SAE CRP: growing high level of confidence that R1234yf can be used safely; “disappointment” with departure of Daimler, BMW and Audi
11 February 2013
The SAE International Cooperative Research Project (CRP1234-4) team, formed last year to review relevant research and testing to finalize the risk assessment of the use of the low global warming potential R1234yf in mobile air conditioning systems (earlier post), met face-to-face during the week of 4 February 2013. SAE reported that as the CRP team continues to review relevant research and testing to finalize the risk assessment, the high level of confidence that R1234yf can be used safely in automotive applications continues to grow.
This review—the fourth such—was launched in October 2012 after Daimler in September announced that findings from its internal investigations raised questions on the safe usage of R-1234yf as a replacement refrigerant in mobile air conditioning (MAC) systems and said that it would not use this chemical in its products. (Earlier post.)
SAE said that the findings of the original CRP1234 remain well founded in that R1234yf poses no greater risk than other engine compartment fluids.
The CRP noted “with disappointment” the recent decision by Daimler to discontinue its participation in the group. This was followed shortly thereafter by BMW and Audi also leaving the CRP. The new CRP began by conducting a detailed review of the original Fault Tree Analysis (FTA). Primarily in response to Daimler’s concerns, the original FTA was significantly expanded to encompass new parameters and incorporate their recent test results. The FTA process is enhanced by having contributions from multiple parties representing a diversity of experience and expertise, building toward consensus under the spirit of collaboration.
The CRP continues its process of carefully reviewing the use of R1234yf by using universally accepted engineering methods, including analysis of recent OEM testing from actual vehicle crash data, on-vehicle simulations, laboratory simulations, bench tests, and more than 100 engine compartment refrigerant releases. Based on this testing the CRP has found that the refrigerant is highly unlikely to ignite and that ignition requires extremely idealized conditions.
The SAE CRP team of OEMs also concluded that the refrigerant release testing completed by Daimler was unrealistic in its creating the extremely idealized conditions for ignition while ignoring actual real world collision scenarios. These conditions include specific combinations of temperature, amount and distribution of refrigerant, along with velocity, turbulence, and atomization, which are highly improbable to simultaneously occur in real-world collisions.
The CRP continues to populate the fault trees to insure completeness of the risk assessment through pragmatic and factual input based on the latest and most accurate data available. Fault tree analysis as conducted by the CRP is the most appropriate approach for evaluating risks of new alternative refrigerants, SAE said. This approach has been recommended and employed by numerous public and private organizations including the US Environmental Protection Agency, the US Department of Energy, the International Electrotechnical Commission, the European Union Joint Research Centre and the United Kingdom Health and Safety Executive.
The CRP is targeting the second quarter of 2013 for the completion of its work and the publication of a final report. The SAE CRP1234-4 team includes European, North American and Asian OEMs including Chrysler/Fiat, Ford, General Motors, Honda, Hyundai, Jaguar Land Rover, Mazda, PSA, Renault and Toyota.
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