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 10: Mechanical volume conversion devices

Table of contents


1.0 Scope

This part of the Specifications applies to mechanical conversion devices/functions submitted for approval.

2.0 Definitions

Mechanical conversion device or function (dispositif ou fonction de conversion mécanique)

Automatic conversion of volume of gas measured at operating conditions to the volume at base temperature or base pressure, or at both, and which may or may not include supercompressibility corrections. Such devices may be incorporated entirely within a meter, be of a modular nature or be intended for use as an ancillary attachment.

3.0 Metrological requirements

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

3.1 Maximum permissible errors

The difference between the error of the converted registration and the unconverted registration shall not exceed the following MPEs at any point within the range for which approval is sought (see Part 10, Table 1).

Part 10, Table 1: Maximum permissible errors for mechanical conversion devices/functions
Conversion type Test conditions MPE
Pressure or temperature Reference ± 0.8%
"Other than reference" ± 1.3%
Pressure + temperature Reference ± 1%
"Other than reference" ± 1.5%
Pressure + temperature+ supercompressibility Reference ± 1.5%
"Other than reference" ± 2%

4.0 Technical requirements

In addition to the applicable requirements of Part 1, section 8.0, the following apply.

4.1 Level indicator

Where the operation of a device depends on it being level, it shall be equipped with a suitable level indicator.

4.2 Frequency of integration

Intermittent type integrators shall integrate at least once for every ten revolutions of the input shaft.

5.0 Marking requirements

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

5.1 Integrator

5.1.1 The following information shall be marked on the device or the host meter, where applicable:

  1. Marking required in Part 1, 9.1.3 (j), 9.2 and 9.3.1;
  2. Fixed parameters for supercompressibility factor (e.g. gas relative density, N2 and CO2 content);
  3. Volume per revolution of input drive;
  4. Non-integral conversion devices shall also be marked with the following:
    1. Maximum speed of rotation of the input drive;
    2. Direction of rotation of the input drive;
    3. Input volume per revolution of the input drive.

5.2 Temperature and pressure sensing elements

The markings required in Part 1, 9.1.3 (b), (c) and (j) shall be marked on the device or the host meter, where applicable.

6.0 Performance tests

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

6.1 General

6.1.1 Integral mechanical conversion devices shall be installed in a host meter for testing.

6.1.2 Non-integral conversion devices shall be driven by a test rig.

6.2 Test conditions

6.2.1 Temperature conversion
6.2.1.1 Working temperatures (tw) at reference environmental conditions

The flowing gas temperature sensing element shall be held at the minimum temperature marked on the nameplate at 25%, 50% and 75% of the span and at the maximum temperature marked on the nameplate.

6.2.1.2 Working temperatures (tw) at "other than reference" environmental conditions

The flowing gas temperature sensing element shall be held at 25% and 75% of the span.

6.2.2 Pressure conversion
6.2.2.1 Working pressures (pw)

The flowing gas pressure shall be at 25%, 50%, 75% and 100% of the pressure range, first with increasing pressure and then with decreasing pressure, ensuring that in reaching any test point, the change in pressure is in one direction only.

6.2.3 Temperature and pressure conversion
6.2.3.1 Reference operating conditions
  1. The flowing gas pressure shall be 50% of pressure range with the flowing gas temperature sensing element held at temperatures stated in 6.2.1.1.
  2. The flowing gas temperature sensing element shall be held at a temperature corresponding to 50% of the span with the flowing gas pressures described in subsection 6.2.2.1.
  3. The flowing gas pressure shall be 25% and 100% of the pressure range with the flowing gas temperature sensing element held at minimum and maximum temperature.
6.2.3.2 "Other than reference" operating conditions

The flowing gas pressure shall be at 25%, 75% and 100% of the maximum pressure with the flowing gas temperature sensing element held at temperatures corresponding to 25% and 75% of the span.

6.3 Flow rate test point

6.3.1 Integral conversion devices/functions shall be tested at 25% of Qmax.

6.3.2 Non-integral conversion devices/functions shall be tested at the maximum speed of rotation or input frequency specified by the manufacturer.

6.4 Evaluation tests

6.4.1 Accuracy testing
6.4.1.1 Temperature conversion
  1. At reference conditions, tests shall be performed at the flow rate as specified in subsection 6.3 at working temperatures as stated in 6.2.1.1 (see Part 10, Table 2).
  2. At "other than reference" conditions, tests shall be performed at the flow rate as specified in subsection 6.3 at working temperatures as stated in 6.2.1.2 (see Part 10, Table 2).
Part 10, Table 2: Temperature conversion — accuracy testing
Integral or non-integral Flow rate (Q) Working temperature (tw) (% of span and Tmin or Tmax marked on the nameplate) Environmental conditions
Integral 0.25 Qmax Tmin, 25%, 50%, 75%, Tmax Reference
25% "Other than reference" (low ambient temperature)
75% "Other than reference" (high ambient temperature)
Non-integral 100% of max speed of rotation or input frequency Tmin, 25%, 50%, 75%, Tmax Reference
25% "Other than reference" (low ambient temperature)
75% "Other than reference" (high ambient temperature)
6.4.1.2 Pressure conversion

At reference and "other than reference" conditions, tests shall be performed at the flow rate as specified in subsection 6.3 at working pressures as stated in subsection 6.2.2.1 (see Part 10, Table 3).

Part 10, Table 3: Pressure conversion — accuracy testing
Integral or non-integral Flow rate (Q) Working pressure (pw) (% of range) Environmental conditions
Integral 0.25 Qmax 25%, 50%, 75%, 100%, 75%, 50%, 25% Reference
"Other than reference"
Non-integral 100% of max speed of rotation or input frequency 25%, 50%, 75%, 100%, 75%, 50%, 25% Reference
"Other than reference"
6.4.1.3 Temperature and pressure conversion

At "reference" and "other than reference" conditions, tests shall be performed at the flow rate as specified in subsection 6.3 at operating conditions as stated in subsection 6.2.3 (see Part 10, Table 4).

Part 10, Table 4: Temperature and pressure conversion accuracy testing
Integral or non-integral Flow rate (Q) Environmental conditions Working temperature (tw) (% of span and Tmin or Tmax marked on the nameplate) Working pressure (pw) (% of range)
Integral 0.25 Qmax Reference Tmin, 25%, 50%, 75%, Tmax 50%
50% 25%, 50%, 75%, 100%, 75%, 50%, 25%
Tmin, Tmax 25%
100%
"Other than reference" (low ambient temperature) 25% 25%, 50%, 75%
"Other than reference" (high ambient temperature) 75%
Non-integral 100% of max speed of rotation or input frequency Reference Tmin, 25%, 50%, 75%, Tmax 50%
50% 25%, 50%, 75%, 100%, 75%, 50%, 25%
Tmin, Tmax 25%
100%
"Other than reference" (low ambient temperature) 25% 25%, 50%, 75%
"Other than reference" (high ambient temperature) 75%
6.4.2 Out-of-level tests

For non-integral conversion devices not equipped with a level indicator, at least two tests at reference conditions shall be selected from those specified in subsections 6.4.1.1, 6.4.1.2 or 6.4.1.3, or as applicable to determine whether the device remains within tolerance when out of level by five degrees.

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