1、PUBLISHED DOCUMENT PD CEN/TR 14739:2004 Scheme for carrying out a risk assessment for flammable refrigerants in case of household refrigerators and freezers ICS 71.100.45; 97.040.30 PD CEN/TR 14739:2004 This Published Document was published under the authority of the Standards Policy and Strategy Co
2、mmittee on 6 October 2004 BSI 6 October 2004 ISBN 0 580 44545 3 National foreword This Published Document is the official English language version of CEN/TR 14739:2004. The UK participation in its preparation was entrusted to Technical Committee RHE/18, Refrigeration safety, which has the responsibi
3、lity to: A list of organizations represented on this committee can be obtained on request to its secretary. Cross-references The British Standards which implement international or European publications referred to in this document may be found in the BSI Catalogue under the section entitled “Interna
4、tional Standards Correspondence Index”, or by using the “Search” facility of the BSI Electronic Catalogue or of British Standards Online. aid enquirers to understand the text; present to the responsible international/European committee any enquiries on the interpretation, or proposals for change, an
5、d keep the UK interests informed; monitor related international and European developments and promulgate them in the UK. Summary of pages This document comprises a front cover, an inside front cover, the CEN/TR title page, pages 2 to 30, an inside back cover and a back cover. The BSI copyright notic
6、e displayed in this document indicates when the document was last issued. Amendments issued since publication Amd. No. Date CommentsTECHNICALREPORT RAPPORTTECHNIQUE TECHNISCHERBERICHT CEN/TR14739 September2004 ICS71.100.45;97.040.30 Englishversion Schemeforcarryingoutariskassessmentforflammable refr
7、igerantsincaseofhouseholdrefrigeratorsandfreezers Schmapourlaralisationduneestimationdesrisques engendrsparlesfluidesfrigorignesinflammablesdans lesrfrigrateursetconglateursmnagers SchemafrdieDurchfhrungeinerRisikobewertungfr brennbareKltemittelbeiHaushaltKhlund Gefriergerten ThisTechnicalReportwasa
8、pprovedbyCENon25November2003.IthasbeendrawnupbytheTechnicalCommitteeCEN/TC182. CENmembersarethenationalstandardsbodiesofAustria,Belgium,Cyprus,CzechRepublic,Denmark,Estonia,Finland,France, Germany,Greece,Hungary,Iceland,Ireland,Italy,Latvia,Lithuania,Luxembourg,Malta,Netherlands,Norway,Poland,Portug
9、al, Slovakia, Slovenia,Spain,Sweden,SwitzerlandandUnitedKingdom. EUROPEANCOMMITTEEFORSTANDARDIZATION COMITEUROPENDENORMALISATION EUROPISCHESKOMITEEFRNORMUNG ManagementCentre:ruedeStassart,36B1050Brussels 2004CEN Allrightsofexploitationinanyformandbyanymeansreserved worldwideforCENnationalMembers. Re
10、f.No.CEN/TR14739:2004:ECEN/TR 14739:2004 (E) 2 Contents page Foreword3 Introduction .4 1 Scope 5 2 Mode of consideration 6 3 Appliances7 4 Life cycles.9 5 Rooms.10 6 Components.11 7 Defects of components .11 8 Probability of component defects12 9 Frequency of occurrence13 10 Probability (for ignitio
11、n sources and explosive atmosphere).13 10.1 Ignition sources .13 10.2 Explosive atmosphere.14 11 Deflagration/Explosion14 12 Consequences .15 13 Flow Charts 16 13.1 General16 13.2 Explanation of the flow charts by examples.16 14 Risk assessment18 CEN/TR 14739:2004 (E) 3 Foreword This document (CEN/T
12、R 14739:2004) has been prepared by Technical Committee CEN/TC 182 “Refrigerat- ing systems; safety and environmental requirements“, the secretariat of which is held by DIN. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to
13、 announce this CEN Technical Report: Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Lux- embourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland and Unite
14、d Kingdom. CEN/TR 14739:2004 (E) 4 Introduction The use of CFC and HCFC is restricted by Council Regulation 2037/2000 of the European Parliament. Both HCs and HFCs can be used as refrigerants as well as blowing agents for insulation foams. HFC 134a is commonly used as refrigerant but can also be use
15、d as a blowing agent for insulation foam. The environmental advantages of HCs are obvious as the Global Warming Potential (GWP) is lower com- pared to the GWP of HFC 134a. Therefore, a majority of household appliance manufacturers are phasing out HFCs in favour of HCs. Table 1 Values for GWP Global
16、Warming Potentials Emissions with impact on the global warming GWP 100 years CFC-12 141b, HCFC 134a, HFC 245 fa, HFC Cyclopentane, Isobutane CO 2Others (CH 4 , N 2 O) 8 500 630 1 300 820 3 1 (24,5, 320) With regard to the global warming impact see as well Annex B of EN 378-1:2000 (TEWI). CEN/TR 1473
17、9:2004 (E) 5 1 Scope The document gives a scheme for carrying out a risk assessment for flammable refrigerants in case of house- hold refrigerators and freezers with refrigerants of group A3 according to EN 378-1, taking into consideration a sealed system and a refrigerant charge of not more than 15
18、0 g. Sealed systems are refrigerating systems in which all refrigerant containing parts are made tight by welding, brazing or similar permanent connection. NOTE For risk assessment the method with flow diagrams is selected, because these are helpful for checking the possible ignition of the whole ap
19、pliances and to estimate the probability of ignition. It takes EN ISO 12100, EN 1050, EN 1127, EN 60335-2-24/A53, E DIN 7003 into consideration. At least the probability of deflagration is the product of multiplication of the probability of defects of different components and the probability for the
20、 presence of explosive atmosphere and the probability for the ignition sources. CEN/TR 14739:2004 (E) 6 2 Mode of consideration Figure 1 Mode of consideration Essential for the developed flow diagrams is the following mode of consideration: First, each refrigerant containing component of a refrigera
21、ting system has to be considered for all stages of life cycle such as design, construction, production, storage, transportation, operation, maintenance, service and disposal. In principle its necessary to sum up the risk assessment for each stage of life cycle. After consider- ing the different stag
22、es of the life cycle it is necessary to consider the space in and around of the refrigerator and freezer where a leak may occur. At least the space is separated into four different rooms (see Figure 4). The next step of risk assessment is the estimation of possible defects of the different component
23、s. The single probability for all possible defects have to add up to the total frequency of occurrence of the hazard. The next step is the calculation of the probability for the presence of explosive atmosphere. And after that its necessary to consider the different possible ignition sources such as
24、 vacuum cleaner, fan heater, etc. CEN/TR 14739:2004 (E) 7 At least the probability of deflagration is the product of multiplication of the probability of defects of different components and the probability for the presence of explosive atmosphere and the probability for the ignition sources. 3 Appli
25、ances Examples of the most usual refrigerating systems: Figure 2a: System with 1 compressor and 2 compartments Figure 2b: System with 2 compressors and 2 compartments Figure 2c: System with 1 compressor and 1 compartment There are refrigerators, freezers and combinations of these appliances. They ca
26、n be free-standing, installa- tions in recess areas or beneath table tops. Key a Fridge b Freezing compartment Figure 2a System with one compressor and solenoid CEN/TR 14739:2004 (E) 8 Key a Fridge b Freezing compartment Figure 2b System with two compressors Key a Fridge/Freezing compartment Figure
27、2c System with one compressor CEN/TR 14739:2004 (E) 9 4 Life cycles Important for customer and maintenance personal is transportation and storage with unpacked appliances, operation, maintenance, service and disposal (Figure 3). Responsible for design, construction, production, and to a certain degr
28、ee for the transport and storage of packed appliances, is the manufacturer. The ad hoc group considered transportation and operation as the most important steps of life cycle. The typical life cycle time of a refrigerator or a freezer is 12 years 1 .Life cycles - design - construction - production -
29、 storage - transportation - operation - maintenance - service - disposal Figure 3 Life cycles Referring to operation it is necessary to consider the behaviour of refrigerators and freezers during “standstill“ and “operation“. The influence factors for the appliance at standstill are the ambient temp
30、erature, charge of refrigerant, oil charge in the compressor and the inside volume of the refrigerating system. Only a quantity of refrigerant is vaporous in the system. The remaining quantity is dissolved in the oil of the compressor. But if the appliance is in operation its necessary to distinguis
31、h the following situations: compressor is running compressor is switched off In general the behaviour of a leakage depends on its location, if lying on the high or on the low pressure side. 112 years is the pragmatical value of the manufacturers. CEN/TR 14739:2004 (E) 10 5 Rooms After considering th
32、e different stages of life cycles, the next step for risk assessment is to consider the differ- ent rooms. Because in case of a leak the space in and around the refrigerator is to be separated into four rooms, which are represented graphically in Figure 4. Room I consists of all inner rooms of the a
33、ppliance, e.g. the fresh food storage compartment and the freezer compartment. Room II is defined as the room outside of the housing of the appliance between the back wall and the condenser of the compressor room. Room III is the room into which the appliance is built and the room for ventilation op
34、enings. And Room IV is the room in the surroundings of the appliance without rooms II and III. In case of transport room IV includes room II and room III because an ignition source is only possible in the surroundings of the appliance (see as well Figure 4). Figure 4 Different rooms CEN/TR 14739:200
35、4 (E) 11 6 Components The refrigerating circuit of a refrigerator or freezer consists basically of the following components, which are assessed by hazard under different aspects: one or more compressors; one or more evaporators; one or more condensors; dryer, filter; connecting pipes; brazed or weld
36、ed connections or equal connections; fan; defrost heater; solenoid; accumulator; thermostat or electronic devices; capillary tube. The components shall be assessed under different aspects depending on the type and material, as well as surface protection. Thus they represent a different risk potentia
37、l. Incorrect material selection or non allowable wall thickness, unsafe installation of piping or poor connections increase the risk; more details will be found under Clause 7. 7 Defects of components After considering the life cycle stages and the rooms, it is necessary to consider the possible def
38、ects of a component. There are defects which are influenced by the manufacturer and defects influenced by the customer or service staff. Defects of the manufacturer are for example: incorrect installation of pipes, susceptible to vibrations; non-secured parts; incorrect material selection, e.g. non
39、corrosion resistant material or surface; bad brazed connection; too thin wall thicknesses; selection and art of component. CEN/TR 14739:2004 (E) 12 Defects influenced by the customer are e.g.: improper use - storage of explosive liquids in the appliance; improper defrosting; non-observance of the in
40、struction manual incorrect installation; damage of evaporator/condensor by sharp objects; incorrect transport; improper disposal; mechanical damages. The manufacturer shall give information about hazards due to possible incorrect use in the enclosed technical documentation for the appliance. 8 Proba
41、bility of component defects More than 35 million refrigerators and freezers with refrigerant R 600a have been produced in Europe since 1993. Not only this time, but also the time before when the refrigerators and freezers were produced with other refrigerants, give us an answer about the quality of
42、these products. Pipe breaks during operation are un- known. That means, considering the last eight years, that the probability of a pipe break is P break operation 1/35.000.000 = 2,9 10 -8 In the case of transport, pipe breaks on a very small scale are known. All appliances which become defect on th
43、e grounds of bad quality of the appliance are meant. P break transportation = 250/ 35.000.000 = 7,1 10 -6The probability of exceeding the LFL giving for the leakage cause and location of it is possible between 0 and 1. In this case the maximum probability of 1 is used. P LFL, max = 1 In principle, t
44、he single probabilities for all possible defects shall be added in order to receive the total fre- quency of occurrence of the hazard. NOTE See as well TV-study “Brennbare Kltemittel eine Gefahr? Ausbreitungsversuche mit einer Khl- Gefrierkombination. Kltemittel Isobutan” (published in “Die Klte- un
45、d Klimatechnik” in August 1999). CEN/TR 14739:2004 (E) 13 9 Frequency of occurrence The frequency of occurrence can be qualitatively expressed as: Table 2 Frequency FREQUENCY Specific individual item Inventory FREQUENT Likely to occur frequently Continuously experienced PROBABLE Will occur several t
46、imes in life of an item Will occur frequently OCCASIONAL Likely to occur sometime in life of an item Will occur several times REMOTE Unlikely but possible to occur in life of an item Unlikely but can reasonably be ex- pected to occur IMPROBABLE So unlikely, it can be assumed occurrence may not be ex
47、peri- enced Unlikely to occur, but possible Possible ignition sources in households are summarized in Table 3. Table 3 Frequency of occurrence for ignition sources ignition source number of the occurrences time of the occurrences whole time frequency description vacuum cleaner 1 10 min 24 h probable
48、 fire 1 10 min 24 h probable fan heater 1 60 min 24 h probable light switch 5 0,1 s 24 h frequent washing machine . The indicated ignition sources are exemplary. 10 Probability (for ignition sources and explosive atmosphere) 10.1 Ignition sources The next step is to consider the possible ignition sources. Possible ignition sources could exist at the appliance (see EN 60335-2-24/A 53) or in the surrounding. Here are to specify e.g. open fire, switches, hot surfaces, vacuum cleaner, cigarette and ventilator. The ignition du- rance of the ignition
copyright@ 2008-2019 麦多课文库（www.mydoc123.com）网站版权所有
备案/许可证编号：苏ICP备17064731号-1