HFO-1234yf was the subject of comprehensive testing conducted by an SAE CRP from 2007 to 2009. That CRP, which was sponsored by 15 global automakers, including all leading German automakers, major suppliers and 18 international, independent research institutes, concluded that HFO-1234yf is safe for use in automobile applications.
SAE initiated the latest CRP after Daimler raised questions about the refrigerant's flammability. SAE said its latest CRP's evaluation was expanded "with input from Daimler ... to realistically address" Daimler's concerns. SAE said the CRP also reviewed and analyzed extensive new data from automakers and used "conservative assumptions" to ensure its analysis "would be more likely to overestimate rather than underestimate the actual risks" of the refrigerant igniting.
Even with those assumptions, the CRP found "risks are still very small compared to the risks of a vehicle fire from all causes and well below risks that are commonly viewed as acceptable by the general public."
The SAE concluded it was 20,000 times more likely for a person to die in a plane crash than be exposed to a vehicle fire caused by a leak and ignition of HFO-1234yf. It also said it was 300,000 times more likely a vehicle would experience a fire for any reason and 100,000 times more likely for an accident to happen because of a brake failure.The CRP has said throughout its evaluation that it used universally accepted engineering methods, including analysis of recent OEM testing from actual vehicle crash data, on-vehicle simulations, laboratory simulations, bench tests, and over 100 engine compartment refrigerant releases. It also employed fault-tree analyses, which it noted have been recommended and employed by numerous public and private organizations, including the U.S. Environmental Protection Agency, the U.S. Department of Energy, the International Electrotechnical Commission, the European Union Joint Research Centre, and the United Kingdom Health and Safety Executive.