BS EN 13136-2013 Refrigerating systems and heat pumps Pressure relief devices and their associated piping Methods for calculation《制冷系统和热泵 压力释放设备及相关管道 计算方法》.pdf

1、BSI Standards PublicationBS EN 13136:2013Refrigerating systems andheat pumps Pressure reliefdevices and their associatedpiping Methods forcalculationBS EN 13136:2013 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of EN 13136:2013. Itsupersedes BS EN 13136:2001 which

2、is withdrawn.The UK participation in its preparation was entrusted to TechnicalCommittee RHE/18, Refrigeration safety.A list of organizations represented on this committee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 contrac

3、t. Users are responsible for its correctapplication. The British Standards Institution 2013. Published by BSI StandardsLimited 2013ISBN 978 0 580 75692 4ICS 27.080; 27.200Compliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard was published under the aut

4、hority of theStandards Policy and Strategy Committee on 31 October 2013.Amendments issued since publicationDate Text affectedBS EN 13136:2013EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 13136 October 2013 ICS 27.080; 27.200 Supersedes EN 13136:2001English Version Refrigerating systems and he

5、at pumps - Pressure relief devices and their associated piping - Methods for calculation Systmes frigorifiques et pompes chaleur - Dispositifs de limitation de pression et tuyauteries associes - Mthodes de calcul Klteanlagen und Wrmepumpen - Druckentlastungseinrichtungen und zugehrige Leitungen -Ber

6、echnungsverfahren This European Standard was approved by CEN on 24 August 2013. 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-date lists and bi

7、bliographical 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 under the resp

8、onsibility 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, Former Yugoslav Re

9、public 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 United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NOR

10、MALISATION EUROPISCHES KOMITEE FR NORMUNG CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels 2013 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 13136:2013: EBS EN 13136:2013EN 13136:2013 (E) 2 Contents Page Foreword

11、 . 3 Introduction 4 1 Scope 5 2 Normative references . 5 3 Terms and definitions 5 4 Symbols 6 5 General . 8 6 Pressure relief devices for protection of system components 8 6.1 General . 8 6.2 Excessive pressure caused by heat sources . 9 6.2.1 External heat sources 9 6.2.2 Internal heat sources . 1

12、0 6.3 Excessive pressure caused by compressors . 11 6.4 Excessive pressure caused by liquid expansion . 11 7 Discharge capacities of pressure relief devices . 12 7.1 General . 12 7.2 Determination of pressure relief valve performance 12 7.2.1 Determination of coefficient of discharge . 12 7.2.2 Crit

13、ical and sub-critical flow 12 7.2.3 Function of the isentropic exponent (C) . 12 7.2.4 Correction factor for sub-critical flow . 13 7.2.5 Discharge capacity of pressure relief valves 13 7.3 Calculation of capacity and flow area of bursting discs or fusible plugs . 14 7.4 Pressure loss in upstream/do

14、wnstream lines. 14 7.4.1 General . 14 7.4.2 Pressure loss in components 14 7.4.3 Pressure loss in the upsteam line . 15 7.4.4 Pressure loss in the downstream line . 15 Annex A (normative) Values of functions, factors and properties of refrigerants . 17 Annex B (informative) Calculation of flow areas

15、 for non-evaporating and evaporating liquids 24 B.1 Calculation of the flow area for non-evaporating liquids . 24 B.2 Calculation of the flow area for evaporating liquids . 24 Annex C (informative) Example of calculation for sizing pressure relief devices with the corresponding pipes 26 C.1 Assumpti

16、ons for the calculation example. 27 C.2 Calculation of the required minimum discharge capacity, Qmd at standard heat flow rate . 27 C.3 Calculation of the required minimum discharge capacity Qmd at reduced heat flow rate 28 C.4 Calculation of flow area Ac, selection of pressure relief valve . 28 C.5

17、 Pressure loss in upstream line (from vessel to pressure relief valve). 29 C.6 Pressure loss in downstream line (from pressure relief valve to atmosphere) . 30 Annex ZA (informative) Clauses of this European Standard addressing essential requirements or other provisions of EU Directives . 32 Bibliog

18、raphy 33 BS EN 13136:2013EN 13136:2013 (E) 3 Foreword This document (EN 13136:2013) has been prepared by Technical Committee CEN/TC 182 “Refrigerating systems, safety and environmental requirements”, the secretariat of which is held by DIN. This European Standard shall be given the status of a natio

19、nal standard, either by publication of an identical text or by endorsement, at the latest by April 2014, and conflicting national standards shall be withdrawn at the latest by April 2014. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent ri

20、ghts. CEN and/or CENELEC shall not be held responsible for identifying any or all such patent rights. This document supersedes EN 13136:2001. This document has been prepared under a mandate given to CEN by the European Commission and the European Free Trade Association, and supports essential requir

21、ements of EU Directive(s). For relationship with EU Directive(s), see informative Annex ZA, which is an integral part of this document. Compared to EN 13136:2001, EN 13136:2013 takes into account the application of CO2 and the amendment A1, published in 2005. According to the CEN-CENELEC Internal Re

22、gulations, the national standards organisations of the following 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,

23、 Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom. BS EN 13136:2013EN 13136:2013 (E) 4 Introduction This European Standard is based on applicable parts of EN ISO 4126-1:2013, EN

24、ISO 4126-2:2003 and EN 12284. It is suited to the specific requirements, and includes the data, of refrigerating systems. It provides means of satisfying the pressure relief devices requirements of EN 378-2:2008+A2:2012. BS EN 13136:2013EN 13136:2013 (E) 5 1 Scope 1.1 This European Standard describe

25、s the calculation of mass flow for sizing pressure relief devices for components of refrigerating systems. NOTE The term “refrigerating system“ used in this European Standard includes heat pumps. 1.2 This European Standard describes the calculation of discharge capacities for pressure relief valves

26、and other pressure relief devices in refrigerating systems including the necessary data for sizing these when relieving to atmosphere or to components within the system at lower pressure. 1.3 This European Standard specifies the requirements for selection of pressure relief devices to prevent excess

27、ive pressure due to internal and external heat sources, the sources of increasing pressure (e.g. compressor, heaters, etc.) and thermal expansion of trapped liquid. 1.4 This European Standard describes the calculation of the pressure loss in the upstream and downstream line of pressure relief valves

28、 and other pressure relief devices and includes the necessary data. 1.5 This European Standard refers to other relevant standards in Clause 5. 2 Normative references The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. F

29、or dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. EN 378-1:2008+A2:2012, Refrigerating systems and heat pumps Safety and environmental requirements Part 1: Basic requirements, definitions, cl

30、assification and selection criteria EN 378-2:2008+A2:2012, Refrigerating systems and heat pumps Safety and environmental requirements Part 2: Design, construction, testing, marking and documentation EN 764-1:2004, Pressure equipment Part 1: Terminology Pressure, temperature, volume, nominal size EN

31、764-2:2012, Pressure equipment Part 2: Quantities, symbols and units EN 12284:2003, Refrigerating systems and heat pumps Valves Requirements, testing and marking EN ISO 4126-1:2013, Safety devices for protection against excessive pressure Part 1: Safety valves (ISO 4126-1:2013) EN ISO 4126-2:2003, S

32、afety devices for protection against excessive pressure Part 2: Bursting disc safety devices (ISO 4126-2:2003) ISO 817, Refrigerants Designation system 3 Terms and definitions For the purposes of this document, the terms and definitions given in EN 378-1:2008+A2:2012, EN 12284:2003, EN ISO 4126-1:20

33、13, EN ISO 4126-2:2003 and EN 764-1:2004 apply. BS EN 13136:2013EN 13136:2013 (E) 6 4 Symbols For the purposes of this document, the symbols given in EN 764-2:2012 and the following apply: Symbol Designation Unit A Flow area of the pressure relief valve =42dAmm2AcCalculated flow area mm2ADNValve cro

34、ss section related to DN mm2AinInside area of inlet tube mm2AliqCalculated flow area of liquid after expansion mm2AoutInside area of outlet tube mm2ARInside area of tube mm2AsurfExternal surface area of the vessel m2AvapCalculated flow area of vapour after expansion mm2C Function of the isentropic e

35、xponents (Table A.2) DN Nominal size (see EN ISO 6708:1995) d Actual most narrow flow diameter of the pressure relief valve mm dcCalculated flow diameter of the pressure relief valve mm dinInside diameter of inlet tube mm doutInside diameter of outlet tube mm DROutside diameter of tube (Table A.4) m

36、m dRInside diameter of tube mm hvapHeat of vaporisation calculated at 1,1 times the set pressure of the pressure relief device (for super critical or superheated conditions see 6.1) kJ/kg KbTheoretical capacity correction factor for sub-critical flow (Table A.3) KdCertified coefficient of discharge

37、taking into account the backpressure ratio pb/poand the possible reduced stroke of the pressure relief valve KdrDe-rated coefficient of discharge 9,0=ddrKK KdrlDe-rated coefficient of discharge for liquid 8,0drdrlKK KvsValve constant (the rate of water flow for a differential pressure p of 1 bar at

38、the rated full opening) m3/h KvViscosity correction factor BS EN 13136:2013EN 13136:2013 (E) 7 K Isentropic exponent of the refrigerant; for calculation, the value of K shall be as measured at 25 C and 1,013 bar L Length of tube mm LinLength of inlet tube mm LoutLength of outlet tube mm n Rotational

39、 frequency min- 1patmAtmospheric pressure (1 bar) bar pbBack pressure at outlet of pressure relief device, absolute bar pcCritical absolute pressure bar poActual relieving pressure po= 1,1 pset+ patmbar psMaximum allowable pressure of a component, gaugeabar psetSet pressure, gauge (the pre-determine

40、d pressure at which a pressure relief valve under operation starts to open) bar P1Pressure at the inlet to downstream line absolute (in practice = pb) bar P2Pressure at the outlet of downstream line absolute bar p Differential pressure bar pinPressure loss in the upstream line of pressure relief val

41、ve bar poutPressure loss in the downstream line of pressure relief valve bar QhRate of heat production, internal heat source kW QliqFlow of liquid after expansion kg/h QmCalculated refrigerant mass flow rate of the pressure relief device kg/h qmTheoretical discharge capacity kg/h mm2qmActual dischar

42、ge capacity determined by tests kg/h mm2QmdMinimum required discharge capacity, of refrigerant, of the pressure relief device kg/h QmdAdjusted discharge capacity of refrigerant, of the pressure relief device, used for pressure drop calculation kg/h QvapFlow of vapour after expansion kg/h R Bending r

43、adius of tube (Table A.4) mm Re Reynolds number s Thickness of insulation m V Theoretical displacement m3voSpecific volume of vapour or liquid m3/kg w0Actual flow speed of liquid in the smallest section of pressure relief valve m/s w1Speed at the inlet into the downstream line m/s x Vapour fraction

44、of refrigerant at pC BS EN 13136:2013EN 13136:2013 (E) 8 Flush connection angle (Table A.4) Pressure loss coefficient =nnn1 DNPressure loss coefficient related to DN nPressure loss coefficient of a single component vVolumetric efficiency estimated at suction pressure and discharge pressure equivalen

45、t to the pressure relief device setting Friction loss coefficient of tube (plain steel tube 0,02) Kinematic viscosity m2/s Density of vapour or liquid ( = 1/vo) kg/m310Vapour density at refrigerant saturation pressure/dew point at 10 C kg/m3 Density of heat flow rate kW/m2redReduced density of heat

46、flow rate kW/m2aThe Pressure Equipment Directive 97/23/EC identifies the maximum allowable pressure by the symbol “PS“. 5 General Requirements for protection against excessive pressure in refrigeration systems and heat pumps are given in EN 378-2. For design and manufacturing of bodies, bonnets and

47、bolts for pressure relief devices safety valves and bursting discs specification of strength pressure test, EN 12284 applies. For other aspects, the requirements of EN ISO 4126-1:2013 Safety Valves, Clause 3, Terms and definitions, Clause 5, Design, Clause 7, Type tests and Clause 10, Marking and se

48、aling and EN ISO 4126-2:2003 Bursting Disc Safety Devices, Clause 17 Marking, 17.2 Bursting discs/bursting disc assemblies and 17.3 Bursting disc holders apply. NOTE Calculations for flow areas for non-evaporating and evaporating liquids are given in Annex B. Calculations for a pressure relief devic

49、e with the corresponding pipes are given in Annex C. 6 Pressure relief devices for protection of system components 6.1 General Calculations shall be based on known or assumed processes which result in increases in pressure. All foreseeable processes shall be considered including those covered in 6.2, 6.3 and 6.4. For the general purposes of this European Standard, hvapis calculated at 1,1 times the set pressure of the pressure relief device. If the set pressu