G-23 – Recognition of test data from specialty gas suppliers and test laboratories

Category: Gas
Issue date: 2023-01-05
Effective date: 2023-01-05
Revision number: 1
Supersedes: G-23


Table of contents


1.0 Purpose

The purpose of this bulletin is to communicate the requirements and conditions that apply to organizations seeking to be recognized by Measurement Canada (MC) to provide test data for natural gas mixtures used in type approval evaluations or inspections and calibration of gas analyzers.

Such data from recognized organizations may be used by MC for the purposes of certifying gas mixtures and generating certificates of calibration accordingly.

2.0 Scope

This bulletin applies to specialty gas suppliers and laboratories seeking to have their test data recognized by MC and able to comply with the specific requirements and conditions set forth in this bulletin.

3.0 References

  • Electricity and Gas Inspection Act
  • Evaluation of Measurement Data — Guide to the Expression of Uncertainty in Measurement (GUM), JCGM 100:2008 (GUM 1995 with minor corrections)
  • Gas Processors Association (GPA) 2145 Standard: Table of Physical Properties for Hydrocarbons and Other Compounds of Interest to the Natural Gas Industry (latest version)
  • GPA 2172 Standard: Calculation of Gross Heating Value, Relative Density, Compressibility and Theoretical Hydrocarbon Liquid Content for Natural Gas Mixtures for Custody Transfer (latest version)
  • GS-ENG-06-12 — Requirements for the Selection and Use of Natural Gas Mixtures Used by Measurement Canada
  • International Organization for Standardization / International Electrotechnical Commission (ISO/IEC) 17025:2005 Standard: General Requirements for the Competence of Testing and Calibration Laboratories (latest version)
  • ISO 5725 Standard: Accuracy (Trueness and Precision) of Measurement Methods and Results (latest version)
  • ISO 6141 Standard: Gas Analysis — Contents of Certificates for Calibration Gas Mixtures (latest version)
  • ISO 6976 Standard: Natural Gas — Calculation of Calorific Values, Density, Relative Density and Wobbe Indices from Composition (latest version)
  • ISO 9001: Quality Management Systems — Requirements (latest version)
  • ISO/IEC 17025 Standard: General Requirements for the Competence of Testing and Calibration Laboratories (latest version)

4.0 Limitations

  1. This recognition does not delegate legal authority to organizations to certify gas mixtures intended for use in the verification of meters pursuant to the Electricity and Gas Inspection Act (EGIA).
  2. To satisfy the requirements of the EGIA, the use of test data from recognized organizations is limited to MC and authorized service providers.
  3. Recognition of data from a particular organization is limited to the capabilities listed for that organization.

5.0 Terminology

Gas analyzer
(analyseur de gaz)
Any gas analysis device of a type approved by Measurement Canada that may be used in a custody transfer application (e.g. gas chromatograph, calorimeter, densitometer, therm-titrator).
Specialty gas supplier
(fournisseur de gaz spéciaux)
An organization (e.g. a laboratory) that prepares gas mixtures or analyzes prepared gas mixtures and that is recognized or seeking to be recognized by MC to provide test data.

6.0 Technical conditions and requirements

6.1 General

A specialty gas supplier (referred to hereinafter as "organization") that seeks to be recognized by MC to provide test data for gas mixtures, including gas composition and calorific valueFootnote 1, must comply with the technical conditions and requirements of section 6.0 and subsections.

6.1.1 Gas composition

The supplied gas mixtures must be in accordance with the requirements stated in GS‑ENG-06-12.

6.1.2 Calorific value and relative density calculations

The true calorific value and relative density of the supplied gas mixtures must be calculated using the true relative concentrations of all components of the gas mixture, as established in accordance with GPA 2172 and GPA 2145 or ISO 6976 standards.

6.1.3 Calibration certificates and test reports

Subject to 4.0(a), the following information must be included on the calibration certificates or test reports provided by a recognized organization:

  • Name and address of the organization and the location where the calibrations were carried out, if different from the address of the organization;
  • Name and address of the supplier, if different from the organization;
  • Unique identification number of the calibration certificate or test report (such as the serial number);
  • Calibration date and certificate expiry date (maximum of 3 years);
  • Name, function and signature or equivalent identification of the person(s) authorizing the test;
  • Authorization date of the calibration certificate or test report;
  • Page number and total number of pages;
  • Method of preparation used;
  • Method of analysis used;
  • Type of container (cylinder) used, including the lot number and cylinder number and size;
  • Name of specified components (nominal value optional);
  • Gas composition (the reported value of all specified components of the gas mixture must be stated in mole fraction and, for methane, the balance value is accepted);
  • Real gas relative density (specific gravity);
  • Gross calorific value for ideal dry gas and real dry gas, expressed in British thermal unit per standard cubic foot (e.g. : Btu(60,5)/scf, Btu(IT)/scf, Btu(59)/scf) or in joule per standard cubic meter;
  • Base or standard temperature and pressure used in establishing the calorific value;
  • Compressibility factor (dry gas);
  • Calorific value calculation and method used;
  • Expanded uncertainty of the content with a coverage factor of two (k=2) /or a statement of compliance with an identified specification or clauses;
  • Evidence that the measurements are traceable (statement of traceability);
  • Filling pressure;
  • Valve outlet connection;
  • Minimum use pressure (below this pressure significant deviations from stated composition may occur); and
  • Storage and use temperature.

In addition to the above information, it is recommended that the following be included on the calibration certificate or test report, when possible:

  • Name and address of the customer;
  • Commercial name of the gas mixture;
  • Equipment used for preparing the gas mixture;
  • Equipment used for analyzing the prepared gas mixture.

6.1.4 Proficiency testing and monitoring of results

The following requirements apply:

  • In order to assess the proficiency of organizations and to ensure their continued compliance with the requirements of this bulletin, the organization must use monitoring processes such as:
    • Participating in intercomparisons with one or more organizations recognized by MC;
    • Monitoring the performance of the equipment used and measurement standards using a suitable statistical process control;
    • Establishing consistency between prepared mixtures and suitable traceable standards;
    • Using monitoring standards;
    • Using other processes approved by MC.
  • The results of these monitoring processes must be provided to MC upon request.

7.0 Applying for recognition

7.1 General

Organizations seeking to be recognized by MC to provide test data for gas mixtures must supply the following information:

  • A written expression of interest, including the name and address of the test facility as well as the telephone number and email address of the contact person;
  • A copy of existing accreditations or certification and reference numbers (e.g. ISO/IEC 17025, ISO 9001), if applicable;
  • A copy of the scope of the accreditation, if applicable;
  • A copy of the most recent audit report;
  • A sample of a calibration certificate or test report;
  • Information required in subsections 7.2, 7.3, 7.4 and 7.5;
  • Any technical information requested by MC's Engineering and Laboratory Services Directorate (ELSD).

7.2 Traceability

The following conditions and requirements apply:

  • The organization must submit sufficient information to demonstrate traceability to relevant national standard recognized by MC.
  • MC's ELSD will perform a technical assessment to determine the organization's ability to provide calibration services within the values claimed in the submission.
  • The method employed is dependent on the location of the organization on the International traceability chain and current certifications or accreditations.
  • When traceability to the National Research Council of Canada (NRC) cannot be achieved, the organization must obtain traceability from a national metrology institute that actively participates in the activities of the Bureau international des poids et mesures (BIPM) either directly or through regional groups and that is recognized by MC.
  • Traceability may also be obtained through a system of calibrated masses and balances that are directly traceable to the NRC or a metrology institute recognized by MC.
  • Traceability to the International System of Units (SI) may also be attained by analytical testing through the use of a validated test method and the use of gas standards traceable to certified reference material.
  • In the case of organizations which have been accredited to ISO/IEC 17025 by an institution recognized by the International Laboratory Accreditation Cooperation (ILAC), of which the Standards Council of Canada (SCC) is a signatory member, a certificate of accreditation to ISO/IEC 17025 will be deemed as proof of compliance.

7.3 Measurement uncertainty

The following conditions and requirements apply:

  • The organization must submit sufficient information on its overall measurement uncertainty and the specific methods used in its determination. The uncertainty must include the contributions from all relevant uncertainty sources. Additional information on the uncertainty evaluation must be provided as required.
  • The measurement uncertainty must be reported at the 95% confidence interval and include all contributors associated with the preparation of the gas mixture and/or calorific value determination. When a contributor is not considered, it must be appropriately noted.
  • When the preparation and analysis methods are rigorous and valid such as methods published in national, regional or international standards, the organization must at least identify all uncertainty components and make a reasonable uncertainty estimation based on the measurement and knowledge of the performance of the method.
  • The method used for uncertainty calculation must comply with GUM or ISO 5725.

7.4 Test equipment

The organization must:

  • submit information related to the test equipment used to obtain test results; and
  • demonstrate that the equipment used for gas mixture preparation and analysis is capable of achieving the accuracy required.

7.5 Technical procedures

The organization must submit copies of the laboratory procedures used in the preparation of gas mixtures as well as the determination of the calorific value. These procedures must make reference to standard test procedures used (national, regional or international standards).

8.0 Evaluation criteria

MC's evaluation process focuses on the items listed in sections 6.0 and 7.0. It is therefore recommended that the documentation in the submission be organized around these items.

9.0 Recognition

  • MC will monitor the performance of recognized organizations and determine whether to continue recognizing the organization based on the results of the review. Recognized organizations will be re-evaluated periodically. MC may perform on-site audits as part of the evaluation and monitoring of recognized laboratories.
  • The suitability of MC's recognition process and requirements will be periodically evaluated for effectiveness and may be modified or discontinued as necessary. Recognized organizations must be prepared to update processes and procedures to take into account any changes in MC requirements.
  • Requirements may be of a technical or administrative nature. Organizations may, in the future, be required to fulfil certain quality system requirements as MC adjusts its recognition program.

10.0 Recognized organizations

A detailed listing of the organizations recognized by MC and retained by ELSD, Gas Engineering, will be published in the next revision of this bulletin.

11.0 Measurement Canada certification of gas mixtures

Any request for the certification of a gas mixture by MC must be sent to the Gas Laboratory Manager, Approval and Calibration Services Laboratory and include the following documentation:

  • A copy of a completed Calibration Services Request Form;
  • The gas mixture's calibration certificate or test report provided by an organization recognized by MC as meeting the requirements of this bulletin.

12.0 Revisions

The purpose of revision 1 was to:

  • reformat this bulletin according to current formatting requirements;
  • revise the terminology (e.g. replace "heating value" with "calorific value");
  • make references to the latest edition of ISO and GPA standards;
  • recognize the ISO 6976 standard.