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Auto Engineering Panel Backs Climate-Friendly Coolant, Faults Daimler's "Unrealistic" and "Highly Improbable" Tests

David Doniger

Posted February 14, 2013 in Curbing Pollution, Solving Global Warming

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A panel of automotive engineers has forcefully reaffirmed the safety and acceptability of the new car air conditioning refrigerant called HFO-1234yf, also known as R1234yf.  The panel’s strongly-worded findings this week rejected safety claims raised last fall by German car maker Daimler.  The new findings will keep most car makers on track to use the new chemical to replace the current coolant (HFC-134a), a powerful greenhouse gas with more than 350 times greater climate-warming impact.  (See prior posts here, here, and here.)

The panel, convened by SAE International (formerly the Society of Automotive Engineers) and composed of engineers from a dozen automobile manufacturers worldwide, stated that “the high level of confidence that R1234yf can be used safely in automotive applications continues to grow.”  The new refrigerant, the panel found, “poses no greater risk than other engine compartment fluids” such as gasoline or brake fluid.

Directly rebutting Daimler’s claims that the new coolant poses a dangerous fire risk, the SAE panel concluded:

[T]he refrigerant release testing completed by Daimler was unrealistic by creating the extremely idealized conditions for ignition while ignoring actual real world collision scenarios. These conditions include specific combinations of temperature, amount and distribution of refrigerant, along with velocity, turbulence, and atomization, which are highly improbable to simultaneously occur in real-world collisions.

In contrast, the panel’s safety conclusions were based on

carefully reviewing the use of R1234yf by using universally accepted engineering methods, including analysis of recent [original equipment manufacturers] testing from actual vehicle crash data, on-vehicle simulations, laboratory simulations, bench tests, and over 100 engine compartment refrigerant releases. Based on this testing the [panel] has found that the refrigerant is highly unlikely to ignite and that ignition requires extremely idealized conditions.

Note the reference to “actual vehicle crash data.”  Some companies – General Motors, for example – have tested R1234yf’s safety in real-life crash tests.  Daimler didn’t – in an earlier post I described Daimler’s contrived, extreme simulations.

The panel explained that its “fault tree analysis” of accident scenarios and probabilities is

the most appropriate approach for evaluating risks of new alternative refrigerants. This approach has been recommended and employed by numerous public and private organizations including the U.S. Environmental Protection Agency, the U.S. Department of Energy, the International Electrotechnical Commission, the European Union Joint Research Centre and the United Kingdom Health and Safety Executive.

Not finding things going its way, Daimler – joined by two other German companies (Audi and BMW) –promptly withdrew from the panel.  In comments to Reuters, a BMW spokesman equivocated masterfully:  “We do not want to say the test results [that SAE relied on] are wrong, but we are not convinced the methods applied are sufficient to achieve a definitive conclusion that guarantees our high safety standards.”

Daimler’s motives in this whole affair are a big puzzle.  Just one week before issuing its surprise safety claims in September, the company had joined all other German auto makers (including BMW, Audi, and VW) in publicly pronouncing R1234yf safe and environmentally acceptable.  Daimler apparently gave no hint of its impending flip-flop to its peers. 

Later in the fall, Daimler resisted formation of the SAE panel – a standard auto industry procedure – to evaluate its claims.  After joining the panel only reluctantly, Daimler has now walked away. 

Some speculate that Daimler management is under the gun to make deep cost cuts, and that its true motive is to save a little money by sticking with a less expensive coolant. 

American, Japanese, and other European car makers believe they have safely engineered their systems to render any R1234yf flammability risks insignificant.  They have already introduced the first models equipped with the new coolant, and they are moving forward with plans to apply it across their fleets.  Privately, other auto companies, as well as refrigerant manufacturers, are baffled by Daimler’s failure to solve any perceived problem by re-routing refrigerant lines or insulating hot surfaces.    

Instead of pursuing an engineering solution, Daimler spent the fall lobbying the European Commission to delay the prohibition on using HFC-134a in significantly redesigned new models (new “type” vehicles) after January 1, 2013.  To its credit, the Commission which refused a delay last December, has held firm again.  But responsibility for enforcement against Daimler – making the company comply or assessing penalties – lies first with the German government.  Regrettably, rather than enforce the law, German authorities are still lobbying the Commission to look the other way. 

NRDC and the Institute for Governance and Sustainable Development have praised the European Commission for holding its ground.  We’re calling on the German government to stop protecting Daimler and to stop throwing its weight around in Brussels. 

It’s time for Germany to demonstrate its commitment to climate protection by enforcing the rules. 

And it’s time for Daimler to show what German engineering can do.

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Switchboard is the staff blog of the Natural Resources Defense Council, the nation’s most effective environmental group. For more about our work, including in-depth policy documents, action alerts and ways you can contribute, visit NRDC.org.

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