Category: Gas
Issue date:
Effective date:
Revision number: 3
Supersedes: S-G-03 (rev. 2)
Part 5: Orifice fittings
Table of contents
- 1.0 Scope
- 2.0 Unit requirements
- 3.0 Metrological requirements
- 4.0 Technical requirements
- 5.0 Marking requirements
- 6.0 Administrative requirements
- 7.0 Performance test requirements
1.0 Scope
This part of the Specifications applies to orifice fittings being part of orifice meters used to measure natural gas.
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 requirements of Part 1, subsection 2.1 apply.
4.0 Technical requirements
Note: The following requirements of Part 1, section 3.0 apply:
- 3.1 Design, composition and construction
- 3.4 Case
4.1 Recognized standard
These specifications adopt the requirements set out in AGA Report No. 3, Part 2 (Fifth edition, 2016).
4.2 Dimensional measurements
Measurements must be made at reference environmental conditions to establish the dimensions of the orifice fitting as set out in AGA Report No. 3, Part 2 (Fifth edition, 2016).
4.3 Maximum permissible beta ratio
All orifice fittings must meet the tolerances for a maximum permissible beta ratio of 0.7.
5.0 Marking requirements
Notes: The following requirements of Part 1, section 4.0 apply:
- 4.1 Permanency and legibility
- 4.2
- (a) Departmental approval number
- (b) Manufacturer's name or registered trademark
- (c) Model or type designation
- (d) Serial number
- (e) Ambient temperature range, where less than -30 °C to 40 °C
- 4.12 Inspection number
- 4.13 Verification marks
According to the characteristics of the device, the following requirements may also apply:
- 4.3 Bar codes or quick response codes
- 4.6 Unidirectional flow measurement
- 4.7 Bidirectional flow measurement
5.1 Nameplate
The following information must be provided on a nameplate located on the orifice fitting:
- Maximum permissible beta ratio (β);
- Nominal thickness of the orifice plate to be used;
- Seat gap width.
6.0 Administrative requirements
Note: The requirements of Part 1, section 6.0 apply.
7.0 Performance test requirements
Note: Test conditions and performance tests can be obtained by contacting MC.