The European MAC (mobile air conditioning) Directive requires the use of alternative refrigerants with GWP of less than 150 to replace R-134a. The first globally agreed candidate alternative fluid, the hydrofluoro-olefin (HFO) R-1234yf, is now entering production and use after an extensive cooperative research program (CRP-1234) administered by the SAE International and involving global car OEMs and chemical suppliers.

R-1234yf has also generated some controversy, as Daimler has refused to use it, based on the company’s own testing of flammability. France has banned the sale of new Mercedes vehicles due to that refusal, and the issue of response to Daimler’s position is being examined at the EC level. (Earlier post.) SAE CRP-1234 has re-evaluated the fluid multiple times, and still supports its use.

Testing for the KBA was performed on four models (Mercedes B-Class, a Hyundai i30, Subaru Impreza and Opel Mokka) under three different levels of severity. During the investigation, vehicles were subjected to a crash test in accordance with UN rules, and damage was analyzed with specific focus on the components of the refrigerant circuit.

KBA found that in the most severe crashes, one of the four models ignited and emitted toxic hydrogen fluoride (HF) gas; “non-negligible amounts” of HF were also found in two other test crashes. Comparison tests with the old R134a refrigerant, however, led to no hazard scenarios.

The KBA sent an interim report to the European Commission with the participation of the Federal Ministry of Transport, Building and Urban Development. The final report will be available in autumn this year. The Federal Motor Vehicle Office recommends in its letter to the EU Commission further investigations the better to assess the potential risks from the use of refrigerant 1234yf in mobile air conditioning systems.

In response to the KBA announcement, Joseph T. Martinko, global business manager, DuPont Opteon products said that the findings were not surprising, and confirmed DuPont’s “high level of confidence” that the refrigerant can be used safely in automotive air conditioning. (DuPont and Honeywell are the developers of R-1234yf.)

All industry-sponsored risk assessments have determined that neither flammability nor hydrogen fluoride formation related to HFO-1234yf present a significant safety concern. Individual car-makers have also conducted testing that confirms they can safely use the refrigerant. Automakers from around the world working under SAE International concluded that the risk of vehicle fire caused by HFO-1234yf is only three chances in a trillion.

DuPont welcomes the proposal of the European Commission to conduct an independent review of all testing conducted to date, and we believe this will help bring clarity to a debate that has continued for far too long.

—Joseph Martinko