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OIMLR75-1 | Measuring Instrument | Flow Measurement
OIMLR75-1
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PT878Brochure.pdf
1663 Instrument Doc List TFE
Unitwise Question Set
OIML R 75-1
Edition 2002 (E)
Heat meters Part 1: General requirements
Compteurs d’énergie thermique Partie 1: Exigences générales
OIML R 75-1 Edition 2002 (E)
.........5 Fast response meter Rated voltage.................................................13 4....... 6 Response time..OIML R 75-1: 2002 (E) Contents Foreword ........................................1 6.......1 7.......................................... 5 Complete instrument Combined instrument Hybrid instrument Sub-assemblies of a heat meter.................2 Scope ...... EUT Terminology and symbols ............................................. RVM Conventional true value Meter model Electronic device Electronic component Minimum immersion depth of a temperature sensor Self-heating effect Rated operating conditions ..... 8 Materials and construction Requirements outside the limiting values of the flow rate Display (indicating device) Protection against fraud Supply voltage Specified working range ..................................... 11 Temperature difference Flow rate 2 ......2 6.......................17 5 5.......................................5 4...4 5......1 4....................................................... 8 Limits of temperature range Limits of temperature differences Limits of flow rate Limits of thermal power Maximum admissible working pressure...........................4 6.................................................6 4................ 5 References ............................................... MAP Maximum pressure loss Technical characteristics ........................................................1 5..3 3...................5 7 7.2 3....... 4 1 2 3 3...8 4........................... Un Rated operating conditions Reference conditions Influence quantity Influence factor Disturbance Types of error Types of fault Reference values of the measurand..........................................................2 5................................. 5 Types of instrument ..........................16 4........................3 5......4 4................7 4....4 3..............2 4........................................6 6 6.................................. which is a combined instrument Equipment under test............5 5......10 4........11 4.........................12 4.15 4............14 4........... τ 0.........................................3 6.......3 4........................................1 3.................................5 4 4...9 4.........................
....................................4 10 10....................... 11 General Values of maximum permissible errors Application of maximum permissible errors Maximum permissible errors in service Environmental classification ...................... 13 Flow sensor Temperature sensor pair Calculator Complete instrument Information to be delivered with the heat meters or sub-assemblies ....... 11 Metrological characteristics (maximum permissible errors............ inscriptions and instruction manual ......... outdoor installations) Environmental class C (industrial installations) Heat meter specifications...... 15 Annex A (Mandatory): Heat coefficient equations .............................3 11 11.1 9.2 9....... 13 Environmental class A (domestic use................................................................................1 10........OIML R 75-1: 2002 (E) 8 9 9............................3 9......................................3 11......................................................... MPE) ........................................ 16 3 ............1 11................................2 11............ indoor installations) Environmental class B (domestic use.......4 12 Heat transmission formula .......2 10............................................
or related organizations. may apply simultaneously OIML publications and those of other institutions. 4 . This publication . It supercedes the former edition dated 1988. OIML Recommendation R 75 includes three parts: Part 1 (General requirements) and Part 2 (Type approval tests and initial verification tests) which have been issued in 2002 as separate publications. with the objective of avoiding contradictory requirements. consequently.org www.org • International Documents (OIML D). etc. International Recommendations and International Documents are published in French (F) and English (E) and are subject to periodic revision.was developed by the OIML Technical Committee TC 11 Instruments for measuring temperature and associated quantities on the basis of Part 1 of the European Standard EN 1434 (1997). This publication was approved for final publication by the International Committee of Legal Metrology in 2001 and will be submitted to the International Conference of Legal Metrology in 2004 for final sanction. which are model regulations that establish the metrological characteristics required of certain measuring instruments and which specify methods and equipment for checking their conformity. Cooperative agreements are established between OIML and certain institutions. of its Member States. manufacturers and users of measuring instruments. which are informative in nature and intended to improve the work of the metrological services.oiml. intergovernmental organization whose primary aim is to harmonize the regulations and metrological controls applied by the national metrological services. the OIML Member States shall implement these Recommendations to the greatest possible extent. rue Turgot . OIML Draft Recommendations and Documents are developed by technical committees or subcommittees which are formed by the Member States. Certain international and regional institutions also participate on a consultation basis. test laboratories. OIML publications may be obtained from the Organization’s headquarters: Bureau International de Métrologie Légale 11. such as ISO and IEC. the relevant paragraphs of which have been reproduced with the agreement of the European Committee for Standardization (CEN).75009 Paris . The two main categories of OIML publications are: • International Recommendations (OIML R).reference OIML R 75-1 edition 2002 . and Part 3 (Test report format) which is expected to be approved and issued at a later stage.France Telephone: Fax: E-mail: Internet: 33 (0)1 48 78 12 82 and 42 85 27 11 33 (0)1 42 82 17 27 biml@oiml.OIML R 75-1: 2002 (E) Foreword T he International Organization of Legal Metrology (OIML) is a worldwide.
after verification.4. Geneva IAPWS-IF97. A heat meter which does not have separable subassemblies as defined in 3. 1993) IEC 61010-1 (2001-02). 3.4 Sub-assemblies of a heat meter.OIML R 75-1: 2002 (E) Heat meters Part 1: General requirements 1 Scope 3. 5 . in a heat-exchange circuit.often called a “compact” instrument which for the purpose of type approval and verification.1 Flow sensor A sub-assembly through which the heat-conveying liquid flows.4. Geneva A heat meter . its subassemblies shall be treated as inseparable. Geneva ISO 7268 (1983-05). and Kruse. the temperature sensor pair and the calculator or a combination of these. International Organization for Standardization. The Industrial Standard for the Thermodynamic Properties and Supplementary Equations for other Properties of Water and Steam. and which emits a signal. However. A. at either the flow or return of a heatexchange circuit. 3.2 Temperature sensor pair 3 Types of instrument A sub-assembly (for mounting with or without pockets). For the purpose of this Recommendation. Berlin-Heidelberg. Amendments IEC 60751am1(1986-01) and IEC 60751-am2(1995-07) Industrial platinum resistance thermometer sensors. which is a function of the volume or the mass or the volumetric or mass flow rate.3 Hybrid instrument International Vocabulary of Terms in Legal Metrology (VIML. that is to instruments intended for measuring the heat which. W. 1998 ISBN 3-540-64339-7 IEC 60751 (1983-01).Definition of nominal pressure. which senses the temperatures of the heatconveying liquid at the flow and return of a heatexchange circuit. 3. Safety requirements for electrical equipment for measurement. is given up by a liquid called the heat-conveying liquid. control and laboratory use. Part 1: General requirements. International Electrotechnical Commission. Amendment ISO 7268-am1(198407). 3. Springer Verlag.4. Heat meters which are submitted for control by legal metrology services shall comply with the requirements formulated in this Recommendation. 2000) International Vocabulary of Basic and General Terms in Metrology (VIM. 2 References 3. by Wagner.4. Ed. heat meters are defined either as complete instruments or as combined instruments.2. which is a combined instrument The flow sensor.2 Combined instrument A heat meter which has separable sub-assemblies as defined in 3.1 Complete instrument This Recommendation applies to heat meters. International Electrotechnical Commission. can be treated as a combined instrument as defined in 3. Pipe components .
2 Intrinsic error (of a measuring instrument) Voltage of the external power supply required to operate the heat meter. and the instant when the response reaches 50 % of its final steady value. determined under reference conditions [VIM 5. τ 0. 4. Quantity that is not the measurand but that affects the result of the measurement [VIM 2. 4. 4. 4. the following terms.20]. conventionally the voltage of the AC mains supply. Conditions of use prescribed for testing the performance of a measuring instrument or for intercomparison of results of measurements [VIM 5.3 Calculator A sub-assembly which receives signals from the flow sensor and the temperature sensors and calculates and indicates the quantity of heat exchanged. 4. definitions and symbols apply.2 Fast response meter 4.7 Influence factor Influence quantity having a value within the rated operating conditions.1 Error (of indication) of a measuring instrument Meter suitable for heat-exchange circuits with rapid dynamic variations in the exchanged heat. Influence quantity having a value outside the rated operating conditions.8 Disturbance Time interval between the instant when the flow. 3. a combination of subassemblies or a complete meter subject to a test.4 Rated operating conditions Conditions of use for which specified metrological characteristics of a measuring instrument are intended to lie within the specified maximum permissible errors [adapted from VIM 5.5 Reference conditions A sub-assembly.OIML R 75-1: 2002 (E) 3.5 4.5 Equipment under test (EUT) 4. the temperature or the temperature difference is subjected to a specified abrupt change.6 Influence quantity For the purposes of this Recommendation. Indication of the measuring instrument minus the conventional true value of the corresponding input quantity [adapted from VIM 5.9 Types of error 4.9. Un 6 .9. 4 Terminology and symbols 4. Error of a measuring instrument. Note: The terminology used in this Recommendation complies with the International Vocabulary of Terms in Legal Metrology (VIML) and the International Vocabulary of Basic and General Terms in Metrology (VIM) of which certain definitions are reproduced below.3 Rated voltage.5]. 4.7].7].1 Response time.24].4.
regarded as sufficiently close to the true value for the difference to be insignificant for the given purpose. having a mean water velocity of 0.13 Meter model 4. 4.21].9.17 Self-heating effect 4. fixed to ensure valid intercomparison of the results of measurements. RVM Specified set of values of the flow rate. 4. MPE Extreme values of the error (positive or negative) permitted by this Recommendation [adapted from VIM 5.11 Reference values of the measurand. Device employing electronic components and performing a specific function. in general.15 Electronic component Smallest physical entity in an electronic device which uses electron or hole conduction in semi-conductors or electron conduction in gases or in a vacuum.1 m/s. 4. the return temperature and the temperature difference. then the significant fault is a fault larger than 2 %.5 Maximum permissible error.1 Fault Difference between the error of indication and the intrinsic error of the instrument.14 Electronic device 4. 4. 4.10.3 Significant fault Fault greater than the absolute value of the MPE which is not a transitory fault. for the purpose of this Recommendation. Different sizes of heat meters or sub-assemblies having a family similarity in the principles of operation. memorized or transmitted as measurements. 4. 7 .2 Transitory fault Momentary variations in the indication which cannot be interpreted. construction and materials.12 Conventional true value Value of a quantity which.1 K.10.3 Initial intrinsic error Intrinsic error of a measuring instrument as determined prior to performance tests and durability tests. Note: A conventional true value is.4 Durability error Difference between the intrinsic error after a period of use and the initial intrinsic error. Example: If the MPE is ± 2 %.16 Minimum immersion depth of a temperature sensor Depth of immersion in a thermostatic bath with a temperature of (80 ± 5) °C at an ambient temperature of (25 ± 5) °C. 4.9. Increase in temperature signal that is obtained by subjecting each temperature sensor of a pair to a continuous power dissipation of 5 mW when immersed to the minimum immersion depth in a water bath.10.OIML R 75-1: 2002 (E) 4. is considered as a true value.10 Types of fault 4. 4. 4.9. beyond which deeper immersion changes the output value by an amount corresponding to less than 0.
is the lowest temperature difference. at which the heat meter shall function within the upper limit of thermal power without the maximum permissible errors being exceeded.2 The permanent flow rate.3 Limits of flow rate The materials used and the construction of heat meters shall ensure sufficient stability to enable the instrument to comply with the maximum permissible errors stated when the device is set up in accordance with the supplier’s instruction manual. 5. at which the heat meter shall function without the maximum permissible errors being exceeded. qi. Θmin. 5.3. 6.2 The lower limit of the temperature range.3. especially those due to impurities in the heat-conveying liquid.2 The upper limit of the temperature difference. is the lowest flow rate. 5. is the highest temperature difference. at which the heat meter shall function without the maximum permissible errors being exceeded. at which the heat meter shall function without the maximum permissible errors being exceeded.1. 5. is the highest flow rate at which the heat meter shall function continuously without the maximum permissible errors being exceeded. 5. Ps.1 The temperature difference. 5.1. 5. ∆Θ. (expressed in K) is the absolute value of the difference between the temperatures of the heat-conveying liquid at the flow and return of the heat-exchange circuit.3 The lower limit of the flow rate.3 The lower limit of the temperature difference. 5. qp. at which the heat meter shall function for short periods (less than 1 h/day and less than 200 h/year) without the maximum permissible errors being exceeded. (expressed in °C) is the highest temperature of the heatconveying liquid.2. 6 Technical characteristics 5. qp. expressed as a PN-series as defined in ISO 7268.3.6 Maximum pressure loss The loss of pressure in the heat-conveying liquid passing through the flow sensor when the flow sensor is operating at the permanent flow rate.2.1 Rated operating conditions Limits of temperature range 5.2.1 Materials and construction All the constituent elements of heat meters shall be solidly constructed of materials having appropriate qualities to resist the various forms of corrosion and wear which occur under rated operating conditions. MAP 5. 5. is the highest flow rate.1 The upper limit of the temperature range. is the highest power at which the heat meter shall function without the maximum permissible errors being exceeded. qs.1 The upper limit of the flow rate.5 Maximum admissible working pressure. (expressed in °C) is the lowest temperature of the heatconveying liquid. Θmax. ∆Θmax.2 Limits of temperature differences The maximum positive internal pressure that the heat meter can withstand permanently at the upper limit of the temperature range. 5.OIML R 75-1: 2002 (E) 5 5.4 Limits of thermal power The upper limit of the thermal power. ∆Θmin. Correctly installed meters shall also be able to 8 . above which the heat meter shall function without the maximum permissible errors being exceeded.
the advance of a figure of a particular significance shall be completed during the time when the figure of next lower significance changes from 9 to 0. 6. 6. Meters shall. all in accordance with IEC 61010-1.3. The 9 . 6.4 The maximum pressure loss at qp shall not exceed 0. shall correspond to at least one digit of lowest significance of the display. in all circumstances.5 The figures indicating decimal fractions of a unit shall be separated from the others by the decimal divider.6 Where the display is of the roller-type. 6. 6. Heat meters shall be so designed that.25 bar. 6. the production of spurious or zero signals.1. measured by a heat meter operating at the upper limit of the thermal power for 1 h.3 Heat meters may be fitted with interfaces allowing the connection of supplementary devices.2 will not necessarily ensure that the heat meter will continue to register the heat consumed in the event of a power supply failure. without malfunction.3.1 Suppliers of heat meters shall declare any limitations with regard to installation of the heat meter and its orientation with respect to the vertical.3. Note: Compliance with 6. withstand the maximum admissible pressure and the temperatures for which they are designed. For flow rates greater than qs. the meter indication of energy at the time of failure is not lost. 6. In addition. no registration is allowed.3 The indicating device shall provide an easily read.1. the behavior of the meter. of which the visible displacement shall then be from bottom to top. a quantity of heat at least equal to the transfer of energy which corresponds to a continuous operation for 3000 h at the upper limit of the thermal power. except where the heat meter includes a flow controller or also acts as a pressure-reducing device. watt-hours or in decimal multiples of those units.3. and remains accessible for a minimum of one year. reliable and unambiguous indication. When the flow rate is less than a threshold value declared by the supplier. name or symbol of the unit in which the quantity of heat is given shall be indicated adjacent to the display.2 Requirements outside the limiting values of the flow rate 6.1 The quantity of heat shall be indicated in joules. the figures indicating decimal fractions of energy shall be clearly distinguishable from the others.1. 6. Such connections shall not modify the metrological qualities of the heat meter.3.2 The display shall include a numerical or seminumerical scale. 6. without overflow. in the event of an external power supply failure (mains or external DC).3.g. The minimum forms of enclosure protection shall be IP54 for enclosures that are to be installed into pipework and IP52 for other enclosures.4 The real or apparent height of the figures on the display for energy shall not be less than 4 mm.3. of the heat meter.2 Casings of heat meters shall protect the parts inside against water and dust ingress. 6.3.1.7 The display indicating the quantity of heat shall be able to register. The quantity of heat. Flow rates greater than qs shall not result in a positive error greater than 10 %. Note: The flow rate through a “nominally” closed valve or the movement of liquid in the pipe behind a closed valve caused by thermal expansion and contraction should not be recorded. e. The roller carrying the figures of lowest significance may have a continuous movement.OIML R 75-1: 2002 (E) withstand normal external influences. 6. Ps.3 Display (indicating device) 6. shall be declared by the manufacturer.
6. removing. • Variations in DC remote voltage of – 50 % to + 75 % related to the instrument’s rated nominal voltage. The moment of switching off may be preprogrammed. These instruments shall: • either comply with the requirements for battery supplied instruments (6.5 Supply voltage 6.OIML R 75-1: 2002 (E) 6. errors exceeding MPE.5. The sites for these marks shall be situated so that the marks are clearly visible when attached.2) with the external supply switched off (manually or by accident).g.5. etc. 6.1 to 6. either to give protection against the meter being disconnected from the power supply or to make it evident that this has taken place. All parts of the heat meter that might be separated after calibration and testing shall have sites for placing an identity mark.5. and shall be at least 2 years.3) with the external supply switched off (manually or by accident). legal status marks) to be sited on that part of the heat meter indicating the quantity of heat for a complete meter or on each sub-assembly for combined meters. Means shall also be provided for meters with external power supply.5. Sites shall be provided for marks (e.).5. both before and after the heat meter has been correctly installed. this shall be clearly indicated by the instrument at a time safely before the instrument starts functioning improperly (resulting in for instance poor display. and shall additionally: 10 . • Variations in AC mains frequency of – 2 % to + 2 % related to the instrument’s rated nominal frequency.5.4 Instruments supplied by internal rechargeable batteries that are intended to be (re)charged during the operation of the measuring instrument The instrument shall be fully operational and shall not exceed the maximum permissible errors if the electric power supply is influenced as described in 6.5.3 Instruments supplied by internal non-rechargeable batteries or rechargeable batteries that cannot be (re)charged during the operation of the measuring instrument When the battery voltage has dropped to a critical value.1 Instruments supplied by AC mains supply • or • Variations in AC mains voltage of – 15 % to + 10 % related to the instrument’s rated nominal voltage.4.5. 6.4 Protection against fraud 6. or altering the heat meter or its adjustment devices without evident damage to the device(s) or seal(s). Note: The incorporation in the meter casing of a counter indicating the hours run will make it evident if the power supply has been disconnected. Heat meters shall have protective devices which can be sealed in such a way that. there is no possibility of dismantling. The minimum period of time during which the instrument shall function properly without renewing or recharging batteries shall be specified by the manufacturer. unstable memory function. or the instrument shall automatically switch off. comply with the requirements for instruments supplied by external AC or DC low voltage (6. after sealing. storing actual data and time at the moment of switching off for a period of at least 1 year.2 Instruments supplied by external AC or DC low voltage (< 50 V) • Variations in AC remote voltage of ± 50 % related to the instrument’s rated nominal voltage.
called the heat coefficient. the thermal power and the flow rates (qs and qi).OIML R 75-1: 2002 (E) • comply with the requirements for AC-powered instruments (6. 100 or 250.1 Temperature difference Q V k is the quantity of heat given up. ISBN 3-8027-2373-2 The ratio of the permanent flow rate to the lower limit of the flow rate (qp/qi) shall be 10. 3. 5 or 10 K. where: Q qm ∆h is the quantity of heat given up. is the difference between the specific enthalpies of the heat-conveying liquid at the flow and return temperatures of the heat-exchange circuit. 8 Heat transmission formula Heat transmitted to or from a body of liquid can be determined from knowledge of its mass. MPEs) Q= t1 t0 qm ∆h dt Heat meters shall meet the tolerances stated which are considered as being the maximum permissible errors 11 . Vulkan-Verlag. Adunka. 2. is a function of the properties of the heat-conveying liquid at the relevant temperatures and pressure. If the measurement of heat is affected by the pressure of the heat-conveying liquid. if it is used as the system heat-conveying liquid. The lower limit shall be stated by the supplier to be either 1. by Dr. is time. Essen.2 Flow rate The conventional true value of the heat coefficient k for water. its equation becomes: V1 V0 Q= k ∆Θ dV where: 7. 7 Specified working range t The working parameters of the heat meter are bounded by the limiting values of the temperature range. ∆Θ is the temperature difference between the flow and return of the heat exchange circuit. where the pressure shall be set to 16 bar. the supplier shall declare the heat coefficient used as a function of temperature and pressure. In a heat meter.1) with the mains supply switched on. specific heat capacity and change in temperature. Note: Tables with values for the heat coefficient for liquids other than water can be found in the book Handbuch der Wärmeverbrauchsmessung. 7. is the volume of liquid passed.5.1. 25.) in Annex A. If the instrument determines the volume instead of the mass. the temperature difference. The equation for its operation is as follows: 9 Metrological characteristics (maximum permissible errors. The preferred value is 3 K. For meters intended for use with heat-conveying liquids other than water. the rate of change of enthalpy between the flow and return through a heat exchanger is integrated with respect to time. The ratio of the upper and lower limits of the temperature difference shall not be less than 10. 50.) to (A. is the mass flow rate of the heat-conveying liquid passing through the heat meter. shall be obtained from the formulas (A. F.5. pressure shall be regarded as a parameter.
1).1. positive or negative.1 Flow sensors of heat meters and complete instruments belong to one of the following three accuracy classes: class 1.2 The maximum permissible errors of heat meters. is the conventional true value.1.2. The classes of heat meters are defined by the class of the flow sensor.2 Temperature sensor pair 9.02 qp/q).2.2. Class 2: Ef = ± (2 + 0.1.1 Calculator Ec = ± (0. Ef.2. in relation to the conventional true value of the heat. positive or negative. Note: E and Ef for class 1 will be defined when improvements in testing procedures and flow sensors make it possible. 9.1.2. relates the value of the heat indicated to the conventional true value of the heat. but not more than ± 5 % where the error.2. The relationship between temperature and resistance of each single sensor of a pair shall not differ from the values of the formula given in IEC 60751 (using the standard values of the constants A.05 qp/q).2 Maximum permissible relative errors of sub-assemblies 9.4 The relative error.3 9.2. B and C) by more than an amount equivalent to 2 K. are calculated from the temperature difference in the case of the calculator and the temperature sensor pair and from the flow rate in the case of the flow sensor.2.1 General (∆Θmin/ ∆Θ) and the flow rate ratio (qp/q).2) and Ef (in 9.2. 9.OIML R 75-1: 2002 (E) in type approval tests. but not more than ± 5 % Class 3: Ef = ± (3 + 0.5 + 3 ∆Θmin / ∆Θ) where the error.2.1 Maximum permissible relative errors of a complete instrument The MPEs of a complete instrument are calculated as a function of the temperature difference ratio 12 . 9. E. initial and subsequent verification. Class 1: see note in 9. Et.5 + ∆Θmin / ∆Θ) where the error. class 2 and class 3.2.3). The MPEs of the complete instrument of accuracy classes 2 and 3 are the arithmetic sums of Ec (in 9. 9.2.2.3 The maximum permissible errors of subassemblies. is expressed as: E= Xd – Xc Xc 100 % 9. relates the indicated value to the conventional true value of the relationship between temperature sensor pair output and temperature difference.2.3 Flow sensor where: Class 1: Ef = See note Xd Xc is the indicated value.2. The class of the complete instrument is determined by the class of the flow sensor. The definitions for class 1 flow sensors could be presumed to be: 9. Ec. are defined as relative errors varying as a function of the temperature difference and flow rate. Class 2 and Class 3: E = Ec + Et + Ef 9.2 Values of maximum permissible errors 9.2. Et = ± (0. Et (in 9. relates the indicated value to the conventional true value of the relationship between flow sensor output signal and mass or volume.
9. which shall include all the information listed in 11.1 Environmental class A (domestic use. the maximum permissible error for the combination is the arithmetic sum of the maximum permissible errors of all sub-assemblies.3 and 11.2.5 %.1 to 11.4.1 For a combination of sub-assemblies as defined in 3. It is presumed that these maximum permissible errors could be applied to heat meters with flow sensors of qp ≥ 100 m3/h. 9.3. the values of the maximum permissible errors in service shall be equal to 2 times the maximum permissible errors fixed for verification. serial number • Accuracy class • Limits of flow rate (qi. qp and qs) • Limits of temperature (Θmin and Θmax) • Maximum admissible working pressure (PN-class) • One or more arrows to indicate the direction of flow 10. but not more than ± 3.3 Suppliers of combined instruments can stipulate that they shall be considered as complete instruments for the application of the maximum permissible errors.4 Maximum permissible errors in service 11 Where different values for maximum permissible errors in service and at verification are prescribed by national regulations.2.1. 10.2 The errors of combined instruments shall not exceed the arithmetic sum of the maximum permissible errors of the sub-assemblies indicated in 9.3 Environmental class C (industrial installations) • • • • Ambient temperature: + 5 °C to + 55 °C Normal level humidity conditions High electrical and electromagnetic conditions Low level mechanical conditions 9.01 qp/q).2. Heat meter specifications. inscriptions and instruction manual Each heat meter shall be accompanied by an instruction manual and data sheets.3.4. A heat meter and/or its sub-assemblies shall be marked clearly and indelibly with the information listed in italics in 11. 11.3 Application of maximum permissible errors 9. 11.2.1 to 9. indoor installations) • Ambient temperature: + 5 °C to + 55 °C • Low level humidity conditions 13 . year of manufacture.3. 10 Environmental classification Heat meters shall conform to one or more of the following environmental classifications according to the application. 11.4. outdoor installation) • • • • Ambient temperature: – 25 °C to + 55 °C Normal level humidity conditions Normal electrical and electromechanical conditions Low level mechanical conditions 9.2.1 Flow sensor • Supplier (name or trade mark) • Type identification.01 qp/q).3. • Normal electrical and electromagnetic conditions • Low level mechanical conditions 10.OIML R 75-1: 2002 (E) For complete meters: E = ± (2 + 4 ∆Θmin / ∆Θ + 0.2 Environmental class B (domestic use. For flow sensors: Ef = ± (1 + 0.
life-time 11. for pocket mounting) Maximum liquid velocity for sensor over 200 mm length • Minimum immersion depth • Output signal for rated operation (type/levels) • τ0.or 2-wire) Total resistance of a 2-cable wire Principle of operation Maximum RMS value of sensor current Physical dimensions Installation requirements (e.) • Environmental class • Installation requirements.2 Temperature sensor pair • Supplier (name or trade mark) • Type identification. year of manufacture. weight.g. height.5 response time 11. type. kWh) • Dynamic behavior (circumstances of temperature measurement and integration) • Maximum value of thermal power (Ps) • Other functions in addition to heat indication • Physical dimensions • Mains power supply (voltage. etc.battery voltage. serial number • Limits of flow rate (qi. width. 4. serial number • Limits of temperature (Θmin and Θmax) • Limits of temperature difference (∆Θmin and ∆Θmax) • Maximum admissible working pressure for direct mounted sensors (PN-class) • Identification of flow and return temperature sensors.g. serial number • Type of temperature sensors (e. e.for fast response meters • Mains power supply requirements . indication if shielding is necessary or not • Limits of temperature (Θmin and Θmax) • Limits of temperature difference (∆Θmin and ∆Θmax) • Required input signal from the flow sensor • Heat conveying liquid if other than water • Flow sensor to be operated at the flow or return temperature • Display unit options (MJ. including installation pipe lengths • Physical dimensions (length.OIML R 75-1: 2002 (E) • Environmental class • Heat conveying liquid if other than water • Nominal meter factor (litres/pulse or corresponding factor for normal output) • Orientation limitations for installing the meter • Maximum pressure loss (pressure loss at qp) • Installation requirements. thread/flange specification) • Output signal for rated operation (type/levels) • Output signal for testing (type/levels) • Performance at flow rates greater than qs • Low flow threshold value • Response time . year of manufacture. Pt 100. year of manufacture. MAP 14 . including wiring of temperature sensors.3 Calculator • Supplier (name or trade mark) • Type identification. frequency) • Battery power supply requirements (battery voltage.g.g. lifetime) • RMS value of temperature sensor current • Maximum permissible flow sensor signal (pulse rate) • Output signal for normal operation (type/levels) • Output signal for testing (type/levels) 11. if needed • • • • • • • Wiring of sensors (e.4 Complete instrument • Supplier (name or trade mark) • Type identification. frequency • Battery power supply requirements . type. qp and qs) • Limits of temperature (Θmin and Θmax) of the flow sensor/temperature sensor pair • Limits of temperature difference (∆Θmin and ∆Θmax) • Accuracy class • Maximum admissible working pressure (PN-class) • Environmental class • Maximum admissible working pressure for the flow sensor. Pt 100 or Pt 500.voltage.
including installation pipe lengths Physical dimensions (length. weight. kWh) Other functions in addition to heat indication Maximum value of thermal power (Ps) Low flow threshold value Maximum pressure loss of flow sensor (pressure loss at qp) Installation requirements. thread/flange specification) Mains power supply requirements (voltage. • use of pockets or fittings for temperature sensor. • distance between meter and other equipment. d) Wiring: • need for earth connection. • minimum straight installation pipe length upstream and downstream. • requirement for mechanical support. e) Other: • initial function check and operation instructions. a) Flow sensor: • flushing the system before installation. • need for adapter plate to fit standardized holes. • installation security sealing. • requirement to avoid installation stresses from pipes and fittings. frequency) Battery power supply requirements (battery voltage. c) Calculator (and flow meter electronics): • free distance around the meter. 15 . type. • need for flow straightener. • maximum cable lengths. • installation in flow or return as stated on calculator. • use of thermal insulation for pipe and sensor heads.OIML R 75-1: 2002 (E) • • • • • • • • • • • • • • • • • • Heat conveying liquid if other than water Meter to be installed in flow or return One or more arrows to indicate the direction of flow Orientation limitations for installing the meter Display unit option (MJ. • requirements for electrical screening. width. • requirement for protection from risk of damage by shock and vibration. for fast response meters b) Temperature sensor pair: • possible need for symmetrical installation in the same pipe size. 12 Information to be delivered with the heat meter or sub-assemblies Installation instructions under the following heading shall include at least the following information. • required separation between signal and power cables. lifetime) Output signal for normal operation (type/levels) Output signal for testing (type/levels) Performance at flow rates greater than qs Response time for the temperature sensor pair Response time. • orientation limitations. height.
1 – π)Ii Ji(τ – 1. hr are the specific enthalpies (f-flow.1. Ii and Ji see Table 1. The heat coefficient is a function of the measurable physical quantities pressure p. Θr). hf and hr can be calculated according to The Industrial Standard for the Thermodynamic Properties of Water and Steam (IAPWS-IF 97) using the International Temperature Scale of 1990 (ITS-90). Θr) = 1 hf – hr (A. and satisfies equation A. flow temperature Θf and return temperature Θr.15 K ≤ T ≤ 623. 16 .53 MPa γπ = Σ – niIi (7. Θf . p RT Specific volume ν = (∂g / ∂p)T ν (π.222) Ji i=1 34 (A. Heat coefficient for water k(p.222) Ji-1 i=1 34 (A.1 – π)Ii –1(τ – 1.1) ν Θf – Θr where ν is the specific volume. ps(T) ≤ p ≤ 100 MPa and R = 461.OIML R 75-1: 2002 (E) Annex A . Ii and Ji see Table 1.2) where g is the specific Gibbs free energy and π = p / p* with p* = 16. Θf.Heat coefficient equations (Mandatory) For the determination of heat exchanged in an exchange circuit. The quantities ν.526 J⋅kg-1⋅K-1 with ps(T): saturation pressure For the figures of ni.5) with 273. τ) = = πγπ (A. r-return).15 K.τ) RT = τγτ Specific enthalpy (A.4) where τ = T* / T and T* = 1386 K γτ = Σ ni(7. heat meters shall take the type of heat-conveying liquid (generally water) into account by means of the heat coefficient k(p. hf.3) For the figures of ni. h = g – T(∂g / ∂T)p . h(π.
157 720 385 132 28 –0.338 551 691 683 85 × 101 –0.127200 ⋅103 4.476 613 939 069 87 × l0-4 i 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 Ii 2 2 3 3 3 4 4 4 5 8 8 21 23 29 30 31 32 Ji 3 17 –4 0 6 –5 –2 10 –8 –11 –6 –29 –31 –38 –39 –40 –41 ni –0.300 017 807 930 26 × 10-3 0.102204 ⋅10-2 ⋅ 0.143 417 299 379 24 × 10-12 –0.294301⋅103 0.144 783 078 285 21 × 10-19 0.528 383 579 699 30 × 10-4 –0.282 707 979 853 12 × 10-5 –0.OIML R 75-1: 2002 (E) Samples of values for Θf = 70 °C and Θr = 30 °C at 16 bar.146 329 712 131 67 –0.189 900 682 184 19 × 10-1 –0.316 796 448 450 54 × 10-4 –0.127 343 017 416 41 × 10-8 –0.100370 ⋅10-2 ⋅ 0.687 621 312 955 31 × 10-18 0.852 051 281 201 03 × 10-9 –0.283 190 801 238 04 × 10-3 –0.957 919 633 878 72 0.1621 Table 1 Coefficients and exponents of equations (A. flow sensor in: Flow position Specific volume in (m3/kg) Specific enthalpyflow in (kJ/kg) Specific enthalpyreturn in (kJ/kg) Heat coefficient in (MJ/(m3 K)) 0.845 481 871 691 14 –0.166 164 171 995 01 × 10-1 0.127200 ⋅103 4.174 248 712 306 34 × 10-9 –0.607 063 015 658 74 × 10-3 –0.218 417 171 754 14 × 10-1 –0.812 146 299 835 68 × 10-3 0.294301⋅103 0.182 280 945 814 04 × 10-23 –0.119 476 226 400 71 × 10-22 0.3) and (A.224 252 819 080 00 × 10-5 –0.441 418 453 308 46 × 10-5 –0.0874 Return position 0.375 636 036 720 40 × 101 0.935 370 872 924 58 × 10-25 17 .325 297 487 705 05 × 10-1 –0.651 712 228 956 01 × 10-6 –0.471 843 210 732 67 × 10-3 –0.726 949 962 975 94 × 10-15 –0.5) i 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 Ii 0 0 0 0 0 0 0 0 1 1 1 1 1 1 2 2 2 Ji –2 –1 0 1 2 3 4 5 –9 –7 –1 0 1 3 –3 0 1 ni 0.263 357 816 627 95 × 10-22 –0.405 169 968 601 17 × 10-6 –0.
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