CEN/TC 237

Date: 2025-02

prEN 14236

Secretariat: BSI

Ultrasonic domestic gas meters

Einführendes Element — Haupt-Element — Ergänzendes Element

Élément introductif — Élément central — Élément complémentaire

ICS:

Contents Page

European foreword 7

1 Scope 9

2 Normative references 9

3 Terms and definitions 11

3.1 Terms and definitions 11

3.2 Symbols 16

4 Working conditions 17

4.1 General 17

4.2 Base conditions 17

4.3 Flow range 18

4.4 Maximum working 18

4.5 Temperature range 18

4.5.1 General 18

4.5.2 Ambient temperature range 18

4.5.3 Gas temperature range 19

4.5.4 Storage temperature range 19

4.6 Range of gases 19

4.6.1 General 19

4.6.2 Test gases 19

4.7 Installation Orientation 20

5 Metrological performance 20

5.1 General 20

5.2 Test Mode comparison 21

5.2.1 General 21

5.2.2 Requirements 21

5.2.3 Test 21

5.2.4 Test Mode in flow (optional) 21

5.3 Permissible errors 22

5.3.1 Requirements 22

5.3.2 Test 22

5.3.3 Air and gas errors 23

5.3.4 Temperature errors 23

5.4 Gas – air relationship 24

5.4.1 General 24

5.4.2 Requirements 24

5.4.3 Test 24

5.5 Pressure absorption 25

5.5.1 Requirements 25

5.5.2 Test procedure ― Pressure absorption 25

5.6 Metrological stability 26

5.6.1 Requirements 26

5.6.2 Test 26

5.7 Immunity to contaminants in gas stream (dust test) 27

5.7.1 Requirements 27

5.7.2 Specification of contamination dust to be used in test 5.7.3 28

5.7.3 Test 28

5.8 Flow disturbances 30

5.8.1 Requirements 30

5.8.2 Test 30

5.9 Zero flow 34

5.9.1 Requirements 34

5.9.2 Test 34

5.10 Reverse flow 35

5.10.1 Requirements 35

5.10.2 Test 35

5.11 Low flow registration 35

5.11.1 Requirements 35

5.11.2 Test 35

5.12 High flow registration 35

5.12.1 Requirement 35

5.12.2 Test 35

5.13 Pulsed (unsteady) flow 35

5.13.1 General 35

5.13.2 Requirements 36

5.13.3 Test 36

5.14 Temperature sensitivity 36

5.14.1 Requirements 36

5.14.2 Test 36

6 Construction and materials 37

6.1 Mechanical Interference 37

6.1.1 Requirements 37

6.1.2 Test 37

6.2 Unauthorized interference 37

6.2.1 Requirements 37

6.2.2 Test 37

6.3 Robustness of meter case 38

6.3.1 Meter case 38

6.3.2 Protection against penetration of dust and water 38

6.3.3 External leak tightness 38

6.3.4 Resistance to internal pressure 38

6.3.5 Heat resistance 39

6.3.6 Resistance to Impact 39

6.3.7 Resistance to mishandling 42

6.4 Connections 42

6.4.1 Orientation 42

6.4.2 Nominal connection diameters for single and two pipe meters 42

6.4.3 Strength 44

6.5 Resistance to vibration 46

6.5.1 Requirement 46

6.5.2 Apparatus 46

6.5.3 Test 47

6.6 Corrosion protection 47

6.6.1 General 47

6.6.2 External corrosion 48

6.6.3 Internal corrosion 49

6.7 Flame retardance of external surfaces 50

6.7.1 Requirements 50

6.7.2 Test 50

6.8 Requirements for rubber components in the gas path 50

6.8.1 Requirements 50

6.8.2 Test 50

6.9 Resistance to storage temperature range 50

6.9.1 Requirement 50

6.9.2 Test 50

6.10 Resistance to the effects of toluene/iso-octane vapour 51

6.10.1 Requirements 51

6.10.2 Test 51

6.11 Resistance to water vapour 53

6.11.1 Requirements 53

6.11.2 Test 53

6.12 Ageing 54

6.12.1 Requirements 54

6.12.2 Test 55

7 Optional features 55

7.1 Pressure measuring point 55

7.1.1 Requirements 55

7.1.2 Test 55

7.2 Electrical insulating feet (optional) 56

7.2.1 Requirements 56

7.2.2 Test 56

7.3 Resistance to high ambient temperature 56

7.3.1 Requirements 56

7.3.2 Test 57

7.3.3 Typical Test Apparatus 57

7.4 Meter fitted with a thermal cut-off valve 58

7.4.1 Requirements 58

7.4.2 Test 58

7.5 Meters with temperature conversion 58

7.6 Additional Functionalities (if fitted) 58

7.6.1 Requirement 58

7.6.2 Test 59

7.7 Use in hazardous zones 59

7.7.1 Requirement 59

7.7.2 Test 59

8 Index 59

8.1 Recording and storage 59

8.1.1 Requirement 59

8.1.2 Test 59

8.2 Display 59

8.2.1 Requirement 59

8.2.2 Test 60

8.3 Display functionality 60

8.3.1 Requirements 60

8.3.2 Test 60

8.4 Non-volatile memory 61

8.4.1 Requirements 61

8.4.2 Test 61

9 Marking 62

9.1 All meters 62

9.2 Two-pipe meters 62

9.2.1 Requirements 62

9.2.2 Test 63

9.3 Durability and legibility of marking 63

9.3.1 Requirement 63

9.3.2 Closed location Test 63

9.3.3 Open location Tests 63

9.4 Indelibility of marking 64

9.4.1 Requirements 64

9.4.2 Test 64

9.5 Accompanying information 64

10 Software 64

10.1 Requirements 64

10.2 Test 65

11 Communications 65

11.1 General 65

11.1.1 Requirements 65

11.1.2 Test 65

11.2 Metrological influence of radio communication function 65

11.2.1 Requirements 65

11.2.2 Test 65

11.3 Test-mode 66

11.3.1 Requirement 66

11.3.2 Test 66

11.4 Data optical port(optional) 66

11.5 Galvanic port (optional) 66

11.6 Diagnostics 66

11.6.1 Requirements 66

11.6.2 Test 67

11.6.3 Display Flags 67

12 Battery 68

12.1 General 68

12.2 Additional Requirements 68

12.2.1 Voltage interruptions 68

12.2.2 Minimal operating voltage 68

12.2.3 Battery life 68

13 Immunity to electromagnetic disturbances 68

13.1 General 68

13.2 Electrostatic discharge 69

13.2.1 Requirements 69

13.2.2 Test 69

13.3 Radio frequency electromagnetic field 69

13.3.1 Requirements 69

13.3.2 Test 69

13.4 Electromagnetic induction (power frequency) 70

13.4.1 Requirements (zero flow) 70

13.4.2 Test 70

13.4.3 Requirements (under flow conditions) 71

13.4.4 Test 71

13.5 Electromagnetic induction (pulsed field) 71

13.5.1 Requirements (zero flow) 71

13.5.2 Test 71

13.5.3 Requirements (under flow conditions) 71

13.5.4 Test 71

13.6 Radio interference suppression 72

13.6.1 Requirements 72

13.6.2 Test 72

14 Ultrasonic (acoustic) noise interference 72

14.1 Requirements 72

14.2 Test 72

14.2.1 Test sequence 72

14.2.2 White noise test 72

14.2.3 Scanning frequency test 73

15 Meters supplied for testing 73

Annex A (informative) Production requirements for meters 76

A.1 General 76

A.2 Technical requirements 76

A.2.1 General 76

A.2.2 Verification of conformity at the temperature of the test laboratory 76

A.2.3 Meters with a built-in gas temperature conversion 77

A.3 Declaration of conformity 77

A.4 Provision of information 78

A.5 Certificates of conformity 78

Annex B (informative) Meters with gas temperature conversion devices 80

B.1 Scope 80

B.2 Metrological performance 80

B.2.1 Errors of indication 80

B.3 Error of indication where the gas and ambient temperatures are not equal 82

B.3.1 Requirements 82

B.3.2 Marking 83

B.3.3 Temperature sensitivity 84

B.3.4 Temperature converted volume 84

Annex C (informative) Test Gases 85

C.1 General 85

C.2 Test gas properties 85

Annex ZA (informative) Relationship between this European Standard and the Essential Requirements of EU Directive 2014/32/EU Measuring Instruments Directive aimed to be covered 87

Bibliography 92

European foreword

This document (prEN 14236:2026) has been prepared by Technical Committee CEN/TC 237 “Gas meters” the secretariat of which is held by BSI.

This document is currently submitted to the CEN Enquiry.

This document will supersede EN 14236:2018.

This document has been prepared under a standardization request addressed to CEN by the European Commission. The Standing Committee of the EFTA States subsequently approves these requests for its Member States.

For the relationship with EU Legislation, see informative Annex ZA, which is an integral part of this document.

prEN 14236:2025 is aligned with EN 17526:2021+A1:2025, the main changes compared to EN 14236: 2018 are the following:

This document specifies requirements and tests for the construction, performance and safety of class 1,0 and class 1,5 battery powered ultrasonic gas meters (hereinafter referred to as meters), having co-axial single pipe, or two pipe connections, used to measure volumes of distributed fuel gases of the 2nd and/or 3rd family gases as given in EN 437:2021, at maximum working pressures not exceeding 0,5 bar ^[1])) and maximum actual flow rates of up to 40 m³/h over a minimum ambient temperature range of −10 °C to +40 °C, and minimum gas temperature span of 40 K. This document applies to meters where the measuring element and the register(s) are enclosed in the same case.

This document applies to meters with and without built-in temperature conversion, that are installed in locations with vibration and shocks of low significance and in

— closed locations (indoor or outdoor with protection as specified by the manufacturer) with condensing or with non-condensing humidity;

or, if specified by the manufacturer;

— open locations (outdoor without any covering) both with condensing humidity or with non-condensing humidity;

and in locations with electromagnetic disturbances likely to be found in residential, commercial and light industrial use.

Unless otherwise stated, all pressures given in this document are gauge pressures.

Clauses 1 to 14 are for design and type testing only.

Requirements for electronic indexes, batteries, valves incorporated in the meter and other additional functionalities are given in EN 16314:2013

Unless otherwise stated in a particular test, the tests are carried out on meters that include additional functionality devices intended by the manufacturer.

When more than one meter type is submitted for testing, then each meter type needs to be tested against this document.

The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.

EN 437:2021, Test gases - Test pressures - Appliance categories

EN 549:2019+A2:2024, Specification for rubber materials for seals and diaphragms for gas appliances and gas equipment

EN 16314:2013, Gas meters - Additional functionalities

EN 55032:2015,^[2] Electromagnetic compatibility of multimedia equipment - Emission Requirements

EN IEC 60079‑0:2018,^[3] Explosive atmospheres - Part 0: Equipment - General requirements (IEC 60079 0:2017)

EN 60079‑7:2015,^[4] Explosive atmospheres - Part 7: Equipment protection by increased safety "e"

EN IEC 60079‑11:2024, Explosive atmospheres - Part 11: Equipment protection by intrinsic safety "i" (IEC 60079-11:2023)

EN IEC 60079‑15:2019,^[5] Explosive atmospheres — Part 15: Equipment protection by type of protection “n” (IEC 60079‑15:2017)

EN 60529:1991,^[6] Degrees of protection provided by enclosures (IP Code) (IEC 60529:1989)

EN 60695‑11-5:2017, Fire hazard testing - Part 11-5: Test flames - Needle-flame test method - Apparatus, confirmatory test arrangement and guidance (IEC 60695-11-5:2016)

EN 60695‑11-10:2013,^[7] Fire hazard testing - Part 11-10: Test flames - 50 W horizontal and vertical flame test methods (IEC 60695-11-10:2013)

EN IEC 60730‑1:2024, Automatic electrical controls for household and similar use - Part 1: General requirements (IEC 60730-1:2022)

EN IEC 61000‑4-2:2025, Electromagnetic compatibility (EMC) - Part 4-2: Testing and measurement techniques - Electrostatic discharge immunity test (IEC 61000-4-2:2025)

EN IEC 61000‑4-3:2020, Electromagnetic compatibility (EMC) — Part 4-3: Testing and measurement techniques — Radiated, radiofrequency, electromagnetic field immunity test (IEC 61000‑4‑3:2020)

EN 61000‑4-8:2010, Electromagnetic compatibility (EMC) - Part 4-8: Testing and measurement techniques - Power frequency magnetic field immunity test (IEC 61000-4-8:2009)

EN 61000‑4-9:2016, Electromagnetic compatibility (EMC) - Part 4-9: Testing and measurement techniques - Impulse magnetic field immunity test (IEC 61000-4-9:2016)

EN IEC 61000‑6-1:2019, Electromagnetic compatibility (EMC) — Part 6-1: Generic standards — Immunity for residential, commercial and light-industrial environments (IEC 61000-6-1:2016)

EN IEC 61000‑6-2:2019, Electromagnetic compatibility (EMC) — Part 6-2: Generic standards — Immunity for industrial environments (IEC 61000‑6‑2:2016)

EN 62056‑21:2002, Electricity metering - Data exchange for meter reading, tariff and load control - Part 21: Direct local data exchange (IEC 62056-21:2002)

EN ISO 1518‑1:2023, Paints and varnishes — Determination of scratch resistance (ISO 1518-1: 2023)

EN ISO 2409:2020, Paints and varnishes - Cross-cut test (ISO 2409:2020)

EN ISO 2812‑1:2017, Paints and varnishes - Determination of resistance to liquids - Part 1: Immersion in liquids other than water (ISO 2812-1:2017)

EN ISO 4628‑2:2016, Paints and varnishes - Evaluation of degradation of coatings - Designation of quantity and size of defects, and of intensity of uniform changes in appearance - Part 2: Assessment of degree of blistering (ISO 4628-2:2016)

EN ISO 4628‑3:2024, Paints and varnishes — Evaluation of degradation of coatings — Designation of quantity and size of defects, and of intensity of uniform changes in appearance — Part 3: Assessment of degree of rusting (ISO 4628‑3:2024)

EN ISO 4892‑3:2024, Plastics - Methods of exposure to laboratory light sources - Part 3: Fluorescent UV lamps (ISO 4892-3:2024)

EN ISO 6270‑1:2018, Paints and varnishes - Determination of resistance to humidity - Part 1: Condensation (single-sided exposure) (ISO 6270-1:2017)

EN ISO 6272‑1:2011, Paints and varnishes - Rapid-deformation (impact resistance) tests - Part 1: Falling-weight test, large-area indenter (ISO 6272-1:2011)

EN ISO 6272‑2:2011, Paints and varnishes - Rapid-deformation (impact resistance) tests - Part 2: Falling-weight test, small-area indenter (ISO 6272-2:2011)

EN ISO 9227:2022, Corrosion tests in artificial atmospheres - Salt spray tests (ISO 9227:2022)

EN ISO/CIE 11664‑4:2019, Colorimetry — Part 4: CIE1976 L*a*b* Colour space (ISO11664-4)

ISO 834‑1:2025, Fire-resistance tests — Elements of building construction — Part 1: General requirements

ASTM D1003-13:2021, Standard Test Method for Haze and Luminous Transmittance of Transparent Plastics

For the purposes of this document, the following terms, definitions, and symbols apply.

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

— IEC Electropedia: available at https://www.electropedia.org/

— ISO Online browsing platform: available at https://www.iso.org/obp/ui/#home

3.1.1

actual flow rate

flow rate at the gas pressure and gas temperature conditions prevailing in the gas distribution line in which the meter is fitted, at the meter inlet

3.1.2

additional functionality

functions over and above that within the meter, which can be integral to the meter, or included within a connected device

3.1.3

air

air of density approximately 1,2 kg/m³

3.1.4

base conditions

fixed conditions to which a volume of gas is converted (e.g. base gas temperature 273,15 K plus 15 K at base gas pressure of 1 013,25 mbar)

3.1.5

contaminants

gas borne dust, vapour and other substances that could affect the operation of the meter

3.1.6

class 1,0 meter

meter which has an error of indication between −2 % and +2 % for flow rates Q, where Q_min ≤ Q < Q_t, and an error of indication between −1 % and +1 % for flow rates Q, where Q_t ≤ Q ≤ Q_max, where Q_max to Q_min > 20 and Q_max to Q_t > 5 and Q_r to Q_max is 1,2

3.1.7

class 1,5 meter

meter which has an error of indication between −2 % and +2 % for flow rates Q, where Q_min ≤ Q < Q_t, and an error of indication between −1 % and +1 % for flow rates Q, where Q_t ≤ Q ≤ Q_max, where Q_max to Q_min > 150 and Q_max to Q_t > 10 and Q_r to Q_max is 1,2

3.1.8

communication port

air of density approximately 1,2 kg/m³

3.1.9

display

device which shows information from the meter (e.g. liquid crystal that displays registers, volume or flags)

3.1.10

distributed gas

locally available gas

3.1.11

error of indication

∈

value which shows the relationship in percentage terms of the difference between the volume indicated by the meter and the volume which has actually flowed through the meter, to the latter volume:

where

3.1.12

distriburbance

influence quantity having a value within the limits specified but outside the specified rated operating conditions of the measuring instrument

3.1.13

durability

ability of an instrument to maintain its performance characteristics over a specified period of use

3.1.14

event

condition requiring action or to log an action

3.1.15

external leak tightness

leak tightness of the gas carrying components of the meter into the atmosphere

3.1.16

flag

single alphabetic character on the index giving a visual signal of significant events and/or change(s) in the operation of the meter

3.1.17

galvanic connection/interface

hard wired serial connection or pulse output from the meter

3.1.18

gas meter

instrument designed to measure, memorize and display the volume of fuel gas that has passed through it

3.1.19

gauge pressure

absolute pressure minus atmospheric pressure

3.1.20

index

current reading of the total volume (mass) passed through the meter

3.1.21

index window

area of transparent material through which the index can be read

3.1.22

maximum error shift

maximum mean error shift at any of the tested flow rates

3.1.23

maximum flow rate

highest flow rate at which the meter provides indications that satisfy the requirements regarding maximum permissible error (MPE)

3.1.24

maximum working pressure

upper limit of the working pressure for which the meter has been designed, as declared by the manufacturer and marked on the index or the casework

3.1.25

mean error

arithmetic mean of consecutive errors of indication at a flow rate

3.1.26

measuring element

part of the meter which produces an electrical signal proportional to the gas flow rate

3.1.27

memory

element which stores digital information

3.1.28

meter case

pressure containing structure of the meter

3.1.29

meter class

class to which a meter belongs, according to the metrological requirements of this document, i.e. class 1,5 or class 1,0

3.1.30

meter cover

rigid enclosure on the front of the meter made either wholly of transparent material, or of opaque material provided with index window(s)

3.1.31

MPE

maximum permissible error for a class

3.1.32

minimum flow rate

lowest flowrate at which the meter provides indications that satisfy the requirements regarding MPE

3.1.33

normal conditions of use

conditions referring to the meter operating:

— at a pressure up to the maximum working pressure (with or without a flow of gas);

— within the range of flow rates;

— within the ambient temperature range;

— within the gas temperature range;

— with the distributed gas

3.1.34

operating mode

method (sample frequency and timing) of obtaining volume flow measurements

3.1.35

working pressure range

limits of working pressure, as declared by the manufacturer, for which the meter will continue to operate within its metrological characteristics

3.1.36

operating temperature range

range of gas and ambient temperatures for which the meter satisfies the metrological requirements of this standard

3.1.37

optical port

serial data port using an infra-red transmitter and receiver

3.1.38

overload flow rate

the highest flow rate at which the meter operates for a short period of time without deteriorating

3.1.39

pressure absorption

difference between the pressure measured at the inlet and outlet connections of the meter whilst the meter is operating

3.1.40

pressure measuring point

permanent fitting on the meter outlet enabling a direct measurement of the outlet pressure to be obtained

3.1.41

range of mean errors

difference between the minimum and maximum mean errors over a specified flow range

3.1.42

reference conditions

conditions of use prescribed for testing the performance of a measuring instrument or for inter comparison of results of results measurements

3.1.43

regression line

straight line, generated using a statistical method, to give a graphical representation of a set of results

3.1.44

register

electronic device comprising both memory and display, which stores and displays information

3.1.45

segment

individual part of a display which is able to show a portion of a character

3.1.46

starting flow rate

lowest flow rate at which the meter is able to indicate a volume of gas passed

3.1.47

storage temperature range

range of temperatures at which the meter can be stored without being adversely affected

3.1.48

temperature conversion device

device which converts the measured volume to a corresponding volume at base gas temperature

3.1.49

test house

organisation used to perform prescribed tests on meters, in accordance with this standard

3.1.50

thermal cut-off valve

heat sensitive valve used to cut off the flow of gas to the meter if the ambient temperature rises above a predetermined level for a specified time

3.1.51

transitional flow rate

flow rate occurring between the maximum and minimum flow rates at which the flow rate range is divided into two zones, the upper zone and the lower zone, each zone having a characteristic MPE

3.1.52

ultrasonic gas meter

meter that uses ultrasound and that is designed to measure, memorize and display the volume of gas that has passed through it

3.1.53

ultrasonic transducer

device used to generate and detect the ultrasound signals within the meter

3.1.54

working pressure

difference between the pressure of the gas at the inlet of the meter and the atmospheric pressure

If no specific requirements are given, the test equipment shall be traceable to a national or international reference standard and the uncertainty shall be equal or better than:

— for type evaluation 1/5 of the maximum permissible error; and

— for verification 1/3 of the maximum permissible error.

Base conditions of temperature (tb) and pressure (pb) shall be specified and marked on the data plate of the meter.

In particular, the following formula applies for the conversion of test volumes to the base conditions of the meter under test:

where

p_a is the absolute inlet pressure of the meter under test, i.e. the sum of two pressure contributes defined as follows:

  p_amb: barometric pressure during test;

  p_gauge: inlet gauge pressure of meter under test;

t_a is the steady temperature of the test volume;

V_a is the volume at actual condition.

The values of maximum flow rates and those corresponding values shall be those given in Table 1.

Table 1 — Flow range

The definitions of the meter classifications applicable in this European Standard are given in Table 2.

Table 2 — Flow rate ranges by meter classification

The maximum working pressure of the meter shall be declared. It shall not exceed 0,5 bar, and this pressure shall be marked on the index or casework of the meter.

Unless otherwise stated, all temperatures given in this document shall be measured to within ± 1 °C.

All meters shall be capable of meeting the requirements for a minimum ambient temperature range of −10 °C to +40 °C, this shall be verified by conforming with the requirements given in Clause 5 and Clause 6.

The manufacturer can declare a wider design temperature range but shall use the minimum and maximum temperature limits as specified in Table 3 and Table 4.

Table 3 — Upper temperature limit

Table 4 — Lower temperature limit

All meters shall be designed for a gas temperature range equal to, or within the ambient temperature range, with a minimum gas temperature span of 40°C. Upper and lower limit of gas temperature shall be chosen in accordance with Table 3 and Table 4. This shall be verified by conforming with the requirements of 5.3.1 and 5.9.

All meters shall be designed for a storage temperature of ≤ −20 °C to ≥ +60 °C and in any case shall have a range equal to or wider than the declared ambient temperature range. This shall be verified by conforming with the requirements of 6.9.

The range of gases for which the meter has been designed, in terms of gas families, for at least one group shall be specified in accordance with EN 437:2021.

Additionally, the meter shall be designed to work on air fulfilling the air-gas relationship requirements specified in 5.4.

The range of gases for which the meter is suitable shall be specified from Table 5.

Table 5 — Gas groups (from EN 437)

Meters suitable for:

— second family gases shall be tested with air and ≥99,5 % CH4;

— third family gases shall be tested with air and ≥99,5 % Propane and/or ≥99,5 % Butane, as appropriate.

By agreement with the Test house any other test gas can be included. The additional gases shall be marked on the meter as defined in 9.1.

NOTE For further information on test gases see Annex B.

Where meters can be installed in orientations other than with the connection ports vertical, meters shall be tested in those other orientations, for durability and as agreed with the Test house.

Where the manufacturer declares that the meter can be used in two directions (forward and reverse flow) then all the tests shall be performed in both directions.

The flow rate shall be determined using sample times that are not readily predictable within discrete time intervals.

These time intervals (τ) shall not exceed 2 s, unless the manufacturer can demonstrate that a proposed longer time interval will not cause the metrological characteristics of the meter to be affected by unsteady flow conditions.

Irrespective of whether the discrete time intervals are longer than 2 s, the requirements specified in 5.13.2 shall still be applied

Provision shall be made for synchronizing the start and finish of test periods (with test equipment), according to the manufacturer’s specification e.g. via a galvanic connection or optical port.

Any failure in synchronising test equipment with the meter under test may introduce an error contribution, calculated as follows in 2.

where

τ is the maximum sampling time of the meter under test in seconds;

t is the test time in seconds.

Where is not specified by manufacturer,  = 2s shall be used in the calculation.

The meter shall have a mode, providing volume resolution of at least 0,1 dm³.

The meter shall have a fast-sampling mode with sampling time not exceeding 0,5 s.

All modes other than the normal mode shall only be available for a maximum of 24h before reverting to normal operating mode, unless explicitly declared by the manufacturer.

The meter, including any additional functionality devices intended by the manufacturer, shall have the error adjusted as close to zero as the adjustments allow, without systematically favouring any party.

After the meter has been subjected to other influences, given in the individual clauses of this standard, the average of the errors of indication of the meter shall either:

— not vary from the average of the initial errors of indication by more than that allowed by those clauses or;

— be within the error limits specified within those clauses.

When the meter has one or more fast sampling modes in addition to the normal operating mode, then provided that the requirements in 5.2.2 are met, all subsequent tests in this European Standard shall be carried out in the test-mode. If the requirement is not satisfied, then all subsequent tests shall be performed in the normal operating mode.

Where specific modes of measurement for managing flow outside the controlled range are present in the normal operating mode, these can be disabled in test mode, unless otherwise specified.

Provision shall be made to ensure that any test gas is properly detected by the meter under test. In particular, where the meter has a gas detection system that occurs at a fixed time interval, the gas detection procedure shall also be performed whenever the test-mode is activated.

The accuracy of the measurements shall not be influenced by different sampling modes.

The difference of the mean errors of the normal operating mode and the test-mode shall not exceed the following limits:

— 0,6% for any flow rate Q_min ≤ Q < Q_t;

— 0,3% for any flow rate between Q_t ≤ Q ≤Q_max.

In both modes, the mean error shall be within the maximum permissible errors as specified in Table 6.

If this requirement is not satisfied, subsequent tests shall be undertaken in the normal operating mode.

Test the meter in the standard mode and in the test-mode in air, in accordance with 5.3.2, Table 6.

Calculate the difference in mean error at each flow rate and ensure requirement in 5.2.2 is met.

General

Where the meter provides instantaneous flow rate readings, these can be used as an alternative to volume for calculating the error of measurement at steady flow profiles, unless otherwise specified in this standard.

Requirements

Select the test mode and carry out the test in accordance with 5.2.4.3 at a given steady test flow rate. The difference of the mean errors of the normal operating mode and the test-mode shall not exceed the following limits:

— 0,6% for any flow rate Q_min ≤ Q < Q_t;

— 0,3% for any flow rate between Q_t ≤ Q ≤ Q_max.

Test

Test the meter in the normal operating mode and in the test-mode in flow in accordance with Table 7, test a).

Calculate the difference in mean error at each flow rate, using either of the following equations, and ensure that error is within the limits specified in 5.2.4.2.

where

is the mean error in volume;

is the mean error in flow;

is the volume read by the meter, at base conditions;

is the volume read by the reference instrument, converted to meter under test base conditions;

is the flow rate read by the meter, at base conditions;

is the flow rate read by the reference instrument, converted to meter under test base conditions. Qc can be either measured directly or inferred by ratio Q_c = V_c / t_x where t_x is the test duration at any given steady test flowrate.

The meter shall be adjusted such that it does not exploit the MPE and is correctly calibrated when the adjustment is as close to zero as possible, by using method a) or b).

It shall be declared which of the following two methods has been adopted:

1) Weighted Mean Error (WME) between ‐0,6 % and 0,6 %; or

2) when the errors between Q_t and Q_max all have the same sign, they do not exceed 1,3 %.

When tested in accordance with 5.3.2, the mean error E_x for both air and test‐gases shall be within the maximum permissible errors specified in Table 6. This shall apply at minimum and maximum declared temperature including any additional test temperature comprised between t_min and t_max.

Table 6 — Maximum permissible errors, class 1,5 and class 1,0

General

Thermally stabilize the meter to be tested to the temperature of the test laboratory.

Pass a volume of air at 20 °C measured by a reference standard, through the meter and note the volume indicated by the meter. The minimum volume of air to be passed through the meter is specified by the manufacturer and agreed with the Test house.

Carry out the tests specified in 5.3.3 and 5.3.4, in air, in any order, then record ‘n’ repeated errors at each of the flow rates and calculate their mean value.

Method a)

If method 5.3.1a) is chosen, calculate the WME using the mean values at different flow rates.

where

is the weighting factor at the flow rate Q_i;

is the mean error in flow rate Q_i.

Method b)

If method b) is chosen (see 5.3.1), determine whether any errors between Q_t and Q_max all have the same sign and the value do not exceed 1,3 %.

Test the meter using air and the test gases specified by the manufacturer in accordance with Table 7, Test a).

Test the meter on air at t_min and t_max in accordance with Table 7, Test b).

Table 7 — Error tests on air and gases

Where meters fulfil the requirements in 5.4.2, all of the following tests shall be carried out on air only.

The difference between the mean errors (i.e. the error of indication of the meter) on the test gases and that on air, at each flow rates, shall be within the limits specified in Table 8.

If the requirements given in Table 8 are not fulfilled, then all subsequent tests shall be carried out using both air and test gases unless otherwise specified. See Figure 1.

Table 8 — Mean error difference between gas and air

Apply the requirements of 5.4.2 to the results from testing the meter in air and gas in accordance with Table 7, Test a).

Key

Figure 1 — Maximum mean error differences between air and gas for class 1,5

The pressure absorption of a meter with a flow of air with a density of 1,2 kg.m⁻³, at a flow rate equal to Q_max, shall not exceed the values given in Table 9.

Table 9 — Pressure Absorption

Supply the meter under test with a flow of air of density 1,2 kg/m³, at a flow rate equal to Q_max and measure the differential pressure across the meter with a suitable measuring instrument, accurate to 0,1 mbar.

The distance between the pressure test points and the meter connections shall not exceed three times the nominal internal connection diameter of the meter connection points for two pipe meters and shall not exceed three times the nominal internal diameter of the minimum typically installed supply pipe to coaxial, single pipe meters.

Alternatively, a measurement method may be used that can subtract the pressure absorption across any adaptors between the test points and the meter.

The difference between any two of the six errors of indication at each flow rate greater than or equal to Q_t shall not exceed the limits given in Table 10.

Table 10 — Difference of error between any two of the errors of indication

Apply the requirements of 0 to the results from testing the meter in accordance with 5.3.3) in air.

Key

Figure 2 — Maximum difference between errors of indication

When meters are tested in accordance with 5.7.3, the errors of these meters shall not exceed the limits specified in Table 11, see Figure 3.

Table 11 — Maximum permissible error after immunity to contaminants test and ageing for Class 1,5 m

Table 12 — Maximum permissible error after immunity to contaminants test and ageing for Class 1 m

Key

Figure 3 — Errors and error shift after dust test

NOTE Figure 3 shows an example of the initial error and shifted error resulting from being subjected to resistance to contaminants test.

After the test in 5.7.3 below, test the meter in accordance with 5.5.2, pressure absorption shall not exceed the values for endurance given in Table 9 pressure absorption.

Four separate batches of dust shall be used with 95 % of the particles in each batch in the appropriate

size range given below:

Each of the above batches shall have a composition by mass of:

Test a minimum of 3 m. Where more than one installation orientation is specified by the manufacturer, test a minimum of 3 m in each orientation.

The test equipment used for this test need not require absolute traceability provided that each meter is calibrated on equipment that does have such traceability prior to commencing the test. An example of a typical test rig is given in Figure 4.

— Dry the dust at 60 °C for 24 hours prior to application of the test.

— Allow the dust to cool down and use it within 8 h in a laboratory with a relative humidity of less than 50%.

The test procedure is a continuous process, with the meter remaining in place, as follows:

1) Test the meter in accordance with Table 7, test d) in air.

2) Attach the meter to a dust rig that has 10 D of vertical pipe before the meter and pass air through the meter for 5 min at Q_max using the appropriate value of D from Table 11;

3) Stop the air supply and add a quantity from Table 13 of 300 𝜇m to 400 𝜇m grade dust to the rig inlet. Start the air supply and maintain a flow of Q_max for a further 5 min. Repeat this procedure with a further quantity from Table 13 of each dust grade in the order 200 to 300 𝜇m, 100 to 200 𝜇m and 5 to 100 𝜇m.

4) Test the meter in accordance 5.3.2. Table 7 test d) in air.

For meters covered by this European Standard, D = 15 mm.

Table 13 — Quantity dust for each dust grade, as function of Q_max

Table 14 — D size as a function of Q_max

Key

1 meter connection

2 dust inlet (screwed plug)

3 air supply (e.g. a fan)

4 fast acting full bore valve

Figure 4 — Example of a typical test rig for the addition of dust

Referring to Figure 4, the apparatus consists of the following components:

a) 10 D of vertical parallel bore pipe, to connect to the meter inlet;

b) a removable screwed plug, for the addition of dust;

c) a ball valve, to release the dust;

d) a length of straight pipe 30 D to 45 D in length, to ensure that all dust is airborne before entering the meter;

e) Copper pipework with soldered or compression fittings is preferred. Steel pipe fittings are not recommended as the dust will adhere to the screw threads.

Other designs of test rig can be used, at the discretion of the Test house.

Check the effectiveness of a test rig design on a regular basis, by connecting the test rig to a test box; ensure that the test box has a similar volume and shape to the meter to be tested and fitted with a filter on the outlet to minimize the dust passing through the outlet. Add 20 g of dust using the procedure mentioned above and confirm that at least 18 g is deposited inside the test box. In the event that this requirement is not fulfilled (e.g. during testing for meters with Q_max - = 2,5m³/h or Q_max = 4m³/h), the length of straight pipe shall be shortened to 10D ± 2D, provided that the dust remains airborne.

When tested in accordance with 5.8.2, the mean errors at all flow rates shall remain within the MPE and the mean error difference at each flow rate shall not exceed the values specified in Table 15. The meter shall recover from the flow disturbance to be within the MPE, specified in Table 6.

Table 15 — Maximum permissible error shift during installation effect and flow disturbance tests

General

Carry out the tests specified in 5.8.2.2, 5.8.2.3 and 5.8.2.4, using air or a representative test gas at atmospheric pressure conditions.

Installation effects

General

The piping configurations illustrated in Figure 5, a) and Figure 5, b) consist of a pipe with nominal diameter D₁ and length of 5 D₁, where D₁ is the diameter of the inlet and outlet connections of the meter, and two elbows with radius equal to 1,5 D₁ not in the same plane.

Test the meter in accordance with Table 7, Test b), using the flow rates specified in 5.8.2 in the following configurations:

a) with a straight pipe of length no less than 10 D1 connected to the meter inlet;

b) with the piping configurations illustrated in Figure 5, a) installed 2 D1 upstream of the meter inlet;

c) with the piping configurations illustrated in Figure 5, b) installed 2 D1 upstream of the meter inlet.

Check the error difference between a) and b), and between a) and c) end ensure is within the value specified in Table 14.

Key

1 direction of flow

Figure 5 — Piping configurations for installation effects test Resistance to harmonic disturbances of the flow (Optional)

Where a manufacturer declares that the meter is suitable for installations that may be subjected to harmonic disturbances then requirement 5.8.2.3 shall be met.

Thermally stabilize the meter to the temperature of the test laboratory.

Connect the meter to the test equipment as shown in Figure 6 with outlet port opened.

Supply a steady flow of air at Q_t and keep it running for the entire duration of the test. The absolute pressure inside the meter during the test shall be within (1 013,25 ± 50) mbar.

Determine the measurement error at Q_t of the meter in this configuration, following the procedure specified in Table 7, Test d).

Generate a pure acoustic tone of given frequency and a peak-to-peak amplitude of (90 ± 0,3) dB and introduce it into the flow.

Detect the measurement error at Q_t, according to 5.3.2.

Repeat the tests at all frequencies below:

— 200 Hz to 500 Hz, at 50 Hz intervals (i.e. 200 Hz, 250 Hz, 300 Hz, etc.);

— 600 Hz to 2000 Hz, at 100 Hz intervals (i.e. 600 Hz, 700 Hz, 800 Hz, etc.).

Test apparatus

Steel or copper piping is preferred.

Plastics such as PVC can also be used, provided that they have a grade of stiffness such to avoid dampening of acoustic vibrations (a minimum wall thickness of 4 mm is recommended).

The internal diameter d is function of the maximum flow rate, as indicated in Table 16.

Care shall be taken in protecting the reference instrument from disturbances, for example placing it in a suitable position along the apparatus.

Table 16 — d size as function of Q_max

Microphone

The amplitude of the acoustic tone, corresponding to sound pressure level, shall be determined at Q_t. The microphone shall be positioned at a distance L of 1 m from the meter inlet, as shown in Figure 6.

The microphone shall be inserted in a suitable pipe hole, ensuring a leak tight connection.

Key

1 air supply (steady flow)

2 box containing acoustic tone generator

3 microphone

4 straight pipe

5 connection to inlet port of meter under test

6 meter under test

Figure 6 — Test apparatus for resistance to harmonic disturbances

Registration of volumes due to flow oscillations (Optional)

General

Where a manufacturer declares that the meter is suitable for installations that may be subjected to flow oscillations then requirement 5.8.2.4 shall be met.

The following test specify the performance of the meter in presence of gas flow due to pressure oscillations in the network.

NOTE This phenomenon can be referred to as backflows in network.

An example of a suitable test rig is shown in Figure 7.

Requirements

When tested in accordance with 5.8.2.4.3.1, the index shall neither decrement nor increment.

When tested in accordance with 5.8.2.4.3.2, the meter shall register the passage of gas, and the error shall be between −50 % absolute error and not exceeding 3 times the MPE, as given in Table 5 for Q_min ≤ Q < Q_t.

All the tests shall be performed on two meters; both shall comply with the requirements given in 5.3.1.

These two meters shall be tested in their normal operating mode in each of the orientations specified by the manufacturer installation instructions.

Tests

Flow oscillation with average value equal to zero

An example of suitable test apparatus is given in Figure 7.

Carry out the error of indication test specified in Table 7, Test d), to ensure that the accuracy of the meters under test is within the maximum permissible initial error limits given in Table 6.

Subject the meter to an equal number of complete peak-to-peak flow oscillations, as specified in Table 17,

by operating the actuator item 3, and by adjusting the valve item 10 in Figure 7 to achieve average flow specified in Table 18, with on/off timings of 1 s ‘on’ and 1 s ‘off’, for a duration of not less than 20 min.

Record the final index reading and confirm pass or fail.

Table 17 — Peak flow oscillations

Flow oscillation with positive average value

An example of suitable test apparatus is given in Figure 7.

Carry out the error of indication test specified in 5.3.2, Table 7, Test d), to ensure that the accuracy of the meters under test is within the maximum permissible initial error limits given in Table 5.

Subject the meter to an equal number of complete peak-to-peak flow oscillations, as specified in Table 17, by operating the actuator item 3, and by adjusting the valve item 10 in Figure 7 to achieve average flow specified in Table 18, with on/off timings of 1 s ‘on’ and 1 s ‘off’, for a duration of not less than 20 min.

Record the final index reading and confirm the meter has registered the passage of gas with error between – 50 % absolute error and 3 times the MPE, as given in Table 6for Qmin ≤ Q < Q_t.

Table 18 — Peak flow oscillations

Key

1 pressure regulator (Q_max = 25 m3/h, inlet pressure Pin = 0,5-5 bar, outlet pressure Pout = 25 mbar)

2 spherical valves

3 fast acting actuator for pressure and flow cycling

4 valves for peak flow setting

5 dumper

6 pressure transducer with monitoring and recording instruments

7 reference meter (bidirectional)

8 meter under test

9 dead volume

10 valve for mean positive flow setting

11 reference meter

Figure 7 — Example of test apparatus for registration of volumes due to pressure oscillations test

When tested in accordance with 5.9.2, neither the meter display nor the internal register shall change in value (increment or decrement).

This test is carried out at −10 °C, +20 °C and +40 °C. If the manufacturer has declared a wider ambient and gas temperature range, then the extreme temperatures declared are substituted for −10 °C and +40 °C above as appropriate.

Fill the meter with dry pure methane at atmospheric pressure and seal the inlet and outlet ports of the meter with gas tight fittings

Seal the inlet and outlet ports of the meter with gas tight fittings. Allow the meter to stabilize at each test temperature and then store for a minimum of 12 h at each test temperature.

Record the index reading and the internal register of the meter after each 12 h period.

If the meter has been designed to only be used in one direction, then when tested in accordance with 5.10.2 the register shall neither increase nor decrease. Where an additional reverse flow register is fitted, this shall indicate the passage of the test volume during the test described in 5.10.2.

A test volume of 0,2 Q_max is passed through the meter in the reverse direction at a nominal flow rate of Q_max. The index reading is recorded before and after the test.

The starting flow rate shall not be greater than 0,25 Q_min.

Using the manufacturers declared Q_start value, Test the meter as specified in 5.3.2 Table 7 d) but at 1,2 Q_start only, with a test volume of 0.01m³ and confirm that flow is registered.

When tested in accordance with 5.12.2 the meter error shall remain within the maximum permissible error stated in Table 6.

The meter shall continue to register the passage of gas.

Consumption during this time outside the 1,2 Q_max ‘may’ be recorded in a separate register.

Supply the meter with air for 20 min at a high flow rate of 1,2 Q_max and confirm that the meter continues to register the passage of gas.

Test the meter in air at a flow rate of Q_max and confirm that the meter error remains within the MPE specified in Table 6.

The normal operating mode of the meter shall have a sample period (T) that does not exceed 2 s, randomized to ± 2 s, unless the manufacturer can demonstrate that a proposed longer sampling rate will not cause the metrological characteristics of the meter to be significantly impaired by pulsed or unsteady flow. Where the mean sample period is longer than 2 s, the tests of 5.13.3 shall still be applied.

The difference between the cumulative volume at the ends of test runs 2 and 5, (see Table 18), and the cumulative volume at runs 1 and 4 respectively, shall not exceed two thirds of the total MPE range specified in Table 6.

The difference between the cumulative volume at the ends of test runs 3and 6, (see Table 18), and the cumulative volume at runs 1 and 4 respectively shall not exceed one third of the total MPE range specified in Table 6.

For 1.05T and 2.3T; The difference between the cumulative volume at the ends of test runs, (see Table 18), and the cumulative volume respectively, shall not exceed two thirds of the total MPE range specified in Table 4.

Test 5.13.3 shall be performed with the meter in its normal operating mode.

Subject the meter to flow conditions specified in Table 19 with either continuous or square wave airflow at the on/off timings and flow rates, for a duration of 3600 x T for runs 1 and 4, and a duration of 7200 x T for runs 2,5, 3 and 6, where T is the time interval specified in 5.1, calculating MPE errors recording the start and end index volumes of each test.

Table 19 — Unsteady flow runs

When tested in accordance with 5.14.2 the meter shall meet the following requirements:

— that all results shall be within the errors shown in Table 6;

— that no error of indication shall differ from its regression line by more than 1 % for class 1,5 and 2/3 % for class 1,0.

Install the meter on an appropriate test rig, see Figure B.1, and stabilize the meter at the starting temperature of the test for a period of 3 h prior to commencing the change of temperature at the rate specified below.

Test the meter in accordance with Table 7test e) using test gas as specified in 4.6.2, according to meter type. Repeat this test at a frequency of three or four tests per hour while changing the ambient temperature from –10 °C to +40 °C at a rate of 2 °C/h with the relative humidity not exceeding 50 %.

Calculate the regression lines of the errors of indication over temperature.

The meter shall be constructed in such a way that any mechanical interference capable of affecting the measuring accuracy results in permanently visible damage to the meter or the verification or protection marks.

The meter connections shall be fitted with suitable non-sealing caps or covers to protect any threads and to prevent the entry of foreign matter during transit and storage.

The meter shall have a meter case that can be sealed in such a way that the internal parts of the meter are accessible only after breaking the metrological seal(s) or causing clear evidence of interference.

A sealing drawing shall be provided and include the metrological sealing as well as all other tamper evident seals.

Visually examine the meter to ensure that access cannot be gained without causing permanent visible damage or protection marks, and the meter connections are covered with non-sealing caps.

Any means of adjusting the performance characteristics of the meter shall be effectively secured and protected against unauthorized interference.

Electronic seals shall comply with the following requirements:

— access shall only be obtained by using a password or a code that can be updated, or by using a specific device;

— the last intervention, at least, shall be registered in the memory, including date and time of intervention and a specific element to identify the intervention;

— it shall be possible to have access to the intervention(s) registered in the memory for a minimum period of two years.

The manufacture shall declare how the above clauses are satisfied and provide the notified with appropriate means to demonstrate this.

Review the manufacturers declaration and ensure the clauses in 6.1.2 are satisfied.

— a) i - enter the correct password and ensure access is gained;

— ii - enter an incorrect password and ensure access is denied;

— b) i – gain access to the memory;

— ii – enter an incorrect password and ensure the date and time and the type of interference is recorded;

— iii – enter a correct password and ensure the date and time of the access is recorded;

— c) confirm that the declaration from the manufacturer has been provided to retain the interference

— data, including any change of parameters, for two years.

The external surface of the meter case in direct contact with the ambient air on the outside and with the gas on the inside shall be deemed of sufficient thickness to when the following clauses are met of 6.3, 6.4, 6.6, 6.9, 6.11, 6.12.

Requirements

The meter shall be designed in such a way that it gives protection against the ingress of dust and water so that it conforms, as a minimum, to the IP 54 degree of protection, in accordance with EN 60529:1991.

Test

Test the meter (including the battery compartment) in accordance with EN 60529:1991.

Requirements

The meter shall be leak tight under normal conditions of use. When tested in accordance with 6.3.3.2, no leakage should be observed.

Test

Pressurize the meter, at normal laboratory temperature, with air to 1,5 times the declared maximum working pressure and check for leaks.

Carry out the test by:

a) immersing the meter in water and observing for leakage for 30 s after any external trapped air has been dispersed; or

b) any equivalent procedure.

Requirements

Resistance to internal pressure tests shall be carried out with no interruptions to the gas flow including, but not limited to, valves in the open position.

When tested in accordance with the method given in 6.3.4.2, any residual deformation of the unpressurized meter case shall not exceed 0,75 % of the linear dimension over which it is measured. After the test, the meter case shall remain leak tight in accordance with 6.3.3.

Test

Pressurize the meter under test, at normal laboratory temperature, with air or water to a minimum of 1,5 times the declared maximum working pressure and not less than 350 mbar.

Maintain the test pressure for 30 min and then release.

Ensure that the rate of pressurization or depressurization does not exceed 350 mbar.s-1.

Record the result as pass or fail.

Requirement

Following the test specified in 6.6.2, the meter shall satisfy the requirements of 6.3.3.1.

Test

Suspend the meter in an ambient temperature of (120 ± 2) °C for 15 min. For safety reasons, any battery, HLC and Supercap (or comparable component) as advised by the manufacturer fitted to the meter shall be removed during the heating period.

Allow the meter to cool to ambient temperature.

Carry out a leak test as specified in 6.3.3.2.

Record the result as pass or fail.

Requirement

When tested in accordance with 6.3.6.3 the meter shall remain leak tight.

Apparatus

The test apparatus consists of a hardened steel hemispherical tipped striker and a rigid smooth-bore tube in which the striker is capable of sliding freely (see 6.3. Figure 8).

The total mass of the striker is 3 kg. There are two sizes of striker tip, one having a radius of 1 mm, the other having a radius of 4 mm (see Figure 9).

Key

1 smooth bore rigid tube

2 hardened hemispherically tipped striker of mass 3 kg

3 radial clearance (0,5 ± 0,25)

4 vent hole

5 meter level

h height in mm above the test area

Figure 8 — Impact test apparatus

Key

1 striker, total mass 3 kg

2 steel tip, angle 30° ± 2°

3 hardened steel ball; R1 = 1 mm radius, R4 = 4 mm radius

Figure 9 — Typical hemispherically tipped strikers used in impact test

Test

Use the apparatus in 6.3.6.2 and carry out the following test.

Use both sizes of striker tip during the test, but do not subject any test area on any one meter sample to more than one impact for each size of striker. In the case of the same area being selected for test with each size of striker tip, use two meter samples.

For each strike, rigidly support the meter on a firm base with the intended area of impact, which can be any area of the meter case, horizontal. Place the end of the guide tube on the chosen impact area of the meter. Allow the striker to fall freely and vertically through the tube onto the test area. The striker tip falls from a height of h mm above the test area, where:

a) for the 1 mm striker, h is 100 mm thus producing an impact energy of 3 J; and

b) for the 4 mm striker, h is 175 mm thus producing an impact energy of 5 J.

NOTE The impact energy, E, (joules) is given by the equation:

E = m · g · h

where

m     is the mass, in kilograms (kg);

g      is the acceleration due to gravity, in metres per square second (m · s-2);

h      is the height of fall, in metres (m).

Test the meter again in accordance with 6.3.3.2 and report the result as passed or fail.

Requirement

When tested in accordance with 6.3.7.2, the meter shall remain leak tight in accordance with 5.3.2 Table 7 b) and the mean errors shall remain within MPE specified in Table 6.

Test

Test the meter in accordance with 6.3.3.2 and confirm leak tightness.

Test the meter in accordance with 5.3.2 Table 7 test b) in air and confirm it is within MPE.

Hold the meter, with no packaging, in the upright position (in its horizontal plane), and drop vertically, from rest, on to a flat, hard, horizontal surface from a height determined in Table 20. This height refers to the distance from the base of the meter to the surface onto which it will fall.

Retest the meter in accordance with 6.3.3.2 and confirm leak tightness

Retest the meter in air in accordance with Table 7 test b) and confirm it is within MPE.

Table 20 — Drop Height

Requirements

The connections of meters having top mounted two pipe connections shall have the centrelines of these connections within 2° of the vertical, with respect to the horizontal plane of the meter.

The distance between the centrelines of the connections, measured at the free end of the connections, shall be within ± 0,5 mm of the nominal distance between the centrelines, or within ± 0,25 % of the nominal distance between centrelines, whichever is the greater, and the centrelines shall be within 2° of being parallel.

The free ends of the connections shall be level within 2 mm, or within 1 % of the nominal distance between the centrelines of the connections, whichever is the greater, with respect to the horizontal plane of the meter.

Test

Take the measurements and report the result as a pass or fail.

Requirements

The nominal connection diameters shall be as specified by the meter manufacturer.

The connections of meters having a co-axial single pipe connection shall be in accordance with Figure 10 or Figure 11 as appropriate.

Test

Take the measurements.

Dimensions in millimetres

Key

1 sealing hole

AF across flats

Figure 10 — Co-axial single pipe screw connections

Figure 11 — Co-axial single pipe flanged connections

Torque

Requirements

The meter connection shall be subjected to the appropriate torque specified in Table 21, in accordance with 6.4.3.1.2 and shall then comply with the following:

— external leak tightness to 6.3.3.2; and

— any residual rotational deformation of the meter connection shall not exceed 2°.

Test

Firmly support the case of the meter and apply the appropriate torque value to each connection in turn using a torque wrench.

Table 21 — Torque and bending moment

Bending moment

Requirements

When tested in accordance with 6.4.3.2.2, the meter shall remain leak tight after this test in accordance with 6.3.3.

The mean errors of the meter shall remain within the MPE specified in Table 6, before and after being subjected to the test described in 6.3.3.2.

After the test, the residual deformation of the connections shall not exceed 5°.

Test

Test the meter in air in accordance with Table 7 test b) in air.

Rigidly support the meter by one of its connections and subject it to the appropriate bending moment, see Table 8, for a period of 2 min. Different meters are used for the lateral test(s) and the fore and aft test (see Figure 12).

In the case of the meter being of two pipe construction, repeat the lateral bending moment test on the other meter connection, but for the fore and aft test support the meter by both connections.

Test the meter in accordance with Table 7 b) in air.

Key

M bending moment

Figure 12 — Arrangement for bending moment test

When tested in accordance with 6.5.3, the meter shall remain leak tight and the metrological performance shall remain within the MPE specified in Table 6 in air.

The apparatus described in Figure 13 shall be used to undertake the test

Key

1 electrodynamic shaker, driven by an amplified sine wave from a voltage generator

NOTE The head of the shaker can be rotated through 90° for fore and aft and planes (see 3a) and 3b))

2 meter under test (vertical plane), mounted to spindle of electrodynamic shaker (1)

3 accelerometer (piezoelectric transducer)

4 charge amplifier, used to condition the output from the accelerometer (piezoelectric transducer) (2)

5 automatic vibration exciter control, capable of being used in a sweeping mode in which the frequency is cycled between a pair of selected frequencies, alternately increasing and decreasing

6 power amplifier, suitable for amplifying the power of the accelerometer

Figure 13 — Layout of vibration test apparatus

Carry out the error of indication test specified in 5.3.2, Table 7, Test b), to ensure that the accuracy of the meter under test is within the maximum permissible initial error limits given in Table 6 and confirm that the meter under test is leak tight, by carrying out the test described in 6.3.3.2.

Secure the meter under test to the vibration test rig without causing damage or distortion to the meter case, as shown in Figure 13, using a horizontal clamp across the top of the meter.

Subject the meter under test to a swept frequency between 10 Hz and 150 Hz (±5 %) at a sweep rate of 1 octave per minute with a peak acceleration of 2 g (±5 %), for 20 sweeps in the vertical plane, 20 sweeps in the fore-aft plane and 20 sweeps in the lateral plane. The displacement amplitude shall be limited to 0,35 mm.

Recheck the error of indication of the meter under test, by carrying out the test specified in Table 7, Test c), and confirm the leak tightness by carrying out the test described in 6.3.3.2.

NOTE An octave is a band of frequency where the upper frequency limit of the band is exactly twice the lower limit, e.g. 10 Hz to 20 Hz, 20 Hz to 40 Hz, 40 Hz to 80 Hz and 80 Hz to 160 Hz. Therefore, the time taken to sweep from 10 Hz to 100 Hz at a sweep rate of 1 octave per minute is 3 min 15 s.

Report the result as pass or fail.

Meters to which only decorative coatings (i.e. coatings not intended to contribute to corrosion protection) are to be applied shall be tested before application of the coating. Such decorative coatings shall not adversely affect the corrosion resistance of the meter.

All parts of meters shall be able to resist any corrosive substances contained in the internal and external atmospheres that they can expect to be exposed to during normal conditions of storage and use.

All tests shall be performed on the gas-containing components themselves or on sample plaques.

Sample plaques shall only be used in place of a component if no forming operations are carried out on the component after the protective finish is applied.

Sample plaques, if used, shall be 100 mm x 100 mm, their thickness being that of the component they are replacing.

The finishes on items supplied for test shall have been fully dried and cured.

Attack on the edges or up to 2 mm from the edge of sample plaques shall be ignored if the component it replaces has no exposed edges when installed in the finished meter.

Scratch resistance of the protective coating

Requirements

When tested in accordance with 6.6.2.1.2, there shall not be evidence of penetration of the protective coating.

Test

When tested using the method given in EN ISO 1518‑1:2023 using a loading of 19,6 N, corrodible base material shall not be exposed.

Where a metallic protective coating is applied directly onto a metal surface, the indicator lamp will light without any penetration of the surface. In this case the surface shall be visually inspected for penetration.

Adhesion of the protective coating

Requirements

When tested using the method given in ISO 2409:2020, the result shall be less than classification 2 given in ISO 2409:2020.

Test

When tested using the method given in ISO 6272‑2 for impact resistance using a falling height of 0,5 m and with the depth of the indentation limited to 2,5 mm, there shall be no cracking or loss of adhesion of the protective coating.

During the test, place the surface of the test piece which would normally be the outside surface of the meter, so that it faces upwards

Impact resistance of the protective coating

Requirements

When tested in accordance with 6.6.2.3.2, there shall be no cracking or loss of adhesion of the protective coating, any indentation shall not exceed 2,5mm in depth.

Test

Place the surface of the test piece which would normally be the outside surface of the meter so that it faces upwards, then test in accordance with the method given in EN ISO 6272‑1:2011 using a drop height of 0,5 m.

Chemical resistance of the protective coating

Requirements

When tested in accordance with 6.6.2.4.2, the result shall be less than that given as ratio density 2/size 2 given in ISO 4628‑2:2016, and the degree of corrosion of the base material shall not be greater than that given as Ri 1 in Table 1 of EN ISO 4628‑3:2024.

Test

Using the liquids specified in EN ISO 2812‑1:2017, A.2.2 and A.3.1, as well as 5 % aqueous solution of sodium salts of sulphated broadcut primary alcohol, chain length C9 to C13 pH values 6,5 to 8,5; test in accordance with EN ISO 2812‑1:2017, 9.3, Method A, using a test period of 168 h.

Resistance to salt spray

Requirements

When tested in accordance with 6.6.2.5.2, the degree of corrosion shall not be greater than that given as Ri 1 in Table 1 of EN ISO 4628‑3:2024.

Test

The sample used for this test shall be a complete meter for sizes of meter having a Q_max of up to and including 10 m³.h-1 and a representative part of the meter, which include at least one connection, for meters above this size.

When tested in accordance with EN ISO 9227:2022, using a salt solution with the pH-Value given in 5.2.2 of EN ISO 9227:2022 (neutral salt spray test), the sample shall be exposed to the salt spray over 500 h and the degree of corrosion of the base material shall not be greater than that given as Ri 1 in Table 1 of EN ISO 4628‑3:2024.

Resistance to humidity

Requirements

When tested in accordance with 6.6.2.6.2, any blistering of the coating shall be less than that given as the ratio density 2/size 2 in EN ISO 4628‑2:2016, and the degree of corrosion of the base material shall be not greater than that given as Ri 1 in Table 1 of EN ISO 4628‑3:2024.

Test

Use a complete meter for sizes of meter having a Q_max not exceeding 10 m³/h; for meter above this size use representative parts of the meter, e.g. deep-drawn parts, including at least one connection.

Test in accordance with EN ISO 6270‑1:2018 using a test duration of 500 h.

Report the result as pass or fail.

Adhesion of the protective coating

Requirements

When tested in accordance 6.6.3.1.2 using the method given in ISO 2409:2020, the result shall be less than classification 2 given in ISO 2409:2020.

Test

Test in accordance with the test method given in EN ISO 2409:2020.

Impact resistance of the protective coating

Requirements

When tested in accordance with 6.6.2.3, there shall be no cracking or loss of adhesion of the protective coating at the side, which is normally the inner side.

Test

Test as per 6.6.2.3.

Chemical resistance of the protective coating

Requirements

When tested in accordance with 6.4.2.4, the blistering of the protective coating shall be less than that given as the ratio density 2/size 2 in EN ISO 4628‑2:2016 and the degree of corrosion of the base material shall not be greater than that given as Ri 1 in Table 1 of EN ISO 4628‑3:2024.

Test

Test as per 6.6.2.4.

Resistance to humidity

Requirements

When tested in accordance with 6.6.2.6 any blistering of the coating shall be less than that given as the ratio density 2/size 2 in EN ISO 4628‑2:2016 and the degree of corrosion of the base material shall not be greater than that given as Ri 1 in Table 1 of EN ISO 4628‑3:2024.

Test

Test as per 6.6.2.6.

All external surfaces of the meter (including the index window) and gas containing casework material shall not support combustion. The material shall have a flammability rating of V-0 in accordance with EN 60695-11-10:2013

Subject the external surfaces of the meter to the flame test as specified in EN 60695‑11‑5:2017. Apply the flame to the edges, corners, and surfaces of the casing, each for a period of 30 s.

All the rubber/elastomeric sealing components required for gas tightness shall be deemed acceptable if they conform to EN 549:2019+A2:2024 or the requirements of 6.10.1.

Confirm all the rubber/elastomeric sealing components required for gas tightness conform to EN 549:2019 +A2:2024.

Report the result as pass or fail.

When tested in accordance with 6.9.2, the mean errors shall stay within the MPE specified in Table 6.

Test the meter in accordance with Table 7 test b).

Maintain the meter, with no gas flowing through it, under the following conditions:

— 3 h at a temperature of –20 °C, or lower if declared by the manufacturer;

— 3 h at a temperature of +60 °C, or higher if declared by the manufacturer.

At the end of each period, return the meter to normal laboratory ambient temperature and test in accordance with Table 7 test b).

Report the result as pass or fail.

When tested in accordance with 6.10.2, the mean errors after any stage of the test shall remain within the MPE specified in Table 6.

General

Test the meter in accordance with Table 7 test b).

Pass nitrogen, to which has been added approximately 3 % by gaseous volume of 30 % toluene/70 % iso-octane mixture (see 6.11.2.2) through the meter, for a period of 42 days (1 008 h) at (20 ± 2) °C, (65 ± 10) % relative humidity and a flow rate of not less than 0,25 Q_max.

Exercise the meter with air for a further period of 7 days (168 h) at (20 ± 2) °C, (65 ± 10) % relative humidity and a flow rate of not less than 0,25 Q_max.

Test the meter in accordance with Table 7 test b).

Example of a typical apparatus

Referring to Figure 14, the apparatus consists of the following components:

a) a meter exercise rig (A), open to atmosphere, fitted with a suitable circulating pump or blower;

b) a nitrogen supply with a flow rate measurement capability (B) (rotameter, meter or both);

c) relative humidity control (C), comprising a water reservoir and valves capable of giving a relative humidity of (65 ± 10) %. The relative humidity is measured by a hair or paper hygrometer or by a moisture meter;

d) solvent addition (D). The toluene/iso-octane mixture is added to the top of the vaporization tower by means of a micro-metering pump. The tower has a bottom diffuser plate and is filled with alternative layers of small glass beads and cotton fabric (or other similar material) to give a large surface area. The tower is surrounded with a heating blanket that produces a high temperature at the blanket/tower interface to speed up vaporization.

Procedure

Allow the toluene/iso-octane mixture (see 6.11.2.4) to percolate down the tower and vaporize. Introduce the carrier gas, at a controlled flow rate, through the diffuser at the bottom of the tower where it picks up the vaporized solvent. Pass the gaseous mixture into the exercise rig where it is circulated through the meter. A fresh supply of solvent is continuously added to give a stable concentration.

Preparation of 3 % by volume of a 30 % toluene/70 % iso-octane mixture with nitrogen

It is estimated that under conditions of normal temperature and pressure 1 mol of an ideal gas would occupy 22,4 dm³. Whilst the vapours of toluene and iso-octane cannot be considered ideal, this principle has been used to calculate the (approximate) concentration of 3 % by volume of a 30 % toluene/70 % iso-octane mixture in nitrogen.

Calculation

Toluene has a molecular mass of 92,13 and a density of 866,94 kg/m³.

Iso-octane has a molecular mass of 114,23 and a density of 691,8 kg/m³.

92,13 g = 106 ml toluene will occupy 22,4 dm³ at normal temperature and pressure (NTP).

114,23 g = 165 ml iso-octane will occupy 22,4 dm³ at normal temperature and pressure (NTP).

A 3 % dosage of 30/70 toluene/iso-octane mixture will therefore require:

0,9 % toluene = 95,4 ml toluene and 2,1 % iso-octane = 346,5 ml iso-octane (per 2 240 l of carrier gas).

The total volume of solvent mixture to be added to 2 240 l of carrier gas to give a 3 % concentration by volume of 30 % toluene/70 % iso-octane is 441,9 ml. This is equivalent to 197 kg per m³of carrier gas.

NOTE The actual amount of solvent to be added to the system will be dependent on the carrier gas flow rate and the conditions inside the tower.

Key

Figure 14 — Typical apparatus for toluene/iso-octane test

When tested in accordance with 6.11.2, the mean errors shall remain within the MPE specified in Table 6.

Test the meter in accordance with Table 7, Test b) in air.

Connect the meter to the water vapour test rig (see Figure 15).

Exercise the meter with air having a relative humidity of less than 20 % for 7 days (168 h) at (20 ± 2) °C and a flow rate of not less than 0,25 Qmax; at the end of this period, test the meter in accordance with Table 7, Test b).

On completion of this low humidity performance test, exercise the meter with air having a relative humidity of (85 ± 5) % for a complete period of 42 days (1 008 h) at (20 ± 2) °C and a flow rate of not less than 0,25 Q_max.

Then exercise the meter with air having a relative humidity of less than 20 % for at least 7 days (168 h) at (20 ± 2) °C and at a flow rate of not less than 0,25 Q_max. Then test the meter in accordance with Table 7, Test b).

Key

1 saturated solution for humidity control

2 moisture meter

3 meter on exercise

4 circulating blower

Figure 15 — Example of a water vapour test apparatus

When tested in accordance with 6.12.2, the following requirements shall be met:

a) the mean errors remain within the maximum permissible error limits specified in Table 11;

b) the index remains legible;

c) there is no damage or variation to the index reading;

d) the meter remains leak tight as specified in 6.3.3;

e) there is no corrosion of the electronic circuits, such that the meter functionality is impaired.

Test the meter in accordance with Table 7 test b) in air.

Use a complete meter having its ports sealed, to protect the internal parts and hold it at any one of the temperatures given in Table 9, for the appropriate time period given in Table 9. The manufacturer declares the temperature at which the test is to be carried out.

Table 22 — Temperature times/ageing periods

At the end of this period, the meter is slowly returned to a temperature of 20 °C ± 2 °C, at a rate of not more than 2 °C/h, and again tested in accordance with Table 7 test b) in air.

If a pressure measuring point is provided on the meter:

a) the maximum diameter of the hole through the pressure measuring point shall be 1 mm;

b) the meter shall remain leak tight after carrying out tests specified in 7.1.2b).

a) Measure the diameter of the hole through the pressure measuring point.

b) Initially check the meter for leak tightness in accordance with 6.3.3.2.

Apply a torque of 8 N ⋅ m to the pressure measuring point in a clockwise and then anti-clockwise direction and then release. Drop a mass of 0,5 kg from a height of 250 mm, through a vertical tube, onto the outer extremity of the body of the pressure measuring point (see Figure 16).

Recheck the meter for leak tightness in accordance with 6.3.3.2.

Report the result as pass or fail.

Key

1 0,5 kg steel mass

2 drop height (250 mm)

3 pressure measuring point

4 meter port

5 diameter of the vertical tube (max 40 mm)

Figure 16 — Example of a pressure measuring point test apparatus

If insulating feet are provided on the meter, there shall be a minimum of 4 and they shall give a minimum

clearance of 5 mm at the base of the meter.

After carrying out the test specified in 7.2.2, the electrical resistance measured shall not be less than 100 kΩ.

When tested at 650 V AC as specified in 7.2.2, there shall be no breakdown of the insulation.

Place the meter under test on a flat metal plate and apply a potential of 500 V DC between the metal plate and each meter connection in turn for 60 s. Measure the electrical resistance between the metal plate and each connection successively. Then apply a potential of 650 V AC between the metal plate and each meter connection, successively, for 60 s. Report the result as pass or fail.

Where the manufacturer declares that the meter is resistant to high ambient temperatures, the meter shall conform to the following requirements:

a) the leakage rate of the meter case, when tested in accordance with 7.3.2, shall not exceed 150 dm³/h;

b) the meter shall be marked in accordance with 9.1.

Connect the meter to the inlet and outlet connections and install the whole meter in the centre of the furnace using supports if necessary.

If it is necessary to take into account the mass of the metering apparatus, place a metal weight equivalent to the mass of the metering apparatus on the meter case.

With the bleed valve closed, pressurize the meter to 100 mbar with nitrogen and verify its tightness.

Perform the test at 100 mbar, irrespective of the pmax of the meter.

With the meter under the nitrogen test pressure, increase the temperature of the furnace according to the temperature rise curve of ISO 834‑1:2025.

When the temperature at the coldest point of the meter reaches 650 °C, control the furnace temperature to maintain at that point a constant temperature of 650 °C for a period of 30 min.

During the complete test, maintain the pressure in the meter at the test pressure by means of the bleed valve. The leakage rate is registered by successive metering, the metering periods not exceeding 5 min.

The leakage is the quotient of the metered nitrogen volume by the measuring time.

NOTE Air can be used in place of nitrogen in this test but be aware that it can support the combustion of volatile emissions.

To avoid blocking of the outlet connections by condensation of materials distilled from the internal components of the meter, it is preferable to carry out the test on an empty meter case without any batteries, supplied as such by the manufacturer. If this is not possible, the outlet pipe of the apparatus should be inclined downwards and a safety tap for the removal of condensation products installed upstream of the bleed valve.

The furnace (see Figure 17) shall allow an ambient temperature rise according to the curve defined in ISO 834‑1:2025.

The dimensions of the furnace shall allow the installation of the meter and its connections to be in identical positions to those used in practice.

Make arrangements to maintain a constant pressure equal to 100 mbar during the complete test.

Key

Figure 17 — Example of a high ambient temperature test apparatus

The thermal cut-off valve shall not close when tested in accordance with 7.4.2.

Maintain the cut-off valve at (70 ± 1) °C for 7 days and confirm that the thermal shut off valve has not closed.

Report the result as pass or fail.

For requirements and tests, see Annex B.

If ancillary devices are fitted, for example prepayment or remote reading devices, they shall not affect the metrological characteristics of the meter, nor obscure the markings specified in 9.1.

When tested in accordance with 7.6.2, the mean errors at all flow rates shall remain within the MPE and the mean error difference at each flow rate shall not exceed one third of the MPE specified in Table 6.

Test without the ancillary device in air in accordance with Table 7 test b).

Repeat with the ancillary device fitted, the meter shall be tested in air in accordance with Table 7 test b).

Confirm by visual inspection that the markings are not obscured.

Ancillary devices approved by the meter manufacturer shall not compromise the battery life specified in Clause 12.

Where the manufacturer declares that the meter is suitable for use in hazardous zones as defined in EN IEC 60079‑10‑1:2021, the design, construction and marking of the meter shall then comply with EN IEC 60079‑0:2018, EN 60079-7:2015 and EN IEC 60079‑11:2024, or EN IEC 60079‑15:2019, as appropriate.

Ensure that the design, construction and marking of the meter comply with EN IEC 60079‑0:2018 and either EN 60079‑7:2015, EN 60079‑11:2012, or EN IEC 60079‑15:2019, as appropriate.

The recorded cumulative volume shall be shown by the display and stored in a non-volatile storage device for a minimum of 36 months.

NOTE This volume is the legal index and not profile data.

Confirm by visual inspection. The memory retention time can be based on calculations from data for the relevant components, or from the results of manufacturer’s own relevant tests.

a) In addition to a flag character, the display shall have a minimum number of numerical characters as specified in Table 23;

b) Any alphabetical flag character chosen shall not be able to be confused as a digit by the user;

c) An index shall have at least a sufficient number of numerals to ensure that the volume passed during 8 000 h at a flow rate of Q_max does not return all of the numerals to their original positions;

d) The index shall be non-resettable, non-volatile and protected with a metrological seal.

e) The index shall be easily readable within an angle of 15° from normal to the window without the use of tools, within the ambient temperature range of −10 °C to 40 °C, or greater if declared by the manufacturer;

f) The numerals in the display shall have a minimum height of 4,8 mm;

g) The unit of measurement (m³) shall be unambiguously and boldly displayed, within the index;

h) The numerals indicating the sub-multiples of the cubic metre shall be clearly distinguishable from the other numerals and they shall be separated from the other numerals by a clearly marked decimal sign;

i) If the index is constructed in such a way that the signal of the measuring part is produced in discrete steps, its internal resolution shall be equivalent or more accurate than the increment of the test element. The increment of the test element or pulse shall occur at least every 60 s at Q_min.

Table 23 — Resolution of meter index

Confirm the requirements of 8.2.1 by either visual inspection, measurement or design.

Where the indicated values, used in the accuracy tests, are obtained exclusively via the communications port, ensure that the inspection confirms that the reading from the communications port(s) is the same as the value registered in the display.

Below is an example confirming how to meet the requirement 8.2.1i).

EXAMPLE A meter with a maximum flow rate Q_max of 6 m³/h and a minimum flow rate Q_min of 0,04 m³/h needs to have a test element of at least (0,04 m³/3 600 s)⋅60 s = 0,000 67 m³.

The test house shall confirm with the manufacturer what information has to be shown on the display.

This information shall be displayed on the index in a complete, readable and legible form.

The meter shall have a test routine that will display all information that is available to be seen.

The test routine shall either occur automatically, or activated on demand for a maximum duration of 5s.

When the test routine is activated automatically, the occurrence shall not be less than 1 min.

By visual inspection, confirm that the information shown on the display is complete, readable and legible.

Using a suitable timing device, confirm that requirements of 8.3.1 are met. If appropriate to the test, inject a test signal in accordance with the manufacturer’s instructions.

Confirm the meter has a test routine and displays all information that is available to be seen.

Confirm the test routine activates the index for a maximum duration of 5 s, automatically, or on demand.

Confirm that, when the test routine is activated automatically, this occurrence is not less than 1 min.

The non-volatile memory shall be updated at least every 1 h and shall:

— be accessible at the extremes of the ambient temperature range; and

— be maintained without any power source across the maximum and minimum storage temperatures, as declared by the manufacturer.

When tested in accordance with 8.4.2a) the non-volatile memory shall remain accessible and constant at the extremes of the temperature range.

When tested in accordance with 8.4.2b) there shall be no difference between the index readings recorded in 3) and 6).

a) Access to non-volatile memory.

1) Determine a method for accessing the volume index in the non-volatile memory. Ensure that there is no difference between the two readings. It shall be declared how this can be performed;

2) cap the meter to prevent any registration;

3) note the meter index on the display and in the non-volatile memory;

4) subject the meter to the extremes of ambient temperature, as specified by the manufacturer, for a minimum of 3 h at each temperature;

5) at each of the temperature extremes, at the end of the dwell time, read the volume index from the non-volatile memory.

6) Report the result as a pass or fail

b) Maintenance of non-volatile memory.

1) Note the meter index;

2) immediately apply a flow rate equal to Q_max to the meter for a period of 5 min;

3) confirm that the meter has registered the gas flow, then cap the meter to prevent further registration and immediately note the new meter index and time;

4) leave the meter at room temperature for a minimum of 6 h 5 min after the time noted in 3);

5) remove the battery and subject the meter to the minimum and maximum storage temperatures, as specified by the manufacturer, for a minimum of 3 h at each temperature;

6) reconnect the battery and compare the current index reading with the reading noted in 3).

7) Report the result as a pass or fail

Each meter shall be marked with at least the following information:

a) type approval mark and number (if appropriate);

b) name, registered trade name or registered trade mark and the postal address of the body placing the meter on the market.;

c) serial number of the meter;

d) year of manufacture;

e) maximum flow rate, Q_max (m³/h);

f) minimum flow rate Q_min (m³/h);

g) maximum working pressure, pmax (bar);

h) the number and date of this standard i.e. EN 14236:—

i) ambient temperature range, if greater than −10 °C to +40 °C, e.g. tm = −20 °C...+55 °C;

j) gas temperature range, if different to −10 °C to +40 °C, e.g. tg = −10 °C...+40 °C;

k) group(s) of gases for which the meter is approved, for example:

Groups H, L, E, P/B;

l) accuracy of the meter, e.g. Class 1,5;

m) any additional marking required by the Annexes of this standard;

NOTE Such additional marking can be required by legislation e.g. the number of type or design examination certificates and marking showing conformance with legislation.

If the meter is resistant to high temperatures (see 7.2) it shall be marked additionally with a ‘T’.

If the meter has a thermal cut-off valve fitted it shall be marked additionally with an ‘F’.

If the meter is declared suitable for use in an open environment it shall be marked additionally with ‘H3’.

The markings shall be in a clearly visible position and shall be durable under the normal conditions of the meter.

If all applicable information cannot be displayed on the meter, this shall be provided on the packaging or with the meter literature.

Meters with two-pipe connections shall be clearly and permanently marked with the direction(s) of flow by means of (an) arrow(s).

Confirm by visual inspection.

All required labels shall remain securely fixed, in that their edges shall not lift from the backing surfaces, and the markings on the meter, on the index and on the index plate when viewed through the index window and any separate data plate if fitted, shall remain legible after being subjected to the tests given in 9.3.2 for a closed location or 9.3.3 for an open location.

Expose the assembled index, index plate, index window and samples of the meter labels to ultraviolet exposure for five periods, each of 8 h duration, using a suspended sun lamp that has been in use for not less than 50 h and not more than 400 h.

Ensure that the light source of the sun lamp is a combination tungsten filament mercury arc, enclosed in glass that has a low transmission below 280 nm, that the glass envelope is conical and silvered internally to form a reflector and that the lamp is rated between 275 W and 300 W.

Position the sample with its normally exposed surface facing the lamp, 400 mm below the

bottom of the lamp and on the axis of the lamp. Ensure that the surrounding air is not confined and is free to circulate.

After each exposure except the last, immerse the sample completely in de ionized water for 16 h. Clean and carefully dry it with cotton wool after each immersion.

Weathering test

One meter shall be exposed for 66 days to artificial weathering and exposure to artificial radiation in accordance with EN ISO 4892‑3:2024 and the parameters in Table 24. Prior to exposure measurements will be made to enable the test criteria to be assessed.

Table 24 — Weathering test criteria

Confirm by visual inspection the following:

— all labels are securely fixed, and their edges do not lift from the backing surfaces;

— the label and all markings on the meter, the index, index plate and any separate data plate, if fitted, are legible.

Confirm that when measured in accordance with EN ISO/CIE 11664‑4:2019, 4.3, the total colour difference is inside the following limits:

DL* ≤ 7

Da* ≤ 7

Db* ≤ 14

Confirm the light transmission in accordance with ASTM D1003-13 has a Haze in % ≤ 15.

Adhesion of metrology label test

Carry out the following test at (20 ± 3) °C.

Apply a finished label to the finished meter surface or a sample of the same finished meter material by pressing half the label area to the surface, with the remaining half folded back through 180°.

Allow the adhesive to condition for a minimum of 48 h at (20 ± 3) °C.

Apply a traction of 300 mm·min−1 separation rate to the unattached portion of the label, for example using a dynamometer.

Record the force (peel adhesion) at which the label loses adhesion or breaks and confirm the force required to remove the label is greater than (0,40 ± 0,04) N·mm−1. Provided that all the attached area of the label continues to adhere to the surface, it is admissible for the label to break during the test.

All markings on the external surface of the meter, which can be touched when the meter is in normal use, shall satisfy the indelibility tests as specified in Annex A of EN IEC 60730‑1:2024.

Confirm the requirements of EN IEC 60730‑1:2024, Annex A are met.

Operating instructions shall be available in written form or as a database and shall identify the name and address of the manufacturer.

Each meter (or a utility responsible for groups of identical meters) shall be delivered with installation, operation and maintenance manuals, in a language acceptable by the user and easily understandable, giving appropriate instructions.

The legally relevant parts of the software of a gas meter and/or its constituents shall be clearly and permanently identified with the software version or any other token. The identification may apply to more than one part but at least one part shall be dedicated to the legal purpose.

The identification shall be inextricably linked to the software and shall be:

— presented or printed on command; or

— displayed during operation; or

— displayed during operation.

Confirm by visual inspection and review the relevant documentation submitted by the manufacturer.

This clause generally refers to EN 62056‑21:2002, but with provisions for:

— an alternative sign-off incorporating acknowledgement from the meter;

— a test-mode message structure, to enable common test procedures for meters.

The meter shall provide access to information stored in the meter’s memory via a serial data link. Data shall be provided through a suitable interface.

The information shall, as a minimum, provide for the transmission of the index reading (volatile and non-volatile memory), the meter serial number and the status flag and provision for error detection.

Meter reading devices shall not affect the metrology of the meter.

A facility shall be provided to clear the battery change flag once the battery has been changed. A procedure shall be defined.

Inactivity time-out shall be between 10 s and 120 s.

Confirm the meter provides access to information stored in the memory of the meter via a serial data link, and that data have been provided by a suitable interface.

Confirm as a minimum that the index reading (volatile and non-volatile memory), the meter serial number and any status flag have been transmitted.

Induce an error and confirm the error has been detected and transmitted.

Change the battery in accordance to the manufacturer’s instructions and confirm the procedures demonstrates how to change battery and clear any related flags.

Confirm the inactivity time-out intervals is between 10 s and120 s.

Where a radio communication module is fitted to the meter, the metrological accuracy shall not be influenced by communication function.

When tested in accordance with 11.2.2 the meter error shall remain within MPE specified in Table 6

Test the meter in accordance with Table 7, Test b) only at 0,1 Q_max in the following two configurations:

a) with radio communication function disabled;

b) with radio communication function in operation at each of the six measurement repetitions.

Check the requirement in 11.2.1 is met.

If the meter has a test-mode, it shall meet the requirements of this clause.

The command structure shall be capable of setting the meter into and out of test-mode, demanding a test measurement, and entering any manufacturer specific test-mode option. The following test-mode commands shall be used:

a) Request test-mode measurement;

b) Enable test-mode – standard measurement period;

c) Enable test-mode – fast measurement period;

d) Disable test-mode;

e) Manufacturer specific test-mode commands.

Confirm a) to e) inclusive are accessible via the communication port.

The optical port and its associated reading head shall comply with 4.3 of EN 62056‑21:2002 and shall be accessible with the meter mounted in its normal orientation.

“Other technologies e.g. wireless are not excluded as agreed with the notified body / test house.

The galvanic port shall conform to the requirements in 4.1 and 4.2 of EN 62056‑21:2002. As a minimum, the connector shall conform to the degree of protection IP 54 in accordance with EN 60529:1991.

The meter shall be capable of indicating key features by the use of an unambiguous alphabetic flag on the display/index. The meter shall record details of any events relating to any displayed flag, including the first and last date when the flag was displayed, the meter-register value on those dates and the number of each type of operation error or other event.

In addition:

1) the configuration of the flag shall be documented, but in any case, the meter shall always record and retain the flag details on its internal memory even if the flag is no longer displayed on the meter-index display;

2) details shall be provided on the type of operational errors and other events that can generate a flag on the display, including the number of errors or other operational-events required to generate a flag on the meter-display, and any time-delay between the initial event(s) and the display of the corresponding flag on the meter-index;

3) it shall be confirmed what action (if any) is taken by the meter when a flag is displayed on the meter-index, and in particular whether or not the meter stops recording gas consumption while the flag is displayed (i.e. whether or not the meter-index is “frozen” while the flag is displayed);

4) a diagnostic tool shall be made available to allow the purchaser to interrogate and extract these details from the meter in the event of a customer related meter-accuracy dispute.

Confirm that the requirements specified in 11.6.1 are met.

Requirements

The meter shall display flags that identify errors that may occur.

The types of incidents that can lead to the display flags shall be published.

Guidance on the process used to categorize and map the operational errors or other events that could trigger display flags shall be provided.

The parameters outside of which a flag will be generated shall be specified and what items are configurable shall be documented.

What action if any will cause the meter index to be “frozen” shall be confirmed.

An example of the flag types, the incident hierarchy and suitable actions are shown in Table 25. It shall be confirmed what flags are supported.

Table 25 — Example of Flag types and of incident descriptions

Test

Confirm that the requirements specified in 11.6.3.1 are met.

The battery shall conform to the requirements of EN 16314:2013 as given in Clause 6.

The battery shall be integral with the meter.

Requirement

When tested in accordance with 12.2.1.2 the difference of the mean errors shall not exceed one fifth of the MPE specified in Table 6.

Test

Test the meter in accordance with Table 7 test b). Remove and replace the battery three times in succession, waiting 5 min before each replacement. Retest the meter in Table 7 test b).

Requirement

When tested in accordance with 12.2.2.2, the errors of indication shall be within the MPE specified in Table 6.

Test

Test the meter in accordance Table 7 test b). with the battery of the meter replaced by a power supply set to the manufacturer's specified minimum operating voltage and ensure the requirement in 12.2.2.1 is met.

Requirement

The expected battery life, declared by the meter manufacturer, shall be at least 5 years.

After 90 % of the useful life of the battery has expired, a warning flag shall be shown (see 11.6.3).

Test

Simulate 90 % of the usage of the battery, as declared by the manufacturer.

The meter electronic hardware shall be designed and manufactured in such a way as to minimize the effect of magnetic fields, electrostatic discharge and other electromagnetic disturbances. The meter shall meet the requirement of 13.2.1, 13.3.1, 13.4.1, 13.5.1 and 13.6.1.

In addition, the meter shall conform to the requirements of 4.12.2 of EN 16314:2013.

When tested in accordance with 13.2.2 the difference in mean errors shall not exceed one half of the MPE specified in Table 6 for the upper zone of the measurement e.g. Class 1.5 would equal 0,75 % or the indication of measurement cannot be interpreted as a valid result such as a momentary variation that cannot be interpreted as, memorised or transmitted as a measuring result.

Following the disturbance the meter shall recover normal operation and remain within the MPE.

Test the meter in accordance with Table 7 test a) and calculate the mean error at each flow rate.

With no flow through the meter, test the meter in accordance with EN 61000‑4‑2 using 10 contact discharges to each of the following:

a) the conductive surfaces;

b) a horizontal coupling plane with a charge voltage of 4 kV according to EN IEC 61000‑6-1:2019 and EN IEC 61000‑6-2:2019 at intervals of a minimum of 1 s, with the battery fitted;

c) a vertical coupling plane with a charge voltage of 4 kV according to EN IEC 61000‑6-1:2019 and EN IEC 61000‑6-2:2019 at intervals of a minimum of 1 s, with the battery fitted.

With no flow through the meter, test the meter in accordance with EN IEC 61000‑4-2:2025 using 10 air discharges (to insulating surfaces) with a charge voltage of 8 kV according to EN IEC 61000‑6-1:2019 and EN IEC 61000‑6-2:2019 at intervals of a minimum of 1 s, with the battery fitted.

During the test, connect the inlet boss of the meter under test to the ‘ground plane’.

Repeat the test in accordance with Table 7 test a) and calculate the difference in mean errors.

The meter shall satisfy the following requirements:

a) during the test specified in 13.3.2a), the meter index shall neither increment nor decrement.

b) during the test specified in 13.3.2b), the measured flow rate calculated from the meter readings shall not vary by more than the MPE and after testing in accordance with 13.3.2b), the mean errors shall be within the MPE specified in Table 6.

c) during the test specified in 13.3.2c), the meter index shall neither increment nor decrement.

Arrange the test equipment so that it is possible to pass air through the test meter while it is being subjected to the electromagnetic field. The flow rate shall be held constant.

Record the initial volume from the meter index.

Set the flow rate to Q_max Test the meter under the conditions given below. During the test, read the index and elapsed time at suitable intervals. From these readings calculate the corresponding flow rates.

a) Set the flow rate to zero and subject the meter to the tests below.

Using the values set out below, test the meter in accordance with EN IEC 61000‑4-3:2020:

Read the volume register and non-volatile memory and compare with the value before the high frequency test.

b) Test the meter in accordance with Table 7 row f), at Q_max only and subject the meter again to the tests below.

Using the values set out below, test the meter in accordance with EN IEC 61000‑4-3:2020:

Read the volume register and non-volatile memory and compare with the value before the high frequency test.

Test the meter in accordance with Table 7 test f).

NOTE This test is applicable for meters used in residential, commercial and light industrial environments.

c) Fill the meter with methane, as the highest attenuating gas ensuring that the meter remains sufficiently filled with methane for the duration of the test.

Using the values set out below, test the meter in accordance with EN IEC 61000‑4-3:2020:

Read the volume register and non-volatile memory and compare with the value before the high frequency test.

When tested in accordance with 13.4.2, the meter index shall neither increment nor decrement.

Set the flow rate to zero.

Read the volume register and non-volatile memory.

Test the meter to test level 4 of EN 61000‑4‑8:2010 for 15min for the continuous field test.

Read the volume register and non-volatile memory and compare with the value before the electromagnetic induction power frequency was applied.

During the test described in 13.4.4, the flow rate calculated from the meter readings shall not vary by more than two times the MPE specified in Table and the average test results shall be within the MPE, during the test without showing an error flag.

After the test in 13.4.4, the mean errors shall be within the MPE specified in Table 6.

Stabilize the meter to room temperature and determine the meter accuracy at 0,2 Q_max in air in accordance with 5.3.2.

Repeat the above whilst subjecting the meter to electromagnetic induction (power frequency) in accordance with test level 4 of EN 61000‑4‑8:2010 for a minimum of 1 min in each of eight orientations, four with the meter horizontal at 0°, 90°, 180° and 270°, and four with the meter vertical at 0°, 90°, 180° and 270°. The test time required shall be stated.

With the power frequency switched off, retest the meter in accordance with at 0,2 Q_max in air in accordance with 5.3.2.

Record the result as a pass or fail.

When tested in accordance with 13.5.2 the meter index shall neither increment nor decrement.

Set the flow rate to zero.

Read the volume register and non-volatile memory.

Test the meter to test level 3 of EN 61000‑4‑9:2016 for 15 min.

Read the volume register and non-volatile memory and compare with the value before the electromagnetic induction power frequency was applied.

a) During the test described in b), the flow rate calculated from the meter readings shall not vary by more than half of the MPE specified in Table 6, during the test without showing an error flag.

b) After the test in b), the mean errors shall be within the MPE specified in Table 6 .

Stabilize the meter to room temperature and determine the meter accuracy in air in accordance with Table 7 test e).

Repeat the above whilst subjecting the meter to electromagnetic induction (pulsed field) in accordance with test level 3 of EN 61000‑4‑9:2016 for 15 min in each of eight orientations, four with the meter horizontal at 0°, 90°, 180° and 270°, and four with the meter vertical at 0°, 90°, 180° and 270°.

With the power frequency switched off, retest the meter in accordance Table 7 test e).

The meter shall not generate radiated noise that can interfere with other equipment.

Check that the meter satisfies class B radio interference limits in EN 55032:2015 at zero flow.

During the period in which the meter is tested in accordance with 14.2.1a) and 14.2.1c), the meter index shall neither increment nor decrement.

During the period in which the meter is tested in accordance with 14.2.1b) and 14.2.1d), the meter shall not read high or low by more than two times the MPE specified in Table 6, without displaying an error flag.

When tested in accordance with 14.2.1b) and 14.2.1d), the difference in mean errors shall not exceed one third of the MPE specified in Table 6.

The meter shall be tested as follows:

a) carry out the test described in 14.2.2 with zero air flow through the meter;

b) carry out the test described in 14.2.2 with a flow rate of Qmax through the meter;

c) carry out the test described in 14.2.3 with zero air flow through the meter;

d) carry out the test described in 14.2.3 with a flow rate of Q_max through the meter.

Ensure that the source of ultrasonic interference is an ultrasonic transducer of the same design(s) as used in the meter.

Use an electronic white noise source to drive the acoustic noise transducer at its maximum acoustic output without damaging it. Filter the white noise source so that its band-pass centre frequency is the same as that of the transducers in the meter. Set the high pass filter at or below the frequency where the output of the transducer used to test the meter falls to 50 %. Set the low pass filter at, or above the frequency where the output of the transducer used to test the meter falls by 50 %.

Connect two 450 mm lengths of 22 mm diameter pipework to the inlet and outlet ports respectively, of the meter. Position the transducer driven by the white noise source, external to and as close as possible to each of the meter’s transducers in turn, without touching the meter, for 15 min at each position. The most sensitive point shall be specified.

Repeat the tests but with the transducer driven by the white noise source in direct external physical contact with the pipework, halfway along both lengths of pipework.

Replace the electronic white noise source of 14.2.2 with a programmable signal generator to scan continuously between the maximum and minimum frequencies of the white noise source specified above. Set the signal generator to give the maximum ultrasonic output that does not damage the transducer. Use ultrasonic transducers of the same design as those used in the meter. Scan repeatedly the frequency range over a period of at least 15 min, covering the complete frequency spectrum under test at least 5 times for any specific scan rate. Carry out the scanning at rates of one, two, three, four and five scans per minute.

Connect two 450 mm lengths of 22 mm diameter pipework to the inlet and outlet ports respectively of the meter. Position the transducer driven by the white noise source, external to and as close as possible to each of the meter’s transducers in turn, without touching the meter, for 15 min at each position.

Repeat the tests but with the transducer driven by the white noise source in direct external physical contact with the pipework, halfway along both lengths of pipework.

The minimum number of meters to be supplied by the manufacturer for test purposes shall be no less than 15. The tests to be carried out on the supplied meters are given in Table 14.

By agreement with the manufacturer, more meters can be supplied, to enable speeding up of the test procedure.

Table 14 indicates the number of meters required for each of the tests in this European Standard. As a guide to planning the order in which tests are performed to evaluate a prototype, the table indicates where it is possible to re-use a meter for a subsequent test. The testing strategy shall be agreed between the manufacturer and the test house.

Table 26 — Meters required for testing

1. 
   (informative)
   
   Production requirements for meters
   1. General

Meters shall be constructed in accordance with this standard, i.e. EN 14236:— and shall be manufactured under an appropriate quality management system.

NOTE 1 An appropriate quality management system standard can be the EN ISO 9000 series of standards or an equivalent quality system standards, including traceability of critical components.

This quality system shall be applied to the construction and testing requirements of this European Standard.

NOTE 2 Attention is drawn to national legislation, statutory and regulatory requirements pertaining to the country in which the meter is used.

NOTE 3 National regulations can constitute compliance with the requirement for a quality system.

NOTE 4 National regulations can require that some inspection and testing of the measuring accuracy have to be witnessed and accepted by an authorized and competent person.

The meter error shall be adjusted as close to zero as the adjustment and MPEs allow, without favouring any party.

• 1. Technical requirements
     1. General

There shall be documented production test procedures, which shall include external leak tightness, error of indication, pressure absorption, markings, test medium (if other than air) and acceptance and rejection criteria. Every meter shall be tested for external leak tightness to 1,5 p_max as follows.

Pressurize the meter at normal laboratory temperature with air to a minimum of 1,5 times the declared maximum working pressure and carry out the test given in either A.2.1a) or A.2.1b).

a) immerse the meter without its index in water and observe it for leakage for 30 s after any external trapped air has been dispersed, after which no leakage should be observed, or

b) use any equivalent procedure utilizing calibrated and certificated test equipment with a declared resolution and full traceability.

Record as pass or fail for each meter.

• • 1. Verification of conformity at the temperature of the test laboratory

Meters which meet the requirements of MPE-Initial limits given in Table 6 or B.2.1.2 for meters with a built in temperature conversion device, and the initial maximum pressure absorption given in Table 9 at flow rates of Q_min, 0,2 Q_max and Q_max shall be deemed to meet the metrological requirements.

The test equipment shall be traceable to a national or international reference standard and the uncertainty (2σ) shall be better than 1/3 of the maximum value of the parameter to be tested.

Verification of conformity with the metrological requirements can be done either:

a) by examination and testing of every meter;

b) by statistical verification of conformity with the metrological requirements.

If tests are carried out on a statistical basis then the product control tests shall be carried out on lots of finished components using sampling procedures based on attributes, with:

— level of quality corresponding to a probability of acceptance of 95 %, with a non-conformity of less than 1 %;

— limit quality corresponding to a probability of acceptance of 5 %, with a non-conformity of less than 7 %.

If tests are conducted at different flow rates to those specified above, the assurance shall be at least equal to that obtained by the tests given in A.2.2.

NOTE For modules D or H1 of the MID a method based on variables can also be used.

• • 1. Meters with a built-in gas temperature conversion

Meters meeting the requirements of A.2.2 and the following shall be deemed to meet the metrological requirements for meters with built-in gas temperature conversion.

A random sample meets the requirements of the MPE-Initial limits given in B.2.1.4, reduced by one third of the MPE at flow rates of Q_min, 0,2 Q_max and Q_max at temperatures of °C and °C. The sampling plan shall be in accordance with Table A.1. The inspection lot shall be of a homogeneous production produced in no more than 10 consecutive working days. All sample size meters shall pass the test.

When an electronic temperature sensor is used, the random sample can be tested in the meter without flow at the temperatures of °C and °C. After thermal stabilization, the temperature sensor shall not deviate by more than 2 °C from the reference temperature.

If tests are conducted at different flow rates to these the assurance shall be at least equal to that obtained by the tests mentioned above.

Table 27 — Sampling plan for meters with built-in gas temperature conversion device

The period of manufacture shall be traceable from the serial number and all relevant quality records shall relate either to a period of manufacture or a serial number. Such records shall be retained for a minimum of five years.

• 1. Declaration of conformity

A declaration of conformity to this harmonized Standard and all relevant Directives shall be provided. The declaration of conformity shall be in accordance with to ISO/IEC 17050‑1.

• 1. Provision of information

It shall be made available for each meter, or group of meters, the installation, operation, testing and maintenance manuals in written form, or electronic format including the name and address of the manufacturer and the date of issue, in a language acceptable by the user and easily understandable, retained for a minimum of 10 years, giving appropriate information including:

NOTE 1 It is the responsibility of the manufacturer to make available any amendments and revisions to this information.

— safe use;

— gas family;

— rated operating conditions;

— battery (where field replaceable);

— meter calibration results

— installation conditions;

— instructions for operation, installation and testing.

Where a test mode is available, instructions shall be provided on how to enter and exit the mode, and any limitations on the features of the test mode, (e.g. index update frequency).

Groups of identical measuring instruments used in the same location or used for utility measurements do not necessarily require individual instruction manuals.

NOTE 2 National standards, national legislation, or work instructions provided to meter installers can make the provision of installation or other instructions unnecessary or unwelcome.

Information should be prepared but only supplied on request in most instances.

EXAMPLE Position, closed or open locations, condensing or with non-condensing humidity

— mechanical and electromagnetic environment classes;

— safety requirements concerning commissioning and de-commissioning procedures;

— safety requirements on filling/discharge of gas of/from the meter;

— statement if a maintenance is necessary and a relevant instruction;

— hazards arising from misuse and particular features of the design when appropriate;

— conditions for compatibility with interfaces;

— provisions, if any, for transport and handling;

— position(s) of seals.

• 1. Certificates of conformity

When required to do so by the customer, Certificates of Conformity, which provide the following minimum information as appropriate to the meters, shall be supplied:

a) manufacturer’s name and address;

b) serial/batch numbers of the meters;

c) customer’s name and address;

d) customer’s purchase order number;

e) description of the meters, the quantity, and where appropriate, the manufacturer's batch, lot, or item identification;

f) type approval number(s) for the meter(s);

g) identification of the specification/drawing to which the meters are supplied;

h) any agreed deviations from the contract;

i) following statement, signed by the person nominated by the manufacturer as responsible for quality control, or his deputy:

“CERTIFIED THAT THE SUPPLIES/SERVICES DETAILED HEREON HAVE BEEN INSPECTED AND TESTED IN ACCORDANCE WITH THE CONDITIONS AND REQUIREMENTS OF THE CONTRACT OR PURCHASE ORDER, AND UNLESS OTHERWISE SPECIFIED AS AN AGREED DEVIATION FROM THE CONTRACT, CONFORM IN ALL RESPECTS TO THE SPECIFICATION(S) AND DRAWING(S) RELEVANT THERETO”.

j) date of the certificate.

1. 
   (informative)
   
   Meters with gas temperature conversion devices
   1. Scope

This annex specifies requirements and tests for meters with built-in gas temperature conversion devices.

• 1. Metrological performance
     1. Errors of indication
        1. General

This clause replaces 5.3.

• • • 1. Requirement

If a test mode is provided, then the conversion should be included when the test mode is active.

• • • 1. Test

Determine the error of indication of the meter three times at a temperature of t_max at the flow rate of Q_max.

At each temperature, ensure that the temperatures of the test gas, the meter and the temperature inside the temperature-controlled cabinet are within 1 K.

The difference of the mean errors of the standard mode and the test-mode shall not exceed 0,3 % at Q_max. In both modes, the mean error shall be within the maximum permissible errors specified in the requirement given in B.2.1.4.

• • • 1. Requirements

For meters with temperature conversion the initial maximum permissible errors shall be increased from the values given in Table 6 by 0,5 % in a range of 30 °C extending symmetrically around the temperature tb specified by the manufacturer that lies between 15 °C and 25 °C. Outside this range, an additional increase of 0,5 % is permitted in each interval of 10 °C.

When the initial maximum permissible errors between 0,1 Q_max (Q_t) and Q_max all have the same sign, they shall all not exceed error limits which are reduced by 0,5 % from the above initial maximum permissible errors.

The meter error shall be adjusted as close to zero as the adjustment and MPEs allow, without favouring any party.

• • • 1. Test

Place the meter in a test rig (an example of which is shown in Figure B.1) and pass a volume of the test gas (dried air), the actual volume of which is measured by a reference standard, through the meter. The minimum volume of the test air to be passed through the meter shall be specified and agreed with the Test house.

Determine the error of indication of the meter six times at a temperature of 20 °C at the flow rates set out in Table 7 a)

Then determine the error of indication of the meter six times at temperatures of t_min and t_max and at temperatures equidistant between t_min and tb and between tb and t_max, at flow rates of 5 Q_min, 0,1 Q_max, 0,4 Q_max and Q_max.

At each temperature, ensure that the temperatures of the test gas, the meter and the temperature inside the temperature-controlled cabinet are within 1 K.

Stabilize the temperatures after each change of temperature and keep within ± 0,5 K during the measurements.

Calculate the error of indication for each temperature and flow as follows:

where

E is the error of indication, expressed as a percentage;

V_M is the volume registered by the test meter in cubic metres (m³);

V_R is the volume registered by the reference standard in cubic metres (m³);

T_R is the temperature of the reference standard in Kelvin (K);

T_B is the base temperature in Kelvin (K);

P_M is the pressure of the test meter inlet in Pascals (Pa);

P_R is the pressure of the reference standard in Pascals (Pa).

NOTE All temperature and pressure values used in the above equation are absolute.

Key

Figure B.1 — Example of test rig for temperature related tests

• 1. Error of indication where the gas and ambient temperatures are not equal
     1. Requirements
        1. General

If a meter is declared suitable for this application, it shall be tested in accordance with Table 7 a), and its error of indication shall be within the initial maximum permissible errors given in B.2.1.4.

• • • 1. Test

Place the meter under test in the test rig (see Figure B.2). Carry out the test using dry air at a flowing temperature of tsp + 20 °C and a meter in an ambient temperature of tsp °C or other temperature as agreed by the test laboratory. The intermittent operation shall consist of repeated cycles of a 2 min run followed by 4 min to 8 min pause. During each cycle, the air temperature at the meter inlet (Ti) shall be (tsp + 20 ± 1) °C at the commencement and throughout each flow period. Laboratory temperature and inlet air temperature to the reference standard shall be (tsp ± 1) °C. The difference in laboratory temperature at the test meter and at the reference standard shall not exceed 1 K.

Stabilize the operating conditions before the volume measurements are taken. Determine the volume indicated and passed over 7 temperature cycles for each of the flowrates Q_max, 0,7 Q_max and 0,2 Q_max. Calculate the error in the volume using the equation given in B.2.1.5.

Key

Figure B.2 — Example of test rig used for differential temperatures under intermittent operation tests

• • 1. Marking

Each meter shall be marked with the following information in addition to that listed in Clause 9, either on the index or on a separate data plate:

a) the base gas temperature expressed as, for example, tb = 15 °C;

b) the manufacturer specified temperature expressed as, e.g. tsp = 20 °C;

c) meters declared suitable for differential temperature and intermittent operation, the base gas temperature expressed as, e.g. t_b = 15 °C;

d) an indication of the converted volume expressed as Vb;

e) if the meter is temperature converted it shall be marked additionally with “tb=”, “tsp”;

f) and the base temperature (e.g. tb = 15 °C).

• • 1. Temperature sensitivity
       1. General

This requirement replaces 5.14.1.

• • • 1. Requirement

When tested in accordance with 5.14.2, the meter shall meet the requirement that no single test result shall differ from the regression line of distributed gas by more than the MPE, specified in Table 6, and all results shall remain within the errors shown in B.2.1.4.

• • • 1. Test

Test in accordance with 5.14.2.

• • 1. Temperature converted volume
       1. Requirement

The only gas volume that can be shown on a temperature converted meter is the temperature converted volume.

• • • 1. Test

Confirm by visual inspection and communication with the meter that it is the temperature converted volume is being shown on the index.

1. 
   (informative)
   
   Test Gases
   1. General

Ultrasonic meter technology has been designed almost exclusively for use on second family gases, although it is feasible to use it to measure gases of the other families as well. The meters are typically designed to operate on gases with speeds of sound in the range 300 m/s to 475 m/s.

Natural gases fall into the second family of gases. The majority of distributed natural gases exist within the high methane groups H and E as defined by EN 437.

One gas that exceeds the limits of ultrasonic meters is the test gas G 222 that has a speed of sound of 497 m/s due to the 23 % hydrogen content. However, this is not felt to be a problem as this gas is designed to test the performance limits of meter appliances and is not intended to represent distributed natural gases.

• 1. Test gas properties

The physical properties of a gas which can change due to variations in gas composition and which are most likely to influence the performance of ultrasonic gas meters are:

a) speed of sound range;

b) attenuation range;

c) viscosity range;

d) density / specific gravity range.

A set of test gases has been developed for second family gases in order to provide a suitably wide range of physical properties to exercise several meter technologies, without requiring tests across a very wide range of different gas mixtures. These are:

Testing on air and 99,5 % distributed gas will provide a thorough assessment of the meter under extreme conditions.

1. 
   (informative)
   
   Relationship between this European Standard and the Essential Requirements of EU Directive 2014/32/EU Measuring Instruments Directive aimed to be covered

This European standard has been prepared under a Commission’s standardization request M/541 to provide one voluntary means of conforming to the essential requirements of Directive 2014/32/EU Measuring Instruments Directive.

Once this standard is cited in the Official Journal of the European Union under that Directive, compliance with the normative clauses of this standard given in Table ZA.1 confers, within the limits of the scope of this standard, a presumption of conformity with the corresponding essential requirements of that Directive, and associated EFTA regulations.

Table ZA.1 — Correspondence between this European Standard and Directive 2014/32/EU Measuring Instruments Directive

WARNING 1 — Presumption of conformity stays valid only as long as a reference to this European Standard is maintained in the list published in the Official Journal of the European Union. Users of this standard should consult frequently the latest list published in the Official Journal of the European Union.

WARNING 2 — Other Union legislation may be applicable to the product(s) falling within the scope of this standard.

Bibliography

EN 60068‑2-30:2005, Environmental testing - Part 2-30: Tests - Test Db: Damp heat, cyclic (12 h + 12 h cycle)(IEC 60068 2 30)

EN 60079‑10 (all parts), Explosive atmospheres — Part 10: Classification of areas (IEC 60079‑10, all parts)

EN IEC 60086‑1:2021,^[8] Primary batteries — Part 1: General (IEC 60086‑1:2021)

EN IEC 60086‑4:2025, Primary batteries — Part 4: Safety of lithium batteries (IEC 60086‑4:2025)

EN ISO 6708:1995, Pipework components - Definition and selection of DN (nominal size) (ISO 6708:1995)

ISO 5168:2005, Measurement of fluid flow — Procedures for the evaluation of uncertainties

ISO 7724‑3:1984, Paints and varnishes — Colorimetry — Part 3: Calculation of colour differences

ASTM D471:2016, Standard Test Method for Rubber Property — Effect of Liquids

1. ⁾ 1 bar =1 000 mbar = 105 Pa. ↑

2. As impacted by EN 55032:2015/A1:2020, EN 55032:2015/A11:2020 and EN 55032:2015/AC:2016-07. ↑

3. As impacted by EN IEC 60079‑0:2018/AC:2020:02 and EN IEC 60079‑0:2018/A11:2024. ↑

4. As impacted by EN IEC 60079 7:2015/A1:2018 and EN 60079 7:2015/A11:2024. ↑

5. As impacted by EN IEC 60079-15:2019/A11:2025. ↑

6. As impacted by EN 60529:1991/corrigendum May 1993, EN 60529:1991/A1:2000, EN 60529:1991/A2:2013, EN 60529:1991/A2:2013/AC:2019-02 and EN 60529:1991/AC:2016-12. ↑

7. As impacted by EN 60695 11-10:2013/AC:2014. ↑

8. As impacted by EN IEC 60086-1:2021/AC:2022-07. ↑