S-G-03–Specifications for the approval of type of gas meters, ancillary devices and associated measuring instruments

Category: Gas
Issue date:
Effective date:
Revision number: 1
Supersedes: LMB-EG-08 and S-G-03


Part 14: Gas chromatographs

Table of contents


1.0 Scope

This part of the Specifications applies to gas chromatographs submitted for approval and used to perform a compositional analysis of a gas sample (calculate the relative density, compressibility and energy density).

2.0 Definitions

Ancillary output signal (signal de sortie auxiliaire)

Output signal that attempts to supply information to an ancillary device other than a dedicated recorder intended for use with the calorimeter.

Energy density (énergie volumique)

Number of energy units per unit of volume at a certain temperature and pressure. Energy density is formally known as calorific power or heating value. It is expressed in British thermal units per cubic foot (BTU/ft³) in the imperial system or in MJ/m³ in the International System of Units (SI).

Laboratory gas chromatograph (chromatographe en phase gazeuse de laboratoire)

Gas chromatograph located at a test facility and used to analyze gas samples taken in situ.

Online gas chromatograph (chromatographe en phase gazeuse en ligne)

Gas chromatograph whose sampling system is directly connected to the gas network and that transmits the energy density, relative density or molecular composition of a gas sample to a correction device or one or more flow computers.

3.0 Metrological requirements

The applicable requirements of Part 1, section 7.0 shall apply unless otherwise stated in this section.

3.1 Maximum permissible error

3.1.1 Where a device provides energy density and/or relative density as a direct output, with or without providing relative concentrations of gas constituents, the energy density error shall not exceed ± 0.1 MJ/m³, and the relative density error shall not exceed ± 0.5%.

3.1.2 Where a device is intended to detect concentrations of only nitrogen and carbon dioxide, the error shall not exceed ± 0.1 mol %.

3.2 Repeatability

The repeatability of error shall be ± 0.3 mol % for constituents over 25 mol %.

4.0 Technical requirements

In addition to the applicable requirements of Part 1, section 8.0, the following apply.

4.1 Calculations

The true energy density and relative density of the sample gas shall be calculated using the true relative concentrations of all components of the sample gas as established in accordance with the following Gas Processors Association standards: GPA 2172—Calculation of Gross Heating Value, Relative Density and Compressibility Factor for Natural Gas Mixtures from Compositional Analysis, and GPA 2145—Table of Physical Properties for Hydrocarbons and Other Compounds of Interest to the Natural Industry.

5.0 Marking requirements

5.1 In addition to the applicable requirements of Part 1, section 9.0, the following information shall be marked on the nameplate or be capable of being displayed by the device:

  1. Ancillary output signal (if provided);Footnote 14-1
    1. Type and range of analogue output signal;
    2. Protocol/interface for digital output.
  2. The recognized standard used by the device in calculating the energy value of the gas composition; and
  3. Where a device provides an indication of energy in the imperial system:
    1. The particular British thermal unit displayed (e.g. BTU(60.5), BTU(IT), BTU(59));
    2. The base temperature and pressure used in establishing the energy density.

6.0 Performance tests

The applicable requirements of Part 1, section 12.0 shall apply unless otherwise stated in this section.

6.1 The chromatograph shall be set up and calibrated according to the manufacturer's instruction.

6.2 Unless the operating range is otherwise specified by the manufacturer, the chromatograph shall be tested at reference and "other than reference" conditions using gases of known composition which may contain any or all of the components as specified in the following table with concentrations within the stated ranges (see Part 14, Table 1).

Part 14, Table 1: Test gas composition
Component MOL %
Oxygen 0.01 to 1
Helium 0.01 to 1
Carbon dioxide 0.01 to 15
Nitrogen 0.01 to 15
Methane 50 to 100
Ethane 0.01 to 20
Propane 0.01 to 10
Isobutane 0.01 to 5
N-butane 0.01 to 5
Iso-pentane 0.01 to 2
N-pentane 0.01 to 2
Hexanes plus 0.01 to 2

6.3 Where one of the above components is used as a carrier gas in the chromatograph, the concentration of that gas in the test sample shall not exceed 0.04 mol %.

6.4 If different ranges are specified by the manufacturer, the device shall be tested using samples of known concentration within the specified ranges.

top of page

Date modified: