USA: The SAE International Cooperative Research Project (CRP) team charged with reviewing the use of R1234yf in car air conditioning sytems has expressed its disappointment at the resignation of German manufacturers Daimler, BMW and Audi from the group but maintains that the new refrigerant is safe and that Daimler's earlier tests ignored 'real world' scenarios.
The group comprising 13 car manufacturers met face-to-face earlier this month and, while continuing to review relevant research and testing to finalize the risk assessment, maintains that it has a growing high level of confidence that R1234yf can be used safely in automotive applications.

'The findings of the original CRP1234 remain well founded in that R1234yf poses no greater risk than other engine compartment fluids,' says the group.

Following this meeting Daimler, Audi and BMW quit the group reportedly citing disagreements with the testing methods and procedures.

The remaining members of the group - Chrysler/Fiat, Ford, General Motors, Honda, Hyundai, Jaguar Land Rover, Mazda, PSA, Renault and Toyota - say that they will continue the process of 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 over 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,' says the group.

The SAE CRP team of OEMs has also questioned Daimler's original test methods that first raised questions regarding the flammability of the new refrigerant and whether it was safe for use in car air conditioning systems.

'The refrigerant release testing completed by Daimler was unrealistic by creating the extremely idealized conditions for ignition while ignoring actual real world collision scenarios,' saya the group. '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.'

The SAE group maintains that fault tree analysis it uses is the most appropriate approach for evaluating risks of new alternative refrigerants.

'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 UK Health and Safety Executive,' the group argues.