S-G-03–Specifications for the approval of type of gas metering devices–Part 1

Category: Gas
Issue date:
Effective date:
Revision number: 3
Supersedes: S-G-03 (rev. 2)


Part 1: General

Table of contents


1.0 Unit requirements

Note: Except where otherwise stated in these specifications, the following requirements apply.

1.1 Use of units

1.1.1 Mixture of units

A gas metering device must not provide an indication or record, or be marked using a mixture of units of measurement based on the International System of Units (SI) and the imperial system.

Note: The following types of gas metering devices are exempt from this requirement:

  • Electronic devices capable of performing calculations to convert between imperial system of units and SI units.
  • Rotary meter pressure bodies designed to accept both metric and imperial modules.
1.1.2 Measurement units

A gas metering device which provides for the selection of SI units or imperial units must have a provision for identifying the units it is set up to measure.

1.2 Metric units of measure

Metric units of measure must be expressed in the SI units of measure listed in the Canadian Standards Association's (CSA) Metric Practice Guide (standard Z234.1).

Note: Where a conflict exists between the CSA standard Z234.1 and the legislation, the legislative requirements apply.

1.3 Display of units of measure for non-trade purposes

The display of units of measure by electronic gas metering devices for non-trade purposes, such as monitoring, is permitted.

1.4 Calorific value units

1.4.1 General

The calorific value of the gas must be established on a real gas, dry basis, at reference combustion temperature of 15 °C in International System of Units (SI) or 60 °F in the imperial system, where applicable.

1.4.2 Mass-basis calorific value

The mass-basis calorific value (Hm) must be expressed in joules (J) or multiples thereof, per kilogram (kg), such as J/kg or MJ/kg.

1.4.3 Volume-basis calorific value

The volume-basis calorific value (Hv) must be expressed in one of the following units and include the base conditions (i.e. base temperature and base pressure) used in establishing the calorific value:

  • Joules (J) or multiples thereof, per cubic meter (m3);
  • British thermal units (BTU) per cubic foot (ft3):
    • The British thermal unit must be defined by its reference temperature, for example, BTU(60.5);
    • The calorific value must be expressed in BTU(60.5) as a minimum.

2.0 Metrological requirements

Note: Except where otherwise stated in these specifications, the following requirements apply.

2.1 Rated operating conditions

  • Ambient temperature range
    • Non-temperature-controlled environment
      In the case of gas metering devices intended for operation in a non-temperature controlled environment, the ambient temperature range must be at least -30 °C to 40 °C.

    • Temperature-controlled environment
      In the case of gas metering devices intended for operation in a temperature controlled environment, the ambient temperature range must be as specified by the applicant.

      Note: Such restrictions must be set out in the notice of approval issued by MC.

  • Ambient relative humidity

    As specified by the applicant and at least up to 93% (non-condensing).

  • Atmospheric pressure

    As specified by the applicant and must cover at least 86 kPa to 106 kPa (absolute).

  • DC mains voltage

    As specified by the applicant.

  • AC mains voltage

    V nom 15 %  to  V nom + 10 %

  • AC mains frequency

    ϝ nom 2 %  to  ϝ nom + 2 %

  • Operating flow rate range

    Qmin to Qmax inclusive.

  • Type of gases

    As specified by the applicant.

  • Working pressure range

    Pmin to Pmax inclusive.

2.2 Flow rate characteristics

2.2.1 Qmin, Qt and Qmax

The flow rate characteristics of a gas metering device must be defined by the values of Qmin, Qt and Qmax.

Note: Qt only applies to turbine meters (Part 4) and Coriolis mass flow meters (Part 6).

2.2.2 Ratios

Unless otherwise specified by MC, the ratios and relations must be within the following ranges:

  1. Where Qmax / Qmin is ≥ 50 → Qmax / Qt must be ≥ 10
  2. Where Qmax / Qmin ≥ 5 and < 50 → Qmax / Qt must be ≥ 5

2.3 Maximum permissible errors

2.3.1 General

A gas metering device must be designed and manufactured such that its errors do not exceed the applicable maximum permissible error (MPE) under rated operating conditions as specified in subsection 2.1.

Note: The applicable MPE to various gas metering devices are set forth in subsequent parts specific thereto.

2.3.2 Correction

The following requirements apply:

  • A gas meter may be equipped with an electronic device incorporating a correction function. Such a device must not allow for the correction of a pre-estimated drift.
  • Unless permitted by the notice of approval, an electronic device incorporating a correction function must not extrapolate a gas meter's performance through characterization of a general gas meter type at or below Qmin.

2.4 Weighted mean error

The weighted mean error (WME) must be within ± 0.4%.

2.5 Repeatability

The repeatability error must be less than or equal to one third of the MPE.

2.6 Working pressure

The requirements as specified in subsection 2.3 must be fulfilled over the whole working pressure range.

2.7 Temperature

The requirements as specified in subsection 2.3 must be fulfilled over the whole temperature range.

2.8 Durability

Subject to subsection 7.4.8, the fault of a gas meter for flow rates from Qt up to Qmax or within the flow rate range where Qt is not applicable, must be less than or equal to half the MPE.

2.9 Vibrations and shocks

2.9.1 Vibrations

A gas metering device must withstand vibrations with the following specifications and the fault must be less than or equal to half the MPE over the whole flow rate range:

  • Total frequency range: 10 Hz – 150 Hz
  • Total root mean square (RMS) level: 7 m∙s-2
  • Acceleration spectral density (ASD) level 10 Hz – 20 Hz: 1 m2s-3
  • ASD level 20 Hz – 150 Hz: -3 dB/octave
2.9.2 Shocks

A gas metering device must withstand shocks from a fall of 50 mm and the fault must be less than or equal to half the MPE over the whole flow rate range.

2.10 Orientation

Where the gas metering device operates correctly while installed in certain orientations recommended by the manufacturer and for which approval is sought, the metrological requirements mentioned in subsections 2.3 and 2.4 must be fulfilled for these orientations only, otherwise they must be fulfilled for all orientations.

2.11 Flow direction

If the gas metering device is designed for bidirectional flow measurement, the requirements mentioned in subsections 2.3 and 2.4 are fulfilled for each direction separately.

Notes:

  1. This requirement also applies to net metering measurements.
  2. Where applicable, the notice of approval states whether the net metering capability is approved for use, including any applicable conditions or limitations on the use of it.

2.12 Flow disturbance

The following requirements apply:

  • For types of gas metering devices whose accuracy is affected by flow disturbances, the shift of the error (i.e. fault) due to these disturbances must not exceed one third of the MPE.
  • Where a gas metering device is specified to be installed in a specific piping configuration in which its accuracy has proven to stay within the requirement and producing only mild flow disturbances, such restrictions must be set out in the notice of approval.

2.13 Drive shaft (torque)

For types of gas meters provided with one or more drive shafts, the manufacturer must provide the maximum torque that can be applied without exceeding one third of the MPE.

2.14 Different gases

The types of gas metering devices which are intended to be used for different gases must comply with the requirements specified in subsection 2.3 over the whole range of gases for which they are specified by the manufacturer.

2.15 Influences from ancillary devices

Gas metering devices with ancillary devices must be designed such that none of the functions of the ancillary devices (for example, provisions for communication purposes) affect the metrological behaviour.

2.16 Supply voltage variation

When a supply voltage variation occurs, the error of the gas metering device requiring a power supply from the mains must not:

  • exceed the MPE;
  • deviate by more than one third from the errors at nominal supply voltage.

3.0 Technical requirements

Note: Except where otherwise stated in these specifications, the following requirements apply according to the gas metering device technology, principle, feature or function.

3.1 Design, composition and construction

The following requirements apply:

  • The design must be suitable for the intended purpose and expected service conditions.
  • The construction must be mechanically and electrically sound, and the materials and finish must be such as to ensure the service life and sustained accuracy of the gas metering device.

3.2 Minimum temperature range

Provisions incorporated in gas meters for sensing flowing gas temperature and the performance of temperature conversion and/or compressibility correction must meet the applicable performance requirements over a minimum temperature range of 40 °C.

3.3 Automatic volume conversion

In situations in which the automatic conversion of metered volume takes place, the gas metering device must provide the registration of at least the unconverted and converted volume.

Notes:

  1. Where the gas metering device is not able to provide the unconverted and converted volume registration, the notice of approval specifies that the device must be used in conjunction with an approved remote indicating device which can provide the specified registration.
  2. Temperature-compensated diaphragm meters are exempt from this requirement.

3.4 Case

The case of a gas metering device intended to contain gas must be so designed and constructed to:

  • withstand environmental conditions;
  • prevent any exterior foreign substance from entering the device; and
  • effectively maintain its accuracy over the entire ranges of its operating parameters.

3.5 Zero flow

The gas meter totalization must not change when the flow rate is zero and the installation conditions are free from flow pulsations.

Note: This condition refers to stationary operating conditions; it does not refer to the response of the gas meter to changed flow rates.

3.6 Flow direction

3.6.1 Bidirectional flow measurement

Where a gas metering device is designed for bidirectional flow measurement, the quantity of gas passed during reverse flow must be recorded and indicated separately.

Note: The gas metering device may also separately record the "net metering" quantity.

3.6.2 Unidirectional flow measurement

Gas metering devices designed for unidirectional flow measurement must withstand incidental or accidental reverse flow without deterioration or change in their metrological properties concerning forward flow measurements.

Note: Where a gas metering device does not comply with the requirement, the notice of approval restricts its use to metering installations where reverse flow is either prevented or not anticipated.

3.7 Indication

The following requirements apply:

  • Every gas metering device whose function is to provide a measured quantity in corresponding units must be equipped with an integral or remote indicating device.
  • Where a gas metering device is approved for use with a remote indicating device, the latter must be approved to be used in conjunction with the former and meet the following conditions:
    • The remote indicating device must be capable of displaying the measured quantities in each legal unit of measurement for which the associated gas metering device is approved;
    • Where an electronic device such as a personal computer or handheld device is used to obtain the measured quantities in each legal unit of measurement, the software or firmware used to obtain these quantities must be approved.

      Note: Therefore any compatible electronic reading device loaded with the approved software or firmware is considered to be an approved indicator, provided that obtaining the readings does not require breaking of the security seal.

  • Gas meters intended to be used in domestic metering installations must be equipped with an indicating device providing access to the measured quantities in corresponding units at the metering site.

    Note: The following gas meters can be used in domestic metering installations:

    • Diaphragm meters
    • Ultrasonic domestic gas meters

3.8 Output

3.8.1 Mechanical output

The capacity per rotating mechanical output shaft (instrument drive or wriggler) of a gas metering device must be such that at Qmax, the output shaft makes at least one rotation every two minutes.

3.8.2 Digital communication

Where the gas metering device output is in a form of digital communication, the poling frequency must be such that the time required to verify the MPE is no more than two minutes.

3.9 Power sources

Note: Electronic gas metering devices may be powered by three types of power sources that may be used alone or in combination:

  • Mains power supply (AC or DC)
  • Non-replaceable battery
  • Replaceable or rechargeable battery
3.9.1 Non-replaceable battery

Electronic gas metering devices powered by a non-replaceable battery must comply with the following requirements:

  • The manufacturer must ensure that the indicated operational lifetime of the battery guarantees that the gas metering device functions correctly for at least as long as the reverification period (i.e. seal period prescribed by MC) of the device.
  • The operational lifetime of the battery stated by the manufacturer or, alternatively, the remaining battery capacity in units of time must be indicated in a clear and unambiguous manner.

    Note: The operational lifetime of the battery or the remaining battery capacity may be prominently indicated on the nameplate or be made visible via the electronic indicating device or output to an external device (by remote interrogation software), or through provisions for printing this information or other method.

3.9.2 Replaceable or rechargeable battery

Electronic gas metering devices powered by a replaceable or rechargeable battery must comply with the following requirements:

  • The remaining battery capacity must be indicated in units of time or an automatic alarm must be incorporated that provides an indication when battery life is below 10%.

    Note: Alternatively, the remaining battery capacity may be made visible via the indicating device or other method.

  • The replacement or recharging of the battery must not adversely affect the programming, metering information or subsequent operation of the gas metering device.
3.9.3 Power failure

Electronic gas metering devices must be designed such that in the event of a power failure (AC, DC or battery), the measured or calculated quantity of gas as well as any configuration parameters, constants and calibration parameters obtained just before the failure are not lost (i.e. non-volatile memory).

3.10 Software

3.10.1 General

Software controlled gas metering devices must comply with the design, construction, performance and sealing/security requirements of S-EG-05.

3.10.2 Software updating and modification capabilities

Where the applicant is seeking approval for a gas metering device with legally relevant software update capability or as a configurable device, the device must comply with the design, construction and performance requirements of S-EG-06.

3.11 Compressibility factors

The calculation of compressibility factors must be in accordance with one of the versions of AGA Report No. 8 or AGA NX-19 listed in the reference section.

3.12 Registration

The means provided for the registration must be non-resettable (i.e. not be reset to any other value, including zero) under normal operating conditions once the gas metering device is sealed.

Note: This section is not applicable to compressed natural gas dispensers (Part 17).

4.0 Marking requirements

Notes:

  1. Except where otherwise stated in these specifications, the following requirements apply according to the gas metering device technology, principle, feature or function.
  2. Alternatively, the markings followed by an asterisk (*) in the subsections below can also be made accessible via a display, printer or interrogation software, in a clear and unambiguous manner.
  3. Integral indicating devices are exempt from the requirements set out in this section.

4.1 Permanency and legibility

All required markings must:

  • be easily legible and indelible under rated operating conditions;
  • not be adversely affected by environmental conditions; and
  • not lead to confusion.

4.2 General

As relevant, the following information must be marked on the casing or on a nameplate permanently affixed to the gas metering device in such a way as to be easily readable when installed:

  1. Departmental approval number;
  2. Manufacturer's name or registered trademark;
  3. Model or type designation;
  4. Serial number;
  5. Ambient temperature range, where less than -30 °C to 40 °C;
  6. Minimum operating pressure Pmin (where applicable) and maximum operating pressure Pmax;
  7. Maximum flow rate Qmax =…<unit>;
  8. Minimum flow rate Qmin =…<unit>;
  9. Transitional flow rate Qt =…<unit>Footnote *;
  10. Gas temperature range for which the errors of the gas metering device must be within the limits of the MPEFootnote *;
  11. Type and range for analogue input and/or output signalFootnote *;
  12. Protocol/interface for digital input and/or outputFootnote *.

4.3 Bar codes or quick response codes

Bar codes or QR (Quick Response) codes must only be used to supplement or duplicate information that is already marked on the gas metering device’s nameplate or displayable on the device’s display as well as interrogation software.

4.4 Temperature converted volumeFootnote *

Devices incorporating temperature conversion functions must have the temperature to which the registered volume is converted (for example, 15 °C or 60 °F) permanently and prominently marked on their nameplate irrespective of background colour.

4.5 Pressure converted volumeFootnote *

Devices incorporating pressure conversion functions must have the following additional information marked on their nameplate:

  1. Pressure transducer range of the device;
  2. Base pressure;
  3. Where a gauge pressure sensor is used, the atmospheric pressure, or range of atmospheric pressures, for which the instrument is suitable.

4.6 Unidirectional flow measurement

Gas meters designed for unidirectional measurement only must be marked to indicate the direction of gas flow (for example, with an arrow) or must have the inlet connection identified.

Note: This requirement is not applicable if the direction of the gas flow is clearly evident from the gas meter's construction.

4.7 Bidirectional flow measurement

Where a gas metering device is designed for bidirectional flow measurement, the following requirements apply:

  • Mechanical operated gas meters must be marked with a double-headed arrow, with a plus (+) and minus (-) sign to indicate which flow direction is positive and which flow direction is negative, respectively.
  • Electronic gas metering devices must:
    • provide for and permit access to the identification of the direction of the flowing gas via its associated display or interrogation software, in a clear and unambiguous manner; and
    • automatically select the applicable set of calibration parameters whenever the flow direction changes.

      Note: This requirement applies where an electronic device is designed to use a different set of calibration parameters for reverse flow, versus those needed for forward flow (such as zeroing and zero cut‑off).

4.8 Output drive shaft

Gas metering devices equipped with an output drive shaft must have their direction of rotation visibly marked in the vicinity of the shaft together with the capacity per revolution of the shaft when another device or a cover is attached.

4.9 External power supply

Gas metering devices requiring an external power supply for operation must have the following information marked on the nameplate:

  • The voltage range;
  • The nominal frequency (applicable for AC supply only).

4.10 SoftwareFootnote *

The gas metering device or component firmware and/or software versions must be prominently indicated.

4.11 Connection terminals

The connection terminals must be identified by markings on the gas metering device or by a table or a schematic diagram permanently affixed to the device.

Note: Where a gas metering device is designed to accept a non-interchangeable cable connector, the connection terminal for that connector is exempted from this requirement.

4.12 Inspection number

Every gas metering device must have an area suitable for affixing the inspection number or the inspection number must be displayed by suitable means such that it is readily accessible at the metering location.

Note: The inspection number may be marked on a nameplate, tag or sticker.

4.13 Verification marks

Every gas metering device must have an area suitable for the application of verification marks.

4.14 Operating information

Where a gas metering device incorporates features which allow adjustments of operating parameters (base pressure, base temperature, etc.) or ranges, the manufacturer must provide a suitable mean for marking or displaying the applicable information.

Note: Suitable mean can be a nameplate, tag, sticker, display or read/write system (with security).

4.15 Ancillary devices

4.15.1 General

If an ancillary device is not subject to legal metrology control, this must be clearly indicated.

4.15.2 Unique identifier

Ancillary devices integral to a gas meter must have a unique identifier (i.e. serial number) marked on the visible face of the device when mounted in the gas meter.

4.15.3 Input drive shaft

Where the ancillary device equipped with an external input is attached to the output drive shaft of a gas meter, the following information must be visibly marked in the vicinity of the input drive shaft:

  • The direction of rotation;
  • The capacity per revolution.

Note: Electronic ancillary devices may have the capacity per revolution of the input drive shaft accessible via their display or by remote interrogation software.

4.16 Modular design

Each interchangeable module of a modular design gas meter must have, as a minimum, the markings, as applicable, specified in the following sections:

  • 4.2 (a), (b), (c), (d), (e) and (j)
  • 4.4
  • 4.5 (b)
  • 4.14

5.0 Sealing requirements

Note: Except where otherwise stated in these specifications, the following requirements apply.

5.1 General

Every gas metering device and any interchangeable measuring component thereof must be constructed so that access to the working parts, adjustments and programming may be effectively prevented by use of the conventional sealing method as per S-EG-02.

5.2 Electronic gas metering devices

Electronic gas metering devices must have sealing provisions designed to accommodate the conventional sealing method, as per S-EG-02, to prevent unauthorized access to fuses, circuit breakers, signal connections and the primary and backup electrical source.

5.3 Modular design

Gas meters of modular design which allow interchangeability of modules (such as rotary meters with interchangeable temperature converting modules) must have suitable provisions for sealing:

  • each module separately;
  • modules together.

5.4 Output drive shaft

The exposed ends of the output drive shaft must be suitably protected when a gas meter is not connected to an attachable ancillary device.

6.0 Administrative requirements

Note:Except where otherwise stated in these specifications, the following requirements apply.

6.1 Approval evaluation

6.1.1 General

The following requirements apply:

  • Gas metering devices must conform to the approved type and the documentation that was submitted in support of approval obtainment.
  • Compliance with the requirements of these specifications must be established on the basis of a combination of performance testing and written attestations of compliance, where applicable and when accepted by MC.
  • All attestations of compliance and testing data must serve as records of compliance and must be maintained as permanent records in a type approval file.
  • Telemetering devices, ancillary devices and indicating devices that are part of a gas metering device submitted for approval by MC must be evaluated and approved as components of it and included in its notice of approval.
  • Retrofit-type separate ancillary devices and telemetering devices subject to approval by MC must be:
    • evaluated to ensure they do not impair or impact the operation of the approved source gas metering device makes and models intended to be retrofitted; and
    • separately approved and issued their own notice of approval.
  • Manufacturers of retrofit-type devices must demonstrate to MC that the use of their devices is authorized by the manufacturer of the approved source gas metering device makes and models intended to be retrofitted.
6.1.2 Attestation of compliance

An attestation of compliance must:

  • contain the company letterhead;
  • be addressed to MC;
  • refer to the approval project and approval number (where applicable);
  • indicate the section(s) of the specifications that the applicant is attesting to;
  • explain how the requirements are met.
6.1.3 Flow measurement types

The applicant must declare whether or not the gas metering device is designed for bidirectional flow measurement or unidirectional flow measurement on installations where incidental or accidental reverse flow is anticipated. Where the device is designed for bidirectional flow measurement, the applicant must also specify any conditions that must be met for the installation and use of the device.

6.2 Samples

Except where otherwise requested by MC, the following rules must apply:

  • Where a gas metering device comes in various sizes and the design, composition and construction are proportional to its size and the pattern remains the same for the series, two samples representing the smallest and the largest size in the series must be submitted for evaluation.
  • Where a homogeneous series extends to gas metering device sizes that exceed the laboratory's capacity, the next nominal size smaller than the largest size in the series must be evaluated.

6.3 Measurement Canada testing

When testing is performed by MC, the following items must be supplied or made available by the applicant:

  • Subject to subsection 6.2, the number of sample gas metering devices manufactured in conformity with the type;
  • Any special equipment required to evaluate the gas metering device;
  • A person with a thorough knowledge of the gas metering device;
  • Other assistance as may be determined throughout the approval process.

6.4 Third party test data from a recognized test facility

6.4.1 Test plan

Where the applicant submits test results from a test facility recognized by MC, the test plan must be approved by MC prior to the testing.

6.4.2 Test conditions not within the scope of the recognized test facility

Where test conditions are not within the scope of recognized test facilities, the applicant must provide MC with the following information :

  • a clear description of the method used to establish and maintain the required test conditions during the applicable testing for evaluation;
  • quality assurance and quality control processes used to establish and maintain the required test conditions.
6.4.3 Operating pressure range

Where test facilities are not available to perform tests over the entire operating pressure range of the gas meter, the applicant must provide test data demonstrating that the pattern to which the gas meter belongs is either insensitive to the operating pressure or may be predicted using a dimensionless number such as the Reynolds number.

Note: This will not cause the gas meter's accuracy to exceed the MPE specified in subsection 2.3.

7.0 Performance test requirements

Note: This section includes general performance test requirements that can be applied. Test conditions and performance tests applicable to a specific type of gas metering device can be obtained by contacting MC.

7.1 General

The following test requirements apply:

  • The applicable general and additional specific test requirements based on the technology, principle of measurement, feature or function of the gas metering device must apply when conducting performance tests.
  • Each required test must meet the requirements as specified in section 2.0, when applicable.
  • All influence quantities except for the influence quantity being tested must remain constant during performance testing of a gas metering device.
  • For electronic gas metering devices, each required test must have no effect on the display, stored data or the device's capability to interpret inputs from connected devices.

7.2 Uncertainty

The following requirements apply:

  • The estimation of the expanded uncertainty U must be made in accordance with the Guide to the expression of uncertainty in measurement (GUM) with a level of confidence of approximately 95%.
  • The expanded uncertainty U of determination of errors of the measured gas quantity must be less than one fifth of the applicable MPE, as specified in subsection 2.3, where applicable.
  • Where the expanded uncertainty U of errors exceeds one fifth of the applied MPE, the test results must be approved by reducing the applied MPE with the excess of the uncertainties.

    New MPE = ± ( 6 5 × MPE U )

7.3 Test conditions

7.3.1 Environmental conditions
  • Reference ambient temperature

    The ambient temperature must be (20.0 ± 5.0) °C with a rate of change not greater than 0.5 °C per hour.

  • "Other than reference" ambient temperature

    Gas metering devices must be tested at ambient temperatures over the range from

    (-30.0 ± 2.0) °C to (40.0 ± 2.0) °C, except when they are intended for use in a temperature-controlled environment, in which case, they must be tested over the range of ambient temperatures specified by the manufacturer.

  • Atmospheric pressure

    The atmospheric pressure used in calculations must be that prevailing at the time of testing.

  • Relative humidity of ambient air

    The relative humidity of the ambient air must be that prevailing at the time of testing.

7.3.2 Operating conditions
  • Reference working temperature

    The flowing gas temperature must be within ± 0.5 °C of the ambient reference temperature, unless temperature corrections are made.

  • "Other than reference" working temperatures

    Based on the environment type where the gas metering device is intended to be used, the requirements specified in Table 1 below apply.

    Note: MC may accept alternative temperature test points, such as those indicated in OIML R137‑2, 12.6.7.1 and 12.6.7.2.

    Part 1, Table 1: "Other than reference" working temperatures
    Environment type where the gas metering device is intended for use "Other than reference" ambient temperature "Other than reference" working temperature
    Non-temperature-controlled environment (-30.0 ± 2.0) °C (-10.0 ± 2.0) °C
    (0.0 ± 2.0) °C
    (40.0 ± 2.0) °C (10.0 ± 2.0) °C
    (30.0 ± 2.0) °C
    Temperature-controlled environment Low ambient temperature (Tmin) specified by the manufacturer 0.25 (TmaxTmin) + Tmin
    High ambient temperature (Tmax) specified by the manufacturer Tmax − 0.25 (TmaxTmin)
  • Working pressure

    The flowing gas pressure must be near atmospheric or the minimum operating pressure (Pmin) specified by the manufacturer, whichever is greater.

    Note: In addition, gas metering devices may be tested at any pressure up to the maximum operating pressure (Pmax).

  • Humidity content of flowing gas

    The humidity content of flowing gas must be such that no condensation occurs during testing.

  • Moisture

    The following requirements must apply:

    • Means must be employed to prevent the accumulation of moisture in the gas metering device during testing.
    • Depending on the dew point of the test gas, it may not be feasible to obtain some of the required temperature values. In these instances, the largest differential temperature obtainable must be considered.
    • The gas metering device must be subjected to the test temperatures for a length of time as is necessary to establish thermal stability.
7.3.3 Power source

Where a gas metering device is powered from an external power supply (i.e. AC or DC), the voltage must be within ± 1% of the rated voltage and the frequency must be within ± 0.2% of the rated voltage.

7.3.4 Flow rate test points

The following requirements apply:

  • The flow rate at which the errors of the gas metering devices need to be determined must be distributed over the measuring range at regular intervals and include Qmin and Qmax (also preferably Qt where applicable).
  • Based on the number of test points per decade (M), the minimum number (N) of test points, ranking from i = 1 to i = N must be calculated according to the following equation:

    N = 1 + M × log  ( Q max Q min )

    Where:

    • N ≥ 6 and rounded to the nearest integer
    • M = 3 unless otherwise specified by MC

    For flow rates covering two decades or more, the following equation presents the distribution of flow rates for i = 1 to i = N-1 and QN = Qmin.

    Q i = ( 10 M ) ( 1 i ) × Q max

    Where:

    • M = 3 unless otherwise specified by MC
  • The flow rate must be within 5% of the value calculated.
7.3.5 Test mediums

The test medium for the performance testing of the gas metering device must be the same as the medium the device is intended to measure.

Note:The test medium is normally natural gas, but air may be used for low-pressure performance testing.

7.3.6 Alternative test mediums

Where the applicant suggests using alternative test mediums for performance testing, the applicant must:

  • contact MC and demonstrate that the performance testing can be done with an alternative medium, at alternative conditions, without introducing a bias, otherwise, the performance testing must be done at the gas metering device's intended operating conditions.
  • obtain MC's requirements for testing and test data submission for the evaluation of the use of the proposed test medium; and
  • ensure the required testing is completed at a test facility recognized by MC and submit the results to MC for evaluation.

7.4 Performance tests

7.4.1 Location of data

Electronic operated gas metering devices equipped with an integral indicating device (e.g. a display) must be evaluated to determine if the indication is derived from the same electronic register as the output signal used for gating the prover during accuracy testing.

7.4.2 Range of programmable parameters

Where a gas metering device incorporates features which allow of making some adjustments of its operating parameters (base pressure, base temperature, etc.) or its range, the device must be tested over a range of such features sufficient to establish that the applicable requirements of these specifications are met throughout the range for which approval is sought.

Note: All adjustments and recalibrations will be performed according to the manufacturer's instructions.

7.4.3 Accuracy testing

The error of the gas metering device must be determined at test conditions as described in subsection 7.3.

7.4.4 Repeatability

At Qmin, Qt, and Qmax, the errors are determined three times and the difference between the minimum and maximum measured error is calculated.

7.4.5 Orientation

The following requirements apply:

  • The applicant must demonstrate that the gas metering device is not orientation sensitive; otherwise, devices must be tested in any orientations recommended by the manufacturer and for which approval is sought.
  • Where no specific mounting orientations are recommended, the accuracy measurements as specified in subsection 7.4.3 must be performed in the following orientations:
    • Horizontal;
    • Vertical flow-up; and
    • Vertical flow-down.

Note: Where the requirements are not fulfilled for all prescribed orientations without intermediate adjustments, the notice of approval sets out only the approved orientations.

7.4.6 Flow direction

The following requirements apply:

  • The accuracy measurements as specified in subsection 7.4.3 for gas meters designed for bidirectional measurement must be performed without intermediate adjustments in both flow directions.
  • Where the requirements are not fulfilled for both flow directions without intermediate adjustments, the bidirectional gas meter must be considered unidirectional and marked according to subsection 4.6, and such restriction must be set out in any notice of approval issued by MC.
7.4.7 Flow disturbance

The following requirements apply:

  • Where gas metering device accuracy is susceptible to the installation configuration, the piping configuration must be the one for which approval is sought that is most likely to cause an error in measurement.
  • Where gas metering device accuracy is not susceptible to the piping configuration, the configuration must be the manufacturer's recommended configuration.
  • Where a piping configuration has been identified, the installation being approved must conform to the configuration identified or to one of the permissible configurations where more than one has been identified.
  • To evaluate the gas meter's swirl susceptibility:
    • The inlet to the installation configuration recommended by the manufacturer must be preceded by a clockwise and a counter-clockwise swirl generator constructed of two ninety-degree elbows connected together orthogonally.
    • The outlet of the upstream disturbance must be placed a distance of two times the nominal pipe diameters from the upstream face of the gas metering device.
    • Downstream piping must be straight and equal in diameter to the upstream piping and a minimum of two pipe diameters in length.
    • At reference conditions, tests must be performed at 0.25 Qmax, 0.4 Qmax and Qmax.
    • If a specific minimum length of straight upstream piping (Lmin) is necessary to meet the requirement, this Lmin must be applied during the tests and its value must be stated in the notice of approval.
7.4.8 Durability

The following requirements apply:

  • The durability test must apply to gas meters having a Qmax ≤ 800 ft3/h (or metric equivalent in m3/h) and where the highest wear is expected.
  • When a gas meter comes in various sizes and the design, composition and construction are proportional to its size and the pattern remains the same for the series, one meter must be submitted for the durability test, except where requested otherwise by MC. For gas meters with no moving parts in the measurement transducer, the smallest size must be selected for durability tests.
  • To evaluate the gas meter's durability, the following requirements must apply:
    • The gas meter must be subjected to a continuous flow rate between 0.8 Qmax and Qmax and comprising a quantity that is equivalent to a flow at Qmax during a period of 2,000 hours.
    • This test must be performed at the minimum operating pressure.
    • The same reference equipment must be used before and after the durability test.
  • After the durability test, the gas meter accuracy, as specified in subsection 7.4.3, must be tested.
7.4.9 Vibration and shocks

The following requirements apply:

  • Gas meters having a mass less than or equal to 10 kg must be submitted to vibrations and shocks specified in section 2.9. For gas metering devices exceeding this weight, only the electronic part of the device must be tested.
  • Before and after these tests, the gas metering device accuracy, as specified in subsection 7.4.3, must be tested.
7.4.10 Supply voltage variation

The following requirement apply:

  • A gas metering device requiring power supply from the mains must be tested, at reference ambient temperature, with one of the following:
    • a supply voltage equal to 85% and 110% of the nominal voltage; or
    • a typical voltage within the input voltage range specified by the manufacturer.

      Note: The typical voltage is selected by MC in consultation with the manufacturer.

  • A battery powered gas metering device must be tested at the reference ambient temperature and at the lowest voltage at which it functions properly according to the manufacture's specifications.
7.4.11 Influence of radiated radio frequency electromagnetic fields

Where the performance of gas metering devices may be affected by the presence of an electromagnetic field, they must be subjected to the testing required in OIML R137-1, Annex A, section A.6.1.1 and the test results must be supplied.

7.4.12 Electromagnetic interference susceptibility

Where the performance of gas metering devices may be affected by the presence of electromagnetic interference (EMI), they must be subjected to testing required in OIML R137-1, Annex A, section A.6.1.2 and the test results must be supplied.

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