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Mercedes and VW ban new Honeywell/Dupont car coolant after tests reveal explosion risk

14 December 2012

Field tests at Daimler-Benz have shown that a revolutionary new refrigerant made by Honeywell and Dupont, HFO-1234yf, can explode and release toxic gases in simulated crash conditions.

Daimler engineers simulated an a/c leak by spraying a mist of refrigerant and compressor oil across the running engine of a Mercedes B-Class tourer, which caused an explosion
Daimler engineers simulated an a/c leak by spraying a mist of refrigerant and compressor oil across the running engine of a Mercedes B-Class tourer, which caused an explosion

Simulating a leak in the air-conditioning line of a Mercedes B-Class tourer, Mercedes engineers released a fine mixture of refrigerant and A/C compressor oil across the car's running engine. The substance caught fire as soon as it hit the hot surface, releasing a toxic, corrosive gas as it burned. The car's windshield turned milky white as lethal hydrogen fluoride began eating its way into the glass.

At stake is not just a lucrative business for Honeywell and Dupont, who have invested hundreds of millions of dollars to develop, market and produce the coolant known as HFO-1234yf. Their refrigerant also happens to be the only product of its kind that meets new EU climate guidelines.

Because of concerns about greenhouse gases, EU legislators in Brussels have ordered the phasing out of the long-time industry standard, R134a, from January.

By 2017, every single air-conditioned car that rolls off assembly lines for sale in Europe - roughly 14 million vehicles a year - could be filled with about $70 worth of HFO-1234yf.

The Daimler test has sent the industry, and Brussels, scrambling to figure out whether years of tests that showed the new product to be perfectly safe could have been flawed.

After confirming their August results in subsequent tests, Mercedes notified the authorities in late September that it wanted to recall all 1,300 cars worldwide that already use the new refrigerant.

A month later, with only a few weeks to go until the phase-in of HFO-1234yf begins, 13 major carmakers quietly began a new fourth round of safety tests to assess the accuracy of the Daimler results, which showed combustion occurring in more than two-thirds of the cases after a simulated head-on collision.

Honeywell and Dupont are in full-blown damage control mode and say the Daimler “are not consistent with the findings of extensive industry evaluations, including a paper that was co-authored by Daimler and presented by the German automakers association (VDA) on Sept. 17, 2012 in Frankfurt. This stated, ‘R1234yf equipped vehicles are as safe as those using R134a – for occupants, mechanics, first emergency responders and fire fighters.”’

Both companies stand to lose a large amount in wasted development costs and forfeited future revenue. Honeywell alone has secured over 100 patents for the product worldwide.

The companies say the simulations were not conducted under real-life conditions and note that cars that were actually crashed to test the material - rather than subject to simulated accidents - did not raise any red flags.

They accuse Daimler of grossly exaggerating the danger and even of deliberately staging the test to provoke a scare out of ulterior motives that have nothing to do with passenger safety - a claim the Stuttgart-based carmaker vehemently denies.

While Honeywell and Dupont concede that HFO1234yf is "mildly flammable", they point to peer-reviewed safety tests from December 2009 that estimate the refrigerant could pose a danger in just one or two cases per year.

Volkswagen chairman Ferdinand Piech joined the Daimler camp in November, saying that his group would work on developing a new A/C system using CO2 since it is not flammable. “Until this comes, we will continue using the proven refrigerant R134a,” he said.

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