S-G-03–Specifications for the approval of type of gas metering devices–Part 22

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


Part 22: Conditioning orifice plate meters

Table of contents


1.0 Scope

This part of the Specifications applies to conditioning orifice plate (COP) meters.

2.0 Unit requirements

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

  • 1.1 Use of units
  • 1.2 Metric units of measure

3.0 Metrological requirements

Note: The following requirements of Part 1, section 2.0 apply:

  • 2.1 Rated operating conditions
  • 2.2 Flow rate characteristics
  • 2.3 Maximum permissible errors
  • 2.4 Weighted mean error
  • 2.5 Repeatability
  • 2.6 Working pressure
  • 2.7 Temperature
  • 2.10 Orientation

According to the characteristics of the meter, the requirement of Part 1, subsection 2.14, may also apply.

3.1 Maximum permissible error

The error must not exceed a maximum permissible error (MPE) of ±1%.

3.2 Algorithm

The algorithm used to translate the primary measurements of pressure and temperature into volumetric flow must be the algorithm derived in Appendix B. However, where the applicant can show sufficient evidence that an alternative algorithm is suitable, that algorithm must be authorized for use in the notice of approval.

3.3 Disturbance factors

The difference between the meter accuracy established during baseline testing and the meter accuracy established during flow disturbance testing must not exceed the MPE and the tolerances set out in Part 1, subsections 2.4 and 2.5.

4.0 Technical requirements

Note: The requirements of Part 1, sub-section 3.1 apply.

4.1 Design, composition and construction

The COP must be used in conjunction with an approved orifice fitting (see Part 5).

5.0 Marking requirements

5.1 Conditioning orifice plate

Note: The following requirements of Part 1, section 4.0 apply:

  • 4.1 Permanency and legibility
  • 4.2
  • 4.12 Inspection number
  • 4.13 Verification marks

The following information must be indelibly marked on the downstream face or on the flange of the COP, without distorting it:

  • Beta ratio;
  • Inside diameter of the meter tube;
  • Calibration factor (Fc).

6.0 Administrative requirements

Note: The requirements of Part 1, section 6.0 apply.

6.1 Application for approval

6.1.1 Dimensional tolerances for conditioning orifice plates

Where a manufacturer intends to have a COP reverified by means of dimensional inspection, the following conditions must apply:

  • Critical physical dimensions and their permitted deviations (tolerances) must be provided by the manufacturer/applicant for inclusion in the notice of approval.

    Note: Critical physical dimensions include, but are not limited to:

    • Pipe inside diameter
    • Plate thickness
    • Number of bore holes
    • Average of bore diameters
    • Diameter of bore hole centres
    • Surface roughness
    • Bevel, if applicable
    • Overall plate diameter
  • The manufacturer or applicant must provide test data demonstrating that the dimensional tolerances do not introduce a deviation in performance that is greater than that specified in section 3.0.

7.0 Performance test requirements

Note: Test conditions and performance tests can be obtained by contacting MC.

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