contain a device to eliminate the effects of 
condensation where there is a risk of condensation forming on the inner fac e of the water meter 
indicator window.  
3.10 Protection from solid particulates  
If the water meter's accuracy is susceptible to being affected by the presence of solid particulates in the 
water, it may be equipped with a rectifier or filter.  
3.11 Meter security and fraud protection  
3.11.1 Mechanical protective devices  
Water meters must contain protective devices that must be sealed in such a way that after being sealed, 
before and after the water meter has been correctly installed, there is no way the me ter can be 
disassembled or modified or its settings changed using an adjustment apparatus without damaging the 
seal or protective devices.  
3.11.2 Electronic sealing devices  
If access to modification of parameters that affect measurement results is not prot ected mechanically, 
then access must be protected electronically using codes, passwords, etc., and simultaneously at least 
the last activity must be stored in memory.  In the case of interchangeable parts and disconnection of 
parts that are not interchangea ble, the insertion of any parts that could affect measurement results must 
be prevented.  
3.12 Grounding of induction water meters  
In order to ensure measurement accuracy and prevent galvanic corrosion, the electrodes of an 
induction water meter and the mea sured liquid must be electrically connected and grounded.  Even 
though in general this means of grounding is water, individual installation instructions from the 
manufacturer for special meter designs must be followed.  
3.13 Liquid conductance  
If the electri cal conductivity of the liquid can affect measurement results, the manufacturer must 
stipulate a requirement for minimum operating conductivity.  
The conductivity of test water for testing inductance water meters must comply with requirements in 
the type -approval certificate, if it was type -approved.  
4 Water meter labelling  
The water meter must be clearly and visibly marked with information pursuant to Article  4.1, so that  
a) it is grouped together on one data plate; or  
b) placed in various places on the casing, the indicator numerical display, the ID plate  or on the 
meter lid, if it is not removable.  
4.1 Markings on the meter  
The water meter must be clearly and visibly marked with the following information:  
 unit of measurement: cubic metre;  
 accuracy class;  General Measure No  0111 -OOP -C051 -16 
10  the numerical value of Q3; 
 the ratio Q3/Q1 (with the prefix ‘R’, e.g. R160);  
 a type -approval mark pursuant to the Metrology Act;  
 the name or trade mark of the manufacturer and postal address;  
 the year of manufacture; at least the last two digits of the yea r of manufacture or the month and 
year of manufacture;  
 serial number (as close as possible to the indicator);  
 the direction of flow (depicted on both sides of the unit, or only on one side with an arrow 
indicating the direction of flow that is easily visib le under all circumstances);  
 the maximum allowable pressure, if different from 1  MPa (10  bar) or 0.6  MPa (6  bar) for DN ≥ 
500; 
 the letter ‘V’ or ‘H’ if the meter can work only in a vertical or horizontal position;  
 the temperature class, if is not T30;  
 the pressure drop class, if it is not P 63; 
 the class of sensitivity to irregularities in the velocity field, if different from U0D0.  
For water meters with electronic devices, the following additional labels must be used, where 
appropriate:  
 for an external power supply: voltage and frequency;  
 for replaceable batteries: the latest date by which the battery should be replaced;  
 for non -replaceable batteries: the latest date by which the meter should be replaced;  
 the environmental class (climactic and physical);  
 electromagnetic environment class  E2; 
 output signals for auxiliary devices (type/level), if they exist.  
4.2 Official mark placement  
Official mark placement is stipulated by the type -approval certificate.  
The water meter must also have a location for placi ng the (main) official mark, which must be visible 
without disassembling the water meter.  
5 Type approval of the meter  
Type approval pursuant to the Metrology Act applies only to water flow quantity meters for uses other 
than residential, commercial  and light industry.  
During the type -approval process for water flow quantity meters, the environmental conditions to 
which the water meters will be exposed must be taken into account.  Environmental classification must 
correspond to ambient climactic, physical , electrical  and electromagnetic conditions for use of these 
water meters.  
5.1 In general  
The type -approval process for a water meter includes the following tests and activities:  
a) an external inspection;  
b) functional tests for all water meters:  
 using static pressure;  
 by determining basic error;  
 using test water temperature;  Draft Measure of a General Nature No  0111 -OOP -C051 -17 
11  by overheating using water;  
 by water pressure;  
 by backflow;  
 by pressure loss;  
 by current interference;  
 of lifespan;  
 by magnetic field;  
 of the water meter's auxiliary devices;  
c) additional fu nctional tests for electronic water meters and mechanical meters with inserted 
electronic devices:  
 tests of resistance to environmental influences of water meters with electronic devices;  
- by dry heat;  
- by cold;  
- by cyclical wet heat;  
- by random vibrations (only for mobile meters);  
- by impact (only for mobile meters);  
 tests of the electromagnetic compatibility (EMC) of water meters with electronic devices;  
- by changing supply voltage;  
- of immunity to dips and short interruptions and AC voltage variations;  
- of im munity to transients/bursts on signal lines;  
- of immunity to transients/bursts in AC and DC grids;  
- of immunity to electrostatic discharge;  
- of immunity to radiated electromagnetic fields;  
- of immunity to electromagnetic fields caused by power lines;  
- of immuni ty to transient surges on signal, data  and control lines;  
- of immunity to transient surges on AC and DC power lines;  
- by static magnetic field;  
- by the absence of flow;  
 a check of the software used in the water meter with an electronic device.  
Only a water me ter type comprising a measuring sensor, counter  and indicator providing primary 
indication may be approved.  However, the water meter may have several indicators and/or auxiliary 
devices making up a remote output system, which may also be subject to type ap proval.  
No adjustment of the meter is allowed during type -approval tests.  If modifications are made, all tests 
already performed that could be affected by the modification must be repeated.  
5.2 External inspection  
The external inspection of the water meter  assesses the following:  
 completeness of the required technical documentation;  
 the conformity of the metrological and technical characteristics specified by the manufacturer in 
the documentation with the requirements under this regulation as referred to in  Chapters  2, 3 and 
4; 
 the completeness and condition of the water meter in accordance with the specified technical 
documentation;  
 a description of the water meter's software version (if software is used).  General Measure No  0111 -OOP -C051 -16 
12 5.3 Functional tests  
5.3.1 Reference conditions  
All suitable influencing quantities, aside from influencing quantities that arise during testing, must be 
maintained within the following values during type -approval testing of the water meter:  
Reference flow rate:  0.7  (Q2 + Q3) ± 0.03  (Q2 + Q3) 
The relative change in flow rate during every test (except for starting and stopping) must not exceed:  
 ±2.5 % for flow rates Q1 ≤ Q < Q2; 
 ±5.0 % for flow rates Q2 ≤ Q ≤ Q4. 
Operating temperature 
(of water):  for T30 and T50 meters:  (20 ± 5) °C; 
 for T70 to T180 meters:  (20 ± 5) °C and (50  ±5) °C; 
 for T30/90 to T30/180 meters:  (50 ± 5) °C. 
The water temperature during testing must not change by more than 5  °C. The maximum uncertainty 
of temperature measurement must not exceed ±1  °C. 
Water pressure in fr ont of the meter must not change during the test by more than 10  %; it must not 
exceed the meter's maximum allowable pressure (MAP) and the maximum uncertainty of pressure 
measurement (or pressure drop) must be ±5  % of the measured value.  
Ambient temperatu re range:  15 °C to 25  °C 
Ambient relative humidity range:  45 % to 75  % 
Ambient atmospheric pressure range:  86 kPa to 106  kPa (0.86  bar to 1.06  bar) 
Supply voltage (AC grid):  nominal voltage Unom ± 5 % 
Supply frequency:  nominal frequency fnom ± 2 % 
Supply voltage (battery):  voltage Ub within the range:  UbminUbUbmax 
During each test, the temperature must not change by more than 5  °C and relative humidity must not 
change by more than 10  % within the limits of the reference range.  
5.3.2 Test equipmen t 
Test equipment for testing water meters must be equipped with a reference standard with valid 
metrological traceability, or relevant international acceptance.  The extended measurement uncertainty 
of the true volume indicated by the test equipment must not exceed 1/5 of the water meter's maximum 
permissible error.  
To determine the measurement error of the tested water meter, the 'collection' method is used: the 
water flowing through the water meter is collected in one or more containers and its amount is 
determined volumetrically or by weighing.  Other methods may be used assuming they meet 
requirements for extended uncertainty of measurement of true volume.  The m easurement error is the 
difference between the measured value of the volume indicated by the tested water meter minus the 
indication on the calibrated test equipment under reference conditions.  
The stipulated minimum volume that must flow through the water  meter during the test depends on 
requirements determined by a test of the effects of starting and stopping (time error) and the type and 
construction of the indicator (the value of the verification scale interval).  
Meters are tested either individually or  in groups.  In the latter case, the individual properties of the 
meter must be precisely determined.  Mutual influences between the meters and the test equipment 
must be eliminated.  If meters are tested in a series, the pressure at the outlet of each meter must be 
sufficient to prevent cavitation.  Draft Measure of a General Nature No  0111 -OOP -C051 -17 
13 5.3.3 Static pressure test  
The tightness of the water meter and its resistance to damage at test water pressure according to the 
chosen maximum allowable pressure class are tested.  
The test is performed at a flow r ate equal to zero.  The water pressure must be set to 1.6  the maximum 
allowable pressure (MAP) for 15  minutes and then 2  the maximum allowable pressure (MAP) for 
1 minute.  For concentric meters the static pressure test must be performed on the meter and c ollection 
pipes together.  
During or after completion of the test, there must be no visible leak from the meter, leak from the 
indicator  or physical damage to the water meter due to testing.  
5.3.4 Determining basic error (of indication)  
The basic measuremen t error of the water meter is determined at the reference operating water 
temperature pursuant to Article  5.3.1 and at specified positions; three times at flow rates  1), 2), and 5) 
and twice at other flow rates:  
1) between Q1 and 1.1 Q1; 
2) between Q2 and 1.1 Q2; 
3) between 0.33( Q2 + Q3) and 0.37( Q2 + Q3); 
4) between 0.67( Q2 + Q3) and 0.74( Q2 + Q3); 
5) between 0.9 Q3 and Q3; 
6) between 0.95 Q3 and Q4; 
and for combined water meters:  
7) between 0.85 Qx1 and 0.95 Qx1; 
8) between 1.05 Qx2 and 1.15 Qx2. 
Errors found for each flow rate must not  exceed the maximum permissible error.  If an error found on 
one or more meters is greater than the maximum permissible error at only one flow rate, then:  
 if only two results were determined at this flow rate, the test at the given flow rate must be 
repeated;  
 the test must be declared satisfactory if two of three results lie within the limits of the maximum 
permissible error and the arithmetic mean of the results of three tests at this flow rate is less than 
or equal to the maximum permissible error.  
The standard deviation for a basic error at flow rates of Q1, Q2, and Q3 must not exceed ⅓ of the 
maximum permissible errors.  
Water meter errors found at each of the given flow rates must not exceed the maximum permissible 
error specified in Articles  2.3.1  and 2.3.2 under conditions of Article  2.3.3.  
5.3.5 Test of the effect of test water temperature  
The effect of water temperature on water meter error is determined at a flow rate of Q2 with incoming 
temperature maintained at:  
(10 ± 5) °C for temperature cl asses T30 to T180;  
( 30 0+5 ) °C for temperature classes T30/90 to T30/180.  
The effect of water temperature on water meter error is determined at a flow rate of Q2 with incoming 
temperature maintained at the water meter's maximum allowable temperature (MAT ) and a tolerance 
of (−5 0) °C. 
Temperature of the incoming water relative to the relevant temperature class are specified in Table  4. General Measure No  0111 -OOP -C051 -16 
14 Table  4 - Test water temperature  
Temperature 
class  T30 T50 T70 T90 T130  T180  T30/90  T30/130  T30/180  
Test water 
temperature  10 °C 10 °C 10 °C 10 °C 10 °C 10 °C 30 °C 30 °C 30 °C 
30 °C 50 °C 70 °C 90 °C 130 °C 180 °C 90 °C 130 °C 180 °C 
Errors found at each of the given test water temperatures must not exceed the maximum permissible 
error specified in Articles  2.3.1 and 2.3.2.  
5.3.6 Test by overheating water  
This test is used for water meters with a maximum allowable temperature MAT  50 °C. 
Once the water meter has achieved thermal stability, it is exposed to water flow at the reference flow 
rate at th e maximum allowable temperature MAT +10  °C ± 2.5 °C for one hour.  After recovery the 
water meter's error at a flow rate of Q2 at the reference temperature is determined.  
The water meter error must not exceed the maximum permissible error specified in Artic les 2.3.1 and 
2.3.2.  
5.3.7 Test by water pressure  
The influence of internal water pressure on water meter error is tested.  Measurement error is 
determined for at least one water meter at a flow rate of Q2 with incoming water pressure maintained 
first at 0. 03 MPa (0.3  bar) ( 0 %+5 %), and then at maximum allowable pressure (MAP) (−10 % 0 %). 
The water meter error for each prescribed pressure at the water meter inlet must not exceed the 
maximum permissible error specified in Articles  2.3.1 and 2.3.2.  
5.3.8 Backflow test  
Water meter operation is tested during backflow.  
5.3.8.1 Water meters designed to measure backflow  
Water meters designed to measure backflow must precisely record the volume of backflow.  The 
following tests must be performed with backflow:  
a) an accuracy test:  
1) between Q1 and 1.1 Q1; 
2) between Q2 and 1.1 Q2; 
3) between 0.9 Q3 and Q3. 
The water meter error at any of the flow rates must not exceed the maximum permissible error 
specified in Articles  2.3.1 and 2.3.2.  
b) a pressure drop test pursuant to Article  5.3.9; 
c) a test of sensitivity to current profile pursuant to Article  5.3.10;  
d) a durability test pursuant to Article  5.3.11.  
Test results must satisfy Articles  5.3.9, 5.3.10, and 5.3.11.  
5.3.8.2 Meters not designed to measure backflow  
A meter that permits backflow but is not designed to record it must be subjected to backflow.  Errors 
must then be determined for forward flow to check that backflow has not negatively affected 
metrological functions.  
The water meter is subjected to backflow of 0.9 Q3 for one mi nute.  Draft Measure of a General Nature No  0111 -OOP -C051 -17 
15 The water meter error is then determined for the following forward flow ranges:  
1) between Q1 and 1.1 Q1; 
2) between Q2 and 1.1 Q2; 
3) between 0.9 Q3 and Q3. 
The water meter error at any of the flow rates must not exceed the maximum permissible error 
specified in Articles  2.3.1 and 2.3.2.  
5.3.8.3 Meters designed to prevent backflow  
A meter designed to prevent backflow is subjected to its maximum allowable pressure at the outlet 
connection and measurement errors are then determined for forward flow to find out wh ether the 
effects of pressure on the water meter had not negatively affected metrological functions.  
The water meter is subjected to maximum allowable pressure under backflow for one minute.  During 
the test, valves are checked for any significant leaks.  
The water meter error is then determined for the following forward flow rates:  
1) between Q1 and 1.1 Q1; 
2) between Q2 and 1.1 Q2; 
3) between 0.9 Q3 and Q3. 
The water meter error at any of the flow rates must not exceed the maximum permissible error 
specified in Article s 2.3.1 and 2.3.2.  
5.3.9 Pressure drop test  
Pressure drop is measured for the pressure drop class.  
The meter's maximum pressure drop is determined at any flow rate between Q1 and Q3. 
The measured pressure drop at any flow rate within the limits of specified operating conditions must 
not exceed the maximum pressure drop value corresponding to the class declared by the manufacturer.  
5.3.10 Flow disturbance tests  
The influence of installation conditions on water meter error is tested.  This test is not appropriate for 
water meters that are not sensitive to installation conditions.  
The error is determined at flow rates between 0.9 Q3 and Q3 for three types of baffles situated in front 
of and past the water meter at distances specified by the manufacturer, at most however 15  DN in 
front of the meter and 5  DN past the meter.  
The water meter error for any of the baffles must not exceed the maximum permissible error specified 
in Articles  2.3.1 and 2.3.2.  
5.3.11 Durability tests  
The tests must be performed in the following order:  
a) a discontinuous flow test at Q3 (for water meters with Q3 ≤ 16 m3/h); 
b) a continuous test at Q3 (for water meters with Q3 > 16 m3/h); 
c) a continuous test at Q4. 
5.3.11.1 Discontinuous flow test  
The test is performed to verify the water meter's immunity to cyclic flow conditions under conditions 
specified in Table  5.The test consists of subjecting the meter to the specified number of flow start and 
stop cycles over a short time, where each constant test flow phase is maintained at the spe cified flow 
rate for the entire duration of the test.  General Measure No  0111 -OOP -C051 -16 
16 The water meter error pursuant to Article  5.3.4 is determined prior to commencing the discontinuous 
test and after it is completed.  
The change in the error curve must not exceed:  
a) for accuracy class  1: 
2 % for flow rates in the lower region ( Q1  Q < Q2); and  
1 % for flow rates in the upper region ( Q2  Q  Q4); 
b) for accuracy class  2: 
3 % for flow rates in the lower region ( Q1  Q < Q2); and  
1.5 % for flow rates in the upper region ( Q2  Q  Q4); 
i.e. for  every flow rate, the error obtained prior to the test is subtracted from the error obtained after 
the test.  
For purposes of stipulating these requirements, the average values of errors for each flow rate must be 
used, and the water meter error must not ex ceed the maximum error limit value:  
a) for accuracy class  1: 
±4 % for flow rates in the lower region ( Q1  Q Q2); and  
±1.5 % for flow rates in the upper region ( Q2  Q  Q4) for T30 meters; or  
±2.5 % for flow rates in the upper region ( Q2 Q  Q4) for meters  other than T30.  
b) for accuracy class  2: 
±6 % for flow rates in the lower region ( Q1  Q Q2); and  
±2.5 % for flow rates in the upper region ( Q2  Q  Q4) for T30 meters; or  
±3.5 % for flow rates in the upper region ( Q2 Q  Q4) for meters other than T30.  
5.3.11.2 Continuous flow test  
The water meter's immunity is tested under constant, continuous, permanent flow Q3 or overload flow 
Q4 pursuant to conditions specified in Table  5. 
The change in the error curve must not exceed:  
a) for accuracy class  1: 
2 % for f low rates in the lower region ( Q1  Q < Q2); and  
1 % for flow rates in the upper region ( Q2  Q  Q4); 
b) for accuracy class  2: 
3 % for flow rates in the lower region ( Q1  Q < Q2); and  
1.5 % for flow rates in the upper region ( Q2  Q  Q4); 
i.e. either:  
I. for every flow rate, the error obtained prior to the test is subtracted from the error obtained after 
the test —this applies to a continuous flow test at Q3; or 
II. for every flow rate, the error obtained prior to the discontinuous flow test, or the continu ous flow 
test at Q3, from the error obtained after the continuous flow test at Q4. 
The water meter error is determined via an accuracy test pursuant to Article  5.3.4.  Draft Measure of a General Nature No  0111 -OOP -C051 -17 
17 For purposes of stipulating these requirements, the average values of errors for each flo w rate must be 
used—the error must not exceed the maximum error limit value:  
a) for accuracy class  1: 
±4 % for flow rates in the lower region ( Q1  Q Q2); and  
±1.5 % for flow rates in the upper region ( Q2  Q  Q4) for T30 meters; or  
±2.5 % for flow rates in  the upper region ( Q2 Q  Q4) for meters other than T30.  
b) for accuracy class  2: 
±6 % for flow rates in the lower region ( Q1  Q Q2); and  
±2.5 % for flow rates in the upper region ( Q2  Q  Q4) for T30 meters; or  
±3.5 % for flow rates in the upper region ( Q2 Q  Q4) for meters other than T30.  
Table 5 - Durability tests  
Temperatur
e class  Permanen
t flow rate  
Q3 Flo
w 
rate 
test Test water 
temperatur
e ±5 °C Test type  Number of 
interruption
s Pause 
duratio
n Duratio
n of 
activity 
at test 
flow rate Start and 
stop 
duration  
T30 and T50  Q3 
16 m3/h Q3 20 °C Discontinuou
s 100 000 15 s 15 s 0.15Q3 (s
) with a 
minimum 
of 1 s 
Q4 20 °C Continuous  - - 100 h - 
Q3 
>16 m3/h Q3 20 °C Continuous  - - 800 h - 
Q4 20 °C Continuous  - - 200 h - 
All other 
classes  Q3 
16 m3/h Q3 50 °C Discontinuou
s 100 000 15 s 15 s 0.15Q3 (s
) with a 
minimum 
of 1 s 
Q4 0.9 MAT  Continuous  - - 100 h - 
Q3 
>16 m3/h Q3 50 °C Continuous  - - 800 h - 
Q4 0.9 MAT  Continuous  - - 200 h - 
continued  
Table 5 – completion  
Temperatur
e class  Permanen
t flow rate  
Q3 Flow 
rate 
test Test water 
temperatur
e ±5 °C Test type  Number of 
interruption
s Pause 
duratio
n Duratio
n of 
activity 
at test 
flow rate Start 
and stop 
duratio
n 
Combined 
meters  Q3 
>16 m3/h Q 
2Qx2 20 °C Discontinuou
s 50 000 15 s 15 s 3 s to 6  s 
Combined 
meters  
(where a 
small meter 
was not pre -
approved)  Q3 
>16 m3/h 0.9Qx
1 20 °C Continuous  - - 200 h - General Measure No  0111 -OOP -C051 -16 
18 5.3.12 Electromagnetic field tests  
This is tested in accordance with Article  5.6.10.  
5.3.13 Tests of the water meter's auxiliary devices  
The influence of permanently or temporarily inserted auxiliary devices on the water meter error is 
tested.  
The water meter error must be determined with temporarily inserted auxiliary devices, for example for 
purposes of testing or data transmission.  The water  meter error must not exceed the maximum 
permissible error specified in Articles  2.3.1 and 2.3.2.  
For permanently inserted and temporarily inserted auxiliary devices, the volume indication from 
auxiliary devices must be checked to determine whether their r eading does not differ from the reading 
on the primary indicator.  Volume indication from an auxiliary device(s) must not differ from the 
indication on the visual display by more than the value of the verification scale interval.  
5.4 Functional tests for electronic water meters and mechanical meters with inserted 
electronic devices  
These functional tests supplement tests specified in Article  5.3, and are applied to compact water 
meters, removable water meter parts  and auxiliary devices.  
During each test, t ypical test conditions are established that correspond to the climactic, mechanical  
and electrical conditions in the environment to which water meters are exposed.  Corresponding 
classification of the water meter into classes must take place in accordance w ith Chapter  3.6.1 and 
3.6.2.  
For test purposes, the tested device must be classified into one of cases  A to E, and the following 
requirements must apply:  
Case  A: performance of the test is not required.  
Case  B: the tested device is a compact meter; the test must be performed with water in the volume 
or flow sensor and with the meter operating as designed.  
Case  C: the tested device is a measurement transducer; the test must be performed with water in 
the volume or flow sensor and with the meter operating as designed.  
Case  D: the tested device is an electronic counter including indicator or auxiliary device; the test 
must be performed with water in the volume or flow sensor and with the meter operating 
as designed.  
Case  E: the tested device is an electronic  counter including indicator or auxiliary device; the test 
may be performed with simulation of measurement signals without water in the volume 
or flow sensor.  
5.5 Tests of resistance to environmental influences  
5.5.1 Dry (non -condensing) heat test  
The wate r meter is subjected to the reference flow rate pursuant to Article  5.3.1 and the water meter 
error is determined under the following test conditions:  
 at an air temperature of (20  ± 5) °C, prior to preliminary stabilisation of the tested device;  
 at an air temperature of (55  ± 2) °C, following preliminary stabilisation of the tested device at 
this temperature for 2  h; 
 at the reference air temperature of (20  ± 5) °C, after the tested device has recovered following 
the preceding test.  Draft Measure of a General Nature No  0111 -OOP -C051 -17 
19 The water meter error for  any of these conditions must not exceed values specified in Article  2.3.2, 
and all of the functions of the tested device must operate as designed.  
5.5.2 Cold test  
The water meter is subjected to the reference flow rate pursuant to Article  5.3.1 and the wa ter meter 
error is determined under the following test conditions:  
 at an air temperature of (20  ± 5) °C, prior to preliminary stabilisation of the tested device;  
 at an air temperature of (+5  ± 3) °C for fixed meters installed in a building (environmental 
class  B) or (−25  ± 3) °C for fixed meters installed in an outdoor environment (environmental 
class  O) and for mobile meters (environmental class  M), following stabilisation of the tested 
device at this temperature for 2  h; 
 at the reference air temperature of (20  ± 5) °C, after the tested device has recovered.  
The water meter error for any of these conditions must not exceed values specified in Article  2.3.2, 
and all of the functions of the tested device must operate as designed.  
5.5.3 Cyclic wet (condensing ) heat test  
Following preliminary stabilisation, the water meter is subjected to two temperature cycles over a 24 -
hour period between the lower temperature (25  ± 3) °C and the higher temperature:  
 (55 ± 2) °C for fixed meters installed in an outdoor environ ment (environmental class  O) and for 
mobile meters (environmental class  M); or  
 (40 ± 2) °C for fixed meters installed in a building (environmental class  B). 
The relative humidity is maintained above 95  % during temperature changes and during the low -
temper ature phase, and above (93  ± 3) % during the higher temperature phases.  The power supply is 
switched on during the test.  
Once the water meter has recovered, its error at the reference flow rate is determined.  
The water meter error must not exceed values specified in Article  2.3.2, and all of the functions of the 
tested device must operate as designed.  
5.5.4 Random vibration test  
This test applies only to mobile meters.  
The water meter is installed in the position in which it is routinely used, and random vibrations are 
applied to the tested device over a frequency range of 10  Hz to 150  Hz, in three mutually 
perpendicular axes, for at least 2 minutes per axis.  During the test the power supply is switched on and 
the following conditions must be met:  
 total RMS: 7 m/s2; 
 ASD of 10 to 20  Hz:1  m2/s3, 
 ASD of 20 to 150  Hz:-3 dB/octave.  
Once the water meter has recovered, its error at the reference flow rate is determined.  
NOTES  
RMS Root mean square  
ASD Acceleration spectral density  
The difference between the indication before and after the test must not exceed ½ the maximum 
permissible error specified in Article  2.3.2, or the tested device must detect a significant error while all 
of its functions continue to operate as designed.  
5.5.5 Impact test  
This test applies only to mobile meters.  General Measure No  0111 -OOP -C051 -16 
20 The water meter must be placed on a hard surface in its normal position for use, and dropped on one 
bottom edge, with the opposite edge of the water meter being 50  mm above the hard surface; however, 
the angle between the bot tom of the water meter and the test surface must not exceed 30°.The impact 
must be repeated on each bottom edge.  The power supply is switched off during the test.  
Once the test has been completed and the water meter has recovered, its error at the referenc e flow rate 
is determined.  
The difference between the indication before and after the test must not exceed ½ the maximum 
permissible error specified in Article  2.3.2, or the tested device must detect a significant error while all 
of its functions continue to operate as designed.  
5.6 Electromagnetic compatibility (EMC) tests  
5.6.1 Change of supply voltage  
5.6.1.1 Water meters powered directly from the grid (AC) or via an adapter (AC/DC)  
The test verifies the influence of a static deviation of an AC mains pow er source.  
During the test the following are applied:  
 upper mains voltage limit Unom + 10 %; 
 upper mains frequency limits fnom + 2 %; 
 lower mains voltage limit Unom − 15 %; 
 lower mains frequency limits fnom + 2 %. 
The water meter error is determined during  test conditions at the reference flow rate.  
The water meter error must not exceed values specified in Article  2.3.2, and all of the functions of the 
tested device must operate as designed.  
5.6.1.2 Water meters powered directly by an external DC power supply or by primary DC batteries  
The test verifies the influence of a static deviation of a DC power source.  
During the test the following are applied:  
 the maximum operating voltage of the battery, as specified by the water meter's manufacturer, 
for the battery or DC voltage for which the water meter was manufactured for automatic 
detection of high -level conditions for external DC power;  
 the minimum operating voltage of the battery, as specified by the water meter's manufacturer, 
for the battery or DC vol tage for which the water meter was manufactured for automatic 
detection of low -level conditions for external DC power.  
The water meter error is determined during test conditions at the reference flow rate.  
The water meter error must not exceed values speci fied in Article  2.3.2, and all of the functions of the 
tested device must operate as designed.  
5.6.1.3 Interruption of battery power  
This test applies only to meters that use replaceable batteries.  
The battery is removed for one hour and then reconnected.  The meter's operation must then be 
examined in detail.  
The value of the total or stored values must remain unchanged and all functions of the tested device 
must operate as designed.  Draft Measure of a General Nature No  0111 -OOP -C051 -17 
21 5.6.2 Immunity to dips and short interruptions and AC voltage variations  
During the application of a power interruption, power must be interrupted for 250  cycles (50  Hz) and 
300 cycles (60  Hz).At least 10 repetitions must be performed with an interval of at least 10  seconds 
between each group of interruptions.  Interruptions are repeated for the entire duration of the time 
needed to determine the water meter error.  
During application of a voltage dip, voltage must be reduced to 0  % or 70  % for 0.5  cycle, 1  cycle, or 
25 cycles (50  Hz)/30 cycles (60  Hz) depending on the type of test  being performed.  Ten repetitions 
must be performed with an interval of at least 10  seconds between each group of dips.  
The difference between the water meter error obtained during the application of voltage dips and the 
error determined prior to the test under reference conditions must not exceed one half of the value 
specified in Article  2.3.2, or the tested device must detect a significant error while all of its functions 
continue to operate as designed.  
5.6.3 Immunity to transients/bursts on signal line s 
Transient voltage spikes are applied, with a double exponential waveform.  The duration of the 
transients must be 15  ms and the rate of repetition of the transient must be 5  kHz.  A voltage of 1  kV is 
used for environmental class  E2. 
The difference between  the water meter error obtained during the application of transients and the 
error determined prior to the test under reference conditions must not exceed one half of the value 
specified in Article  2.3.2, or the tested device must detect a significant erro r while all of its functions 
continue to operate as designed.  
5.6.4 Immunity to transients/bursts in AC and DC grids  
Transient voltage spikes are applied, with a double exponential waveform.  The duration of the 
transients must be 15  ms and the rate of repe tition of the transient must be 5  kHz.  A voltage of 2  kV is 
used for environmental class  E2. 
The difference between the water meter error obtained during the application of transients and the 
error determined prior to the test under reference conditions must not exceed one half of the value 
specified in Article  2.3.2, or the tested device must detect a significant error while all of its functions 
continue to operate as designed.  
5.6.5 Immunity to electrostatic discharge  
During one test, 10  direct (contact ) discharges are applied with a test voltage of 6  kV to metal parts of 
the case at intervals of at least 10  seconds between discharges and 10  indirect (air) discharges with a 
test voltage of 8  kV in the horizontal connection plane and 10  indirect discharge s for each of various 
positions in the vertical connection plane.  
The difference between the water meter error determined during the application of electrostatic 
discharges and the error determined prior to the test under reference conditions must not exce ed one 
half of the value specified in Article  2.3.2, or the tested device must detect a significant error while all 
of its functions continue to operate as designed.  
5.6.6 Immunity to radiated electromagnetic fields  
The test must be performed in the presen ce of interference in the 26  MHz to 2  000 MHz frequency 
range at a field intensity of 10  V/m for environmental class  E2. 
The difference between the water meter error measured during the application of each carrier 
frequency band and the error determined prior to the test under reference conditions must not exceed 
one half of the value specified in Article  2.3.2, or the tested device must detect a significant error 
while all of its functions continue to operate as designed.  General Measure No  0111 -OOP -C051 -16 
22 5.6.7 Immunity to electromagneti c fields caused by power lines  
The test involves exposure to conducted electromagnetic fields in the 0.15  MHz to 80  MHz frequency 
range at an RF amplitude of 10  V for environmental class  E2. 
The difference between the water meter error measured during the application of each carrier 
frequency band and the error determined prior to the test under reference conditions must not exceed 
one half of the value specified in Article  2.3.2, or the tested device must detect a significant error 
while all of its functio ns continue to operate as designed.  
5.6.8 Immunity to transient surges on signal, data  and control lines  
The test verifies the influence of transient surges if they are multiplied on I/O and communication 
ports, and if these lines are longer than 30  m, or on lines installed outside the building regardless of 
their length.  The surges must be applied in line -to-line with a transient voltage of 1  kV and in line -to-
ground with a transient voltage of 2  kV for environmental class  E2. 
The difference between the wa ter meter error obtained during the application of transient voltage 
surges and the error determined prior to the test under reference conditions must not exceed one half 
of the value specified in Article  2.3.2, or the tested device must detect a significa nt error while all of 
its functions continue to operate as designed.  
5.6.9 Immunity to transient surges on AC and DC power lines  
The test verifies the influence of transient surges if they are multiplied on mains power, and if these 
lines are longer than 3 0 m, or on lines installed outside the building regardless of their length.  The 
surges must be applied in line -to-line with a transient voltage of 1  kV and in line -to-ground with a 
transient voltage of 2  kV for environmental class  E2. 
The difference betwee n the water meter error obtained during the application of transient voltage 
surges and the error determined prior to the test under reference conditions must not exceed one half 
of the value specified in Article  2.3.2, or the tested device must detect a s ignificant error while all of 
its functions continue to operate as designed.  If you want commas, they have to be in all paragraphs.  
They aren't in the standard.  
5.6.10 Static magnetic field  
The test must use a permanent ring magnet that has the following m agnetic properties:  
 remanence:385  mT to 400  mT 
 coercivity:100  kA/m to 140  kA/m  
 magnetic field intensity measured less than 1  mm from the surface:90  kA/m to 100  kA/m  
 magnetic field intensity measured 20  mm from the surface:20  kA/m  
The permanent magnet is placed into contact with the water meter in a position where the effect of the 
magnetic field is capable of causing an error that exceeds the maximum permissible error and affects 
the water meter's correct operation.  This location depends on the type and design of the water meter, 
or is based on prior experience; various magnet positions may be investigated.  
The water meter error must not exceed values specified in Article  2.3.2, and all of the functions of the 
tested device must operate as design ed. 
5.6.11 Absence of flow test  
This test verifies changes in water meter indication in the absence either of flow for 15  minutes, or of 
water for 15  minutes.  
The water meter's indication during each test interval must not change by more than the value of the 
verification scale interval.  Draft Measure of a General Nature No  0111 -OOP -C051 -17 
23 5.7 Software check  
The software check is covered by special legislation3. 
6 Initial verification  
Initial approval pursuant to the Metrology Act applies only to water flow quantity meters for uses 
other than residential, com mercial  and light industry and meters after repair.  
The same metrological requirements which were decisive in the placement of water meters into 
circulation will be applied during their verification.  
6.1 Overview of tests conducted  
During initial verificat ion the following activities and tests are performed:  
a) visual inspection;  
b) functional tests:  
 a static pressure test;  
 an accuracy test.  
6.2 Visual inspection  
A visual inspection is performed to assess whether:  
 the meter submitted for verification and its parts conform to the approved type, and attention 
must be paid to checking labelling pursuant to Chapter  4; 
 the meter is not physically damaged and its metal parts bear no traces of corrosion;  
 the condition and lifespan of power supply batteries satisfy th e verification period.  
If the measuring instrument fails to meet visual inspection requirements, no further tests are 
performed.  
6.3 Functional tests  
6.3.1 Test equipment  
Test equipment pursuant to Article  5.3.2 is used, and the extended uncertainty of volume measurement 
indicated by the test equipment must not exceed 1/3 the water meter's maximum permissible error.  
6.3.2 Static pressure test  
The tightness of the water meter and its resistance to damage at test water pressure according to the 
chosen maximum allowable pressure class are tested.  
The test is performed at a flow rate equal to zero.  The water pressure must be equivalent to at least 
1.6 the maximum allowable pressure (MAP) for 1  minute.  For concentric meters the static pressure 
test must be performed on the meter and collection pipes together.  
During or after completion of the test, there must be no visible leak from the meter, leak from the 
indicator  or physi cal damage to the water meter due to testing.  
6.3.3 Accuracy test  
Water meter measurement errors must be determined for at least the following three flow rates:  
 between Q1 and 1.1 Q1; 
 between Q2 and 1.1 Q2; General Measure No  0111 -OOP -C051 -16 
24  between 0.9 Q3 and Q3. 
Additional flow rates may be specified in the type -approval certificate.  
The test water temperature during meter verification must be the following depending on temperature 
class:  
T30, T50:(20  ± 10) °C 
T70 to T180:(20  ± 10) °C and temperature (50  ± 10) °C 
T30/90 to T30/180:(50  ± 10) °C 
Errors found at each of the above -mentioned flow rates must not exceed the maximum permissible 
error specified in Articles  2.3.3. and 2.3.2 under conditions specified by Article  2.3.3.  
For water meters with permanent flow rate Q3 ˃ 20  m3/h classified in any temperature class, a test 
water temperature of (20  ± 10) °C can be used. Errors found at each of the above -mentioned flow rates 
must not exceed the maximum permissible errors  
 at a flow rate greater than or equal to the minimum flow rate Q1 and up to but not including the 
transient flow rate Q2, positive or negative, 5  %; and  
 at a flow rate greater than or equal to the transient flow rate Q2 and less than or equal to the 
overload flow rate Q4, positive or negative, 2  %; 
under conditions spec ified in Article  2.3.3.  
7 Subsequent verification  
Subsequent verification, i.e. every verification of a meter performed after initial verification, is 
performed pursuant to this article.  
The same metrological requirements which were decisive in the placeme nt of water meters into 
circulation will be applied during their verification.  
7.1 Overview of tests conducted  
During subsequent verification the following activities and tests are performed:  
a) visual inspection;  
b) functional tests:  
 a static pressure test;  
 an accuracy test.  
7.2 Visual inspection  
A visual inspection is performed to assess whether:  
 the meter submitted for verification conforms to the approved type, and attention must be paid to 
checking labelling pursuant to Chapter  4; 
 the meter is not physically  damaged and its metal parts bear no traces of corrosion;  
 for water meters with an electronic indicator, the meter did not lose volume indication prior to 
disconnection of power in the place of use, and has remained accessible pursuant to Article  3.7; 
 the condition and lifespan of power supply batteries satisfy the verification period.  
If the measuring instrument fails to meet visual inspection requirements, no further tests are 
performed.  Draft Measure of a General Nature No  0111 -OOP -C051 -17 
25 7.3 Functional tests  
7.3.1 Test equipment  
The test equipment require ments are the same as in Article  6.3.1.  
7.3.2 Static pressure test  
The static pressure test is performed using the same procedure as for initial verification pursuant to 
Article  6.3.2.  
7.3.3 Accuracy test  
The accuracy test is performed using the same proce dure as for initial verification pursuant to 
Article  6.3.3.  
Errors found at each of the above -mentioned flow rates must not exceed the maximum permissible 
error specified in Articles  2.3.3. and 2.3.2 under conditions specified by Article  2.3.3.  
7.4 A check  of the water meter during the verification validity period in the installation 
location  
The check verifies whether the water meter operating as the specified measuring instrument complies 
with the metrological and technical requirements of this Measure of  a General Nature, is correctly 
installed  and complies with requirements for measurement accuracy during operation.  This check is 
performed only if it is technically feasible.  
7.4.1 Tests to be performed  
A check of the water meter in its installation locat ion during its verification validity period comprises:  
 a visual inspection of the tested water meter and its installation;  
 preliminary operating tests;  
 leak checks;  
 accuracy tests.  
7.4.2 Visual inspection  
A visual inspection is performed to assess whether:  
 the tested water meter is the same as the approved type pursuant to the Metrology Act;  
 it is properly installed and is not physically damaged;  
 information on the water meter is in accordance with the type -approval mark pursuant to the 
Metrology Act;  
 it is duly secured by official marks and installation seals.  
In the case of water meters that have failed the visual inspection, this fact is recorded in the test report 
with sufficient specification of the concrete non -compliance.  The water meter test continues.  
7.4.3 Test equipment  
The following test equipment is used to test a water meter in its installation location:  
 a technically suitable reference standard flow meter with verified metrological traceability, with 
metrological parameters that corresp ond to the tested water meter, and with a regulation valve; 
or 
 reference standard measuring containers with a regulation valve for setting the flow rate during 
the test, which must have a verification scale interval of 0.01  L for volumes up to and includin g 
10 L, and 0.03  L for volumes greater than 10  L, with 4  mm scale spacing;  
 a connection hose with a suitable connection to the outlet of the pipe system and a container 
regulation valve;  General Measure No  0111 -OOP -C051 -16 
26  a thermometer with verified metrological traceability and accuracy of  ±1 °C. 
The measurement uncertainty of the entire test apparatus is at most 1/3 of the water meter's maximum 
permissible error.  
7.4.4 Tightness test  
A flow quantity reference standard is connected to the tested water meter to one outlet of the water 
pipe u sing a connection hose.  All other outlets must be closed.  
The tested water meter is left as is, so that its current condition and any effects of installation remain 
preserved during the test.  
The tightness of the shut -off valve is checked, and of all other  valves and outlets from the water 
system that could cause leaks of the measured water between the tested water meter and the reference 
standard.  It must be ensured that all water that flows through the tested water meter also flows through 
the reference s tandard.  
The hose connection is checked visually for absence of leaks.  
7.4.5 Preliminary operating test  
The test is performed for at least 5  minutes at maximum achievable flow from the water system.  
During the test, the water system is checked to ensure it  has no air pockets.  
7.4.6 Accuracy test  
The accuracy test must be performed at a minimum flow rate Q1 and transient flow rate Q2 calculated 
from the water meter's markings and at maximum achievable flow rate from the water system, which 
must be at least w ithin the range of (2  Q2 to Q3).The test flow rates for a test of water meter accuracy 
at the installation location are as follows:  
a) minimum flow rate Q1 of the tested water meter, the average flow rate during the test must be 
within the range ( Q1 to 1.1 Q1); 
b) transient flow rate Q2 of the tested water meter, the average value during the test must be within 
the range ( Q2 to 1.1 Q2); 
c) maximum achievable flow rate, the average value during the test must be within the range 
(2 Q2 to Q3). 
If a flow rate of 2  Q2 cannot be achieved due to the water meter being unsuitable for the specific 
installation and due to water pressure at the installation location, this fact will be recorded in the test 
report.  
If even a flow rate of Q1 cannot be achieved, this fact will also be recorded in the test report, and the 
test is ended.  
The water temperature during a test of a cold -water meter, i.e. with water of temperature (0.1 to 
30) °C, and during a test of a hot -water meter, i.e. with water of temperature (30 to 90)  °C, is 
measured with a thermometer with an accuracy of ±1  °C. 
The minimum volume that must flow through the water meter during the test depends on requirements 
determined by a test of the effects of starting and stopping (time error) and the type and construction 
of the indicator.  
During the accuracy test, at least one measurement must be performed at each test flow rate.  Errors 
found at each of the above -mentioned flow rates must not exceed double the maximum permissible 
errors specified in Articles  2.3.3. and 2.3 .2. 
The accuracy test may be performed using the collection or volume method.  Draft Measure of a General Nature No  0111 -OOP -C051 -17 
27 7.4.6.1 Collection method  
During an accuracy test performed using the collection method, the amount of water flowing through 
the water meter is collected in a measuring container  and its amount is determined on the measuring 
container's scale.  
The error is determined by comparing the volume indicated by the tested water meter with the water 
volume indications on the measuring container.  
The flow rate Q1, Q2, and the maximum achiev able flow rate from the water system pursuant to 
Article  7.4.6(a) to (c) is set by adjusting the regulation valve on the measuring container inlet.  
7.4.6.2 Volume method  
During an accuracy test performed using the volume method, the volume that has passed through the 
water meter is compared with the volume that has passed through a flow quantity reference standard, 
for example an induction flow meter, with valid calibration.  The induction flow meter must be 
calibrated, including calming sections (of minimum  length 10 D before the meter and 5 D past the 
meter) with maximum permissible error 0.6  %.Calibration uncertainty must not exceed ±0.2  %. 
Water pressure at the reference standard outlet must be set using the outlet hose.  The pressure past the 
reference stan dard must be at least 5  kPa (0.05  bar) even at zero flow rate (corresponds to a water 
column of 0.5  m). 
The flow rate Q1, Q2, and the maximum achievable flow rate from the water system pursuant to 
Article  7.4.6(a) to (c) is set by adjusting one of the regu lation valves on the outlet past the reference 
standard with calming sections.  
7.4.6.3 Evaluation of the results of an accuracy test in the installation location  
If the water meter fails the external inspection or accuracy test, it is considered to be in n on-
compliance with stipulated requirements.  
8 Measuring instrument check  
When examining measuring instruments pursuant to §  11a of the Metrology Act at the request of a 
person who may be affected by an incorrect measuring instrument, please proceed according to 
Chapter  7, with the exception of the last sentence of Article  7.2.The maximum permissible error used 
is double the maximum permissible errors pursuant to Articles  2.3.1 and 2.3.2.  
9 Notified standards  
To specify metrological and technical requ irements for measuring devices and to specify verification 
and type -approval test methods stemming from this Measure of a General Nature, the CMI notifies 
Czech technical standards, other technical standards or technical documents of international or forei gn 
organisations or other technical documents containing detailed technical requirements (hereinafter 
‘notified standards’).The CMI shall publish a list of these notified standards attached to the relevant 
measures, together with the general measure, in a manner accessible to the public (on www.cmi.cz ). 
Compliance with notified standards or parts thereof is considered, to the extent and under the 
conditions stipulated by a general measure, to be compliance with the requ irements stipulated by this 
measure to which these standards or parts thereof apply.  
Compliance with notified standards is one way of demonstrating compliance with the requirements.  
These requirements may also be met by using another technical solution gua ranteeing an equivalent or 
higher level of protection of legitimate interests.  
 General Measure No  0111 -OOP -C051 -16 
28 II. 
GROUNDS  
The CMI issues, pursuant to §  14(1)(j) of the Metrology Act, toward the implementation of §  6(2), 
§ 9(1), §  9(9) and §  11a(3) of the Metrology Act, this General Mea sure, stipulating metrological and 
technical requirements for the specified measuring instruments and test methods for the type approval 
and verification of the specified measuring instruments —'Water flow quantity meters —water meters 
that are intended for uses other than residential, commercial  and light industry'.  
Decree  No 345/2002, stipulating measuring instruments for mandatory verification and measuring 
instruments subject to type approval, as amended, classifies this type of measuring instrument among  
measuring instruments subject to type approval and verification under item  1.3.9 a), b), c), d) and e) in 
the Annex 'List of Specified Measuring Device Types'.  
This legislation (General Measure) will be notified in accordance with Directive  (EU)  2015/1535  of 
the European Parliament and of the Council of 9  September  2015 defining a procedure for the 
provision of information in the field of technical regulations and of rules on Information Society 
services.  
 
III. 
INSTRUCTIONS  
In accordance with §  172(l), in conjunction with §  39(l) CAP, the CMI has stipulated a time limit for 
comments of 30  days as of the date of posting on the official notice board.  Comments submitted after 
this time limit will not be considered.  
The persons concerned are hereby invited to c omment on this draft Measure of a General Nature.  With 
a view to the provisions of §  172(4) CAP, the comments shall be submitted in writing.  
In accordance with §  174(l) CAP in conjunction with §  37(l) CAP, it must be clear who is making the 
comments, which  measure of a general nature they concern, how it contradicts legislation or how the 
measure of a general nature is inaccurate, and they must be signed by the person making them.  
The supporting documents for this draft General Measure may be consulted at t he Czech Metrology 
Institute, Legal Metrology Department, Okružní  31, 638  00 Brno, after making arrangements by 
telephone.  
This general measure shall be posted for 15  days.  
 
 
 
 
 
 
 ...…………………………..............  
RNDr.  Pavel Klenovský  
Director -General  
 
 
Person  responsible for accuracy:  Mgr.  Tomáš Hendrych  Draft Measure of a General Nature No  0111 -OOP -C051 -17 
29  
Posted on:  
Signature of the authorised person confirming posting:....................................................  
 
Removed on:  
Signature of the authorised person confirming removal:....................................................