MAC update: Daimler stands firm on CO2; dismisses assertions that 1234yf is safe

By Alexandra Maratou, Dec 19, 2013, 15:38 2 minute reading

Daimler has reconfirmed its position that “R744 is the preferred follow-up refrigerant for R134a”, in a presentation provided in early December 2013 during the 2nd meeting of a European Commission working group assessing safety aspects of the use of refrigerant HFC1234yf in mobile air conditioning (MAC) systems.

The working group was formed following the October 2013 submission by the German type-approval authority (KBA) of a final report and analysis, which concluded that the use of HFC1234yf in MAC systems is “not hazard-free”.

SAE research project on 1234yf safety: dilutes risks & lacks scientific rigour

The December presentation by Daimler disputes the credibility of a Risk Assessment on HFC1234y safety carried out earlier in 2013 by a SAE International Cooperative Research Project, which found that HFC1234yf is safe to use in automotive direct expansion air conditioning systems. The Daimler presentation concludes that:
  • The SAE risk assessment unduly dilutes the risks incurred by HFC1234yf and does not reflect a conservative estimation
  • Assumptions lacking both scientific evidence and diligent conservative estimations exist in the SAE risk assessment
  • Real tests by Daimler showing HFC1234yf ignition and propagation call into question many assumptions of the SAE risk assessment

Daimler maintains R744 as preferred choice, as R1234yf risks cannot be fully mitigated

After thoroughly challenging presentations provided by Dupont, Honeywell and SAE at the first working group meeting in November 2013, and providing direct retorts to some of the claims, Daimler’s presentation concludes:
  • Significant amounts of hydrogen fluoride (HF) can be produced by R1234yf by pyrolitic reaction on hot surfaces, even without ignition
  • New facts generated by Daimler tests: Lower ignition temperature; expected mitigating effects by coolant steam, crush space, folded hood, shields, thermal insulation are not fully effective
  • Daimler AG maintains the position that CO2 is the preferred follow-up refrigerant for R134a

Background & next steps

The European Commission has been requested to provide clarity on the testing plans, procedures and results of the analysis by German type-approval and market surveillance authority (KBA) of the risks involved in the use of refrigerant R1234yf in mobile air-conditioning systems as submitted in a final report in October 2013.

A working group on the safety aspects of the use of refrigerant R1234yf in MAC systems has been formed, with a view to technically and scientifically reviewing the KBA testing procedures, taking into account the risk assessment performed by the SAE and other testing procedures developed by the suppliers, manufacturers and associations.

The working group has held two meetings in Brussels, Belgium in November and December 2013 respectively. A third meeting is planned in January 2014.  


By Alexandra Maratou

Dec 19, 2013, 15:38

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