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 11: Electronic volume conversion devices/functions and flow computers

Table of contents


1.0 Scope

This part of the Specifications applies to electronic volume conversion (EVC) devices/functions and flow computers submitted for approval.

2.0 Definitions

Configurable parameter (paramètre configurable)

Any adjustable or selectable parameter within a configurable device that can have an effect on the accuracy of a device or can significantly increase the potential for fraudulent use of the device and, based on its nature, may need to be updated on an ongoing basis or only during device installation or upon replacement of a component.

Electronic volume conversion device or function (dispositif ou fonctions de conversion du volume électronique)

Device or function that processes information related to the measurement of natural gas and electronically performs calculations based on the information received. Includes devices such as flow computers for use with orifice meters and volumetric meters and to built-in or associated measuring temperature, pressure, supercompressibility and/or mass conversion devices.

Programmable constant (constante programmable)

Configurable parameter used in a flow computation which is constant for a given set of operating conditions, but which may be reprogrammed for another set of operating conditions.

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

3.1.1 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 11, Table 1).

Part 11, Table 1: Maximum permissible errors for electronic volume conversion devices/functions and flow computers
Type Test conditions Conversion type MPE
Flow computers without sensors (delta P, P and T) Reference Temperature ± 0.2%
Pressure
Temperature + pressure
Temperature + pressure + supercompressibility ± 0.3%
"Other than reference" Temperature As specified in subsection 3.1.2
Pressure
Temperature + pressure
Temperature + pressure + supercompressibility
EVC devices/functions and flow computers with sensors Reference Temperature ± 0.5%
Pressure
Temperature + pressure ± 0.8%
Temperature + pressure + supercompressibility ± 1%
"Other than reference" Temperature ± 1%
Pressure ± 1%
Temperature + pressure ± 1.3%
Temperature + pressure + supercompressibility ± 1.5%

3.1.2 For flow computers without sensors (delta P, P and T), the difference between the error established at reference test conditions and the error at "other than reference" test conditions shall not exceed ± 0.2%.

4.0 Technical requirements

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

4.1 Frequency of sampling

The device shall be capable of sampling applicable inputs and calculating the measurement units at least every 30 seconds. Where no input is received from the primary meter, no sampling need take place.

4.2 Calculations

4.2.1 Calculations of accumulated units of measurement shall be according to appropriate flow equations and other provisions of the EGIA and EGIR.

4.2.2 Calculations by flow computers intended for use with orifice meters shall minimally be according to the provisions of the latest edition of AGA Report No. 3, Orifice Metering of Natural Gas and Other Related Hydrocarbon Fluids.

4.3 Flow computers

4.3.1 General

The non-measured data necessary for conversions and correction shall be present in the flow computer before a measurement is made.

4.3.2 Multi-channel flow computers

4.3.2.1 Where a flow computer is designed to process information from more than one meter, it shall be capable of accepting the required meter-specific inputs separately for each meter.

4.3.2.2 The inputs for base pressure, base temperature, atmospheric pressure, relative density and mol % content of the gas components applicable to the calculation method applied or calorific power may be common for all meters, subject to the following requirements:

  1. Common inputs for relative density and mol % content of the gas components applicable to the calculation method applied or calorific power shall be limited to use with groups which are fed from a common supply of gas; and
  2. Common inputs for atmospheric pressure shall be limited to use with groups of meters which are such that the requirements of the EGIR will be complied with.

5.0 Marking requirements

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

5.1 The following information shall appear on the nameplate or be accessible via the device's electronic display or output to an external device, through provisions for printing this information or other method:

  1. MinimumFootnote 11-1 and maximum ranges of measurement parameters for all sources which the device may be configured to measure;
  2. Configured range of measurement parameters for all sources which the device is configured to measure;
  3. Values of all fixed constants or quantities used in the calculation of measurement units;
  4. Values of all live quantities used in the calculation of measurement units;
  5. Value of each of the variables in the equation used to determine measurement units.

5.2 Where codes are used, a legend shall appear on the device.

6.0 Administrative requirements

In addition to the applicable requirements of Part 1, section 11.0, the following apply.

6.1 Where switch settings, jumper locations or other means used to identify the value of a fixed constant is permitted in the NOA, the approval shall identify each fixed constant for which the method is applicable and the configuration or the other means for each value of each fixed constant.

7.0 Performance tests

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

7.1 General

7.1.1 Electronic volume conversion devices/functions and/or flow computers (devices with sensors)

Devices with transducers shall be attached to the host meter for testing.

7.2 Test conditions

7.2.1 Flow computers (devices without sensors (Delta P, P and T))
7.2.1.1 Reference operating conditions
  1. All inputs and programmable constants at their minimum, median and maximum values;Footnote 11-2
  2. Each input and programmable constant in turn at its maximum and minimum valuesFootnote 11-2 with the remaining parameters at their median values.
7.2.1.2 "Other than reference" operating conditions

All inputs and programmable constants shall be at their median values.

7.2.2 Electronic volume conversion devices/functions and/or flow computers (devices with sensors)
7.2.2.1 Temperature conversion
  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.
  2. Working temperatures (tw) at "other than reference" environmental conditions
    The flowing gas temperature sensing element shall be held at temperatures corresponding to 25% and 75% of the span.
7.2.2.2 Pressure conversion
  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.
7.2.2.3 Temperature and pressure conversion
  1. Reference operating conditions for inputs corresponding to a linear meter:
    1. The flowing gas pressure shall be 50% of the pressure range with the flowing gas temperature sensing element held at the temperatures stated in 7.2.2.1(a).
    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 7.2.2.2(a).
    3. The flowing gas pressure shall be 25% of the pressure range and the flowing gas temperature sensing element held at the minimum and maximum temperature marked on the nameplate.
    4. The flowing gas pressure shall be 100% of the pressure range and the flowing gas temperature sensing element held at the minimum and maximum temperature marked on the nameplate.
  2. Reference operating conditions for inputs corresponding to a differential meter:
    1. Operating conditions as specified in 7.2.2.3(a) (i) and (ii) with a differential pressure of 50%.
    2. Operating conditions as specified in 7.2.2.3(a) (iii) with a differential pressure of 10% and 100%.
    3. Operating conditions as specified in 7.2.2.3(a) (iv) with a differential pressure of 10% and 100%.
    4. The flowing gas pressure and temperature shall be held at 50% of their respective ranges with the differential pressures at 10%, 25%, 50%, 75% and 100% of the differential pressure range, first with increasing differential pressure and then with decreasing differential pressure.
  3. "Other than reference" operating conditions for inputs corresponding to a linear meter:
    The flowing gas pressure shall be at 25%, 50% and 75% of the maximum pressure with the flowing gas temperature sensing element held at temperatures corresponding to 25% and 75% of the span.

7.3 Flow rate test points

7.3.1 Integral conversion devices/functions shall be tested at 10% of Qmax and Qmax.

7.3.2 Non-integral conversion devices/functions shall be tested at 10% and at maximum speed of rotation or input frequency specified by the manufacturer.

7.4 Evaluation test

7.4.1 Accuracy testing — Flow computers (devices without sensors (Delta P, P and T))

7.4.1.1 Device without sensors shall be tested by performing the following tests. This does not preclude testing with other external devices.

7.4.1.2 The device shall be tested at "reference" and "other than reference" conditions as stated in subsection 7.2.1 (see Part 11, Table 2).

Part 11, Table 2: Flow computers without sensors — accuracy testing
Environmental conditions Working temperature (tw) (% of span and Tmin or Tmax marked on the nameplate) Working pressure (pw) (% of Pmax) Differential pressure (% of span)
Reference 50% 50% 50%
100% (max.)
0% (min.)Footnote 11-2
50% 100% (max.) 50%
25% (min.)Footnote 11-2
50% 100% (max.)
10% (min.)Footnote 11-2
100% (max.) 100% 100%
0% (min.)Footnote 11-2 25% (min.)Footnote 11-2 10% (min.)Footnote 11-2
"Other than reference" 50% 50% 50%
7.4.2 Accuracy testing of electronic volume conversion devices/functions and/or flow computers (devices with sensors)
7.4.2.1 Temperature conversion
  1. Devices with integral sensors shall be tested by performing the following tests. The device can be an integral or non-integral device to a host gas meter. This does not preclude additional testing with other included devices.
  2. At "reference" and "other than reference" conditions, tests shall be performed at flow rate test points according to subsection 7.3 and at working temperatures as stated in subsection 7.2.2.1 (see Part 11, Table 3).
Part 11, Table 3: Accuracy testing of electronic volume conversion devices/functions and/or flow computers (devices with sensors) – temperature conversion
Integral or non-integral Flow rate (Q) Environmental conditions Working temperature (tw) (% of span and Tmin or Tmax marked on the nameplate)
Integral 0.10 Qmax, Qmax Reference Tmin, 25%, 50%, 75%, Tmax
"Other than reference" (low ambient temperature) 25%
"Other than reference" (high ambient temperature) 75%
Non-integral 10% and 100% of max speed of rotation or input frequency Reference Tmin, 25%, 5%0, 75%, Tmax
"Other than reference" (low ambient temperature) 25%
"Other than reference" (high ambient temperature) 75%
7.4.2.2 Pressure conversion
  1. The device with integral sensors shall be tested. The device can be an integral or non-integral device to a host gas meter.
  2. At "reference" and "other than reference" conditions, tests shall be performed at flow rate test points according to subsection 7.3 and at working pressures as stated in subsection 7.2.2.2(a) (see Part 11, Table 4).
Part 11, Table 4: Accuracy testing of electronic volume conversion devices/functions and/or flow computers (devices with sensors) — pressure conversion
Integral or non-integral Flow rate (Q) Working pressure (pw) (% of range) Environmental conditions
Integral 0.10 Qmax, Qmax 25%, 50%, 75%, 100%, 75%, 50%, 25% Reference
"Other than reference"
Non-integral 10% and 100% of max speed of rotation or input frequency 25%, 50%, 75%, 100%, 75%, 50%, 25% Reference
"Other than reference"
7.4.2.3 Temperature and pressure conversion

At "reference" and "other than reference" conditions, tests shall be performed at test points according to subsection 7.3 and at operating test conditions as stated in subsection 7.2.2.3 (see Part 11, Table 5).

Part 11, Table 5: Accuracy testing of electronic volume conversion devices/functions and/or flow computers (devices with sensors) — temperature and pressure conversion¨
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 0.10 Qmax, 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 10% and 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%

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