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SAE CRP1234-4 analysis of R-1234yf nears completion; finding refrigerant safe and effective in automotive applications

The SAE International Cooperative Research Project (CRP1234-4) team, formed last year to perform an updated engineering safety analysis of the low global warming potential (GWP) R-1234yf refrigerant (earlier post), met during the SAE World Congress in Detroit. The team includes European, North American and Asian OEMs including Chrysler/Fiat, Ford, General Motors, Honda, Hyundai, Jaguar Land Rover, Mazda, PSA, Renault and Toyota.

The SAE CRP has carefully evaluated the extensive testing conducted by its members. The fault tree analysis was subsequently updated with regard to actual collision scenarios and is now complete pending final review.

Based on this analysis, the team believes that the R-1234yf refrigerant is safe and effective to use in automotive applications. The risk of passenger exposure to a vehicle fire associated with this refrigerant is exceptionally remote, according to the team. This is consistent with the overall risk levels established by the original SAE CRP1234-3.

In September of 2012, Daimler announced that it had developed a new test method that demonstrated an additional risk of post-collision fires in vehicles using R-1234yf. In response, SAE CRP1234-4 was formed to further evaluate the safety of R-1234yf. All OEMs, including Daimler, were invited to participate. The SAE CRP team members have conducted numerous additional tests of various types to study ignition of an R-1234yf leak in a crash-damaged vehicle.

The SAE CRP team of OEMs has concluded that the refrigerant release testing conducted by Daimler is unrealistic and that it is not an appropriate test to verify the safety of refrigerant applications in vehicles. The Daimler testing did not include any actual vehicle collisions or the mitigating factors that occur in an actual collision.

These factors include the quenching effect of front end compartment deformation, the extinguishing effect of steam released due to radiator breakage, and dispersion of the refrigerant from the condenser outside the engine compartment. Daimler’s refrigerant release apparatus and nozzle does not represent actual crash-damaged refrigerant lines, and was found to be artificial.

Fault tree analysis, as conducted by the SAE 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 SAE CRP is currently finalizing its report and is targeting June 2013 for publication.



Did Mercedes err on the side of safety?


No, they did not err - CO2 systems are expensive and operate at over 2000 psi offering higher repair bills.

So what's not for MB to like?

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