CEN/TC 237 - Gas meters

This document specifies the measuring conditions, requirements and tests for the construction, performance and safety of class 1,0 axial and radial turbine gas meters with mechanical indicating devices, hereinafter referred to as a meter(s), having in-line pipe connections for gas flow measurement.
This document applies to turbine gas meters used to measure the volume of fuel gases of the 1st and 2nd gas families, the composition of which is specified in EN 437:2021, at maximum working pressures up to 420 bar, actual flow rates up to 25 000 m3/h over a gas temperature range of at least 40 K and for a climatic environmental temperature range of at least 50 K.
This document applies to meters 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) with condensing humidity or with non-condensing humidity;
and in locations with electromagnetic disturbances.
Unless otherwise specified in this document:
-   all pressures used are gauge;
-   all influence quantities, except the one under test, are kept relatively constant at their reference value.
Clauses 1 to 7 and Annex B are for design and type testing only, with the exception of 6.2.4.3, 6.2.5.3, 6.7.1.2.2 and 6.7.2.2.2. Annex C can be used to provide guidance on periodic tests during use. Clause 8 and Annexes D and E are for each meter prior to dispatch. Annex A is intended to be used for both type and individual testing. Annex F is intended to be used for individual testing. Annex G is intended to be used for design.

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 437:2018.
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 1   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 by the manufacturer with a minimum range of 40 °C.
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 by the manufacturer) with condensing humidity 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.
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 intended by the manufacturer.
Clauses 1 to 13 are for design and type testing only.

This document specifies the requirements and tests for the construction, performance, safety and conformity of gas-volume electronic conversion devices associated to gas meters, used to measure volumes of fuel gases of the 1st and 2nd families according to EN 437.
This document is intended for type testing, the detailed relevant provisions of which are given in Annex A.
Only three kinds of conversion are treated in this document:
-   conversion as a function of temperature only (called T conversion);
-   conversion as a function of the pressure and of the temperature with constant compression factor (called PT conversion);
-   conversion as a function of the pressure, the temperature and taking into account the compression factor (called PTZ conversion).
This document is not relevant to temperature conversion integrated into gas meters which only indicate the converted volume.
Gas-volume conversion devices consist of a calculator and a temperature transducer or a calculator, a temperature transducer and a pressure transducer locally installed.
For application of this document, a conversion device may be, as a choice of the manufacturer, considered as a complete instrument (Type 1) or made of separate elements (Type 2), according to the definitions given in 3.1.20.1 and 3.1.20.2.
In this last case, the provisions concerning pressure transducers, temperature sensors and temperature transducers are given in Annexes B, C and D respectively.
Any conversion device can provide an error curve correction for a gas meter.
NOTE   When rendering an account to an end user the readings from the conversion device can be used in conjunction with the readings from a gas meter conforming to EN 1359, EN 12480, or EN 12261, as appropriate, or to any other appropriate and relevant international or national standard for gas meters, without prejudice of national regulations.

This European Standard 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 second and/or third family, as given in EN 437, at maximum working pressures not exceeding 0,5 bar ) and maximum actual flow rates of up to 10 m3/h over a minimum ambient temperature range of -10 °C to +40 °C, and minimum gas temperature span of 40 K, for domestic applications. This European Standard applies to meters where the measuring element and the register(s) are enclosed in the same case.
This European Standard 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) with condensing humidity or with non-condensing humidity
and in locations with electromagnetic disturbances.
Unless otherwise stated, all pressures given in this European Standard are gauge pressures.
When more than one meter type is submitted for testing, then each meter type is required to be tested against this European Standard.
Clauses 1 to 15 and Annex C are for design and type testing only.
NOTE   See Annex A for production requirements.

This European Standard 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 European Standard 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 437:2003+A1:2009, 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 European Standard 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 as specified by the manufacturer) with condensing or with non-condensing humidity
or, if specified by the manufacturer,
-   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 standards apply 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 European Standard applies to meters with a maximum allowable pressure PS and the volume V of less than 6 000 bar · litres or with a product of PS and DN of less than 3 000 bar.
This European Standard can 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 European Standard specifies the requirements and tests for the construction, performance, safety and production of class 1,5 diaphragm gas meters (referred to as meters). This applies to meters with co-axial single pipe, or two pipe connections, that are used to measure volumes of fuel gases, which are within the limits of test gases of the 1st, 2nd and 3rd families described in EN 437. The meters have maximum working pressures not exceeding 0,5 bar and maximum actual flow rates not exceeding 160 m3.h−1 over a minimum ambient temperature range of −10 °C to 40 °C and a gas temperature range as specified by the manufacturer with a minimum range of 40 K.
This standard applies to meters with and without built-in temperature conversion that are installed in locations with vibration and shocks of low significance (see MID Annex 1 Chapter 1.3.2 (a), class M1). It also applies to meters in:
-   closed locations (indoor or outdoor with protection as specified by the manufacturer) both with condensing humidity or with non-condensing humidity;
or, if specified by the manufacturer:
-   open locations (outdoor without any covering) both with condensing humidity and with non-condensing humidity;
-   in locations with electromagnetic disturbances corresponding to those likely to be found in residential, commercial and light industrial buildings (see MID Annex 1 Chapter 1.3.3 (a), class E1).
Unless otherwise stated, all pressures given in this document are gauge pressure.
Requirements for electronic indexes, batteries, valves incorporated in the meter and other additional functionalities are given in EN 16314.
Unless otherwise stated in a particular test, the tests are carried out on meters that include additional functionality devices intended by the manufacturer.
Clauses 1 to 9 and Annexes B and C are for design and type testing only.
NOTE   The content of OIML Publication 'International Recommendation R 137' has been taken into account in the drafting of this standard.
If no specific requirements are given for test equipment, the instruments used should be traceable to a national or international reference standard and the uncertainty (2σ) should be better than 1/5 of the maximum value of the parameter to be tested. For differential results the repeatability (2σ)/resolution should be better than 1/5 of the maximum value of the parameter to be tested.

Part 3 of this European Standard specifies the requirements and tests for the construction, performance, safety and conformity of flow computers (FCs) used to meet the metrological and technical requirements of a high accuracy volume conversion device.
They are used to determine volume of fuel gases, including those of the first and second families according to EN 437.
For the purpose of this European Standard, only flow computers that are intended to operate with ultrasonic meters according to ISO 17089 1 or gas turbine meters conforming to EN 12261 are considered.
For the purpose of this European Standard only classification classes E2 and M1 are considered for the flow computer calculator.
FCs are equipped with external separate transducers for pressure and temperature which may be approved separately.
The provisions concerning pressure and temperature transducers are given in Annex B and C.
Requirements and tests are given for energy calculator in EN 12405 2.

This European Standard specifies the additional requirements and tests for gas meters with a maximum capacity of 40 m3/h and a maximum operating pressure of not exceeding 500 mbar, conforming to EN 1359, EN 12261, EN 12480, EN 12405 and EN 14236, which have battery powered devices providing additional functionalities that form part of the gas meter (hereafter referred to as meter) or contained in an Additional Functionality Device (AFD). It also covers the additional requirements when an electronic index is used rather that a mechanical one. Where the option of an integral valve to the meter is specified, this standard only gives requirements for meters having a maximum capacity not exceeding 10 m3/h.
This European Standard is applicable to first, second and third family gases according to EN 437.
This European Standard specifies the construction requirements for electronic components but communication protocols are dealt within other European Standards, e.g. appropriate parts of EN 13757.
NOTE   This European Standard covers connections to auxiliary devices but not the requirements for these devices.
This European Standard applies to AFDs 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) with condensing humidity or with non-condensing humidity,
-   locations liable to temporary saturation,
and in locations with electromagnetic disturbances corresponding to those likely to be found in residential, commercial buildings or similar buildings.
This European Standard does not cover the changing of metrological software within the meter or the upload/download of metrological software.
This European Standard only covers valves integral to the meter.

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 Technical Report outlines recommendations for "smart gas meters", specifies recommendations where there is clear consensus, and identifies areas where there are barriers to standardisation. It indicates how functions may be implemented in a harmonized way if they are selected. It does not seek to select which functions are to be implemented in a smart meter. The report covers simple to complex implementations of smart metering.
This Technical Report is applicable to 1st, 2nd and 3rd family gases according to EN 437.

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 437:2018.
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 1   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 by the manufacturer with a minimum range of 40 °C.
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 by the manufacturer) with condensing humidity 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.
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 intended by the manufacturer.
Clauses 1 to 13 are for design and type testing only.

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 as specified by the manufacturer) with condensing or with non-condensing humidity
or, if specified by the manufacturer,
-   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 standards apply to mechanical meters with mechanical index, electronic devices are not covered by this document.
Unless otherwise specified in this document:
-   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 can 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 document cover meters with mechanical index only.
The risk philosophy adopted in this document is based on the analysis of hazards including pressure. The document applies principles to eliminate or reduce hazards. Where these hazards cannot be eliminated appropriate protection measures are specified.

This European Standard 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 European Standard applies to rotary displacement gas meters used to measure the volume of at least fuel gases of the 1st, 2nd and 3rd gas families, the composition of which is specified in EN 437, 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 standard applies to meters that are installed in locations with vibration and shocks of low significance (class M1 according to MID) 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) with condensing humidity or with non-condensing humidity.
For use in open location, the meters shall fulfil the specification in annex G
and in locations with electromagnetic disturbances.
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 standard also applies to meters with a maximum allowable pressure PS and the volume V of less than 6 000 bar ž litres or with a product of PS and DN of less than 3 000 bar, as defined by EU directive 97/23/EC.  
The risk philosophy adopted in this standard is based on the analysis of hazards on account of pressure. The standard applies principles to eliminate or reduce hazards. Where these hazards cannot be eliminated appropriate protection measures are specified.
Any residual hazard identified has to be communicated to the user where appropriate.
Depending on the installation situation additional requirements may apply to cover the risks arising from traffic, wind, earthqua

This document specifies the measuring conditions, requirements and tests for the construction, performance and safety of class 1,0 axial and radial turbine gas meters with mechanical indicating devices, herein after referred to as a meter(s), having in-line pipe connections for gas flow measurement.
This document applies to turbine gas meters used to measure the volume of fuel gases of the 1st and 2nd gas families, the composition of which is specified in EN 437, at maximum working pressures up to 420 bar, actual flow rates up to 25 000 m³/h over a gas temperature range of at least 40 K and for a climatic environmental temperature range of at least 50 K.
This document applies to meters 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) with condensing humidity or with non-condensing humidity
and in locations with electromagnetic disturbances.
Unless otherwise specified in this document:
-   all pressures used are gauge;
-   all influence quantities, except the one under test, are kept relatively constant at their reference value.

To revise the Annex ZA, and the associated body text only, of EN 12405-1 to ensure the alignment with the Directive 2014/32/EU.

This European Standard specifies the requirements and tests for the construction, performance, safety and conformity of gas volume electronic conversion devices associated to gas meters, used to measure volumes of fuel gases of the 1st and 2nd families according to EN 437.
This European Standard is intended for type testing, the detailed relevant provisions of which are given in Annex A.
Only three kinds of conversion are treated in this European Standard:
   conversion as a function of temperature only (called T conversion);
   conversion as a function of the pressure and of the temperature with constant compression factor (called PT conversion);
   conversion as a function of the pressure, the temperature and taking into account the compression factor (called PTZ conversion).
!This document is not relevant to temperature conversion integrated into gas meters which only indicate the converted volume."
EN 12405-2 for energy conversion is in preparation.
Gas-volume conversion devices consist of a calculator and a temperature transducer or a calculator, a temperature transducer and a pressure transducer locally installed.
For application of this European Standard, a conversion device may be, as a choice of the manufacturer, considered as a complete instrument (Type 1) or made of separate elements (Type 2), according to the definitions given in 3.1.18.1 and 3.1.18.2.
In this last case, the provisions concerning pressure transducers, temperature sensors and temperature transducers are given in Annexes B, C and D respectively.
Any conversion device can provide an error curve correction for a gas meter.
NOTE   When rendering an account to an end user the readings from the conversion device can be used in conjunction with the readings from a gas meter conforming to EN 1359, EN 12480, or EN 12261, as appropriate, or to any other appropriate and relevant international or national standard for gas meters, without prejudice of national regulations.

This European Standard 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 second and/or third family, as given in EN 437, at maximum working pressures not exceeding 0,5 bar ) and maximum actual flow rates of up to 10 m3/h over a minimum ambient temperature range of -10 °C to +40 °C, and minimum gas temperature span of 40 K, for domestic applications. This European Standard applies to meters where the measuring element and the register(s) are enclosed in the same case.
This European Standard 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) with condensing humidity or with non-condensing humidity
and in locations with electromagnetic disturbances.
Unless otherwise stated, all pressures given in this European Standard are gauge pressures.
When more than one meter type is submitted for testing, then each meter type is required to be tested against this European Standard.
Clauses 1 to 15 and Annex C are for design and type testing only.
NOTE   See Annex A for production requirements.

To harmonize the standard under the MID, 2004/22/EC.  The Target dates have been shortened in order to meet the enforcement date of the MID.

This Standard specifies the range of application, the requirements and tests for the design, performance and safety of turbine gas meters having in line pipe connections for gas flow measurement. This standard applies to turbine gas meters used to measure the volume of fuel gases of the 1st and 2nd gas families at maximum working pressures up to 25 000 m3/h over a temperature range of at least -5 °C to +35 °C.

This European Standard 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 European Standard 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 437:2003+A1:2009, 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 European Standard applies to meters 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) with condensing humidity or with non-condensing humidity;
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 European Standard also applies to meters with a maximum allowable pressure PS and the volume V of less than 6 000 bar • litres or with a product of PS and DN of less than 3 000 bar.
NOTE   These limits are the same as in EU directive 97/23/EC.
This European Standard can 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 on account of pressure. The standard applies principles to eliminate or reduce hazards. Where these hazards cannot be eliminated appropriate protection measures are specified.

To harmonize the standard under the MID, 2004/22/EC.  The Target dates have been shortened in order to meet the enforcement date of the MID.

This European Standard specifies the requirements and tests for the construction, performance and safety of diaphragm gas meters (hereinafter referred to as meters) having co-axial single pipe, or two pipe connections, used to measure volumes of fuel gases of the 1st, 2nd and 3rd families according to EN 437:1993, at maximum working pressures of up to 1 bar and maximum actual flow rates of up to 160 m3/h over a minimum ambient and gas temperature range of -5°C to + 35 °C.

To harmonize the standard under the MID, 2004/22/EC.  The Target dates have been shortened in order to meet the enforcement date of the MID.

This European Standard 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 European Standard applies to rotary displacement gas meters used to measure the volume of fuel gases of the 1st, 2nd and 3rd gas families, the composition of which is specified in EN 437, at a maximum working pressure up to and including16 bar over a gas temperature range of at least -10 °C to +40 °C.
Unless otherwise specified in this standard, all pressures used are gauge pressures.

After third paragraph insert:This document is not relevant to temperature conversion integrated into gas meters which only indicate the converted volume.

This European Standard specifies the requirements and tests for the construction, performance, safety and conformity of gas volume electronic conversion devices associated to gas meters, used to measure volumes of fuel gases of the 1st and 2nd families according to EN 437.
This European Standard is intended for type testing, the detailed relevant provisions of which are given in Annex A.
Only three kinds of conversion are treated in this European Standard:
-   conversion as a function of temperature only (called T conversion);
-   conversion as a function of the pressure and of the temperature with constant compression factor (called PT conversion);
-   conversion as a function of the pressure, the temperature and taking into account the compression factor (called PTZ conversion).
EN 12405-2 for energy conversion is in preparation.
Gas-volume conversion devices consist of a calculator and a temperature transducer or a calculator, a temperature transducer and a pressure transducer locally installed.
For application of this European Standard, a conversion device may be, as a choice of the manufacturer, considered as a complete instrument (Type 1) or made of separate elements (Type 2), according to the definitions given in 3.1.18.1 and 3.1.18.2.
In this last case, the provisions concerning pressure transducers, temperature sensors and temperature transducers are given in Annexes B, C and D respectively.
Any conversion device can provide an error curve correction for a gas meter.
NOTE   When rendering an account to an end user the readings from the conversion device can be used in conjunction with the readings from a gas meter conforming to EN 1359, EN 12480, or EN 12261, as appropriate, or to any other appropriate and relevant international or national standard for gas meters, without prejudice of national regulations.

This European Pre-standard specifies requirements and tests for the construction, performance and safety of 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 first and/or second and/or third family, as given in EN 437, at maximum working pressures of up to 0,5 bar ) and maximum actual flow rates of up to 10 m³/h over a minimum ambient and gas temperature range of -10 °C to +40 °C, for domestic applications. This Pre-standard applies to meters where the measuring element and the register(s) are enclosed in the same case.
Unless otherwise stated, all pressures given in this document are gauge pressures.
Clauses 1 to 15 and annex B are for design and type testing only.
NOTE   See annex A for production requirements

This European Standard specifies the requirements and tests for the construction, performance, safety and conformity of gas-volume electronic conversion devices associated to gas meters, used to measure volumes of fuel gases of the 1st and 2nd families according to EN 437.
Only three kinds of conversion are treated in this standard:
- conversion as a function of temperature only (called T conversion);
- conversion as a function of the pressure and of the temperature with constant compressibility factor (called PT conversion);
- conversion as a function of the pressure, the temperature and taking into account the compressibility factor (called PTZ conversion).
These gas-volume conversion devices consist of a calculator and a temperature transducer or a calculator, a temperature transducer and a pressure transducer locally installed.
Any conversion device can provide an error curve correction for a gas meter.
NOTE   When rendering an account to an end user the readings from the conversion device can be used in conjunction with the readings from a gas meter conforming to EN 1359, prEN 12480, or prEN 12261, as appropriate, or to any other appropriate and relevant international or national standard for gas meters, without prejudice of national regulations.
This standard is intended for type testing only.
Annex A is normative and annex B is informative.

TC - 5.2.7.1, E.2.1, working pressure