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 16: Pressure regulators

Table of contents


1.0 Scope

This part of the Specifications applies to pressure regulators submitted for approval and intended for use in pressure factor metering (PFM).

2.0 Metrological requirements

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

2.1 Maximum permissible error

2.1.1 For the purpose of this section, the error shall be determined as follows:

E = ((Po-Pset) ÷ (Pset + Ps)) × 100%

where,

2.1.1.1 Strictly speaking, the ambient atmospheric pressure should be used in place of Ps in the denominator of the above equation. However, in this case, standard pressure shall be used to eliminate the effect varying atmospheric pressure would have on the repeatability of tests.

2.1.2 The MPE of the regulator output shall be ±1% over the range of flow rates and inlet pressures for which approval is sought.

3.0 Marking requirements

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

3.1 Subject to 3.1.1, a nameplate, tag, sticker or other suitable means shall be provided for marking inlet pressure range, outlet pressure set point, orifice size(s) and spring identification.

3.1.1 The method used for providing the markings shall ensure the markings are accessible during PFM inspections without the requirement for specialized equipment.

4.0 Performance tests

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

4.1 The applicant shall conduct tests at various combinations of inlet pressures, outlet pressures, flow rates, springs and orifices for which approval of type is sought at reference and "other than reference" test conditions.

4.2 Test points shall be selected from within the regulator's operating range to establish the acceptability of the manufacturer's published performance data.

4.3 Tests for any combination of orifices, springs and any other interchangeable components will consist of adjusting the regulator according to the manufacturer's instructions, varying the flow rate while maintaining the inlet pressure constant, and varying the inlet pressure while maintaining the flow rate constant.

4.3.1 Where no specific adjustment instructions are provided by the manufacturer, the set pressure shall be adjusted with the inlet pressure at 50% of its range and the flow rate at 10% of its range.

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