Refrigerant news: HFO-1234yf
The US EPA has proposed to list HFO-1234yf as an acceptable alternative refrigerant in mobile air-conditioning (MAC) systems. The proposed decision only applies to new MAC systems in passenger cars and trucks since EPA had previously determined that use of flammable refrigerants in existing equipment as a retrofit was unacceptable. It includes several use conditions; in particular, auto manufacturers that adopt this refrigerant will be required to mitigate risks of fire in the event of an accidental release during servicing or vehicle operation. HFO-1234yf systems must incorporate engineering strategies and/or devices so that leaks into the passenger compartment do not result in HFO-1234yf concentrations at or above the lower flammability limit of 6.2% v/v for more than 15 seconds. EPA also notes that one concern about HFO-1234yf atmospheric effects is trifluoroacetic acid (CF3COOH, TFA) which is produced from atmospheric oxidation of HFO-1234yf. The EPA proposal can be consulted at http://edocket.access.gpo.gov/2009/pdf/E9-25106.pdf Furthermore, Honeywell announced on January 5, 2010 that it had received a patent from the European Patent Office covering the use of HFO-1234yf in automotive air conditioning.