M/626 - MID

This document specifies ranges, construction, performances, output characteristics and testing of rotary displacement gas meters (hereinafter referred to as RD meters or simply meters) for gas volume measurement.
This document applies to rotary displacement gas meters used to measure the volume of fuel gases of at least the 1st, 2nd and 3rd gas families, the composition of which is specified in EN 437:2021, at a maximum working pressure up to and including 20 bar over an ambient and gas temperature range of at least −10 °C to +40 °C.
This document applies to meters that are installed in locations with vibration and shocks of low significance (class M1) and in
-   closed locations (indoor or outdoor with protection) with condensing or with non-condensing humidity
or,
-   open locations (outdoor without any covering) with condensing humidity or with non-condensing humidity,
and in locations with electromagnetic disturbances (class E1 and E2). The standard applies to mechanical meters with mechanical index, electronic devices are not covered by this standard.
Unless otherwise specified in this standard:
-   all pressures used are gauge;
-   all influence quantities, except the one under test, are kept relatively constant at their reference value.
This document applies to meters with a maximum allowable pressure PS and the volume V of less than 6 000 bar · L or with a product of PS and DN of less than 3 000 bar.
This document is to be used for both pattern approval and individual meter testing. Cross-reference tables are given in:
-   Annex A for the tests that need to be undertaken for pattern approval;
-   Annex B for individual meter testing.
Some parts of this standard cover meters with mechanical index only.
The risk philosophy adopted in this standard is based on the analysis of hazards including pressure. The standard applies principles to eliminate or reduce hazards. Where these hazards cannot be eliminated appropriate protection measures are specified.

This document specifies ranges, construction, performances, output characteristics and testing of rotary displacement gas meters (hereinafter referred to as RD meters or simply meters) for gas volume measurement.
This document applies to rotary displacement gas meters used to measure the volume of fuel gases of at least the 1st, 2nd and 3rd gas families, the composition of which is specified in EN 437:2021, at a maximum working pressure up to and including 20 bar over an ambient and gas temperature range of at least −10 °C to +40 °C.
This document applies to meters that are installed in locations with vibration and shocks of low significance (class M1) and in
-   closed locations (indoor or outdoor with protection) with condensing or with non-condensing humidity
or,
-   open locations (outdoor without any covering) with condensing humidity or with non-condensing humidity,
and in locations with electromagnetic disturbances (class E1 and E2). The standard applies to mechanical meters with mechanical index, electronic devices are not covered by this standard.
Unless otherwise specified in this standard:
-   all pressures used are gauge;
-   all influence quantities, except the one under test, are kept relatively constant at their reference value.
This document applies to meters with a maximum allowable pressure PS and the volume V of less than 6 000 bar · L or with a product of PS and DN of less than 3 000 bar.
This document is to be used for both pattern approval and individual meter testing. Cross-reference tables are given in:
-   Annex A for the tests that need to be undertaken for pattern approval;
-   Annex B for individual meter testing.
Some parts of this standard cover meters with mechanical index only.
The risk philosophy adopted in this standard is based on the analysis of hazards including pressure. The standard applies principles to eliminate or reduce hazards. Where these hazards cannot be eliminated appropriate protection measures are specified.

This document specifies the metrological and technical requirements for water meters for cold potable water and hot water flowing through a fully charged, closed conduit. These water meters incorporate devices which indicate the accumulated volume.
In addition to water meters based on mechanical principles, this document applies to devices based on electrical or electronic principles, and mechanical principles incorporating electronic devices, used to measure the volume of cold potable water and hot water.
This document also applies to electronic ancillary devices. Ancillary devices are optional. However, it is possible for national or regional regulations to render some ancillary devices mandatory in relation to the utilization of water meters.
NOTE            Any national regulations apply in the country of use.

This document is applicable to the type evaluation and initial verification testing of water meters for cold potable water and hot water as defined in ISO 4064-1:2024|OIML R 49‑1:2024. OIML Certificates of conformity can be issued for water meters under the scope of the OIML Certificate System, provided that this document, ISO 4064-1:2024|OIML R 49‑1:2024 and ISO 4064-3:2024|OIML R 49‑3:2024 are used in accordance with the rules of the system.
This document sets out details of the test programme, principles, equipment and procedures to be used for the type evaluation, and initial verification of a meter type.
The provisions of this document also apply to ancillary devices, if required by national regulations.
The provisions include requirements for testing the complete water meter and for testing the measurement transducer (including the flow or volume sensor) and the calculator (including the indicating device) of a water meter as separate units.

This document specifies the metrological and technical requirements for water meters for cold potable water and hot water flowing through a fully charged, closed conduit. These water meters incorporate devices which indicate the accumulated volume.
In addition to water meters based on mechanical principles, this document applies to devices based on electrical or electronic principles, and mechanical principles incorporating electronic devices, used to measure the volume of cold potable water and hot water.
This document also applies to electronic ancillary devices. Ancillary devices are optional. However, it is possible for national or regional regulations to render some ancillary devices mandatory in relation to the utilization of water meters.
NOTE            Any national regulations apply in the country of use.

This document is applicable to the type evaluation and initial verification testing of water meters for cold potable water and hot water as defined in ISO 4064-1:2024|OIML R 49‑1:2024. OIML Certificates of conformity can be issued for water meters under the scope of the OIML Certificate System, provided that this document, ISO 4064-1:2024|OIML R 49‑1:2024 and ISO 4064-3:2024|OIML R 49‑3:2024 are used in accordance with the rules of the system.
This document sets out details of the test programme, principles, equipment and procedures to be used for the type evaluation, and initial verification of a meter type.
The provisions of this document also apply to ancillary devices, if required by national regulations.
The provisions include requirements for testing the complete water meter and for testing the measurement transducer (including the flow or volume sensor) and the calculator (including the indicating device) of a water meter as separate units.

This document specifies requirements and tests for the construction, performance, safety and production of battery powered class 1,5 Capillary Thermal-Mass Flow sensor gas meters (hereinafter referred to as meter(s)). This applies to meters having co-axial single pipe, or two pipe connections, which are used to measure volumes of fuel gases of the 2nd and/or 3rd family, as given in EN 437:2021.
In general, the term "thermal mass flow meters" applies to a flow-measuring device using heat transfer to measure and indicate gas flowrate, as defined in ISO 14511.
NOTE    Although the word "mass" is present in the definition of the measurement principle, gas meters covered by this document provide measurement of gas at base conditions of temperature and pressure.
These meters have a maximum working pressure not exceeding 0,5 bar and a maximum flowrate not exceeding 160 m3/h over a minimum ambient temperature range of −10 °C to +40 °C and a gas temperature range as specified in the marking, with a minimum range of 40 °C.
For meters designed for hydrogen measurement, the maximum flowrate is not exceeding 480 m3/h, whilst the other characteristics are as stated above.
This document applies to meters indicating volume at base conditions, which are installed in locations with vibration and shocks of low significance. It applies to meters in:
-   closed locations (indoor or outdoor with protection, as specified in the instruction manual) with condensing humidity or with non-condensing humidity;
or, if specified in the marking:
-   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. For meters which indicate unconverted volume, reference can be made to Annex C.
Unless otherwise stated, all pressures given in this document are gauge pressures.
Requirements for electronic indexes, valves and additional requirements for batteries incorporated in the meter and any 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, as indicated in the instruction manual.
Clauses 1 to 13 are for design and type testing only.
For meters designed for blended gas and/or hydrogen measurement, refer to Annex E.
This document refers only to hydrogen as specified in ISO 14687:2025 with a purity of type I grade A or better.
Unless otherwise stated, all tests applicable to 2nd and 3rd family gases are applicable also to blended gas and hydrogen.
Mixtures with a hydrogen concentration above 20 % and below 98 % by volume are not covered by this document.

This European Standard specifies the requirements and tests for the construction, performance, safety and conformity of conversion devices used to determine the energy of fuel gases described in the Table 1, including those of the 1st and 2nd families according to EN 437.
The energy conversion device (ECD) considered in this standard consists of an energy calculator (EC) and is associated with the following devices and/or functions:
-   a volume conversion device (VCD) or a flow computer used as gas meter conversion, either conforming to EN 12405-1, or to prEN 12405-3, for high accuracy measurements;
-   a calorific value determination device (CVDD).
Requirements for type approval tests of the devices, not included in the above-mentioned standards are described in appropriate annexes specified in Table 6.
For the purpose of this European Standard, the term "volume conversion devices" (VCDs) includes flow computers (FCs).
A single calculator may undertake the volume conversion functions for different metering lines.

This document specifies requirements and tests for the construction, performance, safety and production of battery powered class 1,5 Capillary Thermal-Mass Flow sensor gas meters (hereinafter referred to as meter(s)). This applies to meters having co-axial single pipe, or two pipe connections, which are used to measure volumes of fuel gases of the 2nd and/or 3rd family, as given in EN 437:2021.
In general, the term "thermal mass flow meters" applies to a flow-measuring device using heat transfer to measure and indicate gas flowrate, as defined in ISO 14511.
NOTE    Although the word "mass" is present in the definition of the measurement principle, gas meters covered by this document provide measurement of gas at base conditions of temperature and pressure.
These meters have a maximum working pressure not exceeding 0,5 bar and a maximum flowrate not exceeding 160 m3/h over a minimum ambient temperature range of −10 °C to +40 °C and a gas temperature range as specified in the marking, with a minimum range of 40 °C.
For meters designed for hydrogen measurement, the maximum flowrate is not exceeding 480 m3/h, whilst the other characteristics are as stated above.
This document applies to meters indicating volume at base conditions, which are installed in locations with vibration and shocks of low significance. It applies to meters in:
-   closed locations (indoor or outdoor with protection, as specified in the instruction manual) with condensing humidity or with non-condensing humidity;
or, if specified in the marking:
-   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. For meters which indicate unconverted volume, reference can be made to Annex C.
Unless otherwise stated, all pressures given in this document are gauge pressures.
Requirements for electronic indexes, valves and additional requirements for batteries incorporated in the meter and any 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, as indicated in the instruction manual.
Clauses 1 to 13 are for design and type testing only.
For meters designed for blended gas and/or hydrogen measurement, refer to Annex E.
This document refers only to hydrogen as specified in ISO 14687:2025 with a purity of type I grade A or better.
Unless otherwise stated, all tests applicable to 2nd and 3rd family gases are applicable also to blended gas and hydrogen.
Mixtures with a hydrogen concentration above 20 % and below 98 % by volume are not covered by this document.

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  )) 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.

This European Standard specifies the requirements and tests for the construction, performance, safety and conformity of conversion devices used to determine the energy of fuel gases described in the Table 1, including those of the 1st and 2nd families according to EN 437.
The energy conversion device (ECD) considered in this standard consists of an energy calculator (EC) and is associated with the following devices and/or functions:
-   a volume conversion device (VCD) or a flow computer used as gas meter conversion, either conforming to EN 12405-1, or to prEN 12405-3, for high accuracy measurements;
-   a calorific value determination device (CVDD).
Requirements for type approval tests of the devices, not included in the above-mentioned standards are described in appropriate annexes specified in Table 6.
For the purpose of this European Standard, the term "volume conversion devices" (VCDs) includes flow computers (FCs).
A single calculator may undertake the volume conversion functions for different metering lines.

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  )) 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.