The Measuring Instruments Regulations 2016 PART I — SPECIFIC REQUIREMENTS

1

Rated operating conditions The manufacturer shall specify the rated operating conditions of the gas meter, taking into account:

1

The flowrate range of the gas shall fulfil at least the following conditions:

1

The temperature range of the gas, with a minimum range of 40 °C.

The fuel/gas related conditions

1

The gas meter shall be designed for the range of gases and supply pressures of the United Kingdom. In particular the manufacturer shall indicate: — the gas family or group; — the maximum operating pressure.

The fuel/gas related conditions

1

A minimum temperature range of 50 °C for the climatic environment.

1

The nominal value of the AC voltage supply and/or the limits of DC supply.

Gas meter indicating the volume at metering conditions or mass

2

The gas meter shall not exploit the MPEs or systematically favour any party.

Gas meter indicating the volume at metering conditions or mass

2

For a gas meter with temperature conversion, which only indicates the converted volume, the MPE of the meter is increased by 0.5 % in a range of 30 °C extending symmetrically around the temperature specified by the manufacturer that lies between 15 °C and 25 °C. Outside this range, an additional increase of 0.5 % is permitted in each interval of 10 °C.

Electromagnetic immunity

3

The effect of an electromagnetic disturbance on a gas meter shall be such that: — the change in the measurement result is no greater than the critical change value as defined in paragraph 3.1.3, or — the indication of the measurement result is such that it cannot be interpreted as a valid result, such as a momentary variation that cannot be interpreted, memorised or transmitted as a measuring result.

3

After undergoing a disturbance, the gas meter shall: — recover to operate within MPE, and — have all measurement functions safeguarded, and — allow recovery of all measurement data present just before the disturbance.

3

The critical change value is the smaller of the two following values: — the quantity corresponding to half of the magnitude of the MPE in the upper zone on the measured volume; — the quantity corresponding to the MPE on the quantity corresponding to one minute at maximum flowrate.

Effect of upstream-downstream flow disturbances

3

Under installation conditions specified by the manufacturer, the effect of the flow disturbances shall not exceed one third of the MPE.

Durability

4

After an appropriate test, taking into account the period of time estimated by the manufacturer, has been performed, the following criteria shall be satisfied:

Class 1.5 Gas Meters

4

The variation of the measurement result after the durability test when compared with the initial measurement result for the flow rates in the range Q t to Q max shall not exceed the measurement result by more than 2 %.

4

The error of indication after the durability test shall not exceed twice the MPE in paragraph 2.

Class 1.0 Gas Meters

4

The variation of the measurement result after the durability test when compared with the initial measurement result shall not exceed one-third of the MPE in paragraph 2.

4

The error of indication after the durability test shall not exceed the MPE in paragraph 2.

Suitability

5

A gas meter powered from the mains (AC or DC) shall be provided with an emergency power supply device or other means to ensure, during a failure of the principal power source, that all measuring functions are safeguarded.

5

A dedicated power source shall have a lifetime of at least five years. After 90 % of its lifetime an appropriate warning shall be shown.

5

An indicating device shall have a sufficient number of digits to ensure that the quantity passed during 8,000 hours at Q max does not return the digits to their initial values.

5

The gas meter shall be able to be installed to operate in any position declared by the manufacturer in its installation instruction.

5

The gas meter shall have a test element, which shall enable tests to be carried out in a reasonable time.

5

The gas meter shall respect the MPE in any flow direction or only in one flow direction clearly marked.

Units

6

Metered quantity shall be displayed in cubic metre, or in kilogram.