1、BSI Standards PublicationBS EN 12405-3:2015Gas meters ConversiondevicesPart 3: Flow computerBS EN 12405-3:2015 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of EN 12405-3:2015.The UK participation in its preparation was entrusted to TechnicalCommittee GSE/25, Gas Me
2、ters.A list of organizations represented on this committee can beobtained on request to its secretary.This publication does not purport to include all the necessaryprovisions of a contract. Users are responsible for its correctapplication. The British Standards Institution 2015.Published by BSI Stan
3、dards Limited 2015ISBN 978 0 580 84180 4ICS 91.140.40Compliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard was published under the authority of theStandards Policy and Strategy Committee on 31 December 2015.Amendments/corrigenda issued since publicatio
4、nDate T e x t a f f e c t e dBS EN 12405-3:2015EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 12405-3 December 2015 ICS 91.140.40 English Version Gas meters - Conversion devices - Part 3: Flow computer Compteurs de gaz - Dispositifs de conversion - Partie 3: Calculateurs de dbit Gaszhler - Umw
5、erter - Teil 3: Flowcomputer This European Standard was approved by CEN on 19 September 2015. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-dat
6、e lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN member. This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
7、under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management Centre has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Form
8、er Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey andUnited Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT E
9、UROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels 2015 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 12405-3:2015 EBS EN 12405-3:2015EN 12405-3:2015 (E) 2 Cont
10、ents Page European foreword . 5 Introduction 6 1 Scope 8 2 Normative references 8 3 Terms, definitions and symbols 10 3.1 Terms and definitions 10 3.2 Symbols and subscripts . 16 3.3 Abbreviations 18 3.4 Environmental classification for flow computers 18 3.4.1 Climatic conditions 18 3.4.2 Mechanical
11、 conditions 18 3.4.3 Electrical and Electromagnetic conditions . 18 4 Principle of measurement 18 4.1 General . 18 4.2 Correction functions . 19 4.2.1 General . 19 4.2.2 Correction of the volume at measurement conditions . 20 4.2.3 Temperature and pressure correction of USM body dimension . 23 4.2.4
12、 Temperature and pressure measurement correction for conversion . 23 5 Rated operating conditions 23 5.1 Specified field of measurement . 23 5.1.1 General . 23 5.1.2 Specified measurement range for gas pressure 23 5.1.3 Specified measurement range for gas temperature 24 5.1.4 Gas characteristics . 2
13、4 5.1.5 Base conditions . 24 5.2 Environmental conditions 24 5.2.1 Ambient temperature range 24 5.2.2 Humidity range . 24 5.3 Power supply . 24 6 Construction requirements 25 6.1 General . 25 6.2 Sealing 25 6.3 Time measuring functions 27 6.3.1 Clock 27 6.3.2 Time interval . 27 6.4 Casings . 28 6.5
14、Indications 28 6.5.1 General . 28 6.5.2 Electronic indicating device . 30 6.6 Inputs for volume conversion 30 6.7 Alarms in flow computer . 31 6.7.1 Detection of defective operation situations . 31 BS EN 12405-3:2015EN 12405-3:2015 (E) 3 6.7.2 Handling of volumes during maintenance 31 6.7.3 Memoriza
15、tion of metrological data 31 6.7.4 Handling of alarms . 31 6.8 Specific monitoring functions performed by flow computer 31 6.8.1 General . 31 6.8.2 Turbine Meter health check (Mechanical meter) . 33 6.8.3 USM health check (meter integrity check) 34 6.8.4 Gas analysis devices health check 35 6.8.5 p-
16、T transducer health check . 36 6.8.6 Self check of the Z algorithm . 36 6.8.7 Volume comparison . 36 6.8.8 Gas quality comparison 38 6.9 Cut-off function 38 6.10 Long-term data storage 38 6.10.1 General . 38 6.10.2 Categories of data to be stored 39 6.10.3 Triggers and methods for storage 39 6.10.4
17、Clock-time stamps 40 6.10.5 Security (physical, electronic and software) 40 6.10.6 Error handling . 41 6.10.7 Long term data storage Security audit . 41 7 Installation requirements . 42 7.1 General . 42 7.2 Calculator. 43 7.3 Temperature transducer . 43 7.4 Pressure transducer 43 8 Performance . 44
18、8.1 Reference conditions . 44 8.2 Rated operating conditions . 44 8.3 Maximum permissible errors. 44 8.3.1 General . 44 8.3.2 Global approach: error of main indication 45 8.3.3 Modular approach: specific errors for a FC . 45 8.4 Conditions of matching the constituent elements of a FC 45 8.5 Influenc
19、e factors . 46 8.6 Disturbances . 46 8.7 Durability. 46 8.8 Repeatability 46 8.9 Reliability 46 8.10 Adjustment and calibration of the transducers . 47 9 Tests of conformity 47 9.1 Verification of the construction requirements 47 9.2 Verification of the performance requirements . 48 9.2.1 Test condi
20、tions 48 9.2.2 Samples of FC required for testing . 49 10 Marking 50 11 Installation and operating instructions . 51 Annex A (normative) Type test 52 A.1 General conditions . 52 A.2 Accuracy tests under reference conditions . 54 BS EN 12405-3:2015EN 12405-3:2015 (E) 4 A.3 Effect of ambient temperatu
21、re 55 A.4 Effect of damp heat, steady-state test . 55 A.5 Effect of damp heat, cyclic test . 56 A.6 Electrical power variation 56 A.7 Short time power reductions . 57 A.8 Electrical bursts 58 A.9 Electromagnetic susceptibility 58 A.10 Electrostatic discharges . 59 A.11 Overload of pressure (only for
22、 pressure transducers) 59 A.12 Effect of vibrations . 60 A.13 Effect of shocks 60 A.14 Overload of pressure (mechanical) (only for pressure transducer) . 61 A.15 Durability 61 A.16 Alarms operation . 62 A.17 Repeatability 63 A.18 Short time DC power variations 63 A.19 Surges on supply lines and/or s
23、ignal lines . 64 A.20 Power frequency magnetic field . 64 Annex B (normative) Pressure transducers . 65 B.1 Scope . 65 B.2 Rated operating conditions 65 B.3 Construction requirements 65 B.4 Performances 66 B.5 Tests of conformity 67 B.6 Marking 67 Annex C (normative) Temperature transducers . 68 C.1
24、 Scope . 68 C.2 Rated operating conditions 68 C.3 Construction requirements 68 C.4 Performances 69 C.5 Tests of conformity 70 C.6 Marking 70 Annex D (normative) Requirements and testing of meter error correction . 71 D.1 General . 71 D.2 Verification of the volumetric flow rate determination. 71 D.3
25、 Verification of the gas density calculation procedure 71 D.4 Verification of the gas viscosity calculation procedures . 72 D.5 Verification of the error transposition from e(Qi) to e(Rei) 72 D.6 Verification of the error function (Q) or (Re) interpolation or approximation 73 D.7 Verification of cor
26、rection factor F(Q) or F(Re), corrected flow rate and corrected volume determination 73 D.8 Verification of the activation and deactivation of error correction calculations on limits of its application . 73 Annex E (informative) Range of application of meter error correction with functions: e(Q) or
27、e (Re) 74 E.1 General . 74 E.2 Range of application 74 E.3 Example for turbine meters working at popnearly constant 75 Bibliography . 77 BS EN 12405-3:2015EN 12405-3:2015 (E) 5 European foreword This document (EN 12405-3:2015) has been prepared by Technical Committee CEN/TC 237 “Gas meters”, the sec
28、retariat of which is held by BSI. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by June 2016, and conflicting national standards shall be withdrawn at the latest by June 2016. Attention is drawn to
29、 the possibility that some of the elements of this document may be the subject of patent rights. CEN and/or CENELEC shall not be held responsible for identifying any or all such patent rights. EN 12405 consists of the following parts: Part 1: Volume conversion (and its amendments EN 12405-1:2005/A1:
30、2006 and EN 12405-1:2005+A2:2010 to allow the harmonization of the standard with the Measuring Instruments Directive 2004/22/EC); Part 2: Energy conversion; Part 3: flow computer (this European Standard). In the preparation of this European Standard, the content of OIML Publication, “Recommendation
31、140 measuring systems for gaseous fuel”, has been taken into account. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark
32、, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom. BS EN 12405-3:201
33、5EN 12405-3:2015 (E) 6 Introduction A high accuracy volume conversion device can be needed depending of the intended use. EN 12405-3 is established in order to meet severe requirements concerning accuracy and related functions. For the purpose of this European Standard, functions are described, alth
34、ough these functions can be physically located in different components (e.g. calibration curve programmed in the measuring equipment itself or in the calculator). Four main categories of functions are described to achieve data processing: Sensor signal Acquisition functions: to process signals from
35、physical quantity provided by sensors and transducers to measurands; Sensor functions: to convert measurands to correct measurements, mostly based upon calibration results and filtering procedures; Metering functions: to calculate derived values such as volume, calorific value, compression factor et
36、c. based upon international standards and formulas and to take care of the supervision and monitoring for the purpose of high accuracy and substitution values; Long Term Data Storage functions: to keep all relevant information necessary to construct or reconstruct calculated values: for later legall
37、y relevant purposes (e.g. the conclusion of a commercial transaction); for back up of the relevant data. BS EN 12405-3:2015EN 12405-3:2015 (E) 7 Figure 1 Description of the functionalities of the flow computer calculator Modular and global approaches In the modular approach, the flow computer is an
38、assembly of separate associated measuring instruments and a calculator, which are verified separately. Each instrument is verified according to its testing procedure, using the indication available on the calculator or on the associated measuring instrument itself. In this case, the indication shall
39、 correspond to the indication of that measuring instrument, which is directly performing volume conversion. The verification of the functions consists in verifying the calculation concerning each characteristic quantity of the gas and/or the calculation for the volume conversion. In case of external
40、 communication, sufficient resolution of required data is ensured during data transmission. The associated measuring instruments are validated for or with a type calculator in order to ensure the interoperability of the association. CVDD is covered in EN 12405-2. In the global approach, the flow com
41、puter is tested as a package including the calculator and its associated measuring instruments and functions. The testing procedures are given in Annex A. BS EN 12405-3:2015EN 12405-3:2015 (E) 8 1 Scope Part 3 of this European Standard specifies the requirements and tests for the construction, perfo
42、rmance, safety and conformity of flow computers (FCs) used to meet the metrological and technical requirements of a high accuracy volume conversion device. They are used to determine volume of fuel gases, including those of the first and second families according to EN 437. For the purpose of this E
43、uropean Standard, only flow computers that are intended to operate with ultrasonic meters according to ISO 17089-1 or gas turbine meters conforming to EN 12261 are considered. For the purpose of this European Standard only classification classes E2 and M1 are considered for the flow computer calcula
44、tor. FCs are equipped with external separate transducers for pressure and temperature which may be approved separately. The provisions concerning pressure and temperature transducers are given in Annex B and C. Requirements and tests are given for energy calculator in EN 12405-2. 2 Normative referen
45、ces The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. EN
46、437, Test gases Test pressures Appliance categories EN 1776, Gas supply systems Natural gas measuring stations Functional requirements EN 12261, Gas meters Turbine gas meters EN 12405-1:2005+A2:2010, Gas meters Conversion devices Part 1: Volume conversion EN 12405-2, Gas meters Conversion devices Pa
47、rt 2: Energy conversion EN 55011, Industrial, scientific and medical equipment Radio-frequency disturbance characteristics Limits and methods of measurement (CISPR 11, modified) EN 60068-2-1, Environmental testing Part 2-1: Tests Test A: Cold (IEC 60068-2-1) EN 60068-2-2, Environmental testing Part
48、2-2: Tests Test B: Dry heat (IEC 60068-2-2) EN 60068-2-30, Environmental testing Part 2-30: Tests Test Db: Damp heat, cyclic (12 h + 12 h cycle) (IEC 60068-2-30) EN 60068-2-31, Environmental testing Part 2-31: Tests Test Ec: Rough handling shocks, primarily for equipment-type specimens (IEC 60068-2-
49、31) EN 60068-2-64, Environmental testing Part 2-64: Tests Test Fh: Vibration, broadband random and guidance (IEC 60068-2-64) EN 60068-2-78, Environmental testing Part 2-78: Tests Test Cab: Damp heat, steady state (IEC 60068-2-78) BS EN 12405-3:2015EN 12405-3:2015 (E) 9 EN 60068-3-1, Environmental testing Part 3-1: Supporting documentation and guidance Cold and dry heat tests (IEC 60068-3-1) EN 60079-0, Explosive atmospheres Part 0: Equipment General requirements (IEC 60079-0) EN 60079-7, Explosive
