EN 12178-2016 en Refrigerating systems and heat pumps - Liquid level indicating devices - Requirements testing and marking《制冷系统和热泵-液位指示装置-要求 试验和作标记》.pdf

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1、BS EN 12178:2016Refrigerating systemsand heat pumps Liquidlevel indicating devices Requirements, testing andmarkingBSI Standards PublicationWB11885_BSI_StandardCovs_2013_AW.indd 1 15/05/2013 15:06BS EN 12178:2016 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of EN 1

2、2178:2016. It supersedes BS EN 12178:2003 which is withdrawn.The UK participation in its preparation was entrusted to Technical Committee RHE/18, Refrigeration safety.A list of organizations represented on this committee can be obtained on request to its secretary.This publication does not purport t

3、o include all the necessary provisions of a contract. Users are responsible for its correct application. The British Standards Institution 2016.Published by BSI Standards Limited 2016ISBN 978 0 580 92798 0 ICS 27.080; 27.200 Compliance with a British Standard cannot confer immunity from legal obliga

4、tions.This British Standard was published under the authority of the Standards Policy and Strategy Committee on 31 December 2016.Amendments/corrigenda issued since publicationDate T e x t a f f e c t e dBS EN 12178:2016EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 12178 November 2016 ICS 27.0

5、80; 27.200 Supersedes EN 12178:2003English Version Refrigerating systems and heat pumps - Liquid level indicating devices - Requirements, testing and marking Systmes de rfrigration et pompes chaleur - Indicateurs de liquide - Exigences, essais et marquageKlteanlagen und Wrmepumpen - Flssigkeitsstand

6、anzeiger - Anforderungen, Prfung und Kennzeichnung This European Standard was approved by CEN on 8 August 2016. 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 alt

7、eration. Up-to-date 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 ma

8、de by translation 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, Esto

9、nia, 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 andUnited Kingdom. EUROPEAN COMMITTEE FOR STAND

10、ARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels 2016 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 12178:2016 EBS EN 12178:2016EN 12178:201

11、6 (E) 2 Contents Page European foreword 4 1 Scope . 5 2 Normative references . 5 3 Terms and definitions 5 4 List of Symbols . 7 5 General requirements 7 5.1 Installation and operation 7 5.2 Components under pressure . 8 5.3 Excessive mechanical stress . 8 5.4 Leakage 8 6 Materials 8 6.1 Material pr

12、operties . 8 6.2 New materials 8 6.3 Using non-metallic materials . 8 6.4 Requirements for materials to be used for pressurized parts 8 6.5 Compatibility of connections . 8 6.6 Ductility . 8 6.7 Brittle fracture 8 6.8 Ageing . 8 6.9 Castings 9 6.10 Forged and welded components . 9 6.11 Nuts, bolts a

13、nd screws 9 6.12 Glass materials 9 6.13 Gasket materials . 9 7 Design . 9 7.1 General . 9 7.2 Requirements for glass 9 7.3 Surface requirements 11 7.4 Corrosion protection 11 7.5 Inner cleanness 11 8 Fitting requirements 11 9 Testing . 12 10 Application 12 10.1 Liquid hammer . 12 10.2 Frosting tubes

14、 . 12 10.3 Liquid level indicators with magnetically operated indication . 12 10.4 Maximum and minimum liquid level . 12 11 Marking and additional information . 12 11.1 General 12 11.2 Marking . 13 11.3 Level indicators of nominal size DN 25 and smaller 13 12 Documentation . 13 12.1 Documentation fo

15、r level indicators 13 BS EN 12178:2016EN 12178:2016 (E) 3 12.2 Documentation for level indicators of nominal size DN 25 and smaller . 14 Annex ZA (informative) Relationship between this European Standard and the essential requirements of EU Directive 2014/68 EU of the European Parliament and of the

16、Council of 15 May 2014 on the harmonisation of the laws of the Member States relating to the making available on the market of pressure equipment aimed to be covered. 15 Bibliography 16 BS EN 12178:2016EN 12178:2016 (E) 4 European foreword This document (EN 12178:2016) has been prepared by CEN/TC 18

17、2, “Refrigerating systems, safety and environmental requirements”, the secretariat of which is held by DIN. 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 May 2017, and conflicting national stand

18、ards shall be withdrawn at the latest by May 2017. Attention is drawn to 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. This document supersedes EN 12178:2

19、003. EN 12178:2016 includes the following significant technical changes with respect to EN 12178:2003: a) Introduction of the safety factors in 7.2.1; b) Harmonisation of Annex ZA with Directive 2014/68/EU. This document has been prepared under a mandate given to CEN by the European Commission and t

20、he European Free Trade Association, and supports essential requirements of EU Directive(s). For relationship with EU Directive(s), see informative Annex ZA, which is an integral part of this document. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the foll

21、owing countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands,

22、Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom. BS EN 12178:2016EN 12178:2016 (E) 5 1 Scope This European Standard specifies safety requirements, safety factors, test methods, test pressures and marking of liquid level indicating devi

23、ces, referred to throughout this standard as “level indicators”, for use in refrigerating systems and heat pumps. It applies to devices connected to refrigerant vessels (e.g. on high-pressure liquid receivers, intercoolers and low-pressure receivers) and to devices connected to other parts of a refr

24、igerating system (e.g. oil-level sight glasses on a compressor). This European Standard applies to those types of level indicators that are direct and indirect reading devices (e.g. sight glasses, frosting tubes), and includes electrical and pneumatic indicators. This European Standard describes the

25、 procedure to be followed when designing (by calculation or by an experimental design method) level indicator parts subjected to pressure as well as the criteria to be used for the selection of materials. This European Standard applies to the design of level indicators with respect to pressure conta

26、inment and describes methods by which the reduced impact values at lower temperatures may be taken into account in a safe manner. It also gives guidance on some aspects of application and installation. 2 Normative references The following documents, in whole or in part, are normatively referenced in

27、 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 378-1, Refrigerating systems and heat pumps Safety and environmental requiremen

28、ts Part 1: Basic requirements, definitions, classification and selection criteria EN 378-2, Refrigerating systems and heat pumps Safety and environmental requirements Part 2: Design, construction, testing, marking and documentation EN 378-4, Refrigerating systems and heat pumps Safety and environmen

29、tal requirements Part 4: Operation, maintenance, repair and recovery EN 764-1, Pressure equipment Part 1: Vocabulary EN 12284:2003, Refrigerating systems and heat pumps Valves Requirements, testing and marking EN 60529, Degrees of protection provided by enclosures (IP Code) (IEC 60529) 3 Terms and d

30、efinitions For the purposes of this document, the terms and definitions given in EN 378-1 and EN 764-1 and the following apply. 3.1 min t0 100lowest temperature at which pressurized parts can be used at a load of up to 100 % of the allowable design stress at 20 C, taking the safety factors according

31、 to EN 12284:2003, Table A.2 into account BS EN 12178:2016EN 12178:2016 (E) 6 3.2 min t0 75lowest temperature at which pressurized parts can be used, if its load amounts to 75 % maximum of the allowable design stress at 20 C, taking the safety factors according to EN 12284:2003, Table A.2 into accou

32、nt 3.3 min t0 25lowest temperature at which pressurized parts can be used, if their load amounts to 25 % maximum of the allowable design stress at 20 C, taking the safety factors according to EN 12284:2003, Table A.2 into account 3.4 self-closing balls self-closing shut-off arrangement Note 1 to ent

33、ry: The arrangement comprises balls positioned in the connecting channel close to the sight glass in such a manner that the balls will not be affected at low flow rates. At high flow rates the balls will be carried forward with the flow and block the connections to the sight glass. 3.5 reflex glass

34、glasses having prismatic flutes on the inside, which will break up the incoming light Note 1 to entry: The liquid zone will absorb the light and will correspondingly appear dark. The gas/vapour zone will reflect the light and will correspondingly appear bright. 3.6 direct reading level indicator lev

35、el indicator where it is possible to see the liquid level 3.7 indirect reading level indicator level indicator where the liquid level is not visible Note 1 to entry: The level is indicated by auxiliary means; electrically, magnetically or by observing the frost on a tube. 3.8 self-contained unit lev

36、el indicator which is assembled and tested by the manufacturer 3.9 add-on unit level indicator delivered in parts from the manufacturer for mounting directly onto the system and which can only be tested after assembly and connection on site 3.10 level indicator with magnetically operated indication

37、device which transfers the measured value at any particular moment to an indicating device by means of a float with a built-in permanent magnet system 3.11 sight glass direct reading level indicator consisting of a glass plate and holder to enable viewing of the liquid surface BS EN 12178:2016EN 121

38、78:2016 (E) 7 Note 1 to entry: The shape of the glass plate can be either circular or oblong. The glass can be smooth or provided with flutes to break up incoming light which will make the liquid-filled part darker than the vapour-filled part. A sight glass can be a self-contained or add-on unit. 3.

39、12 frosting tube device, the principle of which is based on the frosting of the humidity of the surrounding air, and which consists of a corrosion protected tube arranged vertically outside the vessel and connected to the vessel at top and bottom. It is especially suitable for refrigerant temperatur

40、es below 3 C and ambient temperature above freezing point. The top level of the frosting on the tube will indicate the liquid level in the vessel 3.13 auxiliary powered level indicator device which operates electrically or pneumatically to indicate the level by means such as the following: a) differ

41、ential pressure transducer; b) capacitive transducer; c) inductive transducer; d) ultrasonic transducer; e) displacement principle with a displacement float 3.14 operating range temperature and pressure conditions at which the liquid level can be safely operated 3.15 nominal size DN alpha-numeric de

42、signation of size for components of a pipework system SOURCE: EN ISO 6708:1995 3.16 nominal pressure (PN) value of a pressure in the range of the maximum allowable pressure for planning a plant or a component SOURCE: ISO 7268 4 List of Symbols For symbols, see EN 12284:2003, Clause 4 (Table 1). 5 Ge

43、neral requirements 5.1 Installation and operation Level indicators shall be designed for installation and operation in accordance with EN 378-1, EN 378-2 and EN 378-4. BS EN 12178:2016EN 12178:2016 (E) 8 5.2 Components under pressure All parts of the level indicator shall be designed and manufacture

44、d to remain leakproof and withstand the pressures which may occur during operation, standstill and transportation, taking into account the thermal, physical and chemical stresses to be expected. 5.3 Excessive mechanical stress After installation, level indicators, especially in systems where hot gas

45、 defrosting is used, shall not be under excessive mechanical stress from fitting of the pipe or from temperature variations during operation. NOTE Hot gas defrosting can produce hydraulic shocks resulting in transient pressures in excess of PS. Further information can be obtained from EN 378 (all pa

46、rts). 5.4 Leakage See EN 12284:2003, 5.4. 6 Materials 6.1 Material properties Materials, including welding filler metals, solders, braze, sealant and glass, shall allow for the thermal, chemical and mechanical stresses arising in system operation. The material shall be resistant to the refrigerants,

47、 solvents (in absorption systems) and refrigerant-oil mixtures used in each particular case. 6.2 New materials New materials shall be tested in accordance with EN 12284:2003, Annex A to Annex D. 6.3 Using non-metallic materials See EN 12284:2003, 6.1.2. 6.4 Requirements for materials to be used for

48、pressurized parts See EN 12284:2003, 6.2. 6.5 Compatibility of connections Materials, which are to be physically linked, shall be suitable for an effective connection, depending on the particular materials used and on the dimensions of piping specified. 6.6 Ductility Materials which are to be consid

49、erably deformed shall be sufficiently ductile and capable of being heat treated where necessary. 6.7 Brittle fracture Level indicators shall be designed and constructed so that they are not subject to brittle fraction at the minimum operating temperature (min to) using the method specified in EN 12284: 2003, Annex D. 6.8 Ageing Materials for pressurized parts shall not be significantly affected by ageing. BS EN 12178:2016EN 12178:2016 (E) 9 6.9 Castings Castings shall exhibit a low residual stress level. If they are not subjected to stress