The Measuring Instruments Regulations 2016

Regulations 2 and 39(1)

[F1 SCHEDULE 1C E+W+S WATER METERS (MI-001) (Annex III to the Directive)

Textual Amendments

F1 Schs. 1A-1K inserted (E.W.S.) (31.12.2020) by The Product Safety and Metrology etc. (Amendment etc.) (EU Exit) Regulations 2019 (S.I. 2019/696), reg. 1, Sch. 27 para. 49 (with Sch. 27 para. 50(a)) (as amended by S.I. 2020/676, regs. 1(1), 2); 2020 c. 1, Sch. 5 para. 1(1)

The relevant requirements of Schedule 1A, the specific requirements of this Schedule and the conformity assessment procedures listed in this Schedule, apply to water meters intended for the measurement of volumes of clean, cold or heated water in residential, commercial and light industrial use.

DEFINITIONS

Minimum Flowrate (Q1)	The lowest flowrate at which the water meter provides indications that satisfy the requirements concerning the maximum permissible errors (MPEs.)
Transitional Flowrate (Q2)	The transitional flowrate is the flowrate value occurring between the permanent and minimum flowrates, at which the flowrate range is divided into two zones, the ‘upper zone’ and the ‘lower zone’. Each zone has a characteristic MPE.
Permanent Flowrate (Q3)	The highest flowrate at which the water meter operates in a satisfactory manner under normal conditions of use, i.e. under steady or intermittent flow conditions.
Overload Flowrate (Q4)	The overload flowrate is the highest flowrate at which the meter operates in a satisfactory manner for a short period of time without deteriorating.

SPECIFIC REQUIREMENTS

Rated Operating Conditions E+W+S

The manufacturer shall specify the rated operating conditions for the instrument, in particular:

1.   The flowrate range of the water. E+W+S

The values for the flowrate range shall fulfil the following conditions:

• Q₃/Q₁ ≥ 40

• Q₂/Q₁ = 1.6

• Q₄/Q₃ = 1.25

2.   The temperature range of the water. E+W+S

The values for the temperature range shall fulfil the following conditions:

0.1 °C to at least 30 °C

3.   The relative pressure range of the water, the range being 0.3 bar to at least 10 bar at Q₃. E+W+S

4.   For the power supply: the nominal value of the AC voltage supply and/or the limits of DC supply. E+W+S

MPE

5.   The MPE, positive or negative, on volumes delivered at flowrates between the transitional flowrate (Q₂) (included) and the overload flowrate (Q₄) is: E+W+S

2 % for water having a temperature ≤ 30 °C,

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

6.   The MPE, positive or negative, on volumes delivered at flowrates between the minimum flowrate (Q₁) and the transitional flowrate (Q₂) (excluded) is 5 % for water having any temperature. E+W+S

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

Permissible Effect of Disturbances

Electromagnetic immunity E+W+S

7.1.1.   The effect of an electromagnetic disturbance on a water meter shall be such that: E+W+S

• — the change in the measurement result is no greater than the critical change value as defined in paragraph 7.1.3, 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.

7.1.2.   After undergoing an electromagnetic disturbance the water meter shall: E+W+S

• — recover to operate within MPE, and

• — have all measurement functions safeguarded, and

• — allow recovery of all measurement data present just before the disturbance.

7.1.3.   The critical change value is the smaller of the two following values: E+W+S

• — the volume corresponding to half of the magnitude of the MPE in the upper zone on the measured volume;

• — the volume corresponding to the MPE on the volume corresponding to one minute at flowrate Q₃.

Durability E+W+S

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

7.2.1.   The variation of the measurement result after the durability test, when compared with the initial measurement result, shall not exceed: E+W+S

• — 3 % of the metered volume between Q₁ included and Q₂ excluded;

• — 1.5 % of the metered volume between Q₂ included and Q₄ included.

7.2.2.   The error of indication for the volume metered after the durability test shall not exceed: E+W+S

• — ± 6 % of the metered volume between Q₁ included and Q₂ excluded;

• — ± 2.5 % of the metered volume between Q₂ included and Q₄ included for water meters intended to meter water with a temperature between 0.1 °C and 30 °C,

Suitability E+W+S

8.1.   The meter shall be able to be installed to operate in any position unless clearly marked otherwise.

8.2.   The manufacturer shall specify whether the meter is designed to measure reverse flow. In such a case, the reverse flow volume shall either be subtracted from the cumulated volume or shall be separately recorded. The same MPE shall apply to both forward and reverse flow. E+W+S

Water meters not designed to measure reverse flow shall either prevent reverse flow or shall withstand an accidental reverse flow without any deterioration or change in metrological properties.

Units of Measurement E+W+S

9.   Metered volume shall be displayed in cubic metres.

Putting into Use E+W+S

10.   The requirements under paragraphs 1, 2 and 3 are determined by the utility or the person legally designated for installing the meter, so that the meter is appropriate for the accurate measurement of consumption that is foreseen or foreseeable.

CONFORMITY ASSESSMENT The conformity assessment procedures specified in the modules in Schedule 1B applicable to water meters that the manufacturer can choose between are:

(a) B and F;

(b) B and D; or

(c) H1.]