Minimum Throughset (Q ₁ )

The lowest flow rate for which the hot water meter displays results that meet the maximum tolerated error requirements.

Transient rate (Q ₂ )

The rate between the stable flow and the minimum flow rate that is delineating two zones of the flow range, namely the upper and lower load extents to which different maximum tolerated errors apply.

Stable rate (Q ₃ )

The maximum flow rate for which the hot water meter operates satisfactorily under normal conditions of use, that is, in stable or variable flow conditions.

Overload rate (Q ₄ )

The maximum rate for which the meter operates satisfactorily, without disturbance, for a short time.

1.1

The manufacturer shall indicate the nominal operating conditions for the flow rate of the hot water.

The values of the flow range must meet the following conditions:

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Q ₃ /Q ₁ ³ 10;

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Q ₂ /Q ₁ = 1.6;

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Q ₄ /Q ₃ = 1.25.

Within five years after the coming into force of this Order, the Q ₂ /Q ₁ May have values of 1.5; 2.5; 4 or 6.3.

1.2

The manufacturer shall indicate the nominal operating conditions for the temperature range of the hot water.

The temperature range should range from 30 ° C to at least 90 ° C.

1.3

The manufacturer shall indicate the nominal operating conditions for the relative pressure range of the hot water.

The relative pressure range should range from 0.3 bar to at least 10 bars for Q ₃ .

1.4

The manufacturer shall indicate the nominal operating conditions for the power supply: nominal values of the ac power supply and/or limit values of the dc power supply.

2.1

Maximum tolerated, positive or negative errors are 3 % on the volumes provided for flow rates between the transitory flow rate (Q ₂ ) (included) and overload rate (Q ₄ ).

2.2

Maximum tolerated, positive or negative errors are 5 % on the volumes provided for flows between the minimum flow rate (Q ₁ ) And the transient rate (Q ₂ ) (excluded).

3.1

An electromagnetic disturbance cannot influence the hot water meter:

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If the change in the result of the measure does not exceed the limit value specified in the c. 3.3, or

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If the indication of the result of the measure is such that it cannot be regarded as valid, as is the case in a short fluctuation which cannot be interpreted, recorded or transmitted as a result of the measure.

3.2

After an electromagnetic disturbance, the hot water meter shall:

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Resume operation within the limits of maximum tolerated errors;

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Have all of its measurement functions insured, and

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To recover all available measurement data just before the disturbance.

3.3

The limit value is the smallest of the following two values:

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The volume that corresponds to one-half of the maximum permissible error on the volume measured for the upper load range;

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The volume that corresponds to the maximum tolerated error for the volume that transited in one minute at flow Q ₃ .

4.1

After an appropriate review has been carried out taking into account the time limits proposed by the manufacturer, the following criteria must be met:

4.2

At the end of the durability test, the variation of the measurement against the result of the initial measurement shall not exceed the following values:

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± 3 % of the volume measured between Q ₁ (included) and Q ₂ (excluded);

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± 1.5 % of the volume measured between Q ₂ (included) and Q ₄ (included).

4.3

The measurement deviation for the volume measured after the durability test shall not exceed the following values:

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± 6 % of the volume measured between Q ₁ (included) and Q ₂ (excluded);

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± 3.5 % of the volume measured between Q ₂ (included) and Q ₄ (included).

5.1

Unless otherwise indicated, the meter shall be capable of being used in all positions.

5.2

The manufacturer must specify whether the meter is designed to measure inverted flows. If this is the case, the reverse flow volume must be either subtracted from the cumulative volume or entered separately. The maximum tolerated error is the same for the normal flow and the reverse flow.

5.3

Hot water meters which are not designed to measure reverse flow shall either prevent or withstand an accidental spill without damage or modification of their metrological characteristics.

The measured volume should be displayed in m ³ .

If the user makes use of at least 150 hot water meters and thermal energy meters, the user may apply to METAS for a procedure to extend the verification period under the following conditions:

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The procedure should ensure proper measurements of correct measurements;

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All hot water meters and thermal energy meters in service must have been placed on the market in accordance with s. 5 or 8 of this order, and none of these meters, at any time, may have been in service for more than ten years without further verification under Schedule 7, c. 1, of the Ordinance on Measuring Instruments;

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Defective meters shall be replaced by conforming meters;

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All meters in service must be operated under comparable conditions;

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The user informs METAS once a year of the results of the procedure.

If the rated power of the thermal energy metering installation is at least 10 MW, the user may choose the calibration according to Annex 7, c. 6, of the order on measuring instruments to ensure the maintenance of stability of measurement if the following conditions are met:

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The exchange of thermal energy takes place by fixed pipes between two permanent partners, the quantity supplied being determined in a measurement station on the basis of the data supplied by one or more thermal energy meters, including the Sum of the nominal powers is at least 10 MW;

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The thermal energy metering installation is in place between two trading partners, both of whom are able to judge the outcome of the measures;

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The thermal energy metering installation is subject to regular metrological monitoring of qualified operating personnel;

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If parts of the metering installation cannot be calibrated in the undertaking, the calibration of the measuring instruments shall be performed by a calibration laboratory recognized by METAS, by an authorized verification laboratory or by METAS. The installation of thermal energy measurement shall be sealed in an identifiable manner after calibration;

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The thermal energy metering installation is calibrated as required, but generally every 12 months. The validity of the calibration of each part of the metering installation shall not exceed two years;

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All work (maintenance, adjustment, calibration) performed on the thermal energy metering installation is recorded in minutes. The data collected must be used to determine what work has been done, when and by whom. In the event of a dispute, the minutes must be able to be submitted to the appropriate body.

A thermal energy meter for liquids is either a complete meter or a combined meter consisting of the subsets "flow sensor", "pair of temperature sensors" and "unit of calculation" or a combination thereof.

1.1

The manufacturer shall indicate the nominal operating conditions for the temperature of the liquid: Q _Max , Q _{Min .}

1.2

The manufacturer shall indicate the nominal operating conditions for the temperature difference of the liquid: ∆ Q _Max , ∆ Q _Min , the following limitations are imposed: ∆ Q _Max /∆ Q _Min ³ 10; ∆ Q _Min = 3 K or 5 K or 10 K.

1.3

The manufacturer shall indicate the nominal operating conditions for the liquid flow: q _S , q _P , q _I , the following limitation is imposed on the values of q _P And q _I : q _P /q _I ³ 10.

1.4

The manufacturer shall indicate the nominal operating conditions for the heat power: P _S .

The following accuracy classes are fixed for thermal energy meters: 1 2 3.

The maximum tolerated relative errors for the full thermal energy meters expressed as % of the true value are for each accuracy class:

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E = E _F + E _T + E _C .

E _F , E _T And E _C Are set to c. 7.1 to 7.3.

4.1

The instrument of measurement shall not be influenced by a static magnetic field or an electromagnetic field at the frequency of the network.

4.2

An electromagnetic disturbance can influence the thermal energy meter only:

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If the change in the result of the measure does not exceed the limit value specified in the c. 4.3, or

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If the indication of the result of the measure is such that it cannot be regarded as valid.

4.3

The limit value for complete thermal energy meters is equal to the absolute value of the maximum permissible error fixed for this thermal energy meter (see c. 3).

5.1

After an appropriate review has been carried out taking into account the time limits proposed by the manufacturer, the following criteria must be met:

5.2

Flow sensors: at the end of the durability test, the variation of the measurement relative to the result of the initial measurement shall not exceed the limit value.

5.3

Temperature sensors: at the end of the durability test, the measured values shall not differ from the initial values of more than 0.1 ° C.

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Class of accuracy;

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Flow limit values;

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Temperature limit values;

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Temperature difference limit values;

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Flow sensor installation location: entry or return;

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Indication of flow direction.

Subset provisions may apply to sub-assemblies manufactured by one or more manufacturers. The essential requirements for thermal energy meters shall apply equally to sub-assemblies. The following additional requirements apply:

7.1

Relative maximum tolerable error for flow sensor expressed as % in accuracy classes:

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Class 1: E _F = (1 + 0.01 q _P /q), but not more than 5 per cent;

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Class 2: E _F = (2 + 0.02 q _P /q), but not more than 5 per cent;

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Class 3: E _F = (3 + 0.05 q _P /q), but not more than 5 %.

E _F Is the difference between the specified value and the true value of the relationship between the output signal of the flow sensor and the mass or volume.

7.2

Relative maximum permissible error for pair of temperature sensors expressed as %:

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E _T = (0.5 + 3-∆ Q _Min /∆ Q ).

E _T Is the difference between the indicated value and the true value of the relationship between the output signal of the temperature sensor pair and the temperature difference.

7.3

Relative maximum tolerable error for calculation unit expressed as %:

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E _C = (0.5 + ∆ Q _Min /∆ Q ).

E _C Is the difference between the value of the specified heat energy and the true value.

7.4

The limit value for a subset of a thermal energy meter is equal to the absolute value of the maximum permissible error for the subset (see ch. 7.1, 7.2 or 7.3).

7.5

Subset subscriptions

An overheated steam thermal energy meter is a complete meter consisting of the subassemblies "flow sensor", "pair of temperature sensors" and "unit of calculation".

1.1

The manufacturer shall indicate the nominal operating conditions for the temperature of the coolant: Q _Max , Q _{Min .}

1.2

The manufacturer shall indicate the nominal operating conditions for the temperature difference of the coolant: ∆ Q _Max , ∆ Q _{Min .}

1.3

The manufacturer shall indicate the nominal operating conditions for the overheated steam flow: q _S , q _P , q _I .

1.4

The manufacturer shall indicate the nominal operating conditions for the heat power: P _S .

The maximum allowable errors for the full thermal energy meters expressed as % of the true value are as follows:

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E = 4 + 4-∆ Q _Min /∆ Q + 0.05 q _P /q, but at least E = 6 + 4-∆ Q _Min /∆ Q .

3.1

The instrument of measurement shall not be influenced by a static magnetic field or an electromagnetic field at the frequency of the network.

3.2

An electromagnetic disturbance can influence the thermal energy meter only:

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If the change in the result of the measure does not exceed the limit value specified in the c. 3.3, or

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If the indication of the result of the measure is such that it cannot be regarded as valid.

3.3

The limit value for complete thermal energy meters is equal to the absolute value of the maximum permissible error fixed for this thermal energy meter (see c. 2).

At the end of an appropriate inspection review carried out taking into account the time limits proposed by the manufacturer, the variation of the result of the measure in relation to the result of the initial measure must not exceed the maximum tolerated errors (see ch. 2).

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Flow limit values;

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Temperature limit values;

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Temperature difference limit values;

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Flow sensor installation location: entry or return;

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Indication of flow direction.

A cold meter is either a complete meter or a combined meter consisting of the subsets "flow sensor", "pair of temperature sensors" and "unit of calculation" or a combination thereof.

1.1

The manufacturer shall indicate the nominal operating conditions for the temperature of the refrigerated liquid: Q _Max , Q _{Min .}

1.2

The manufacturer shall indicate the nominal operating conditions for the temperature difference of the refrigerated liquid: ∆ Q _Max , ∆ Q _{Min .}

1.3

The manufacturer shall indicate the nominal operating conditions for the liquid flow: q _S , q _P , q _I, Q values _P And q _I Being limited as follows: q _P /q _I ³ 10.

1.4

The manufacturer shall indicate the nominal operating conditions for the refrigeration capacity: P _S .

The following accuracy classes are fixed for cold meters: 2 3.

The maximum tolerated relative maximum errors for full cold meters expressed as % of the true value are for each accuracy class:

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E = E _F + E _T + E _C .

E _F , E _T And E _C Are set to c. 7.1 to 7.3.

4.1

The instrument of measurement shall not be influenced by a static magnetic field or an electromagnetic field at the frequency of the network.

4.2

An electromagnetic disturbance may influence the cold meter only:

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If the change in the result of the measure does not exceed the limit value specified in the c. 4.3, or

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If the indication of the result of the measure is such that it cannot be regarded as valid.

4.3

The limit value for complete cold meters is equal to the absolute value of the maximum permissible error fixed for this cold meter (see c. 3).

5.1

After an appropriate review has been carried out taking into account the time limits proposed by the manufacturer, the following criteria must be met:

5.2

Flow sensors: at the end of the durability test, the variation of the result of the measure in relation to the result of the initial measurement shall not exceed the limit value.

5.3

Temperature sensors: at the end of the durability test, the variation of the result of the measure with respect to the result of the initial measurement shall not exceed 0.1 ° C.

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Class of accuracy;

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Flow limit values;

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Temperature limit values;

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Temperature difference limit values;

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Flow sensor installation location: entry or return;

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Indication of flow direction.

The sub-set provisions may apply to sub-assemblies manufactured by one or more manufacturers. The essential requirements for cold meters shall also apply to the subsets of the cold meters. The following additional requirements apply:

7.1

Relative maximum tolerable error for flow sensor expressed as % in accuracy classes:

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Class 2: E _F = (2 + 0.02 q _P /q), but not more than 5 per cent;

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Class 3: E _F = (3 + 0.05 q _P /q), but not more than 5 %.

E _F Is the difference between the specified value and the true value of the relationship between the output signal of the flow sensor and the mass or volume.

7.2

Relative maximum permissible error for pair of temperature sensors expressed as %:

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E _T = (0.5 + 3-∆ Q _Min /∆ Q ).

E _T Is the difference between the indicated value and the true value of the relationship between the output signal of the temperature sensor pair and the temperature difference.

7.3

Relative maximum tolerable error for calculation unit expressed as %:

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E _C = (0.5 + ∆ Q _Min /∆ Q ).

E _C Is the difference between the specified value of the thermal energy and the true value.

7.4

The limit value for a subset of a cold meter is equal to the absolute value of the maximum permissible error for the subset (see ch. 7.1, 7.2 or 7.3).

7.5

Subset subscriptions

The construction requirements and the metrological characteristics of cold meters shall be deemed to be observed if the meter meets the requirements contained in the following Swiss and European standard-setting documents:

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SN EN 1434-1:2002, thermal energy meters-Part 1: general requirements;

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SN EN 1434-4:2002, Thermal Energy Meters-Part 4: Examination for Model Approval.