S-G-03–Specifications for the approval of type of gas metering devices–Part 14

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


Part 14: Electronic gas metering devices incorporating mass to base volume and/or energy conversion functions

Table of contents


1.0 Scope

This part of the Specifications applies to electronic gas metering devices incorporating functions that convert their mass registration or mass flow rate, as measured by a Coriolis-type mass flow meter, to accumulated units of base volume and/or energy.

Note: For the purposes of this part, the term "calorific value" represents the gross volume-basis calorific value (Hv) established on a real, dry basis by measurement or calculation.

2.0 Unit requirements

Note: The requirements of Part 1, section 1.0, apply.

2.1 Units of measurement of density

The density of the gas calculated by the device is to be expressed in SI units of kg/m3 and/or imperial units of lb/ft3.

3.0 Metrological requirements

3.1 Conversion function accuracy

The accuracy of the device's mass to base volume and/or energy conversion functions are to be assessed for each recognized standard and/or method of calculation of gas properties (i.e. density, relative density or calorific value) for which approval is sought.

3.2 Maximum permissible errors

3.2.1 Mass to base volume conversion

The relative error of the device's mass to base volume conversion function must not exceed a maximum permissible error (MPE) of ±0.1%.

3.2.2 Mass to energy conversion

The relative error of the device's mass to energy conversion function must not exceed a MPE of:

  • ±0.1%, where the calorific value is received as a live input or configured parameter, or
  • ±0.2%, where the calorific value is calculated by the device using gas composition data received as a live input or configured parameters.

4.0 Technical requirements

4.1 Device inputs

The device must be capable of receiving and using:

  • the type and range of output signals from a compatible, approved Coriolis-type mass flow meter;
  • the type and range of output signals representing gas composition data and/or gas properties (i.e. relative density and/or calorific value) from a compatible, approved gas analysis device (for example, a gas chromatograph);
  • locally or remotely configured gas composition data and/or gas properties; and
  • fixed value parameters (density, relative density, calorific value, etc.) calculated in accordance with standards and/or methods currently recognized by MC.

4.2 Calculation of density

The device's calculation of the density of the gas referenced to base conditions of pressure and temperature is to be in accordance with any of the following standards and/or methods:

  • AGA Report No. 8, Part 1, detail and gross characterization methods;
  • AGA Report No. 8 ,Part 2, GERG-2008 characterization method;
  • the relative density of the gas and the density of air as expressed in equation 1.
    • Equation 1

      ρ b = G r × ρ b ( air )

      Where:

      • ρb is the density of gas at base conditions of pressure and temperature
      • Gr is the relative density of gas at base conditions of pressure and temperature
      • ρb(air) is the density of air at base conditions of pressure and temperature

4.3 Calculation of relative density and/or air density

Where applicable, the device’s calculation of relative density and/or density of air must be in accordance with standards and/or methods currently recognized by MC (for example, GPA 2145, GPA 2172, AGA Report No. 8, ISO 6976).

4.4 Calculation of calorific value

Where applicable, the device’s calculation of calorific value must be in accordance with standards and/or methods currently recognized by MC (for example, GPA 2145, GPA 2172, ISO 6976).

5.0 Markings and accessibility of parameters

The value and units of the parameters (whether fixed, configurable, received as live inputs or calculated) listed below that are used by the device's mass to base volume and/or energy conversion functions are to appear on its nameplate or be made accessible by means of a display, printer or interrogation software:

  1. Base pressure to which base volume and items (d) to (g) are referenced
  2. Base temperature to which base volume and items (d) to (g) are referenced
  3. Mole fraction or mole percent gas composition
  4. Relative density
  5. Density of air
  6. Density of gas
  7. Calorific value

6.0 Administrative requirements

6.1 Verifiability of standard and/or method of calculation selected

Where the device is capable of calculating any of the parameters listed below using more than one standard and/or method, the one selected for use in service is to be readily apparent:

  • Relative density
  • Density of air
  • Density of gas
  • Calorific value

top of page