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 5: Orifice meters

Table of contents


1.0 Scope

This part of the Specifications applies to orifice fittings being part of orifice meters used to measure natural gas and submitted for approval.

2.0 Definitions

Orifice fitting (raccord à orifice)

A primary element component of an orifice meter which is used to contain and position the orifice plate.

Orifice meter (AGA Report No. 3) (compteur à orifice)

A fluid flow measuring device that produces a differential pressure to infer flow rate.

3.0 Metrological and technical requirements

3.1 General

3.1.1 Subject to 3.1.2, these specifications adopt the requirements set out in AGA Report No.3: Orifice Metering of Natural Gas and Other Related Hydrocarbon Fluids, Part 2: Specification and Installation Requirements, (fourth edition, 2000).

3.1.2 All orifice fittings shall meet the tolerances for a maximum permissible beta ratio of 0.7.

4.0 Marking requirements

In addition to the applicable requirements of Part 1, section 9.0, the following shall apply.

4.1 Nameplate

The following information shall be provided on a nameplate located on the orifice fitting:

  1. Published inside diameter of meter tubes;
  2. Maximum permissible beta ratio;
  3. Nominal thickness of the orifice plate to be used;
  4. Nominal thickness of the orifice sealing ring(s) or gaskets to be used.

5.0 Performance tests

5.1 Dimensional measurements

5.1.1 Measurements shall be made at reference environmental conditions to establish the dimensions of the orifice fitting as set out in AGA Report No. 3 Part 2, (fourth edition, 2000).

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