Many automakers have engineered their vehicles for because they saw it as the safest, most cost-effective and environmentally-friendly solution to comply with the EU Mobile Air Conditioning (MAC) Directive. Their selection was backed by comprehensive testing conducted over a three-year period under the Cooperative Research Program (CRP) of SAE International, sponsored by 15 global automakers, including all leading German automakers. SAE’s study—recently reaffirmed by another CRP—concluded that HFO-1234yf is safe for use in automobile applications.

It is unfortunate that in the wake of controversy over implementation of the MAC Directive, caused by a single automaker’s public declaration that it will not comply [Daimler], media reports have surfaced misinformation about HFO-1234yf.

—Honeywell

Honeywell emphasized two points:

• Industry safety experts agree that appropriate vehicle design vastly minimizes any refrigerant combustion risks. SAE has concluded that it is 300,000 times more likely that a vehicle would experience a fire for reasons unrelated to the refrigerant than due to its refrigerant—and that there is no significant risk caused by using HFO-1234yf. Independent research has demonstrated that both HFC-134a—the very safe automobile refrigerant in use for the past two decades—and HFO-1234yf, when mixed with oil in automotive air-conditioning systems, can combust when sprayed on extremely hot surfaces.

• Fluorocarbons such as HFC-134a and HFO-1234yf are alike in the sense that that they can emit small quantities of hydrofluoric acid (HF) when they combust. SAE research demonstrated these quantities are well below thresholds that would affect human health. Fluorocarbon refrigerants have been used safely in automobiles for six decades, and there is no reason to believe HFO-1234yf will be different, Honeywell said.

Under the hood of an automobile are many flammable materials, including gasoline or diesel, lubricating oils, and brake and transmission fluids. Proper vehicle design allows these otherwise hazardous materials to be used safely by billions of people in automobiles every day to the benefit of society as a whole. Honeywell continues to stand firmly behind the safety of HFO-1234yf, and it will continue to supply its customers to enable them to comply with the MAC Directive.

—Honeywell