S-G-03–Specifications for the approval of type of gas metering devices–Part 15

Category: Gas
Issue date:
Effective date:
Revision number: 3
Supersedes: S-G-03 (rev. 2)


Part 15: Indicating devices

Table of contents


1.0 Scope

This part of the Specifications applies to indicating devices. These devices may be of one of the following types:

  • mechanical (e.g. mechanical register);
  • electronic;
  • a combination of both.

2.0 Unit requirements

Note: The requirements of Part 1, section 1.0 apply.

3.0 Metrological requirements

Note: The requirements of Part 1, subsection 2.1, apply.

3.1 Mechanical registers

3.1.1 Gear ratios

The following requirements apply:

  • Mechanical register gear ratios between all dials or drums must be correct and in agreement with the intended values.
  • The overall gear ratio of mechanical registers from the input shaft to the lowest reading dial or drum must be correct for use on the meter.
3.1.2 Proving and test provision capacities

Proving and test provision (dial or drum) capacities, where present, must be correct as marked on the faceplate of the mechanical register.

3.1.3 Operation

Mechanical registers must function as intended at any "other than reference" environmental conditions (gears must mesh and must not bind).

3.2 Electronic indicating devices

The following requirements apply:

  • Electronic indicating device input parameters and displayed numerals must be correct and in agreement with the intended values.
  • The capacity of proving and test provisions, where present, must be correct as marked.
  • The operation and readability of electronic indicating devices must not be affected by variations in temperature.

4.0 Technical requirements

Note: The following requirements of Part 1, section 3.0 apply:

  • 3.1 Design, composition and construction
  • 3.7 Indication
  • 3.9 Power sources
  • 3.10 Software
  • 3.12 Registration

4.1 Capacity

4.1.1 Mechanical registers

A mechanical register, whether converted or unconverted, must be so designed that the registration will not repeat when the host meter operates continuously at its rated or maximum capacity for a period of 90 days, unless stated otherwise in the subsequent sections of these specifications.

4.1.2 Electronic indicating devices

The electronic indicating device must be able to provide an indication corresponding to at least 90 days of operation at the rated or maximum capacity, without returning to the original indication. In addition, the registration must be available for the same period of time.

4.2 Legibility

The following requirements apply:

  • The indicating device face and markings thereon must be of contrasting colours to provide for ease of reading.
  • The size of letters and numerals must be such that they are clearly legible.

4.3 Mechanical registers

4.3.1 Pointer type mechanical registers

The following requirements apply:

  • The minimum diameter of clock dial circles must be 10 mm;
  • Each dial must be divided into 10 equal and clearly numbered divisions;
  • The dial centres must be located so as to avoid any possibility of ambiguity in reading;
  • Each dial must be marked to indicate the number of measured units per revolution of the pointer;
  • The dials must be distinctly separated from each other;
  • The mechanical register gearing must be such that a complete revolution of any pointer must cause the adjacent pointer on the left to advance one division;
  • There must be no overall multiplier indicated on the mechanical register.
4.3.2 Drum type mechanical registers

The following requirements apply:

  • The digits of the counter must be in a straight horizontal line and easily visible through one or more cut-outs in the mechanical register face;
  • The arrangement of the counter drums and the cut-out(s) on the mechanical register face must be such that, with the exception of the fastest rotating drum, only one digit per drum is in full view at all times except when a drum is advancing from one position to another;
  • The duration of this change period must not exceed the time required for the fastest-rotating drum to make one-tenth of a revolution;
  • Where the last digit shown on a drum type mechanical register represents a multiple of applicable units of measurement, there must be one of the following:
    • A number of zeros marked on the mechanical register face immediately to the right of the last digit, and in line with it, so that the reading of the mechanical register with the additional zeros is in applicable units; or
    • An inscription below the drum digits on the mechanical register face to show the applicable multiplier, such as "Reading × l00 = m3". The multiplier must be an integral power of 10.
4.3.3 Proving provisions for mechanical registers

Mechanical registers must be equipped with one of the following means to facilitate proving and testing:

  • A proving dial;
  • A proving drum that meets the following requirements:
    • The proving drum must be divided into 10 equal numbered divisions;
    • The diameter of the proving drum in relation to the size of the cut-out in the register face must be such that for any rotational position of the drum there is at least one numbered division in full view;
    • There must be a reference mark or marks designed in a manner to reduce or eliminate reading errors caused by parallax;
    • The volume per revolution of the proving drum must be marked on the face of the mechanical register in the vicinity of the proving drum;
    • The proving drum division markings and the size and location of the reference mark must be such that the position of the drum with respect to the reference mark can be accurately determined;
    • The measured quantity per revolution of the proving drum must be such that the proving drum makes at least one revolution every two minutes at Qmax.
  • A proving dial and a test dial that meet the following requirements:
    • They must not be in the same geometric line as the reading dials;
    • They must have a minimum of 10 equally spaced divisions and arrows must show the direction of rotation of the pointers;
    • The quantity per revolution of the associated pointer must be clearly marked;
    • No numbers must appear on the divisions;
    • The measured quantity per revolution of the proving pointer must be such that the proving pointer makes at least one revolution every two minutes at Qmax.
4.3.4 Gas meters incorporating converting provisions

Where mechanical registers are employed on gas meters incorporating converting provisions, both the converted and unconverted mechanical registers must meet the requirement set out in subsection 4.3.3.

4.4 Electronic indicating devices

4.4.1 Operation and readability

The operation and readability of electronic indicating devices must be suitable for use under the variety of environmental conditions which may be encountered in the intended operation, such as temperature, bright light, humidity, etc.

4.4.2 Multiple quantities

Where one electronic indicating device is used to indicate several different quantities, the following requirements apply:

  • The quantity and the direction of bidirectional measurement must be indicated;
  • When not controlled by the operator, the minimum indication time must be six seconds;
  • The units associated with the registration and applicable multiplier, if other than unity, must be indicated by use of one of the following:
    • Abbreviations accepted by MC;
    • A code (an explanation of the codes must be available without the use of specialized equipment); or
    • Other methods which clearly identify the units and applicable multiplier, without the use of specialized equipment.

5.0 Marking requirements

Note: The requirements of Part 1, section 4.0 apply, except for an indicating device forming an integral part of a gas metering device.

5.1 Integral indicating devices

5.1.1 Part number

Indicating devices which are an integral component of the host meter must bear an indelible marking of the manufacturer's part number, which must be unique for each model of indicating device.

Note: Where only one model and version is available, the device is exempt from this requirement.

5.2 Remote indicating devices

The following information must be identified on the remote indicating device nameplate and/or displayed by the remote indicating device:

  • make and name and/or model number of the remote indicating device;
  • Notice of Approval number for the remote indicating device and gas metering device combination;
  • approved firmware version and, where applicable, hash codes for the remote indicating device and gas metering device;
  • serial number of the remote indicating device; and
  • serial number of the gas metering device to which the remote indicating device is connected.

5.3 Units

Where an indicating device is not intended to display more than one quantity, the units or symbol being indicated must be prominently marked or indicated on or adjacent to the indicating device face.

6.0 Sealing requirements

Note: The requirement of Part 1, subsection 5.1 applies.

According to the characteristics of the device, the requirement of Part 1, subsection 5.2 may also apply.

7.0 Administrative requirements

Note: The requirements of Part 1, section 6.0 apply.

8.0 Performance test requirements

Note: Test conditions and performance tests can be obtained by contacting MC.

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