Transcription

An introduction to A2L refrigerants and their use in Refrigeration,Air Conditioning and Heat Pump applicationsOVERVIEWThe 2015 F-gas regulation is driving industry to use lower GWP1 refrigerants in many applications.The EU regulation (517/2014), which came into force on the 1st January 2015, introduces a ban onnew equipment using HFC refrigerants with a GWP of over 2500 by 2020. The regulation alsointroduces a phase down, related to GWP and measured in CO2 equivalent tonnes, which will driveindustry to use lower GWP options.As a result, a new family of refrigerants – both pure fluids and blends – has been (and continues tobe) developed - these are Hydro Fluoro Olefins (HFO).A feature of many of these products (and some existing refrigerants such as R32 and Ammonia) isthat they exhibit lower flammability2, and hence a new classification has been introduced byASHRAE3 to cover this feature – A2L. (In the case of Ammonia the classification is B2L, due to itstoxicity)This guidance note has been written by members of FETA Associations to give an overview of thesenew refrigerants, and some basic advice as to their use in the field.REGULATORY BACKGROUNDISO4 and IEC5 standards are international safety in use type standards. European Norms or ENstandards are typically based on an international standard. The relationship between Internationaland European Union standards is highlighted in the table below.1Global Warming PotentialA2L refrigerants are commonly referred to as “mildly flammable”. This guide uses “lower flammability” to beconsistent with standards phraseology3American Society of Heating, Refrigerating and Air Conditioning Engineers4International Standards Organisation5International Electrotechnical Commission2

The graphic below shows the interaction between the various standards noted above, and EN378 inparticular, which is the primary standard that designers and installers use when considering thesafety and design limitations of a system.[CEN – European Committee for Standardisation][CENELEC – European Committee for Electrotechnical Standardisation]Standards and regulations are constantly evolving, and future changes will enable the industry tomake use of the new family of A2L refrigerants more extensively.It should be noted, however, that the A2L classification is only used in reference to refrigeration, airconditioning and heat pump system safety, and is used by standards such as EN378 and ISO 5149 todetermine maximum allowable charge size, etc. It IS NOT recognised by transport regulations (ADR6)and is not a recognised classification on Material Safety Data Sheets (MSDS). GHS7 is the agreedinternational standard in this instance. When A2L products are stored and transported, they areclassified as an extremely flammable gas, much the same as acetylene and MAP gas, commonly usedby the industry for brazing. The exception to this is HFO R-1234ze (E), which GHS classifies as nonflammable (at 20 deg C). There should be no significant changes required to vehicles that transportA2L refrigerants, but there should be some form of ventilation and signage to inform authorities ifthere is an accident. Storage on site and at installer’s premises should also comply with ADR andMSDS rules.67International Carriage of Dangerous Goods by RoadGlobal Harmonised System of Classification and Labelling of Chemicals

Currently, the HSE8 in the UK does not recognise the A2L classification and views these products ashighly flammable. Hence, safety guidance will also need to be reviewed for installations containingA2L refrigerants using DSEAR9 in the UK, and ATEX10 guidance in Europe. This requires a riskassessment to be undertaken, reviewing the application, location of components, and the installedrefrigerant charge. In these circumstances, installation guidelines can form the framework for suchrisk assessments. By choosing the right refrigerant, equipment and location as dictated by EN378 theprobability of forming a flammable atmosphere can be eliminated, making this assessmentpotentially very straightforward as many manufacturers are including data to carryout riskassessments within their technical documentation.CURRENT REFRIGERANTSRefrigerants are classified as below:ISO 817 Refrigerant Classification SchemeA3B3Higher FlammabilityA2B2FlammableA2LB2LLower FlammabilityA1B1Non-FlammableLower ToxicityHigher ToxicityThe vast majority of HFC and HFC/HFO blend refrigerants in current use are classified as A1, with lowtoxicity and zero flammability. Ammonia, which has been in use for many years, is classified as B2L;R-152a is an A2 refrigerant, and all hydrocarbons are classified as A3. It is vital to understand whatrefrigerants are in your system, and to make sure that the system complies with the requirementsfor leak checking and the phase down schedule of your particular gas. All refrigerants in the tablebelow are A1.8Health and Safety ExecutiveDangerous Substances and Explosive Atmospheres Regulation10ATmosphere EXplosibles (French)9

List of Common refrigerantsRefrigerantGWP11CommentsHFC R-407C 1774AC/HP most DX systems using thisrefrigerant are now several years old sohaving a replacement plan would beadvisable.Some chiller manufactures are still usingthis refrigerant in new equipment so checkthat this is the best refrigerant to use foryour application.HFC R2107/1825 These refrigerants are being used in407A/Fcommercial refrigeration as an interimreplacement for systems currently usingR404AHFO/HFC 1400These refrigerants are now being used inR-448A/commercial refrigeration as a longer term449Areplacement for systems currently usingR404A/R507HFC R-410A 2088This refrigerant is predominately used in DXequipment in the A/C industry.HFC R-404A3922This refrigerant will be banned in most newequipment and for service use from 2020HFC R-134a1430HFO/HFCR-452A2141This refrigerant has applications in A/C andrefrigeration. It has a medium GWP andavailability is likely to be effected in thelater stages of the phase down.This refrigerant is now being used intransport and small commercialrefrigeration as a longer term replacementfor systems currently using R404A/R507These refrigerants are now being used incommercial refrigeration and AC as a longerterm replacement for systems currentlyusing R134aHFO/HFCR-513A/R-450A11Taken from the IPCC 4 assessment as recognised in the F-Gas regulationSuggested ActionNew equipment should not beinstalled using R-404A/507New equipment should not beinstalled using R-404A/507.Plan to retrofit existingequipment with R448A/R449AEnsure that when using R410Athat the correct F-Gas checks arein place. If installing smallsystems, try to use equipmentmanufacturer recommended lowGWP alternatives wherepossible.Plan to replace this gas as soonas possible using either R407A/F,or one of the lower GWP HFOblends such as R448A, R449A orR452A.This gas can continue to be usedfor the time being, but it issensible to review thealternatives available.New equipment should not beinstalled using R-404A/507.

List of A2L refrigerants(those in bold are in current use; the others are beginning to appear on the R-455AR-447AR-452BR-454BOther namesXL40XL20L40XL41XL55XL41GWP46675238146145 500676467ApplicationsAutomotive A/CChillers, Aerosol PropellantR-410A replacementR-404A replacementR-404A replacementR-404A replacementR-410A replacementR-410A replacementR-410A replacementWHAT DOES THE A2L CLASSIFICATION MEAN?The main differences between A1 refrigerants, such as R-410A, R-134a, R-407C, and A2L refrigerantssuch as R-32, HFO R-1234yf and HFO R-1234ze is the ability to propagate a flame. A2L refrigerantswill burn, but their burning velocity is below 10cm/s, which is lower than an A3 refrigerant such asR-290 which actually burn explosively when ignited; hence the new classification. In practical terms,it is very difficult to ignite 2L gases, but some precautions must be taken to prevent accidental buildup of refrigerant, particularly during charging of systems. Manufacturers are suggesting that extractfans be used during this process, especially if the outdoor unit is in an enclosed areaAll flammable refrigerants (class 2L and above) will not ignite if the concentration level in a roomstays below their lower flammability limit (LFL). International and European safety legislation andstandards such as ISO 5149 and EN 378 define requirements to remain far below the lowerflammable limit in case of accidental leakage.USE OF A2L REFRIGERANTSIT IS VITAL TO UNDERSTAND THAT A2L REFRIGERANTS MUST ONLY BE USED IN SYSTEMS DESIGNEDSPECIFICALLY TO TAKE INTO ACCOUNT THEIR FLAMMABILITY CHARACTERISTICS. THEY SHOULDNEVER BE USED TO REPLACE NON-FLAMMABLE REFRIGERANTS IN RETROFIT SITUATIONS without afull risk assessment and necessary modifications.This is because of safety issues and the possibility of a relatively large charge of an A2L beingreleased by accident into an area that has not been risk assessed for use with this class ofrefrigerants.Due to their lower flammability, A2L refrigerants are intended for use in equipment specificallydesigned for these products and should always be used in accordance with the relevant national andinternational standards. Please consult the appropriate equipment manufacturer regarding whichrefrigerants can be used in the equipmentAPPLICATIONSA2L refrigerants are already in use in a variety of applications.

From 1st January 2017, all NEW cars produced in Europe must contain a refrigerant with a GWP ofless than 150 in their A/C system. The product of choice is HFO R-1234yf. There are currently over12.5m cars on European roads that use this refrigerant, and this is expected to rise to 29m by theend of 2017. The automotive industry carried out exhaustive tests and risk assessments beforeusing R-1234yf, and found it to present no more risk than its predecessor, R-134a. Manufacturersare well versed in the use of this refrigerant on production lines, although it does require thoseservicing cars to be aware of the differences.R-32 (an HFC classified as A2L) is now being widely marketed as an alternative to R-410A in new airconditioning systems, due to its similarity in performance to R-410A. There are well over 4msystems operating on R-32 in Japan – although it should be noted that their regulations on the use offlammable refrigerants are different to Europe.Some large chillers are now using R-1234ze as an alternative to R-134a. R-1234ze is an HFO and isclassified as A2L, but, as previously noted, it is actually non-flammable at temperatures below 300C.R-1234yf is a closer match to the performance of R-134a, which makes it suitable for use in chillerswhere the system is designed to use a lower flammability refrigerant. Because of its nonflammability at ambient temperatures, R-1234ze is also being used in some aerosol applications.Refrigerant manufacturers are also trialling A2L HFO blends as replacements for R-404A, R-410A, etctype applications.PRACTICAL ASPECTS OF USING A2L REFRIGERANTSAll technicians that carry out work on stationary RACHP systems must hold an F-Gas handlingcertificate. This requirement applies both to in house staff and to personnel employed by externalcontractors. Existing certificates issued in accordance with the 2006 EU F-Gas Regulation remainvalid, in accordance with the conditions under which they were originally issued, and thereforeinstallers existing training covers new A2L refrigerants. However, it should be noted that additionaltraining has to be given on alternatives when the F-gas certificate is updated.Service EquipmentMany of the service tools used for current A1 refrigerants can be used for servicing A2L refrigerants.However, some service equipment, due to the electrical components and motors, should bespecifically designed for use with lower flammability A2L refrigerants (e.g. R-1234yf, R-32, etc.). Allservice should be conducted in a safe manner and relevant risk assessments need to be carried out.Equally, tools such as manifolds, leak detectors and reclaim devices need to be compatible for usewith A2L refrigerants. Flare connections and pipework, as well as pressure testing requirements,remain the same. Providing the required assessments have been made beforehand, installation ofan A2L system should be no more difficult than an A1 system. New A2L service items should beavailable as there are an increasing number of service equipment companies providing these tools.Safe working considerations1. Make sure all relief and purge vent piping is routed outdoors and away from all air intakes to thebuilding, per local codes, regulations and EN standards.2. Make certain the area is well ventilated. Use auxiliary ventilation, rated for A2L refrigerants,such as blowers or fans, if necessary, to disperse refrigerant vapours, especially in confined areassuch as light wells and enclosed plant rooms. (This is a recommendation for R-410A anyway)3. Test the work area for available oxygen before entering enclosed areas. Do not use a leak

monitor to test for oxygen. A refrigerant leak detector will not tell you if adequate oxygen ispresent to sustain life.4. Install an A2L flammable rated refrigerant leakage detection and oxygen monitoring equipmentin the work areas. Guidance is available in EN378Leakage situations (applicable to ALL refrigerants)Do not attempt to enter the area to repair equipment until the vapours are dispersed, OR until youare equipped with proper breathing apparatus. Evacuate everyone until the area has beenventilated. Use blowers or fans to circulate air at the floor level and in any basement or low areas.1. Appropriate protection systems should be readily available in case of a large release, especiallywhen dealing with large charges in enclosed areas.2. Personnel should be trained how to use this equipment.3. Consult the most recent version of ISO 5149 or EN378 for additional information.System Filling Charges for A2L RefrigerantsFilling charges are usually covered by the respective standards for refrigeration equipment - thegeneral safety and use standard ISO 5149 and EN378 “Refrigeration systems and heat pumps”.There are also more specific standards covering selected appliances, such as the IEC 60335-2 series,that manufacturers use when designing equipment.The new version of EN378:2016 gives guidelines for ensuring that systems do not exceed themaximum amount of charge in a specific area, which is normally referred to as the Lower FlammableLimit. Check your local regulations and the correct standards such as those listed above to verify theallowable filling charge, new equipment design and safe handling requirements for the intendedapplication, or ask your manufacture for guidance on the subjectSee appendix A for examples of calculationsThe graph below shows that you can typically use more than 10 times the charge of an A2Lrefrigerant compared to an A3 highly flammable refrigerant (consult EN378 for the limits for specificequipment, location and application)

SUMMARYTo meet the requirements of the F Gas regulation phase down process, it will be necessary to makeuse of refrigerants with much lower GWPs. This means that the RACHP industry will need to beginto use the new A2L refrigerants as part of this process, as the effects of the HFC phase down begin tobite. There is no reason why these new refrigerants cannot be used safely in a wide range ofapplications, providing guidance and regulations are observed, and good practice is used.FETA acknowledges the contribution of a number of its member companies in the preparation ofthis articleREFERENCESThere are a number of useful reference documents that add further detail to this document:BS EN378:2016This standard (in four parts) can be purchased /Institute of RefrigerationThe IoR have issued a guidance note (29) on the changes to BS EN378, summary-of-changes-ior-gn29AREAAREA (European Association of RACHP Contractors) has published a guide to equipment forflammable refrigerants, available at ow-gwp-refrigerantsREAL alternativesThis European project offers e-learning which covers A2L refrigerants and their properties.http://www.realalternatives.eu/home

Appendix A - Practical Advice on using A1 and A2L refrigerants inAir Conditioning, Heat Pump and Refrigeration applications usingEN378:2016As mentioned previously, EN378:2016, now recognises the use of A2L refrigerants, and also changesthe methodology for calculating charge limits based on three characteristics: Refrigerant propertiesAccess categoriesLocation classificationThe table below gives an overview of the process.ChargeLimitIt should be noted that Class 1 and 2 have charge limits, whereas Class 3 systems in general have nocharge limitations except for refrigerants in flammability class 3. Machinery room requirementsapply at all times. The process can be defined as in the diagram below:DETERMINECHARGEBASED ONEffect in timeTOXICITYA,BInstantaneouseffectFLAMMABILITY2L, 2, 3LOWESTCHARGESHALL BEAPPLIED

Examples of this are:ExamplesR-717(Ammonia)R-32Toxicity limitFlammabilitylimit*Charges are defined by0,00035 kg/m³0,023 kg/m³ Toxicity0,3 kg/m³0,061 kg/m³ FlammabilityEN378 also allows for the provision of leak detection and ventilation that are Requirements foralternative provisions. This brings into play the following terms; QMLV, QLAV, and RCLQLMV: Quantity Limit with Minimum Ventilation in kg/m3QLAV: Quantity Limit with Additional Ventilation in kg/m3RCL: Refrigerant Concentration Limit in kg/m3The standard now accepts that the maximum leakage into an occupied space is assumed to be notgreater than a pinhole leak, and the maximum charge is calculated on that basis. This has enabledthe allowable refrigerant charges to be calculated. The full methodology is stated in the standard sothat the QLAV and QLMV can be calculated for all refrigerants. The table below states the figures forthe most popular gases in use /m3)0.280.280.440.420.0740.0630.0600.0630.50 a0.58 a0.49 a0.42 a0.18 b0.15 c0.14 c0.15 ca Based on ODLb Based on a volume fraction of 10 %c Based on 50 % LFLThe table above is used where additional measures are required, for example when an indoor unit orpiping passes through an occupied space and the whole gas charge was to escape into the space.

There are also further stipulations that take precedence: If the indoor unit is below 1.8 metres high a fan or ventilation system must be activated toprevent stagnation of the gas in the space, this can be started by a leak detection system.Pipe work must be securely mounted to prevent accidental damage occurringVentilation and dilution transfer openings must have sufficient volume to prevent the QLMVlimit from being exceeded. Extract fans must have a grille no higher than 0.2 metres abovethe floor level and can be continuously operated or switched on by a leak detection system.Transfer grills must be used at high and low levels and can be divided into more than onegrille. Safety shut off valves may also be used but must be located to prevent an ingress ofgas that would exceed the QLMV, which generally means close to the indoor unit or pipework that is running through the enclosed area.Safety alarms must provide a visual and audible warning with the latter being at least 15dB(A) louder than the ambient sound level.SYSTEM EXAMPLEA VRF/VRV system using R-410A in a hotel with bedrooms of 5m x 3m x 2.2mAs the refrigerant is designated A1, this example would use Table C.1 in EN378Hotel rooms are designated as general access (a) and the location classification is designated as II.Hence, the maximum charge would be calculated as follows:Room size 5m x 3m x 2.2mRoom volume 33m3RCL 0.39QLAV 0.42QLMV 0.42

Maximum charge at RCL 33m3 x 0.39 kg/m3 12.87 kgMaximum charge at QLAV 33m3 x 0.42 kg/m3 13.86 kgMaximum charge at QLMV 33m3 x 0.42 kg/m3 13.86 kg[Note QLAV and QLMV for R-410A are the same]If part of the system is below ground, the RCL room volume has to be used, and if any of the roomvolumes are exceeded, a leak detection system must be used.It should be noted that for all other occupancy types b & c there are no charge restrictions unlessthe office space is below ground levelThe calculations for A2L refrigerants are more complex, as there are more limitations due to the mildflammability properties of these gasses. The same process regarding charge limits is used, but thereare differing limits depending on the location of indoor unit and access category as can be seen inthe table below.The procedure for calculating the charge limit are broken down into 3 cap factors m1,m2, and m3these equate to— m1 4 m3 LFL— m2 26 m3 LFL— m3 130 m3 LFLCalculate formula C1 (A2L)C1 - mmax 2.5 LFL 5/4 h0 A1/2

Mmax is the allowable maximum charge in a room in kg;m is the refrigerant charge amount in the system in kg;Amin is the required minimum room area in m2;A is the room area in m2;LFL is the Lower Flammable Limit in kg/m3, as defined in Annex E;h0 is the height factor of the appliance:— 0.6 for floor location;— 1.8 for wall mounted;— 1.0 for window mounted;— 2.2 for ceiling mounted,Where the LFL is in kg/m3 from Annex E and the molecular mass of the refrigerant is greater than 42g/mol.Procedure for calculating A2L charge limitIf mmax less than M1 No restrictionsIf mmax more than M1 but less than M2Then one additional measure is required plusleak detectionIf mmax more than M2 but less than M3Two additional measures are required plus leakdetectionIf mmax more than M3 the system is notallowed

Addition measures 1. Leak detection system2. Ventilation to meet section C3 QLAV3. Isolation valves are requiredThe calculation will vary depending on the unit location so to clarify the graph below gives anindication of charge limits that will one additional measure and the second graph uses the samecalculation with two additional measuresTo clarify the additional measures, we can use the following diagram to explain the different types ofadditional measures used across the standard

For other cooling systems such as chillers, the standard remains the same and there no restrictionsother than chillers that are using A3 refrigerants and the limitations are as follows: Refrigerant class 3System class IIIa general occupancy5kg (except below ground 1kg)b supervised occupancy10kg (except below ground 1kg)c authorised occupancyNo restrictions (except below ground 1kg) Federation of Environmental Trade Associations Ltd 2017All rights reserved. Apart from any fair dealing for the purposes of private study or research allowed under applicable copyright legislation, no part of the publication maybe reproduced, stored in a retrieval system, or transmitted in any form by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior permission of theFederation of Environmental Trade Associations, 2 Waltham Court, Milley Lane, Hare Hatch, Reading, Berkshire RG10 9TH.FETA uses its best efforts to promulgate Standards and Guidelines for the benefit of the public in the light of available information and accepted industry practices but donot intend such Standards and Guidelines to represent the only methods or procedures appropriate for the situation discussed. FETA does not guarantee, certify or assure the safety orperformance of any products, components, or systems tested, installed or operated in accordance with FETA's Standards or Guidelines or that any tests conducted under its Standardsor Guidelines will be nonhazardous or free from risk.FETA, and the individual contributors, disclaims all liability to any person for anything or for the consequences of anything done or omitted to be done wholly or partly inreliance upon the whole or any part of the contents of this booklet.

An introduction to A2L refrigerants and their use in Refrigeration, Air Conditioning and Heat Pump applications OVERVIEW The 2015 F-gas regulation is driving industry to use lower GWP1 refrigerants in many applications. The EU regulation (517/2014), stwhich came into force on the 1 January 2015, introduces a ban on