MAC: SAE considers R1234yf as “safe and effective” and AC5 and AC6 blends as “technically credible”

The SAE International Cooperative Research Project team has concluded that “R1234yf refrigerant is safe and effective to use in automotive applications. It also concluded that “based on a detailed fault tree analysis, AC6 offers a risk profile that is equal to or better than that of R1234yf in all significant respects. AC5 is comparable to R1234yf.”
- The SAE International Cooperative Research Project team, formed last year to perform an updated engineering safety analysis of the use of R1234yf in mobile air conditioning (MAC) systems has concluded that “R1234yf 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.” The research team is composed of European, North American and Asian manufacturers including Chrysler/Fiat, Ford, General Motors, Honda, Hyundai, Jaguar Land Rover, Mazda, PSA, Renault and Toyota.
The SAE CRP team has also concluded that “the refrigerant release testing conducted by Daimler is unrealistic and 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.”
In September 2012, Daimler announced that it had developed a new test method which demonstrated an additional risk of post-collision fires in vehicles using R1234yf. It also announced in March 2013 that it had tasked its engineers with developing a completely new MAC system using CO2 instead of R1234yf, which is favoured by most car manufacturers as an alternative to R134a (see Newsletter of the IIR, No. 53 and 54). Volkswagen also announced during the Geneva International Motor Show that it had “chosen CO2 as the future refrigerant for its air conditioning systems.”
However, Audi, BMW and Porsche did not confirm that they had opted for CO2 .
www.sae.org/servlets/pressRoom?OBJECT_TYPE=PressReleases&PAGE=showRelease&RELEASE_ID=2063
www.volkswagenag.com/content/vwcorp/info_center/en/news/2013/03/cooling.html

- The SAE International MAC Refrigerant Blend Cooperative Research Program (MRB CRP) has been assessing the operating, technical and safety performance of two low-GWP blended refrigerants developed by Mexichem which meet the requirements of the EU MAC Directive. AC5 is a mixture of R32, R152a and R1234ze(E) while AC6 is a mixture of R744, R134a and R1234ze(E). MRB CRP concluded that “based on a detailed fault tree analysis, AC6 offers a risk profile that is equal to or better than that of R1234yf in all significant respects.  AC5 is comparable to R1234yf.”
www.sae.org/servlets/pressRoom?OBJECT_TYPE=PressReleases&PAGE=showRelease&RELEASE_ID=2084
www.sae.org/standardsdev/tsb/cooperative/mrbpresentations.htm